期刊文献+
共找到436篇文章
< 1 2 22 >
每页显示 20 50 100
Standard-state entropies and their impact on the potential-dependent apparent activation energy in electrocatalysis
1
作者 Kai S.Exner 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第8期247-254,I0008,共9页
The apparent activation energy,Eapp,is a common measure in thermal catalysis to discuss the activity and limiting steps of catalytic processes on solid-state materials.Recently,the electrocatalysis community adopted t... The apparent activation energy,Eapp,is a common measure in thermal catalysis to discuss the activity and limiting steps of catalytic processes on solid-state materials.Recently,the electrocatalysis community adopted the concept of Eappand combined it with the Butler-Volmer theory.Certain observations though,such as potential-dependent fluctuations of Eapp,are yet surprising because they conflict with the proposed linear decrease in Eappwith increasing overpotential.The most common explanation for this finding refers to coverage changes upon alterations in the temperature or the applied electrode potential.In the present contribution,it is demonstrated that the modulation of surface coverages cannot entirely explain potential-dependent oscillations of Eapp,and rather the impact of entropic contributions of the transition states has been overlooked so far.In the case of a nearly constant surface coverage,these entropic contributions can be extracted by a dedicated combination of Tafel plots and temperature-dependent experiments. 展开更多
关键词 ELECTROCATALYSIS Standard-state entropy Microkinetic modeling apparent activation energy Degree of rate control
下载PDF
Revealing the potential of apparent critical current density of Li/garnet interface with capacity perturbation strategy
2
作者 Zhihao Guo Xinhai Li +6 位作者 Zhixing Wang Huajun Guo Wenjie Peng Guangchao Li Guochun Yan Qihou Li Jiexi Wang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第4期56-63,共8页
Apparent critical current density(j_(Ac)^(a))of garnet all-solid-state lithium metal symmetric cells(ASSLSCs)is a fundamental parameter for designing all-solid-state lithium metal batteries.Nevertheless,how much the p... Apparent critical current density(j_(Ac)^(a))of garnet all-solid-state lithium metal symmetric cells(ASSLSCs)is a fundamental parameter for designing all-solid-state lithium metal batteries.Nevertheless,how much the possible maximum apparent current density that a given ASSLSC system can endure and how to reveal this potential still require study.Herein,a capacity perturbation strategy aiming to better measure the possible maximum j_(Ac)^(a)is proposed for the first time.With garnet-based plane-surface structure ASSLSCs as an exemplification,the j_(Ac)^(a)is quite small when the capacity is dramatically large.Under a perturbed capacity of 0.001 mA h cm^(-2),the j_(Ac)^(a)is determined to be as high as 2.35 mA cm^(-2)at room temperature.This investigation demonstrates that the capacity perturbation strategy is a feasible strategy for measuring the possible maximum j_(Ac)^(a)of Li/solid electrolyte interface,and hopefully provides good references to explore the critical current density of other types of electrochemical systems. 展开更多
关键词 All-solid-state lithium batteries Li/solid electrolyte interface apparent critical current density Interfacial state variation Capacity perturbation strategy
下载PDF
Apparent Kinetics of 1-Decene Polymerization Catalyzed Using the Ionic Liquid[Bmim]_(x)[C_(2)H_(5)NH_(3)]_(1-x)[Al_(2)Cl_(7)]
3
作者 Chen Yingze He Jinxue +8 位作者 Wang Ben Pan Shiguang Zhang Di Bai Zhongxiang An Liangcheng Liu Dan Ma Aijing Li Hu Gui Jianzhou 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS CSCD 2023年第4期16-22,共7页
Poly-α-olefin(PAO)synthetic oil,a regular long-chain alkane produced from the catalytic polymerization ofα-olefin,is a high-quality lubricating base oil with huge market potential.In this study,PAO synthesis based o... Poly-α-olefin(PAO)synthetic oil,a regular long-chain alkane produced from the catalytic polymerization ofα-olefin,is a high-quality lubricating base oil with huge market potential.In this study,PAO synthesis based on the catalytic polymerization of 1-decene using the ionic liquid(IL)[Bmim]_(x)[C_(2)H_(5)NH_(3)]_(1-x)[Al_(2)Cl_(7)]as the catalyst was studied.Compared with the conventional catalyst[Bmim][Al_(2)Cl_(7)],the obtained PAO product incorporates more trimers and tetramers of 1-decene and contains few double-bond end groups,demonstrating a better catalytic system for PAO-10 production.The apparent polymerization kinetics of 1-decene in this catalytic system were studied based on the 1-decene concentration,catalyst concentration,and reaction temperature.An apparent kinetic equation for PAO formation was determined,providing a promising strategy for PAO production using 1-decene polymerization. 展开更多
关键词 poly-α-olefin 1-DECENE ionic liquid apparent kinetics catalytic polymerization
下载PDF
Deep Bimodal Fusion Approach for Apparent Personality Analysis
4
作者 Saman Riaz Ali Arshad +1 位作者 Shahab S.Band Amir Mosavi 《Computers, Materials & Continua》 SCIE EI 2023年第4期2301-2312,共12页
Personality distinguishes individuals’ patterns of feeling, thinking,and behaving. Predicting personality from small video series is an excitingresearch area in computer vision. The majority of the existing research ... Personality distinguishes individuals’ patterns of feeling, thinking,and behaving. Predicting personality from small video series is an excitingresearch area in computer vision. The majority of the existing research concludespreliminary results to get immense knowledge from visual and Audio(sound) modality. To overcome the deficiency, we proposed the Deep BimodalFusion (DBF) approach to predict five traits of personality-agreeableness,extraversion, openness, conscientiousness and neuroticism. In the proposedframework, regarding visual modality, the modified convolution neural networks(CNN), more specifically Descriptor Aggregator Model (DAN) areused to attain significant visual modality. The proposed model extracts audiorepresentations for greater efficiency to construct the long short-termmemory(LSTM) for the audio modality. Moreover, employing modality-based neuralnetworks allows this framework to independently determine the traits beforecombining them with weighted fusion to achieve a conclusive prediction of thegiven traits. The proposed approach attains the optimal mean accuracy score,which is 0.9183. It is achieved based on the average of five personality traitsand is thus better than previously proposed frameworks. 展开更多
关键词 apparent personality analysis deep bimodal fusion convolutional neural network long short-term memory bimodal information fusion approach
下载PDF
Distributions of dissolved oxygen and apparent oxygen utilization in the Cosmonaut Sea and Amundsen Sea in austral summer 2021
5
作者 GUO Jiaying YANG Xufeng +3 位作者 ZHAO Jun ZHU Yuanli LI Dong PAN Jianming 《Advances in Polar Science》 CSCD 2023年第4期272-303,共32页
Dissolved oxygen(DO)and apparent oxygen utilization(AOU)are crucial parameters for investigating marine ecosystem evolution and the marine environment.In this study,DO and AOU data were obtained and their spatial dist... Dissolved oxygen(DO)and apparent oxygen utilization(AOU)are crucial parameters for investigating marine ecosystem evolution and the marine environment.In this study,DO and AOU data were obtained and their spatial distribution characteristics were explored in the Cosmonaut Sea and Amundsen Sea in austral summer 2021.The standard deviation range of DO parallel samples was<0.1–3.7μmol·L–1,which met the accuracy requirements of the survey method.The DO concentration decreased sharply with water depth in the photic zone and increased slowly to the bottom.AOU in the surface layer of the two seas was significantly negatively correlated with chlorophyll a(p<0.01),and AOU was significantly lower in the south Cosmonaut Sea than in the north Cosmonaut Sea and Amundsen Sea(p<0.01).In austral summer,AOU was as low as<130μmol·L–1 in the nearshore Cosmonaut Sea with thicker Antarctic Surface Water down to ca.500 m.In early winter,AOU was lower than 50μmol·L–1 in the north Amundsen Sea in subsurface water(75–150 m).The unmodified Circumpolar Deep Water with high AOU(>160μmol·L–1)could surge up to ca.150–200 m in both seas,with stronger intrusion in the Amundsen Sea.The AOU in bottom water was significantly lower(p<0.01)in the Cosmonaut Sea(118.9±11.8μmol·L–1)than the Amundsen Sea(141.7±7.4μmol·L–1),indicating the stable existence of fresh oxygen-rich Antarctic Bottom Water in the Cosmonaut Sea. 展开更多
关键词 dissolved oxygen apparent oxygen utilization ANTARCTIC Cosmonaut Sea Amundsen Sea
下载PDF
Apparent stress as an indicator of stress meta-instability:The 2021 M_(S)6.4 Yangbi earthquake in Yunnan,China
6
作者 Yan′e Li Xuezhong Chen +2 位作者 Lijuan Chen Yaqiong Ren Xiangyun Guo 《Earthquake Science》 2023年第6期433-444,共12页
Investigating spatiotemporal changes in crustal stress associated with major earthquakes has implications for understanding seismogenic processes.However,in individual earthquake cases,the characteristics of the stres... Investigating spatiotemporal changes in crustal stress associated with major earthquakes has implications for understanding seismogenic processes.However,in individual earthquake cases,the characteristics of the stress after it reaches its maximum value are rarely discussed.In this study,we use the 2021 M_S6.4 Yangbi earthquake in Yunnan,China and events of magnitudes M_L≥3.0 occurred in the surrounding area in the previous 11 years to investigate the spatiotemporal evolution of apparent stress.The results indicate that apparent stress began to increase in January 2015 and reached a maximum in January 2020.Apparent stress then remained at a high level until October 2020,after which it declined considerable.We suggest that the stress was in the accumulation stage from January 2015 to January 2020,and entered the meta-instability stage after October 2020.During the meta-instability stage,the zone of decreasing stress expanded continuously and the apparent stress increased around the Yangbi earthquake source region.These features are generally consistent with the results of laboratory rock stress experiments.We propose that apparent stress can be a good indicator for determining whether the stress at a specific location has entered the meta-instability stage and may become the epicenter of an impending strong earthquake. 展开更多
关键词 2021 M_(S)6.4 Yangbi earthquake apparent stress relative change meta-instability
下载PDF
Pharmacoepidemiologic study of association between apparent treatment resistant hypertension, cardiovascular disease and interaction effect by sex and age
7
作者 Julianne Theresa Nelson Longjian Liu 《World Journal of Cardiology》 2023年第5期262-272,共11页
BACKGROUND A limited number of studies have been conducted to test the magnitudes of the association between apparent treatment resistant hypertension(aTRH)and risk of cardiovascular disease(CVD).AIM To investigate th... BACKGROUND A limited number of studies have been conducted to test the magnitudes of the association between apparent treatment resistant hypertension(aTRH)and risk of cardiovascular disease(CVD).AIM To investigate the association between aTRH and risk of CVD and examine whether sex and age modify this association.METHODS We applied an observational analysis study design using data from the United States Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial(ALLHAT).ALLHAT recruited participants(n=25516)from 625 primary care settings throughout the United States,Canada,Puerto Rico,and United States Virgin Islands,aged 55 and older with hypertension and at least one additional risk factor for heart disease.aTRH was assessed from the year 2 visit.CVD event was defined as one of the following from the year 2 follow-up visit:Fatal or non-fatal myocardial infarction,coronary revascularization,angina,stroke,heart failure,or peripheral artery disease.Cox proportional hazards regression was used to examine the effect of aTRH on CVD risk.Potential modifications of sex and age on this association were examined on the multiplicative scale by interaction term and additive scale by joint effects and relative excess risk for interaction.RESULTS Of the total study participants(n=25516),5030 experienced a CVD event during a mean of 4.7 years follow-up.aTRH was associated with a 30%increase in risk of CVD compared to non-aTRH[hazards ratio(HR)=1.3,95%CI:1.19-1.42].Sex and age modified this relationship on both multiplicative and additive scales independently.Stratified by sex,aTRH was associated with a 64%increase in risk of CVD(HR=1.64,95%CI:1.43–1.88)in women,and a 13%increase in risk of CVD(HR=1.13,95%CI:1.01–1.27)in men.Stratified by age,aTRH had a stronger impact on the risk of CVD in participants aged<65(HR=1.53,95%CI:1.32–1.77)than it did in those aged≥65(HR=1.18,95%CI:1.05–1.32).Significant two-way interactions of sex and aTRH,and age and aTRH on risk of CVD were observed(P<0.05).The observed joint effect of aTRH and ages≥65 years(HR=1.85,95%CI:1.22–2.48)in males was less than what was expected for both additive and multiplicative models(HR=4.10,95%CI:3.63–4.57 and 4.88,95%CI:3.66–6.31),although three-way interaction of sex,age,and aTRH on the risk of CVD and coronary heart disease did not reach a statistical significance(P>0.05).CONCLUSION aTRH was significantly associated with an increased risk of CVD and this association was modified by both sex and age.Further studies are warranted to test these mechanisms. 展开更多
关键词 apparent treatment resistant hypertension Cardiovascular disease outcomes Chronic kidney disease SEX Age
下载PDF
Dopamine and cyclic adenosine monophosphate-regulated phosphoprotein with an apparent Mr of 32000 promotes colorectal cancer growth
8
作者 Kuan He Chao-Zheng Xie +6 位作者 Ya Li Zhen-Zhou Chen Shi-Hao Xu Si-Qi Huang Jian-Guo Yang Zheng-QiangWei Xu-Dong Peng 《World Journal of Gastrointestinal Oncology》 SCIE 2023年第11期1936-1950,共15页
BACKGROUND Dopamine and cyclic adenosine monophosphate(cAMP)-regulated phosphop-rotein with an apparent Mr of 32000(DARPP-32)is a protein that is involved in regulating dopamine and cAMP signaling pathways in the brai... BACKGROUND Dopamine and cyclic adenosine monophosphate(cAMP)-regulated phosphop-rotein with an apparent Mr of 32000(DARPP-32)is a protein that is involved in regulating dopamine and cAMP signaling pathways in the brain.However,recent studies have shown that DARPP-32 is also expressed in other tissues,including colorectal cancer(CRC),where its function is not well understood.AIM To explore the effect of DARPP-32 on CRC progression.METHODS The expression levels of DARPP-32 were assessed in CRC tissues using both quantitative polymerase chain reaction and immunohistochemistry assays.The proliferative capacity of CRC cell lines was evaluated with Cell Counting Kit-8 and 5-ethynyl-2’-deoxyuridine assays,while apoptosis was measured by flow cytometry.The migratory and invasive potential of CRC cell lines were deter-mined using wound healing and transwell chamber assays.In vivo studies involved monitoring the growth rate of xenograft tumors.Finally,the underlying molecular mechanism of DARPP-32 was investigated through RNA-sequencing and western blot analyses.RESULTS DARPP-32 was frequently upregulated in CRC and associated with abnormal clinicopathological features in CRC.Overexpression of DARPP-32 was shown to promote cancer cell proliferation,migration,and invasion and reduce apoptosis.DARPP-32 knockdown resulted in the opposite functional effects.Mechanistically,DARPP-32 may regulate the phosphoinositide 3-kinase(PI3K)/AKT signaling pathway in order to carry out its biological function.CONCLUSION DARPP-32 promotes CRC progression via the PI3K/AKT signaling pathway. 展开更多
关键词 Colorectal cancer Dopamine and cyclic adenosine monophosphate-regulated phosphoprotein with an apparent Mr of 32000 Proliferation Migration Phosphoinositide 3-kinase Akt
下载PDF
Nutritional value of a partially defatted and a highly defatted black soldier fly larvae (Hermetia illucens L.) meal for broiler chickens: apparent nutrient digestibility,apparent metabolizable energy and apparent ileal amino acid digestibility 被引量:27
9
作者 Achille Schiavone Michele De Marco +8 位作者 Silvia Martínez Sihem Dabbou Manuela Renna Josefa Madrid Fuensanta Hernandez Luca Rotolo Pierluca Costa Francesco Gai Laura Gasco 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2017年第4期897-905,共9页
Background: The study aimed to determine the apparent total tract digestibility coefficients(ATTDC) of nutrients, the apparent metabolizable energy(AME and AMEn) and the amino acid(AA) apparent ileal digestibility coe... Background: The study aimed to determine the apparent total tract digestibility coefficients(ATTDC) of nutrients, the apparent metabolizable energy(AME and AMEn) and the amino acid(AA) apparent ileal digestibility coefficients(AIDC)of a partially defatted(BSFp) and a highly defatted(BSFh) black soldier fly larvae meal. The experimental diets were: a basal diet and two diets prepared by substituting 250 g/kg(w/w) of the basal diet with BSFp or BSFh, respectively.Results: Significant differences were found between BSFp and BSFh meals for ATTDC of the nutrients: BSFp resulted more digestible than BSFh, except for ATTDC of CP which did not differed between meals, while a statistical trend was observed for ATTDC of DM and EE. The AME and AMEn values were significantly(P < 0.05) different between the two BSF meals, with higher levels for BSFp(16.25 and 14.87 MJ/kg DM, respectively). The AIDC of the AA in BSFp ranged from 0.44 to 0.92, while in BSFh they ranged from 0.45 to 0.99. No significant differences were observed for the AA digestibility(0.77 and 0.80 for BSFp and BSFh, respectively), except for glutamic acid, proline and serine that were more digestible in the BSFh meal(P < 0.05).Conclusions: Defatted BSF meals can be considered as an excellent source of AME and digestible AA for broilers with a better efficient nutrient digestion. These considerations suggested the effective utilization of defatted BSF larvae meal in poultry feed formulation. 展开更多
关键词 Amino acid apparent digestibility BLACK SOLDIER FLY MEAL Broiler chicken Metabolizable energy
下载PDF
Prediction of different stages of rectal cancer: Texture analysis based on diffusion-weighted images and apparent diffusion coefficient maps 被引量:15
10
作者 Jian-Dong Yin Li-Rong Song +1 位作者 He-Cheng Lu Xu Zheng 《World Journal of Gastroenterology》 SCIE CAS 2020年第17期2082-2096,共15页
BACKGROUND It is evident that an accurate evaluation of T and N stage rectal cancer is essential for treatment planning.It has not been extensively investigated whether texture features derived from diffusion-weighted... BACKGROUND It is evident that an accurate evaluation of T and N stage rectal cancer is essential for treatment planning.It has not been extensively investigated whether texture features derived from diffusion-weighted imaging(DWI)images and apparent diffusion coefficient(ADC)maps are associated with the extent of local invasion(pathological stage T1-2 vs T3-4)and nodal involvement(pathological stage N0 vs N1-2)in rectal cancer.AIM To predict different stages of rectal cancer using texture analysis based on DWI images and ADC maps.METHODS One hundred and fifteen patients with pathologically proven rectal cancer,who underwent preoperative magnetic resonance imaging,including DWI,were enrolled,retrospectively.The ADC measurements(ADCmean,ADCmin,ADCmax)as well as texture features,including the gray level co-occurrence matrix parameters,the gray level run-length matrix parameters and wavelet parameters were calculated based on DWI(b=0 and b=1000)images and the ADC maps.Independent sample t-tests or Mann-Whitney U tests were used for statistical analysis.Multivariate logistic regression analysis was conducted to establish the models.The predictive performance was validated by receiver operating characteristic curve analysis.RESULTS Dissimilarity,sum average,information correlation and run-length nonuniformity from DWIb=0 images,gray level nonuniformity,run percentage and run-length nonuniformity from DWIb=1000 images,and dissimilarity and run percentage from ADC maps were found to be independent predictors of local invasion(stage T3-4).The area under the operating characteristic curve of the model reached 0.793 with a sensitivity of 78.57%and a specificity of 74.19%.Sum average,gray level nonuniformity and the horizontal components of symlet transform(SymletH)from DWIb=0 images,sum average,information correlation,long run low gray level emphasis and SymletH from DWIb=1000 images,and ADCmax,ADCmean and information correlation from ADC maps were identified as independent predictors of nodal involvement.The area under the operating characteristic curve of the model reached 0.802 with a sensitivity of 80.77%and a specificity of 68.25%.CONCLUSION Texture features extracted from DWI images and ADC maps are useful clues for predicting pathological T and N stages in rectal cancer. 展开更多
关键词 RECTAL cancer DIFFUSION weighted imaging apparent DIFFUSION COEFFICIENT TEXTURE analysis
下载PDF
Diagnostic Study of Apparent Heat Sources and Moisture Sinks in the South China Sea and its Adjacent Areas during the Onset of 1998 SCS Monsoon 被引量:7
11
作者 王世玉 钱永甫 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2000年第2期285-298,共14页
The apparent heat sources (<Q l>) and moisture sinks (<Q 2>) are calculated based on the reanalyzed data of the South China Sea Monsoon Experiment (SCSMEX) from May I to August 31, 1998. It is found that t... The apparent heat sources (<Q l>) and moisture sinks (<Q 2>) are calculated based on the reanalyzed data of the South China Sea Monsoon Experiment (SCSMEX) from May I to August 31, 1998. It is found that the formation and distribution of the atmospheric heat sources are important for the monsoon onset. The earlier onset of the SCS monsoon is the result of enduring atmospheric heating in the Indo-china Peninsula and South China areas. The atmospheric heating firstly appears in the indo-China Peninsula area and the sensible heat is the major one. The 30is0 day periodic oscillation of atmospheric heat sources between the SCS area and the western Pacificwarm pool has a reverse phase distribution before the middle of July and the low frequency oscillation of heat sources in SCS area has an obvious longitudinal propagation. The 30-50 day low frequency oscillation has vital modificatory effects on the summer monsoon evolution during 1998. 展开更多
关键词 apparent heat sources apparent MOISTURE SINKS The South China Sea MONSOON Diagnostic study
下载PDF
Apparent permeability variation of underground water aquifer induced by an earthquake:A case of the Zhouzhi well and the 2008 Wenchuan earthquake 被引量:8
12
作者 Guijuan Lai Fuqiong Huang Hongkui Ge 《Earthquake Science》 CSCD 2011年第5期437-445,共9页
Taking the M_2 wave as calibration signals,we extract the phase shifts of the water level relative to the Earth tide in the Zhouzhi well by utilizing the cross-correlation function.And we further obtain the apparent p... Taking the M_2 wave as calibration signals,we extract the phase shifts of the water level relative to the Earth tide in the Zhouzhi well by utilizing the cross-correlation function.And we further obtain the apparent permeability variation in the aquifer of the Zhouzhi well in 2008.Comparison with the commonly used tidal analysis software Baytap-G shows that phase shifts obtained by cross-correlation function are more stable.The resulting apparent permeability of the Zhouzhi well aquifer fluctuates with time,indicating it is a dynamically controlled parameter.The 2008 Wenchuan earthquake caused the apparent permeability increasing drastically, which is interpreted as the combination effects of effective stress changes and the barriers removing in the flow channel due to seismic wave pressure pulse.After the Wenchuan earthquake,the effective stress began to recover and the impurities deposited gradually,causing the apparent permeability to decrease a month later and almost recover to the pre-earthquake level in six months. 展开更多
关键词 apparent permeability Zhouzhi well underground water Earth tide 2008 Wenchuan earth-quake
下载PDF
Apparent diffusion coefficient-based histogram analysis differentiates histological subtypes of periampullary adenocarcinoma 被引量:6
13
作者 Jing-Yu Lu Hao Yu +4 位作者 Xian-Lun Zou Zhen Li Xue-Mei Hu Ya-Qi Shen Dao-Yu Hu 《World Journal of Gastroenterology》 SCIE CAS 2019年第40期6116-6128,共13页
BACKGROUND For periampullary adenocarcinoma,the histological subtype is a better prognostic predictor than the site of tumor origin.Intestinal-type periampullary adenocarcinoma(IPAC)is reported to have a better progno... BACKGROUND For periampullary adenocarcinoma,the histological subtype is a better prognostic predictor than the site of tumor origin.Intestinal-type periampullary adenocarcinoma(IPAC)is reported to have a better prognosis than the pancreatobiliary-type periampullary adenocarcinoma(PPAC).However,the classification of histological subtypes is difficult to determine before surgery.Apparent diffusion coefficient(ADC)histogram analysis is a noninvasive,nonenhanced method with high reproducibility that could help differentiate the two subtypes.AIM To investigate whether volumetric ADC histogram analysis is helpful for distinguishing IPAC from PPAC.METHODS Between January 2015 and October 2018,476 consecutive patients who were suspected of having a periampullary tumor and underwent magnetic resonance imaging(MRI)were reviewed in this retrospective study.Only patients who underwent MRI at 3.0 T with different diffusion-weighted images(b-values=800 and 1000 s/mm^2)and who were confirmed with a periampullary adenocarcinoma were further analyzed.Then,the mean,5th,10th,25th,50th,75th,90th,and 95th percentiles of ADC values and ADCmin,ADCmax,kurtosis,skewness,and entropy were obtained from the volumetric histogram analysis.Comparisons were made by an independent Student's t-test or Mann-Whitney U test.Multiple-class receiver operating characteristic curve analysis was performed to determine and compare the diagnostic value of each significant parameter.RESULTS In total,40 patients with histopathologically confirmed IPAC(n=17)or PPAC(n=23)were enrolled.The mean,5th,25th,50th,75th,90th,and 95th percentiles and ADCmax derived from ADC1000 were significantly lower in the PPAC group than in the IPAC group(P<0.05).However,values derived from ADC800 showed no significant difference between the two groups.The 75th percentile of ADC1000 values achieved the highest area under the curve(AUC)for differentiating IPAC from PPAC(AUC=0.781;sensitivity,91%;specificity,59%;cut-off value,1.50×10^-3 mm^2/s).CONCLUSION Volumetric ADC histogram analysis at a b-value of 1000 s/mm2 might be helpful for differentiating the histological subtypes of periampullary adenocarcinoma before surgery. 展开更多
关键词 Periampullary ADENOCARCINOMA apparent DIFFUSION COEFFICIENT HISTOGRAM analysis HISTOPATHOLOGY Differential diagnosis
下载PDF
Histogram analysis of apparent diffusion coefficient predicts response to radiofrequency ablation in hepatocellular carcinoma 被引量:5
14
作者 Xiaohong Ma Han Ouyang +3 位作者 Shuang Wang Meng Wang Chunwu Zhou Xinming Zhao 《Chinese Journal of Cancer Research》 SCIE CAS CSCD 2019年第2期366-374,共9页
Objective: The aim of this study was to predict tumor progression in patients with hepatocellular carcinoma(HCC) treated with radiofrequency ablation(RFA) using histogram analysis of apparent diffusion coefficients(AD... Objective: The aim of this study was to predict tumor progression in patients with hepatocellular carcinoma(HCC) treated with radiofrequency ablation(RFA) using histogram analysis of apparent diffusion coefficients(ADC).Methods: Breath-hold diffusion weighted imaging(DWI) was performed in 64 patients(33 progressive and 31 stable) with biopsy-proven HCC prior to RFA. All patients had pre-treatment magnetic resonance imaging(MRI)and follow-up computed tomography(CT) or MRI. The ADC values(ADC_(10), ADC_(30_, ADC_(median) and ADC_(max))were obtained from the histogram's 10 th, 30 th, 50 th and 100 th percentiles. The ratios of ADC_(10), ADC_(30_,ADCmedian and ADCmax to the mean non-lesion area-ADC(RADC_(10), RADC_(30_, RADC_(median), and RADC_(max)) were calculated. The two patient groups were compared. Key predictive factors for survival were determined using the univariate and multivariate analysis of the Cox model. The Kaplan-Meier survival analysis was performed, and pairs of survival curves based on the key factors were compared using the log-rank test.Results: The ADC_(30_, ADCmedian, ADCmax, RADC_(30_, RADC_(median), and RADC_(max) were significantly larger in the progressive group than in the stable group(P<0.05). The median progression-free survival(PFS) was 22.9 months for all patients. The mean PFS for the stable and progressive groups were 47.7±1.3 and 9.8±1.3 months,respectively. Univariate analysis indicated that RADC_(10), RADC_(30_, and RADC_(median) were significantly correlated with the PFS [hazard ratio(HR)=31.02, 43.84, and 44.29, respectively, P<0.05 for all]. Multivariate analysis showed that RADCmedian was the only independent predictor of tumor progression(P=0.04). And the cutoff value of RADC_(median) was 0.71.Conclusions: Pre-RFA ADC histogram analysis might serve as a useful biomarker for predicting tumor progression and survival in patients with HCC treated with RFA. 展开更多
关键词 DIFFUSION-WEIGHTED imaging apparent diffusion coefficient HISTOGRAM analysis HEPATOCELLULAR carcinoma RADIOFREQUENCY ablation survival time
下载PDF
Characterization and Apparent Kinetics of Polymerization of 1-Decene Catalyzed by Boron Trifluoride/Alcohol System 被引量:7
15
作者 Wang Sihan Wang Libo +3 位作者 Liu Tong Ma Lili Huo Hongliang Wang Jian 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2017年第3期16-22,共7页
Poly-α-olefin(PAO) synthetic oil is the base oil of high-quality lubricants, and has a huge market potential.We illustrate PAO synthesis by catalytic polymerization of 1-decene with a boron trifluoride(BF_3)/alcohol ... Poly-α-olefin(PAO) synthetic oil is the base oil of high-quality lubricants, and has a huge market potential.We illustrate PAO synthesis by catalytic polymerization of 1-decene with a boron trifluoride(BF_3)/alcohol system. Gas chromatography–mass spectrometry, proton nuclear magnetic resonance and ^(13) C nuclear magnetic resonance analysis confirmed dimer, trimer and tetramer structures of PAO. Each component contained branched chains with a 1,2 insertion of a head-to-tail link; a 2,1 insertion of a tail-to-tail link and a methyl-containing linked structure. At a low conversion rate, the reaction rate was related directly with the reaction temperature and the catalyst/1-decene concentration. An apparent kinetic equation for PAO formation was determined during 1-decene polymerization. 展开更多
关键词 poly-α-olefin 1-DECENE BORON TRIFLUORIDE product structure apparent kinetics
下载PDF
Influence of Perpendicular Magnetic Field on Apparent Density and Microstructure of Magnetic Fluid 被引量:6
16
作者 李艳琴 李学慧 《Chinese Physics Letters》 SCIE CAS CSCD 2012年第10期204-208,共5页
The formula for a magnetic fluid's apparent density is derived based on Bernoulli's equation of magnetic fluid,and the distribution of the magnetic fluid's apparent density is measured by the intelligent a... The formula for a magnetic fluid's apparent density is derived based on Bernoulli's equation of magnetic fluid,and the distribution of the magnetic fluid's apparent density is measured by the intelligent apparatus of measuring a magnetic fluid's apparent density in an applied perpendicular magnetic field.Magnetic particle chain-like alignments are observed by a transmission electron microscope(TEM).Without an applied magnetic field,the magnetic fluid's density is equal everywhere and the distribution of magnetic particles is homogeneous and unordered.When magnetic induction and magnetic induction gradient gather strength in an applied perpendicular magnetic field,the magnetic fluid's apparent density increases gradually,and more chain-like structures are formed and aligned with the direction of the magnetic field.The results of magnetic particle alignments are correspondent with the distribution of the magnetic fluid's apparent density.Both of them result from particle-particle interactions and particle-carrier liquid interactions,which are eventually controlled by the applied magnetic induction and magnetic induction gradient distribution. 展开更多
关键词 MICROSTRUCTURE apparent MAGNETIC
原文传递
Combined value of apparent diffusion coefficient-standardized uptake value max in evaluation of post-treated locally advanced rectal cancer 被引量:5
17
作者 Davide Ippolito Davide Fior +5 位作者 Chiara Trattenero Elena De Ponti Silvia Drago Luca Guerra Cammillo Talei Franzesi Sandro Sironi 《World Journal of Radiology》 CAS 2015年第12期509-520,共12页
AIM:To assess the clinical diagnostic value of functional imaging,combining quantitative parameters of apparent diffusion coefficient(ADC) and standardized uptake value(SUV)max,before and after chemo-radiation therapy... AIM:To assess the clinical diagnostic value of functional imaging,combining quantitative parameters of apparent diffusion coefficient(ADC) and standardized uptake value(SUV)max,before and after chemo-radiation therapy,in prediction of tumor response of patients with rectal cancer,related to tumor regression grade at histology.METHODS:A total of 31 patients with biopsy proven diagnosis of rectal carcinoma were enrolled in our study.All patients underwent a whole body ^(18)FDG positron emission tomography(PET)/computed tomography(CT) scan and a pelvic magnetic resonance(MR)examination including diffusion weighted(DW) imaging for staging(PET1,RM1) and after completion(6.6 wk)of neoadjuvant treatment(PET2,RM2).Subsequently all patients underwent total mesorectal excision and the histological results were compared with imaging findings.The MR scanning,performed on 1.5 T magnet(Philips,Achieva),included T2-weighted multiplanar imaging and in addition DW images with b-value of 0 and 1000 mm^2/s.On PET/CT the SUVmax of the rectal lesion were calculated in PET1 and PET2.The percentage decrease of SUVmax(△SUV) and ADC(△ADC) values from baseline to presurgical scan were assessed and correlated with pathologic response classified as tumor regression grade(Mandard's criteria;TRG1 = complete regression,TRG5 = no regression).RESULTS:After completion of therapy,all the patients were submitted to surgery.According to the Mandard's criteria,22 tumors showed complete(TRG1) or subtotal regression(TRG2) and were classified as responders;9tumors were classified as non responders(TRG3,4 and5).Considering all patients the mean values of SUVmax in PET 1 was higher than the mean value of SUVmax in PET 2(P < 0.001),whereas the mean ADC values was lower in RM1 than RM2(P < 0.001),with a △SUV and △ADC respectively of 60.2%and 66.8%.The best predictors for TRG response were SUV2(threshold of4.4) and ADC2(1.29 × 10^(-3) mm^2/s) with high sensitivity and specificity.Combining in a single analysis both the obtained median value,the positive predictive value,in predicting the different group category response in related to TRG system,presented R^2 of 0.95.CONCLUSION:The functional imaging combining ADC and SUVmax in a single analysis permits to detect changes in cellular tissue structures useful for the assessment of tumour response after the neoadjuvant therapy in rectal cancer,increasing the sensitivity in correct depiction of treatment response than either method alone. 展开更多
关键词 Advanced RECTAL cancer Functional IMAGING FDG-PET/CT Magnetic resonance IMAGING apparent diffusion coefficient NEOADJUVANT treatment Tumor regression grade
下载PDF
Distribution of apparent stress in western China 被引量:3
18
作者 吴忠良 黄静 林碧苍 《Acta Seismologica Sinica(English Edition)》 CSCD 2002年第3期309-317,共9页
Distribution of apparent stress in Chinese mainland and its surrounding regions was presented using the NEIC broadband radiated energy catalogue and the Harvard CMT catalogue from January 1987 to December 1998. Due to... Distribution of apparent stress in Chinese mainland and its surrounding regions was presented using the NEIC broadband radiated energy catalogue and the Harvard CMT catalogue from January 1987 to December 1998. Due to the limitation on the number of samples, reliable results are only for the western China. It is observed that the average apparent stress in Chinese mainland is 0.8 MPa; The maximum apparent stress to the east of the Tibetan plateau is 2.6 MPa; And the average apparent stress in the north-south seismic belt is more than one time higher than its adjacent regions. Distribution pattern of apparent stress seems to have a large-scale correlation with the cumulative energy release level in the 20th century. 展开更多
关键词 apparent stress EARTHQUAKE energy SEISMIC MOMENT EARTHQUAKES in China
下载PDF
Relation between the evolution of seismic apparent strain field and the region of strong earthquake occurrence 被引量:3
19
作者 黄福明 易志刚 《Acta Seismologica Sinica(English Edition)》 EI CSCD 2000年第6期616-627,共12页
In this paper, according to the data on the middle and strong earthquakes in China, we have preliminarily studied the relation between the characteristic of space-time evolution of the seismic apparent strain field an... In this paper, according to the data on the middle and strong earthquakes in China, we have preliminarily studied the relation between the characteristic of space-time evolution of the seismic apparent strain field and the regions of 31 macroseism events since 1955. The result shows that, there is a rather well correlation between the anomaly region of seismic apparent strain and the zone of macroseism event occurrence within the time range of one to about five years. The R value of the application of the abnormal region of seismic apparent strain to predicting the area of strong earthquake occurrence is 0.458, and the empirical possibility of forecasting the region of macroseism occurrence is 0.625, and so the forecasting effect is comparatively well. Finally, the main results obtained above are discussed preliminarily. 展开更多
关键词 seismic apparent strain anomaly region EVOLUTION region of macroseism occurrence earthquake prediction R value
下载PDF
Diffusion-weighted magnetic resonance imaging in cancer: Reported apparent diffusion coefficients,in-vitro and invivo reproducibility 被引量:2
20
作者 Maysam M Jafar Arman Parsai Marc E Miquel 《World Journal of Radiology》 CAS 2016年第1期21-49,共29页
There is considerable disparity in the published apparent diffusion coefficient(ADC) values across different anatomies. Institutions are increasingly assessing repeatability and reproducibility of the derived ADC to d... There is considerable disparity in the published apparent diffusion coefficient(ADC) values across different anatomies. Institutions are increasingly assessing repeatability and reproducibility of the derived ADC to determine its variation,which could potentially be used as an indicator in determining tumour aggressiveness or assessing tumour response. In this manuscript,a review of selected articles published to date in healthy extracranial body diffusion-weighted magnetic resonance imaging is presented,detailing reported ADC values and discussing their variation across different studies. In total 115 studies were selected including 28 for liver parenchyma,15 for kidney(renal parenchyma),14 for spleen,13 for pancreatic body,6 for gallbladder,13 for prostate,13 for uterus(endometrium,myometrium,cervix) and 13 for fibroglandular breast tissue. Median ADC values in selected studies were found to be 1.28 × 10-3 mm2/s in liver,1.94 × 10-3 mm2/s in kidney,1.60 × 10-3 mm2/s in pancreatic body,0.85 × 10-3 mm2/s in spleen,2.73 × 10-3 mm2/s in gallbladder,1.64 × 10-3 mm2/s and 1.31 × 10-3 mm2/s in prostate peripheral zone and central gland respectively(combined median value of 1.54×10-3 mm2/s),1.44 × 10-3 mm2/s in endometrium,1.53 × 10-3 mm2/s in myometrium,1.71 × 10-3 mm2/s in cervix and 1.92 × 10-3 mm2/s in breast. In addition,six phantom studies and thirteen in vivo studies were summarized to compare repeatability and reproducibility of the measured ADC. All selected phantom studies demonstrated lower intra-scanner and inter-scanner variation compared to in vivo studies. Based on the findings of this manuscript,it is recommended that protocols need to be optimised for the body part studied and that system-induced variability must be established using a standardized phantom in any clinical study. Reproducibility of the measured ADC must also be assessed in a volunteer population,as variations are far more significant in vivo compared with phantom studies. 展开更多
关键词 Diffusion-weighted magnetic resonance IMAGING apparent DIFFUSION COEFFICIENT REPRODUCIBILITY apparent DIFFUSION COEFFICIENT CANCER IMAGING Extracranial organs
下载PDF
上一页 1 2 22 下一页 到第
使用帮助 返回顶部