期刊文献+
共找到2,569,074篇文章
< 1 2 250 >
每页显示 20 50 100
中国1961-2010年气象干旱的时空规律——基于SPEI和Intensity analysis方法的研究 被引量:16
1
作者 栗健 岳耀杰 +1 位作者 潘红梅 叶信岳 《灾害学》 CSCD 北大核心 2014年第4期176-182,共7页
利用中国752个气象站降水、气温资料,选择标准化降水蒸散发指数SPEI为干旱指标,采用Intensity analysis方法,从时间间隔、干旱等级变化和转换三个层面分析了1961-2010年中国气象干旱变化规律。结果表明:1961-2010年中国气象干旱的变化... 利用中国752个气象站降水、气温资料,选择标准化降水蒸散发指数SPEI为干旱指标,采用Intensity analysis方法,从时间间隔、干旱等级变化和转换三个层面分析了1961-2010年中国气象干旱变化规律。结果表明:1961-2010年中国气象干旱的变化速率趋于上升,总变化面积由60%上升至80%以上,1980-1990年代、1990年代至21世纪初两个时间段的年平均变化相对于整个时间段较快。1960-1980年代干旱变化较为平缓,1960-1970年代干旱等级的转换主要以中等以下的干旱等级之间的转换为主导;1970-1980年代以无干旱与轻微、中等和严重干旱等级之间的相互转换为主导。1980年代至21世纪初干旱有加重的趋势,1980-1990年代以无干旱向极端干旱的转换为主导;1990年代至21世纪初中等以下的干旱向严重和极端干旱的转变成为了主导,而严重干旱则以向极端干旱转换为主导,极端干旱以向中等干旱转换为主导。 展开更多
关键词 SPEI INTENSITY analysis 气象干旱 时空规律 中国
下载PDF
知识共享与创新绩效的关系研究——基于MetaAnalysis方法 被引量:1
2
作者 王炳成 闫晓飞 《山东工商学院学报》 2017年第6期52-59,共8页
对45篇中外有效文献中的67个效应值,运用元分析(Meta Analysis)研究方法,对2008年至2016年有关员工知识共享与创新绩效关系的实证研究进行定量综合研究。研究结果表明,员工知识共享与创新绩效呈显著正相关关系,相关系数r=0.503;文献数... 对45篇中外有效文献中的67个效应值,运用元分析(Meta Analysis)研究方法,对2008年至2016年有关员工知识共享与创新绩效关系的实证研究进行定量综合研究。研究结果表明,员工知识共享与创新绩效呈显著正相关关系,相关系数r=0.503;文献数据发表年份、知识共享测量维度和不同文化背景对知识共享和创新绩效的关系具有显著调节作用;研究样本量对知识共享与创新绩效的关系不具有显著调节作用。在此基础上,对未来研究进行了展望。 展开更多
关键词 创新绩效 知识共享 META analysis 调节作用
下载PDF
基于Conjoint Analysis方法的延边黄牛肉安全性价值评价
3
作者 金成哲 鲜于晓龙 +1 位作者 严昌国 严红梅 《延边大学农学学报》 2015年第3期249-253,共5页
本文应用选择型Conjoint Analysis方法,根据概率及效用理论(Random Utility Theory)设计了选择型实验模型,并利用问卷调查数据测定消费者对牛肉安全性各属性的重要度、危害度和支付意愿。结果显示,消费者对等级(2.26)和价格(2.59... 本文应用选择型Conjoint Analysis方法,根据概率及效用理论(Random Utility Theory)设计了选择型实验模型,并利用问卷调查数据测定消费者对牛肉安全性各属性的重要度、危害度和支付意愿。结果显示,消费者对等级(2.26)和价格(2.59)的重要度为2~3之间,意味着消费者购买牛肉时两者均不太重要;牛肉安全性标识和人体有害性评价中,对生产牧场(1.93)、绿色食品认证(1.89)和有机食品认证标识(1.65)的重要度比较高,对抗生素(1.83)、生长激素(1.81)的属性指标的平均统计量是2以下,说明消费者购买牛肉时,很重视安全性标识、抗生素和生长激素的残留问题。利用多项对数模型测定了延边黄牛肉的边际支付意愿(MWTP),结果表明:对安全性标识的追加支付为3.05元/kg,对生长激素、抗生素和等级因素的追加支付分别为8.25、7.70和3.45元/kg。 展开更多
关键词 CONJOINT analysis 支付意愿 延边黄牛肉
下载PDF
Meta-analysis方法与应用 被引量:2
4
作者 赵宁 俞顺章 《肿瘤》 CAS CSCD 北大核心 1995年第S1期136-137,131,共3页
Meta-analysis方法与应用赵宁,俞顺章一、Meta-analysis概况在科学研究中,需要对所研究问题的有关信息进行综合分析。如今有了一种科学的定量综合方法,这就是Meta-analysis,其定义为对具有... Meta-analysis方法与应用赵宁,俞顺章一、Meta-analysis概况在科学研究中,需要对所研究问题的有关信息进行综合分析。如今有了一种科学的定量综合方法,这就是Meta-analysis,其定义为对具有共同研究目的相互独立的多个研究结果... 展开更多
关键词 META-analysis 固定效应模型 流行病学研究 综合方法 随机效应模型 综合分析 分析统计方法 慢性病预防与控制 模型方法 现代预防医学
下载PDF
Meta-analysis方法及其应用 被引量:3
5
作者 赵宁 俞顺章 《中国公共卫生》 CAS CSCD 1993年第10期459-461,共3页
Meta—analysis是一种较新的研究手段和分析方法,其定义为对先前相同目的的相互独立的多个研究的结果给予综合评价和定量统计分析。它把先前的研究结果作为观察单位,有人称之为“结果流行病学”或“分析的分析”。一般来讲,除非所研究... Meta—analysis是一种较新的研究手段和分析方法,其定义为对先前相同目的的相互独立的多个研究的结果给予综合评价和定量统计分析。它把先前的研究结果作为观察单位,有人称之为“结果流行病学”或“分析的分析”。一般来讲,除非所研究的作用很强或样本很大,往往因样本量有限,缺乏足够的统计功效,随机误差较大,而不能获得明确结论。Meta—analysis可提高统计功效,解决各研究间结果的矛盾,综合评价研究的问题,定量合并结果,使结论更可靠,更适用于总体。目前,此方法已应用于医学卫生健康领域。 展开更多
关键词 流行病学 分析方法 META分析
下载PDF
Meta-analysis方法及其在药物临床评价中的应用 被引量:6
6
作者 罗湘 曾繁典 《中国临床药理学杂志》 CAS CSCD 北大核心 1995年第3期164-171,共8页
Meta-analysis是一评价药物有效性和安全性的重要方法。该法试图综合所有相关临床试验的结果而得到药物疗效的全面和准确的评价。该法运用特定的统计学方法,量化并合并分析各单独临床试验的结果而得出结论。对肯定或排除... Meta-analysis是一评价药物有效性和安全性的重要方法。该法试图综合所有相关临床试验的结果而得到药物疗效的全面和准确的评价。该法运用特定的统计学方法,量化并合并分析各单独临床试验的结果而得出结论。对肯定或排除在单个临床试验中,可能不易观察到的相对较弱的药理作用或不良反应,Meta-analysis也是一强有力的工具。本文简要介绍该法,并列举其在抗心律失常药物和抗高血压药物等临床评价中的应用实例进行了验证。对实施该法应注意的一些问题也进行了探讨。 展开更多
关键词 META-analysis 药物临床评价 药物临床试验
下载PDF
Meta-Analysis方法浅析 被引量:2
7
作者 陶峻 《统计与决策》 CSSCI 北大核心 2006年第17期149-150,共2页
关键词 META 统计分析方法 MORE 定量分析 超常规 理论界 国内
下载PDF
Meta-analysis(元分析)Ⅱ.Meta—analysis方法比较与应用 被引量:8
8
作者 赵宁 俞顺章 《山西医学院学报》 1995年第4期295-297,共3页
本文对固定效应模型和随机效应模型方法进行了比较。固定效应模型OR值与随机效应模型OR值相关性分析,结果说明:在同质条件下,二法结果很接近,r=0.97(95%CI:0.93—0.99);而在异质条件下,二法结果可能不... 本文对固定效应模型和随机效应模型方法进行了比较。固定效应模型OR值与随机效应模型OR值相关性分析,结果说明:在同质条件下,二法结果很接近,r=0.97(95%CI:0.93—0.99);而在异质条件下,二法结果可能不同,r=0.69(95%CI:0.25—0.89)。当无显著异质性时,两者结果相似,选用Peto法计算简便;反之,当无显著异质性时应使用后者,这时D-L法可能提供更适于实际的估计值和可信限。仅用随机效应模型方法进行分析可以替代固定效应模型;从两模型原理和流行病学研究的特点来讲,固定效应模型并不适合于综合流行病学研究的结果。另外.作者对Meta分析在流行病学中应用一些问题进行了讨论。 展开更多
关键词 元分析 固定效应模型 随机效应模型
下载PDF
基于Intensity Analysis方法的四川省农村居民边际储蓄倾向变化特征分析
9
作者 谢舒蕾 周廷刚 +1 位作者 任彦霓 尹振南 《农业灾害研究》 2020年第9期180-182,共3页
利用2000—2019年四川省各地市州农村居民收入与消费数据,采用边际储蓄倾向和Intensity Analysis等方法,从边际储蓄倾向等级变化的强度和等级转换的特征等方面,对四川省农村居民边际储蓄倾向的变化特征进行分析。结果表明:2000—2019年... 利用2000—2019年四川省各地市州农村居民收入与消费数据,采用边际储蓄倾向和Intensity Analysis等方法,从边际储蓄倾向等级变化的强度和等级转换的特征等方面,对四川省农村居民边际储蓄倾向的变化特征进行分析。结果表明:2000—2019年,四川省农村居民边际储蓄倾向的等级变化强度表现出“快—快—快—慢”的特点;2010—2014年边际储蓄倾向变化最快,2015年后变化逐渐趋于平稳,即四川省农村居民储蓄随着收入的变化在2015年前变化不均衡,2015年后变化逐渐趋向平稳,以中等速率增长;2000—2019年,四川省农村居民边际储蓄倾向等级转换较活跃,各等级转换速率不尽相同,主要集中在3、4等级,但在2015年后变化有进入休眠状态的趋势。 展开更多
关键词 四川 边际储蓄倾向 Intensity analysis
下载PDF
Pooled Analysis方法的应用:一个研究实例
10
作者 陈建国 《肿瘤》 CAS CSCD 北大核心 1995年第S1期240-,200,共2页
PooledAnalysis方法的应用:一个研究实例陈建国启东肝癌研究所流行病学研究室(启东226200)Friedenreich曾讨论了"现成的流行病学研究"资料的合并及作PooledAnalysis(PA)分析的... PooledAnalysis方法的应用:一个研究实例陈建国启东肝癌研究所流行病学研究室(启东226200)Friedenreich曾讨论了"现成的流行病学研究"资料的合并及作PooledAnalysis(PA)分析的问题,并将PA的过程大致归纳成八个... 展开更多
关键词 方法的应用 流行病学研究 结直肠癌 膳食纤维素 analysis 胡萝卜素 负相联 非齐性 病例一对照研究 研究实例
下载PDF
使用FaultTreeAnalysis方法对轨道交通运营线信号系统软件升级的风险分析
11
作者 隋鹏 《中文科技期刊数据库(全文版)工程技术》 2021年第11期225-227,共3页
自上世纪90年代以来,城市轨道交通的信号系统设备逐渐有继电联锁向微机联锁普及,联锁的逻辑关联由继电器组合间的配线向微机联锁的布尔代数转变,同时信号系统在联锁设备外,又增加了列车自动防护系统(ATP)、列车自动运行系统(ATO)、列车... 自上世纪90年代以来,城市轨道交通的信号系统设备逐渐有继电联锁向微机联锁普及,联锁的逻辑关联由继电器组合间的配线向微机联锁的布尔代数转变,同时信号系统在联锁设备外,又增加了列车自动防护系统(ATP)、列车自动运行系统(ATO)、列车自动监控系统(ATS)、列车自动控制系统(ATC)等功能,上述系统设备都是基于数据的逻辑运算电子单元。此外,信号系统与多专业间的数据接口也越来越多,例如与电力监控系统、时钟系统、安全门系统等。因此,对信号系统的逻辑或者数据的调整,就必然需要考虑到信号系统内部间以及和信号系统与外部各接口间的相互影响。 展开更多
关键词 必要性 方法 轨道交通
下载PDF
Screening biomarkers for spinal cord injury using weighted gene co-expression network analysis and machine learning 被引量:5
12
作者 Xiaolu Li Ye Yang +3 位作者 Senming Xu Yuchang Gui Jianmin Chen Jianwen Xu 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第12期2723-2734,共12页
Immune changes and inflammatory responses have been identified as central events in the pathological process of spinal co rd injury.They can greatly affect nerve regeneration and functional recovery.However,there is s... Immune changes and inflammatory responses have been identified as central events in the pathological process of spinal co rd injury.They can greatly affect nerve regeneration and functional recovery.However,there is still limited understanding of the peripheral immune inflammato ry response in spinal cord inju ry.In this study.we obtained microRNA expression profiles from the peripheral blood of patients with spinal co rd injury using high-throughput sequencing.We also obtained the mRNA expression profile of spinal cord injury patients from the Gene Expression Omnibus(GEO)database(GSE151371).We identified 54 differentially expressed microRNAs and 1656 diffe rentially expressed genes using bioinformatics approaches.Functional enrichment analysis revealed that various common immune and inflammation-related signaling pathways,such as neutrophil extracellular trap formation pathway,T cell receptor signaling pathway,and nuclear factor-κB signal pathway,we re abnormally activated or inhibited in spinal cord inju ry patient samples.We applied an integrated strategy that combines weighted gene co-expression network analysis,LASSO logistic regression,and SVM-RFE algorithm and identified three biomarke rs associated with spinal cord injury:ANO10,BST1,and ZFP36L2.We verified the expression levels and diagnostic perfo rmance of these three genes in the original training dataset and clinical samples through the receiver operating characteristic curve.Quantitative polymerase chain reaction results showed that ANO20 and BST1 mRNA levels were increased and ZFP36L2 mRNA was decreased in the peripheral blood of spinal cord injury patients.We also constructed a small RNA-mRNA interaction network using Cytoscape.Additionally,we evaluated the proportion of 22 types of immune cells in the peripheral blood of spinal co rd injury patients using the CIBERSORT tool.The proportions of naive B cells,plasma cells,monocytes,and neutrophils were increased while the proportions of memory B cells,CD8^(+)T cells,resting natural killer cells,resting dendritic cells,and eosinophils were markedly decreased in spinal cord injury patients increased compared with healthy subjects,and ANO10,BST1 and ZFP26L2we re closely related to the proportion of certain immune cell types.The findings from this study provide new directions for the development of treatment strategies related to immune inflammation in spinal co rd inju ry and suggest that ANO10,BST2,and ZFP36L2 are potential biomarkers for spinal cord injury.The study was registe red in the Chinese Clinical Trial Registry(registration No.ChiCTR2200066985,December 12,2022). 展开更多
关键词 bioinformatics analysis BIOMARKER CIBERSORT GEO dataset LASSO miRNA-mRNA network RNA sequencing spinal cord injury SVM-RFE weighted gene co-expression network analysis
下载PDF
Social-ecological perspective on the suicidal behaviour factors of early adolescents in China:a network analysis 被引量:4
13
作者 Yuan Li Peiying Li +5 位作者 Mengyuan Yuan Yonghan Li Xueying Zhang Juan Chen Gengfu Wang Puyu Su 《General Psychiatry》 CSCD 2024年第1期143-150,共8页
Background In early adolescence,youth are highly prone to suicidal behaviours.Identifying modifiable risk factors during this critical phase is a priority to inform effective suicide prevention strategies.Aims To expl... Background In early adolescence,youth are highly prone to suicidal behaviours.Identifying modifiable risk factors during this critical phase is a priority to inform effective suicide prevention strategies.Aims To explore the risk and protective factors of suicidal behaviours(ie,suicidal ideation,plans and attempts)in early adolescence in China using a social-ecological perspective.Methods Using data from the cross-sectional project‘Healthy and Risky Behaviours Among Middle School Students in Anhui Province,China',stratified random cluster sampling was used to select 5724 middle school students who had completed self-report questionnaires in November 2020.Network analysis was employed to examine the correlates of suicidal ideation,plans and attempts at four levels,namely individual(sex,academic performance,serious physical llness/disability,history of self-harm,depression,impulsivity,sleep problems,resilience),family(family economic status,relationship with mother,relationship with father,family violence,childhood abuse,parental mental illness),school(relationship with teachers,relationship with classmates,school-bullying victimisation and perpetration)and social(social support,satisfaction with society).Results In total,37.9%,19.0%and 5.5%of the students reported suicidal ideation,plans and attempts in the past 6 months,respectively.The estimated network revealed that suicidal ideation,plans and attempts were collectively associated with a history of self-harm,sleep problems,childhood abuse,school bullying and victimisation.Centrality analysis indicated that the most influential nodes in the network were history of self-harm and childhood abuse.Notably,the network also showed unique correlates of suicidal ideation(sex,weight=0.60;impulsivity,weight=0.24;family violence,weight=0.17;relationship with teachers,weight=-0.03;school-bullying perpetration,weight=0.22),suicidal plans(social support,weight=-0.15)and suicidal attempts(relationship with mother,weight=-0.10;parental mental llness,weight=0.61).Conclusions This study identified the correlates of suicidal ideation,plans and attempts,and provided practical implications for suicide prevention for young adolescents in China.Firstly,this study highlighted the importance of joint interventions across multiple departments.Secondly,the common risk factors of suicidal ideation,plans and attempts were elucidated.Thirdly,this study proposed target interventions to address the unique influencing factors of suicidal ideation,plans and attempts. 展开更多
关键词 NETWORK analysis PREVENTION
下载PDF
Advances in microfluidic-based DNA methylation analysis 被引量:1
14
作者 Jiwen Li Tiechuan Li Xuexin Duan 《Nanotechnology and Precision Engineering》 EI CAS CSCD 2024年第1期116-134,共19页
DNA methylation has been extensively investigated in recent years,not least because of its known relationship with various diseases.Progress in analytical methods can greatly increase the relevance of DNA methylation ... DNA methylation has been extensively investigated in recent years,not least because of its known relationship with various diseases.Progress in analytical methods can greatly increase the relevance of DNA methylation studies to both clinical medicine and scientific research.Microflu-idic chips are excellent carriers for molecular analysis,and their use can provide improvements from multiple aspects.On-chip molecular analysis has received extensive attention owing to its advantages of portability,high throughput,low cost,and high efficiency.In recent years,the use of novel microfluidic chips for DNA methylation analysis has been widely reported and has shown obvious superiority to conventional methods.In this review,wefirst focus on DNA methylation and its applications.Then,we discuss advanced microfluidic-based methods for DNA methylation analysis and describe the great progress that has been made in recent years.Finally,we summarize the advantages that microfluidic technology brings to DNA methylation analysis and describe several challenges and perspectives for on-chip DNA methylation analysis.This review should help researchers improve their understanding and make progress in developing microfluidic-based methods for DNA methylation analysis. 展开更多
关键词 Microfluidic chip DNA methylation analysis Molecular analysis High throughput Low cost
下载PDF
A Review on Sources,Extractions and Analysis Methods of a Sustainable Biomaterial:Tannins 被引量:2
15
作者 Antonio Pizzi Marie-Pierre Laborie Zeki Candan 《Journal of Renewable Materials》 EI CAS 2024年第3期397-425,共29页
Condensed and hydrolysable tannins are non-toxic natural polyphenols that are a commercial commodity industrialized for tanning hides to obtain leather and for a growing number of other industrial applications mainly ... Condensed and hydrolysable tannins are non-toxic natural polyphenols that are a commercial commodity industrialized for tanning hides to obtain leather and for a growing number of other industrial applications mainly to substitute petroleum-based products.They are a definite class of sustainable materials of the forestry industry.They have been in operation for hundreds of years to manufacture leather and now for a growing number of applications in a variety of other industries,such as wood adhesives,metal coating,pharmaceutical/medical applications and several others.This review presents the main sources,either already or potentially commercial of this forestry by-materials,their industrial and laboratory extraction systems,their systems of analysis with their advantages and drawbacks,be these methods so simple to even appear primitive but nonetheless of proven effectiveness,or very modern and instrumental.It constitutes a basic but essential summary of what is necessary to know of these sustainable materials.In doing so,the review highlights some of the main challenges that remain to be addressed to deliver the quality and economics of tannin supply necessary to fulfill the industrial production requirements for some materials-based uses. 展开更多
关键词 TANNINS FLAVONOIDS SOURCES extraction methods analysis methods
下载PDF
Telomerase-related advances in hepatocellular carcinoma:A bibliometric and visual analysis 被引量:2
16
作者 Hai-Yang Li Lin-Lin Zheng +9 位作者 Nan Hu Zhi-Hao Wang Chang-Cheng Tao Ya-Ru Wang Yue Liu Zulihumaer Aizimuaji Hong-Wei Wang Rui-Qi Zheng Ting Xiao Wei-Qi Rong 《World Journal of Gastroenterology》 SCIE CAS 2024年第9期1224-1236,共13页
BACKGROUND As a critical early event in hepatocellular carcinogenesis,telomerase activation might be a promising and critical biomarker for hepatocellular carcinoma(HCC)patients,and its function in the genesis and tre... BACKGROUND As a critical early event in hepatocellular carcinogenesis,telomerase activation might be a promising and critical biomarker for hepatocellular carcinoma(HCC)patients,and its function in the genesis and treatment of HCC has gained much attention over the past two decades.AIM To perform a bibliometric analysis to systematically assess the current state of research on HCC-related telomerase.METHODS The Web of Science Core Collection and PubMed were systematically searched to retrieve publications pertaining to HCC/telomerase limited to“articles”and“reviews”published in English.A total of 873 relevant publications related to HCC and telomerase were identified.We employed the Bibliometrix package in R to extract and analyze the fundamental information of the publications,such as the trends in the publications,citation counts,most prolific or influential writers,and most popular journals;to screen for keywords occurring at high frequency;and to draw collaboration and cluster analysis charts on the basis of coauthorship and co-occurrences.VOSviewer was utilized to compile and visualize the bibliometric data.RESULTS A surge of 51 publications on HCC/telomerase research occurred in 2016,the most productive year from 1996 to 2023,accompanied by the peak citation count recorded in 2016.Up to December 2023,35226 citations were made to all publications,an average of 46.6 citations to each paper.The United States received the most citations(n=13531),followed by China(n=7427)and Japan(n=5754).In terms of national cooperation,China presented the highest centrality,its strongest bonds being to the United States and Japan.Among the 20 academic institutions with the most publications,ten came from China and the rest of Asia,though the University of Paris Cité,Public Assistance-Hospitals of Paris,and the National Institute of Health and Medical Research(INSERM)were the most prolific.As for individual contributions,Hisatomi H,Kaneko S,and Ide T were the three most prolific authors.Kaneko S ranked first by H-index,G-index,and overall publication count,while Zucman-Rossi J ranked first in citation count.The five most popular journals were the World Journal of Gastroenterology,Hepatology,Journal of Hepatology,Oncotarget,and Oncogene,while Nature Genetics,Hepatology,and Nature Reviews Disease Primers had the most citations.We extracted 2293 keywords from the publications,120 of which appeared more than ten times.The most frequent were HCC,telomerase and human telomerase reverse transcriptase(hTERT).Keywords such as mutational landscape,TERT promoter mutations,landscape,risk,and prognosis were among the most common issues in this field in the last three years and may be topics for research in the coming years.CONCLUSION Our bibliometric analysis provides a comprehensive overview of HCC/telomerase research and insights into promising upcoming research. 展开更多
关键词 TELOMERASE Bibliometric analysis Telomerase reverse transcriptase PROGNOSIS Treatment Hepatocellular carcinoma
下载PDF
Micro segment analysis of supercritical methane thermal-hydraulic performance and pseudo-boiling in a PCHE straight channel 被引量:2
17
作者 Qian Li Zi-Jie Lin +3 位作者 Liu Yang Yue Wang Yue Li Wei-Hua Cai 《Petroleum Science》 SCIE EI CAS CSCD 2024年第2期1275-1289,共15页
The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the... The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 mm.Numerical simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow features.The results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleateboiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were analyzed.In calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover,heat transfer deterioration will always appear, since the supercritical flow will finally develop into a filmboiling-like state. So heat transfer deterioration should be taken seriously in the design and safe operation of vaporizer PCHE. The study of this work clarified the local heat transfer and flow feature of supercritical methane in microchannel and contributed to the deep understanding of supercritical methane flow of the vaporization process in PCHE. 展开更多
关键词 Printed circuit heat exchanger Vaporization Supercritical methane Pseudo-boiling Micro segment analysis
下载PDF
Causal Analysis Between Rice Growth and Cadmium Accumulation and Transfer under Arbuscular Mycorrhizal Inoculation 被引量:2
18
作者 ZHAO Ting WANG Li +1 位作者 YANG Jixian MA Fang 《Rice science》 SCIE CSCD 2024年第2期226-236,共11页
Cadmium(Cd)contamination in rice has been a serious threat to human health.To investigate the effects of arbuscular mycorrhizal fungi(AMF)on the Cd translocation in rice,a controlled pot experiment was conducted.The r... Cadmium(Cd)contamination in rice has been a serious threat to human health.To investigate the effects of arbuscular mycorrhizal fungi(AMF)on the Cd translocation in rice,a controlled pot experiment was conducted.The results indicated that AMF significantly increased rice biomass,with an increase of up to 40.0%,particularly in root biomass by up to 68.4%.Notably,the number of prominent rice individuals also increased,and their plasticity was enhanced following AMF inoculation.AMF led to an increase in the net photosynthetic rate and antioxidant enzyme activity of rice.In the AMF treatment group,the Cd concentration in the rice roots was significantly higher(19.1%‒68.0%)compared with that in the control group.Conversely,the Cd concentration in the rice seeds was lower in the AMF treatment group,indicating that AMF facilitated the sequestration of Cd in rice roots and reduced Cd accumulation in the seeds.Path coefficients varied across different treatments,suggesting that AMF inoculation reduced the direct impact of soil Cd concentration on the total Cd accumulation in seeds.The translocation of Cd was consistently associated with simultaneous growth dilution and compensatory accumulation as a result of mycorrhizal effects.Our study quantitatively analyzed this process through path analysis and clarified the causal relationship between rice growth and Cd transfer under the influence of AMF. 展开更多
关键词 cadmium transfer dilution effect heavy metal immobilization mycorrhizal effect path analysis phenotypic plasticity
下载PDF
Lagrangian coherent structure analysis on transport of Acetes chinensis along coast of Lianyungang,China 被引量:1
19
作者 Kexin WANG Xueqing ZHANG +2 位作者 Qi LOU Xusheng XIANG Ying XIONG 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2024年第1期345-359,共15页
Spatial heterogeneity or“patchiness”of plankton distributions in the ocean has always been an attractive and challenging scientific issue to oceanographers.We focused on the accumulation and dynamic mechanism of the... Spatial heterogeneity or“patchiness”of plankton distributions in the ocean has always been an attractive and challenging scientific issue to oceanographers.We focused on the accumulation and dynamic mechanism of the Acetes chinensis in the Lianyungang nearshore licensed fishing area.The Lagrangian frame approaches including the Lagrangian coherent structures theory,Lagrangian residual current,and Lagrangian particle-tracking model were applied to find the transport pathways and aggregation characteristics of Acetes chinensis.There exist some material transport pathways for Acetes chinensis passing through the licensed fishing area,and Acetes chinensis is easy to accumulate in the licensed fishing area.The main mechanism forming this distribution pattern is the local circulation induced by the nonlinear interaction of topography and tidal flow.Both the Lagrangian coherent structure analysis and the particle trajectory tracking indicate that Acetes chinensis in the licensed fishing area come from the nearshore estuary.This work contributed to the adjustment of licensed fishing area and the efficient utilization of fishery resources. 展开更多
关键词 plankton accumulation hydrodynamic model Lagrangian particle-tracking model Lagrangian analysis
下载PDF
Iron and ferritin effects on intensive care unit mortality:A metaanalysis 被引量:1
20
作者 Deng-Can Yang Bo-Jun Zheng +1 位作者 Jian Li Yi Yu 《World Journal of Clinical Cases》 SCIE 2024年第16期2803-2812,共10页
BACKGROUND The effect of serum iron or ferritin parameters on mortality among critically ill patients is not well characterized.AIM To determine the association between serum iron or ferritin parameters and mortality ... BACKGROUND The effect of serum iron or ferritin parameters on mortality among critically ill patients is not well characterized.AIM To determine the association between serum iron or ferritin parameters and mortality among critically ill patients.METHODS Web of Science,Embase,PubMed,and Cochrane Library databases were searched for studies on serum iron or ferritin parameters and mortality among critically ill patients.Two reviewers independently assessed,selected,and abstracted data from studies reporting on serum iron or ferritin parameters and mortality among critically ill patients.Data on serum iron or ferritin levels,mortality,and demographics were extracted.RESULTS Nineteen studies comprising 125490 patients were eligible for inclusion.We observed a slight negative effect of serum ferritin on mortality in the United States population[relative risk(RR)1.002;95%CI:1.002-1.004].In patients with sepsis,serum iron had a significant negative effect on mortality(RR=1.567;95%CI:1.208-1.925).CONCLUSION This systematic review presents evidence of a negative correlation between serum iron levels and mortality among patients with sepsis.Furthermore,it reveals a minor yet adverse impact of serum ferritin on mortality among the United States population. 展开更多
关键词 IRON FERRITIN MORTALITY Critically ill Meta analysis
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部