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Linkage between precipitation isotopes and water vapor sources in the monsoon margin:Evidence from arid areas of Northwest China
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作者 CHEN Fenli ZHANG Qiuyan +3 位作者 WANG Shengjie CHEN Jufan GAO Minyan Mohd Aadil BHAT 《Journal of Arid Land》 SCIE CSCD 2024年第3期355-372,共18页
The isotope composition in precipitation has been widely considered as a tracer of monsoon activity.Compared with the coastal region,the monsoon margin usually has limited precipitation with large fluctuation and is u... The isotope composition in precipitation has been widely considered as a tracer of monsoon activity.Compared with the coastal region,the monsoon margin usually has limited precipitation with large fluctuation and is usually sensitive to climate change.The water resource management in the monsoon margin should be better planned by understanding the composition of precipitation isotope and its influencing factors.In this study,the precipitation samples were collected at five sampling sites(Baiyin City,Kongtong District,Maqu County,Wudu District,and Yinchuan City)of the monsoon margin in the northwest of China in 2022 to analyze the characteristics of stable hydrogen(δD)and oxygen(δ18O)isotopes.We analyzed the impact of meteorological factors(temperature,precipitation,and relative humidity)on the composition of precipitation isotope at daily level by regression analysis,utilized the Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)-based backward trajectory model to simulate the air mass trajectory of precipitation events,and adopted the potential source contribution function(PSCF)and concentration weighted trajectory(CWT)to analyze the water vapor sources.The results showed that compared with the global meteoric water line(GMWL),the slope of the local meteoric water line(LMWL;δD=7.34δ^(18)O-1.16)was lower,indicating the existence of strong regional evaporation in the study area.Temperature significantly contributed toδ18O value,while relative humidity had a significant negative effect onδ18O value.Through the backward trajectory analysis,we found eight primary locations that were responsible for the water vapor sources of precipitation in the study area,of which moisture from the Indian Ocean to South China Sea(ITSC)and the western continental(CW)had the greatest influence on precipitation in the study area.The hydrogen and oxygen isotopes in precipitation are significantly influenced by the sources and transportation paths of air mass.In addition,the results of PSCF and CWT analysis showed that the water vapor source areas were primarily distributed in the south and northwest direction of the study area. 展开更多
关键词 water vapor monsoon margin stable water isotope transport trajectory air mass d-excess Δ18O δd
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Evaporative enrichment of stable isotopes(δ^(18)O and δD) in lake water and the relation to lake-level change of Lake Qinghai, Northeast Tibetan Plateau of China 被引量:4
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作者 WU Huawu LI Xiaoyan +3 位作者 LI Jing JIANG Zhiyun LI Guangyong LIU Lei 《Journal of Arid Land》 SCIE CSCD 2015年第5期623-635,共13页
Stable isotopic compositions (δ18O and 6D) have been utilized as a useful indicator for evaluating the current and historical climatic and environmental changes. Therefore, it is vital to understand the relationshi... Stable isotopic compositions (δ18O and 6D) have been utilized as a useful indicator for evaluating the current and historical climatic and environmental changes. Therefore, it is vital to understand the relationship be- tween the stable isotopic contents in lake water and the variations of lake level, particularly in Lake Qinghai, China. In this study, we analyzed the variations of isotope compositions (δ18O, 6D and d-excess) in lake water and pre- cipitation by using the samples that were collected from Lake Qinghai region during the period from 2009 to 2012. The results showed that the average isotopic contents of δ18O and 6D in lake water were higher than those in pre- cipitation, which were contrary to the variations of d-excess. The linear regression correlations between δ18O and 6D in lake water and precipitation showed that the local evaporative line (LEL) in lake water (δD=5.88δ18O-2.41) deviated significantly from the local meteoric water line (LMWL)in precipitation (δD=8.26δ18O+16.91), indicating that evaporative enrichment had a significant impact on isotopic contents in lake water. Moreover, we also quanti- fied the Eli ratio (evaporation-to-input ratio) in Lake Qinghai based on the lake water isotopic enrichment model derived from the Rayleigh equation. The changes of E/I ratios (ranging from 0.29 to 0.36 between 2009 and 2012) clearly revealed the shifts of lake levels in Lake Qinghai in recent years. The average E/I ratio of 0.40 reflected that water budget in Lake Qinghai was positive, and consistent with the rising lake levels and the increasing lake areas in many lakes of the Tibetan Plateau. These findings provide some evidences for studying the hydrological balance or water budget by using δ18O values of lake sedimentary materials and contribute to the reconstruction of paleo- lake water level and paleoclimate from an isotopic enrichment model in Lake Qinghai. 展开更多
关键词 stable isotopes d-excess lake level E/I ratio isotopic enrichment model PALEOCLIMATE
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超声血流参数、D-二聚体手术前后变化及复合模型在创伤骨折患者下肢DVT预警中的应用价值 被引量:1
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作者 王蕾 路鑫铭 《临床误诊误治》 CAS 2024年第5期55-60,共6页
目的探究超声血流参数[收缩期峰值血流速度(Vs)、舒张末期血流速度(Vd)、阻力指数(RI)]、D-二聚体手术前后变化及复合模型在创伤骨折患者下肢深静脉血栓形成(DVT)预警中的应用价值。方法选取2021年7月—2023年7月收治的创伤骨折200例,... 目的探究超声血流参数[收缩期峰值血流速度(Vs)、舒张末期血流速度(Vd)、阻力指数(RI)]、D-二聚体手术前后变化及复合模型在创伤骨折患者下肢深静脉血栓形成(DVT)预警中的应用价值。方法选取2021年7月—2023年7月收治的创伤骨折200例,根据术后是否发生下肢DVT分为发生组25例与未发生组175例。收集2组基线资料及手术前后Vs、Vd、RI、D-二聚体数据,根据创伤骨折患者术后下肢DVT发生影响因素构建预测复合模型,评估Vs、Vd、RI、D-二聚体手术前后差值联合及复合模型对创伤骨折患者术后下肢DVT发生的预测价值。绘制决策曲线分析(DCA),分析超声血流参数、D-二聚体与复合模型预测创伤骨折患者术后下肢DVT发生的获益情况。结果发生组手术时间长于未发生组,术中使用止血带比例高于未发生组(P<0.01);发生组术后3 d Vs、Vd低于未发生组,RI、D-二聚体高于未发生组(P<0.01);发生组Vs、Vd、RI及D-二聚体手术前后差值均大于未发生组(P<0.01);多因素Logistic回归分析显示,手术时间、术中使用止血带及Vs、Vd、RI、D-二聚体手术前后差值为创伤骨折患者术后下肢DVT发生的独立危险因素(P<0.01);以Vs、Vd、RI、D-二聚体手术前后差值联合预测下肢DVT的曲线下面积(AUC)为0.882(95%CI:0.829,0.923),敏感度、特异度均为0.88。构建下肢DVT预测模型,其AUC为0.920(95%CI:0.873,0.954);DCA显示,复合模型在阈值概率为0.10~0.90时具有更高的临床价值。结论手术时间、术中使用止血带及Vs、Vd、RI、D-二聚体手术前后差值为创伤骨折患者术后下肢DVT发生的独立危险因素;与Vs、Vd、RI、D-二聚体手术前后差值相比,多指标联合建立的复合模型在创伤骨折术后下肢DVT早期预警中应用价值更高。 展开更多
关键词 深静脉血栓形成 下肢 创伤与损伤 骨折 收缩期峰值血流速度 阻力指数 舒张末期血流速度 d-二聚体
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The Deconvolution Method for Obtaining Correspondence in Data-Independent Acquisition Mass Spectrometry Data
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作者 Mingming Lyu Xinye Bian Changjiu He 《Journal of Computer and Communications》 2024年第2期11-25,共15页
Although data-independent acquisition (DIA) shows powerful potential in achieving comprehensive peptide information acquisition, the difficulty in determining the precursor m/z and distinguishing fragment ions has pos... Although data-independent acquisition (DIA) shows powerful potential in achieving comprehensive peptide information acquisition, the difficulty in determining the precursor m/z and distinguishing fragment ions has posed challenges in DIA data analysis. To address this challenge, a common approach is to recover the correspondence between precursor ions and fragment ions, followed by peptide identification using traditional data-dependent acquisition (DDA) database searching. In this study, we propose a cosine similarity-based deconvolution method that rapidly establishes the correspondence between chromatographic profiles of precursor ions and fragment ions through matrix calculations. Experimental results demonstrate that our method, referred to as CosDIA, yields a peptide identification count close to that of DIA-umpire. However, compared to DIA-umpire, we can establish the correspondence between original MS/MS spectra and pseudo-MS/MS spectra. Furthermore, compared to the CorrDIA method, our approach achieves higher efficiency in terms of time, reducing the time cost of the analysis process. These results highlight the potential advantages of the CosDIA method in DIA data analysis, providing a powerful tool and method for large-scale proteomics research. 展开更多
关键词 MS/MS Spectra XICs CORRESPONdENCE Matrix isotopic peak Cluster
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The O and H isotope characteristics of water from major rivers in China 被引量:5
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作者 Si-Liang Li Fu-Jun Yue +3 位作者 Cong-Qiang Liu Hu Ding Zhi-Qi Zhao Xiaodong Li 《Chinese Journal Of Geochemistry》 EI CAS CSCD 2015年第1期28-37,共10页
Isotopic compositions of the water sources and evapotranspiration in large rivers of China are not well explored. In this investigation, d18 O and dD values of water from major large rivers of China are integrated to ... Isotopic compositions of the water sources and evapotranspiration in large rivers of China are not well explored. In this investigation, d18 O and dD values of water from major large rivers of China are integrated to understand the spatial and temporal variations in the isotopes of water and d-excess. River water samples were collected from the channels and tributaries of the Changjiang, Yellow, Songhua and Liao Rivers in China. Water from upstream was generally enriched with light isotopes relative to that from downstream areas. Water from the Songhua River and upper reach of the Changjiang River has relatively negative isotopic values impacted by latitude and altitude effects, respectively. The spatial pattern showed that d18O-H2 O values in rivers mainly ranged from-9 to-7 % in most of China based on roughly mapped contours, and rivers enriched in light isotopes were primarily located in the Tibetan Plateau and northeast China The slopes of linear regression from the Yellow and Liao Rivers suggested that the loss of water by direct evaporation shifted the isotopes of water, especially in some small tributaries. Additionally, there was a narrow range of low d18OH2 O values from the main channel of rivers during the lowflow season relative to the high-flow season due to influence of the monsoon climate. No distinct spatial variation of d-excess values was found in the rivers of China. However, water samples in some rivers with low d-excess values had high d18 O values, indicating that evaporation in the tributaries has led to significant water loss, especially in tributaries of the Yellow and Liao Rivers. 展开更多
关键词 中国东北地区 同位素特征 河流 水源 长江上游 蒸发损失 同位素组成 时空变化
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Hydrogen isotopic composition of plant leaf wax in response to soil moisture in an arid ecosystem of the northeast Qinghai-Tibetan Plateau, China 被引量:4
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作者 Yuan YAO WeiGuo LIU 《Journal of Arid Land》 SCIE CSCD 2014年第5期592-600,共9页
The hydrogen isotopic composition of plant leaf wax(δDwax) is used as an important tool for paleohydrologic reconstruction. However, the understanding of the relative importance of environmental and biological fact... The hydrogen isotopic composition of plant leaf wax(δDwax) is used as an important tool for paleohydrologic reconstruction. However, the understanding of the relative importance of environmental and biological factors in determining δDwax values still remains incomplete. To identify the effects of soil moisture and plant physiology on δDwax values in an arid ecosystem, and to explore the implication of these values for paleoclimatic reconstruction, we measured δD values of soil water(δDwater) and δDwax values in surface soils along two distance transects extending from the lakeshore to wetland to dryland around Lake Qinghai and Lake Gahai on the northeast Qinghai-Tibetan Plateau. The results showed that the δDwater values were negatively correlated with soil water content(SWC)(R^2=0.9166), and ranged from –67‰ to –46‰ with changes in SWC from 6.2% to 42.1% in the arid areas of the Gangcha(GCh) and Gahai(GH) transects. This indicated that evaporative D-enrichment in soil water was sensitive to soil moisture in an arid ecosystem. Although the shift from grasses to shrubs with increasing aridity occurred in the arid area of the GH transect, the δDwax values in surface soils from the arid areas of the two transects still showed a negative correlation with SWC(R^2=0.6835), which may be due to the controls of primary evaporative D-enrichment in the soil water and additional transpirational D-enrichment in the leaf water on the δDwaxvalues. Our preliminary research suggested that δDwax values can potentially be applied as a paleo-humidity indicator on the northeast Qinghai-Tibetan Plateau. 展开更多
关键词 hydrogen isotope d-enrichment soil water content northeast Qinghai-Tibetan Plateau
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Investigation of isotope effects of dynamic properties for H(D) + OF reactions by the quasi-classical trajectory method
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作者 赵娟 许燕 孟庆田 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第6期272-276,共5页
Quasi-classical trajectory (QCT) calculations are employed to study the dynamic properties for H(D)+OF reactions on the adiabatic potential energy surface (PES) of the 1^3A″ triplet state. Obvious differences ... Quasi-classical trajectory (QCT) calculations are employed to study the dynamic properties for H(D)+OF reactions on the adiabatic potential energy surface (PES) of the 1^3A″ triplet state. Obvious differences between the reaction probabilities for J=0, integral cross sections for J≠0, branch ratios of the product and internuclear distances as well as product rotational alignments between the title reactions axe found. These differences are attributed mainly to the different reduced masses of the reactants and the different zero-point energies (ZPEs) of the transition state. 展开更多
关键词 isotope effects H(d)+OF reactions quasi-classical trajectory
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Shear behavior of intact granite under thermo-mechanical coupling and three-dimensional morphology of shear-formed fractures 被引量:1
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作者 Bing Chen Baotang Shen Haiyang Jiang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第3期523-537,共15页
The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear... The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear-formed fractures are prone to secondary instability,posing a severe threat to deep engineering.Although numerous studies regarding three-dimensional(3D)morphologies of fracture surfaces have been conducted,the understanding of shear-formed fractures under TM coupling conditions is limited.In this study,direct shear tests of intact granite under various TM coupling conditions were conducted,followed by 3D laser scanning tests of shear-formed fractures.Test results demonstrated that the peak shear strength of intact granite is positively correlated with the normal stress,whereas it is negatively correlated with the temperature.The internal friction angle and cohesion of intact granite significantly decrease with an increase in the temperature.The anisotropy,roughness value,and height of the asperities on the fracture surfaces are reduced as the normal stress increases,whereas their variation trends are the opposite as the temperature increases.The macroscopic failure mode of intact granite under TM coupling conditions is dominated by mixed tensileeshear and shear failures.As the normal stress increases,intragranular fractures are developed ranging from a local to a global distribution,and the macroscopic failure mode of intact granite changes from mixed tensileeshear to shear failure.Finally,3D morphological characteristics of the asperities on the shear-formed fracture surfaces were analyzed,and a quadrangular pyramid conceptual model representing these asperities was proposed and sufficiently verified. 展开更多
关键词 Thermo-mechanical(TM)coupling peak shear strength Three-dimensional(3d)morphological characterization Failure mode Quadrangular pyramid model
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陕西北洛河流域地下水水化学和同位素特征及其水质评价 被引量:3
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作者 周殷竹 马涛 +4 位作者 袁磊 李甫成 韩双宝 周金龙 李勇 《中国地质》 CAS CSCD 北大核心 2024年第2期663-675,共13页
【研究目的】北洛河是黄河的重要二级支流,研究该流域典型支流地下水的水质状况对于黄河流域生态保护和高质量发展具有重要意义。【研究方法】本文以北洛河流域为主要对象,系统查明流域地下水水质现状,圈定劣质地下水分布区,为饮水安全... 【研究目的】北洛河是黄河的重要二级支流,研究该流域典型支流地下水的水质状况对于黄河流域生态保护和高质量发展具有重要意义。【研究方法】本文以北洛河流域为主要对象,系统查明流域地下水水质现状,圈定劣质地下水分布区,为饮水安全提供保障。此外,对该区地下水水化学和D-18O同位素组成进行分析,研究地下水水化学特征及演化机制,揭示水文地质条件及人为因素对区域地下水水文地球化学特征的控制和影响作用。【研究结果】区内地下水水化学成分除受岩石风化和蒸发浓缩作用的共同控制之外,部分还受到人类活动的影响。D-18O同位素组成指示了地下水整体上受蒸发浓缩作用影响。【结论】上游碎屑岩中的石膏、盐岩等易溶矿物经溶滤进入地下水,下游松散孔隙水在蒸发浓缩的作用下积聚盐分导致上、下游地下水TDS较高;奥陶系岩溶含水岩组和新生界断陷盆地含水岩组地下水水化学组成主要受蒸发盐岩影响,此外还受到人类活动的影响。白垩系和石炭系—侏罗系含水岩组地下水主要分布于岩石风化区,说明该地下水水化学组分主要受岩石风化作用控制,且主要受硅酸盐岩和蒸发盐岩风化影响,人类活动影响的扰动相对较小。上、下游地区地下水受工矿活动影响较严重,中游地下水受工矿活动、农业活动、生活污水影响均较小,水质整体较好。 展开更多
关键词 水化学 d-18O同位素 地下水水质评价 北洛河流域 水文地质调查工程 陕西
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喀斯特峰丛洼地3个建群树种“植物-凋落物-土壤”系统氮同位素特征 被引量:1
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作者 吴凤婵 蔡国俊 +3 位作者 李安定 张红玉 张丽敏 彭熙 《贵州师范大学学报(自然科学版)》 CAS 北大核心 2024年第1期12-18,共7页
以喀斯特峰丛洼地3种常见次生林及其建群树种为研究对象,测定3种林分建群种的不同器官及凋落物、土壤的氮含量及氮同位素丰度值(δ^(15)N),探讨植物-凋落物-土壤氮含量及稳定氮同位素组成变化及内在联系。结果显示:3种次生林建群种植物... 以喀斯特峰丛洼地3种常见次生林及其建群树种为研究对象,测定3种林分建群种的不同器官及凋落物、土壤的氮含量及氮同位素丰度值(δ^(15)N),探讨植物-凋落物-土壤氮含量及稳定氮同位素组成变化及内在联系。结果显示:3种次生林建群种植物中叶片氮含量最高,茎的氮含量最低,3种次生林建群树种叶片氮含量均显著高于掉落物和土壤氮含量,0~30 cm土壤氮含量显著高于30~90 cm土壤氮含量,土壤养分主要集中于表层土壤;白栎、栓皮栎和光皮桦器官中δ^(15)N变化范围分别为-2.82‰~14.94‰、-1.37‰~9.35‰和-4.39‰~26.06‰,3种建群种器官间氮同位素组成均表现出显著差异(P<0.05);3种建群种群落表层土壤δ^(15)N差异显著,3种林分中0~30 cm土壤δ^(15)N均显著低于30~60 cm和60~90 cm的土壤,δ^(15)N可能是这些群落土壤氮循环过程中的敏感指标,光皮桦叶片氮含量略大于白栎和栓皮栎,光皮桦林土壤表层δ^(15)N大于白栎林和栓皮栎林,光皮桦可能比白栎和栓皮栎更为适应喀斯特生境。 展开更多
关键词 氮同位素 植物-凋落物-土壤 生态策略 适应机制 喀斯特峰丛洼地
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创新要素错配对碳排放效率的影响——基于空间溢出效应视角的研究
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作者 田泽 徐兴武 +1 位作者 张瀚亓 任阳军 《科技管理研究》 CSSCI 2024年第14期205-213,共9页
合理配置创新要素、不断提高碳排放效率是中国在加快实现“双碳”目标过程中亟须解决的现实问题,而相关研究对其可能存在的空间效应的讨论相对不足。从理论层面剖析创新要素错配对碳排放效率的影响机制和空间溢出效应,将要素错配以一种... 合理配置创新要素、不断提高碳排放效率是中国在加快实现“双碳”目标过程中亟须解决的现实问题,而相关研究对其可能存在的空间效应的讨论相对不足。从理论层面剖析创新要素错配对碳排放效率的影响机制和空间溢出效应,将要素错配以一种扭曲税的形式表现,从投入产出视角通过超效率SBM模型测度碳排放效率,通过全要素生产率离散度法和数据包络分析法构建创新要素错配和碳排放效率的测度框架,基于2012—2021年中国30个省份的面板数据,利用空间杜宾模型、空间自相关检验方法实证检验创新要素错配对碳排放效率的影响及空间溢出效应,并将30个省份划为五大区域展开异质性分析。结果发现:创新要素错配显著抑制本地区碳排放效率提升并对空间关联地区的碳排放效率产生不利影响;创新要素错配对碳排放效率的影响存在地区异质性,中部和西南地区创新要素错配对本地区碳排放效率起到抑制作用,而东部和东北、西北地区的影响不明显;五大地区创新要素错配对空间关联地区的碳排放效率均起到抑制作用。据此,提出不断优化创新要素市场配置机制、有效鼓励企业开展低碳技术创新和应用、形成区域创新合力等助力中国碳排放效率提升的政策建议。 展开更多
关键词 创新要素错配 R&d资源配置 碳排放效率 空间溢出效应 全要素生产率离散度 低碳技术 区域创新 “双碳”目标
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新疆三工河流域土壤水δD和δ^(18)O特征及其补给来源 被引量:11
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作者 孙芳强 尹立河 +4 位作者 马洪云 张俊 王晓勇 王化齐 郭莉 《干旱区地理》 CSCD 北大核心 2016年第6期1298-1304,共7页
采用环境同位素示踪技术研究旱区不同土地利用类型下的土壤水来源与运移机理,通过以新疆三工河流域为研究区,对三工河流域四个土壤剖面分层采集了不同土地利用类型的土壤水,测定了其稳定同位素(δD、δ^(18)O)的含量,分析了非饱和带土... 采用环境同位素示踪技术研究旱区不同土地利用类型下的土壤水来源与运移机理,通过以新疆三工河流域为研究区,对三工河流域四个土壤剖面分层采集了不同土地利用类型的土壤水,测定了其稳定同位素(δD、δ^(18)O)的含量,分析了非饱和带土壤水稳定同位素沿土壤剖面的垂向变化规律。结果表明:区内非饱和带中的土壤水在入渗的同时经历了明显的混合作用,荒地土壤水比耕地受蒸发作用影响更强烈,荒地蒸发影响深度为1.2~1.6 m,耕地蒸发影响深度为0.8~1.2m;荒地与耕地土壤水中氢氧同位素在垂向上呈现旋回变化,每个旋回经历了一次新水入渗补给的过程,即新水入渗与土壤老水混合-土壤水氢氧同位素逐渐变小直到贫化极值-地表入渗补给结束,土壤水向下运移并逐渐与土壤老水混合同时受蒸发作用-同位素逐渐富集直到土壤老水本底值;耕地土壤剖面补给水δD值为-112.93‰^-102.58‰,荒地土壤剖面补给水δD值为-111.07‰^-94.44‰,比地下水、地表水同位素值更贫化,可见土壤水中的补给水主要来源于大气降水;灌溉水入渗地表后,在强烈的蒸发作用下,很难向非饱和带深部运移对地下水补给,节水灌溉方式改变了绿洲内土壤水入渗补给机制。研究结论为进一步厘定绿洲内垂向补给量,准确评价三工河流域水资源量提供重要依据。 展开更多
关键词 非饱和带 三工河流域 氢氧同位素 δd峰值
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黑河下游不同林龄胡杨水分来源的D、^(18)O同位素示踪 被引量:22
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作者 刘树宝 陈亚宁 +2 位作者 李卫红 陈亚鹏 任志国 《干旱区地理》 CSCD 北大核心 2014年第5期988-995,共8页
对黑河下游不同林龄胡杨木质部水及其不同潜在水源稳定同位素组成(δD、δ18O)的测定分析,探讨不同潜在水源对胡杨的贡献。结果表明:(1)不同林龄胡杨木质部δ18O差异显著,胡杨幼苗、成熟木、过熟木的δ18O值分别为-5.368 14‰、-6.032 7... 对黑河下游不同林龄胡杨木质部水及其不同潜在水源稳定同位素组成(δD、δ18O)的测定分析,探讨不同潜在水源对胡杨的贡献。结果表明:(1)不同林龄胡杨木质部δ18O差异显著,胡杨幼苗、成熟木、过熟木的δ18O值分别为-5.368 14‰、-6.032 75‰和-6.924 18‰;(2)不同林龄胡杨所利用的水分来源不同,胡杨幼苗主要利用30~50 cm的土壤水,利用率在70%左右,对地下水的利用仅为6%;成熟木主要利用200~220 cm的土壤水及地下水,对地下水的利用最多达85%;胡杨过熟木主要利用100~260 cm的土壤水及地下水,深度范围较幼苗和成熟木都广,对地下水的利用较高,最多达96%,胡杨成熟木和过熟木主要利用的是地下水。 展开更多
关键词 水分来源 不同林龄胡杨 氢、氧同位素 黑河
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MC-ICP-MS法测量铀同位素丰度UH峰校正方法研究
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作者 谢卫华 靳姗 +2 位作者 陈禄敏 许杰 张海路 《核电子学与探测技术》 CAS 北大核心 2024年第6期984-989,共6页
由于多接收电感耦合等离子体质谱(MC-ICP-MS)法具有基体耐受性强、精密度高和仪器测量快速的优点,使得采用MC-ICP-MS法分析铀同位素丰度的应用越来越广泛。但是,在MC-ICP-MS法测量铀同位素丰度的分析中,水溶液进样会产生UH多原子离子,... 由于多接收电感耦合等离子体质谱(MC-ICP-MS)法具有基体耐受性强、精密度高和仪器测量快速的优点,使得采用MC-ICP-MS法分析铀同位素丰度的应用越来越广泛。但是,在MC-ICP-MS法测量铀同位素丰度的分析中,水溶液进样会产生UH多原子离子,而伴随^(235)U^(+)产生的极微量^(235)UH^(+),在质荷比(m/Z)为236处与^(236)U^(+)形成质量双峰,这对于小丰度^(236)U的准确测量会产生干扰,影响^(236)U丰度测量的准确性。本文建立了针对小丰度^(236)U准确测定的UH校正方法,采用该校正方法测量铀同位素丰度,n(^(236)U)/n(^(235)U)丰度比测定下限为4×10^(-6),测量n(^(236)U)/n(^(235)U)丰度比为2.20×10^(-5)的样品时,相对传统热电离质谱法(TIMS)误差小于3×10^(-6),相对标准偏差小于4%。 展开更多
关键词 ^(236)U 同位素丰度比 UH峰校正
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川东北宋家洞高分辨率石笋δ^(13)C记录与D/O事件5-1 被引量:9
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作者 刘淑华 杨亮 +5 位作者 黄嘉仪 陈琳 陈琼 米小建 贺海波 周厚云 《地球化学》 CAS CSCD 北大核心 2015年第5期413-420,共8页
基于川东北宋家洞石笋SJ1的399个稳定碳同位素组成(δ13C)数据建立了末次冰期中晚期(14~43 ka)高分辨率δ13C时间序列。SJ1的δ13C变化与已发表的该石笋稳定氧同位素组成(δ18O)变化趋势非常一致,清晰地记录了该地区植被对D/O事件5-10... 基于川东北宋家洞石笋SJ1的399个稳定碳同位素组成(δ13C)数据建立了末次冰期中晚期(14~43 ka)高分辨率δ13C时间序列。SJ1的δ13C变化与已发表的该石笋稳定氧同位素组成(δ18O)变化趋势非常一致,清晰地记录了该地区植被对D/O事件5-10的敏感响应。东亚夏季风气候控制的地表植被(包括C3和C4植被比例C3/C4变化和植被密度变化)和土壤微生物活动变化可能是影响SJ1的δ13C变化的主要因素。在这些D/O事件发生时δ13C变轻,指示了C3/C4植被比例上升和植被密度增加。此外,受降水控制的岩溶地下水流速影响的水-岩相互作用,石笋表面滴水时间间隔、洞穴空气的CO2分压和洞穴通风效应等因素影响的CO2脱气作用和先期碳酸盐沉积也可能对SJ1的δ13C变化产生了影响。 展开更多
关键词 末次冰期中晚期 石笋 碳同位素 d/O事件 川东北
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应用D、^(18)O同位素峰值位移法求解大气降水入渗补给量 被引量:6
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作者 王福刚 廖资生 《吉林大学学报(地球科学版)》 EI CAS CSCD 北大核心 2007年第2期284-287,334,共5页
采用D、18O同位素峰值位移法求出研究区大气降水入渗补给量。通过野外地中渗透计法和降水入渗系数法对同位素法计算结果检验,发现D、18O同位素法计算结果具有较高精度,同时验证了在研究区用D、18O同位素方法求大气降水入渗补给量是可行... 采用D、18O同位素峰值位移法求出研究区大气降水入渗补给量。通过野外地中渗透计法和降水入渗系数法对同位素法计算结果检验,发现D、18O同位素法计算结果具有较高精度,同时验证了在研究区用D、18O同位素方法求大气降水入渗补给量是可行和可靠的。用该方法求解大气降水入渗补给量具有方便快捷、经济省时的优点,在湿润、半湿润地区大气降水补给研究方面,具有很大的应用潜力和重要的应用价值。 展开更多
关键词 降水 入渗补给 同位素峰值位移法 地下水
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裸露型岩溶区人类活动输入对地下河水化学的影响
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作者 王荷英 吴贻创 +3 位作者 杨应增 何守阳 吴攀 罗维 《地球与环境》 CAS CSCD 北大核心 2024年第4期466-478,共13页
地下河是西南岩溶水的重要赋存形式,在区域人畜供水中发挥重要作用,裸露型岩溶区因其特殊水文地质结构,地下河易受到人类活动输入的影响。利用水文地球化学分析、水化学演化图(Hydrochemical Facies Evolution Diagram,HFE-D)、环境同... 地下河是西南岩溶水的重要赋存形式,在区域人畜供水中发挥重要作用,裸露型岩溶区因其特殊水文地质结构,地下河易受到人类活动输入的影响。利用水文地球化学分析、水化学演化图(Hydrochemical Facies Evolution Diagram,HFE-D)、环境同位素辨析等多手段研究人类活动输入对开阳地下河水化学的影响。结果表明:阴阳主要离子分别是HCO_(3)^(-)、SO_(4)^(2-)和Ca^(2+)、Mg^(2+),水化学类型为HCO_(3)-Ca·Mg,主要受控于岩石风化控制,但地下河系统中SO_(4)^(2-)、NO_(3)^(-)及Cl^(-)受到南部县城、垃圾填埋场和渣场输入的影响。HFE-D发现地下河下游始终处于受影响状态,δ^(34) S-SO_(4)^(2-)同位素表明SO_(4)^(2-)主要来源生活污水输入(71%),其次是大气降雨(22%)。δ^(15) N-NO_(3)^(-)-δ^(18) O-NO_(3)^(-)同位素计算显示NO_(3)^(-)主要来源于污水排放(42%)、大气降雨(37%)和农业输入(21%),地下河系统的开放性不利于氮素的反硝化降解。 展开更多
关键词 裸露岩溶地下河 水化学 水化学相演化图 环境同位素 人类活动
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谱图准确度在高分辨飞行时间质谱分析硝铵类有机炸药RDX中的应用 被引量:2
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作者 刘占芳 孙玉友 +4 位作者 周红 吴郑家男 李斌 徐建中 乔婷 《理化检验(化学分册)》 CAS CSCD 北大核心 2015年第4期466-469,共4页
应用实时直接分析-高分辨飞行时间质谱(DART-HR-TOFMS)对硝胺类有机炸药黑索金(RDX)及其爆炸残留物进行精确质量质谱分析,借助MassWorks质谱解析软件对质谱数据进行了噪音过滤及峰形校正处理,获得了炸药准确的同位素分布模式,然后通过... 应用实时直接分析-高分辨飞行时间质谱(DART-HR-TOFMS)对硝胺类有机炸药黑索金(RDX)及其爆炸残留物进行精确质量质谱分析,借助MassWorks质谱解析软件对质谱数据进行了噪音过滤及峰形校正处理,获得了炸药准确的同位素分布模式,然后通过实际同位素分布模式的校正峰形与理论峰形匹配的谱图准确度对待选的分子式进行排序,实现了RDX的准确识别和鉴定。 展开更多
关键词 实时直接分析-高分辨飞行时间质谱 谱图准确度 黑索金 同位素峰形
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D-二聚体在评估下肢深静脉血栓形成溶栓效果中的价值 被引量:7
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作者 李俊涛 潘扬 +1 位作者 姜庆 袁平 《贵州医科大学学报》 CAS 2017年第2期205-208,共4页
目的:观察下肢深静脉血栓形成(DVT)患者在溶栓过程中D-二聚体(DD)的达峰速度,探讨DD的达峰速度与溶栓效果的关系。方法:41例DVT患者分为系统溶栓组和导管接触性溶栓组,观察两组患者的DD峰值、达峰速度及疗效,采用Pearson法分析DD达峰速... 目的:观察下肢深静脉血栓形成(DVT)患者在溶栓过程中D-二聚体(DD)的达峰速度,探讨DD的达峰速度与溶栓效果的关系。方法:41例DVT患者分为系统溶栓组和导管接触性溶栓组,观察两组患者的DD峰值、达峰速度及疗效,采用Pearson法分析DD达峰速度与血栓溶栓率及下肢消肿率的相关性。结果:两组都在溶栓治疗后的第2天DD达峰值,但导管接触性溶栓组DD峰值及达峰速度明显高于系统溶栓组,导管接触性溶栓组溶栓治疗显效率亦高于系统溶栓组(P<0.01);相关性分析显示,DD的达峰速度分别与静脉通畅、大小腿消肿率呈正相关(r=0.912、0.85、0.86,P<0.01)。结论:可通过监测DD的达峰速度简单评估溶栓效果,导管接触性溶栓临床疗效优于系统溶栓。 展开更多
关键词 静脉血栓形成 d-二聚体 溶栓 达峰速度 治疗效果
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雷暴云准静电场对夜间电离层D区的影响 被引量:3
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作者 黄文耿 古士芬 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2003年第2期162-166,共5页
利用一个自洽的准静电场 (QE)模型 ,计算了雷暴云电荷突然对地放电后QE场大小在 0~ 90km高度上的分布 .对 2 0 0C的正电荷对地放电后的计算表明 ,在放电 1ms后 ,在 6 5~ 78km的区域内 ,QE场大于大气的雪崩电场 ,而 0 .5s后 ,该电场迅... 利用一个自洽的准静电场 (QE)模型 ,计算了雷暴云电荷突然对地放电后QE场大小在 0~ 90km高度上的分布 .对 2 0 0C的正电荷对地放电后的计算表明 ,在放电 1ms后 ,在 6 5~ 78km的区域内 ,QE场大于大气的雪崩电场 ,而 0 .5s后 ,该电场迅速衰减到很低的水平 .在电离层高度上 ,由于电子的热化时标和电离时标极短 ,在QE场的作用下 ,夜间局部低电离层会有比较大的响应 .对Boltzmann方程数值求解的结果表明 ,在某些高度上 ,电子分布函数有明显的高能尾巴 ;在 6 3~ 83km的高度上 ,电子平均能量为 3eV <ε <6eV ;计算的电子数密度的峰值扰动表明 ,在 6 5~ 78km的高度上 ,电子的数密度增加 ,最大的电离峰值约在 74km处 ,大约增加了 3个数量级 ,比电磁脉冲(EMP)的电离效果大得多 . 展开更多
关键词 QE场 夜间电离层 d 峰值电离
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