检索结果-南通市图书馆

Comparison of geochemical parameters derived from comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry and conventional gas chromatography-mass spectrometry

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2011年第11期54卷 1892-1901页

作者： WANG HuiTong weng na ZHANG ShuiChang ZHU GuangYou WEI CaiYun Petroleum Geology Research and Laboratory Center Institute of Petroleum Exploration ＆ Development PetroChina Beijing 100083 China Key Laboratory of Petroleum Geochemistry ofPetroChina Beijing 100083 China State Key Laboratory of Enhanced Oil Recovery R1PED PetroChina Beijing 100083 China

The saturated and aromatic hydrocarbon fractions of crude oil samples have been analyzed by using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry （GCxGC-TOFMS） and conventional gas chro- matography-mass spectrometry （GC-MS）. In order to investigate the consistency and discrepancy of the obtained data from the two instruments, some petroleum geochemical parameters have been compared. A comparison of 23 geochemical parameters indicates that 10 parameters are comparable from the two instruments with less than 5% deviations. Therefore, GCxGC-TOFMS is equivalent to conventional GC-MS in some geochemical parameter acquisitions. However, the other 13 parameters are discrepant, including gammacerane / αβ-hopane, Ts/Tm, 2-ethyl-naphthalene / 1-ethyl-naphthalene （ENR）, （2, 6-dimethyl-naphthalene ＋2,7-dimethyl-naphthalene） / 1,5-dimethyl-naphthalene （DNR）, etc. Furthermore, compared to GCxGC-TOFMS, some low concentration compounds could not be detected by the conventional GC-MS, which results in the missing of related geochemical data. Normally, this is caused by the limited separation power and peak capacity of the conventional GC column. Besides, the co-eluting peak integrations are also affected significantly due to the incomplete separation of the compounds. Some low concentration compounds might not be detected because of the interference from the baseline noise or from other substances. GCxGC-TOFMS prevails in compound separation against the conventional GC-MS by avoiding co-elution, which achieves more accurate and precise peak area measurement with the presence of a true baseline. So petroleum geochemical parameters obtained from the GCxGC-TOFMS GCxGC-TOFMS may become one of the most effective analytical are more reliable than those from the conventional GC-MS tools for the oil and gas geochemical study.

关键词： comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry gas chromatography-mass spectrometry geochemical parameters

同方期刊数据库

磁共振髓鞘探针Gd-DTDAS在多发性硬化大鼠髓鞘损伤模型中的实验研究

在线全文

学校读者我要写书评

暂无评论

磁共振成像 2024年第2期15卷 122-128页

作者：刘彩云邵翠杰翁娜李国栋黄丹琪刘珈宾莉王旭滨州医学院附属医院核医学科滨州256600 滨州医学院附属医院医学研究中心滨州256600

目的探讨MRI对比剂Gd-DTDAS在多发性硬化(multiple sclerosis,MS)大鼠髓鞘损伤模型中的应用价值。材料与方法细胞实验中,将少突胶质细胞前体细胞(oligodendrocyte precursor cells,OLN-93)随机分为对照组2(n=3)和溶血磷脂酰胆碱(lysophosphatidylcholine,LPC)组(n=3),LPC组细胞置于无菌共聚焦培养皿中与1 mL 800μM LPC溶液共孵育30 min。通过噻唑蓝比色法(methyl thiazolyl tetrazolium,MTT)评价细胞毒性,计算OLN-93与Gd-DTDAS共孵育24 h后的吸光度和存活率;细胞摄取实验中,对照组2和LPC组对比,定量两组细胞对Gd-DTDAS的摄取值以及相应荧光强度的变化。动物实验中,将6~8周龄SD大鼠随机分为对照组(n=12)与实验组(n=18),实验组大鼠左侧胼胝体注射1%LPC溶液(1%LPC溶于PBS)。造模后(1、3、7 d)进行行为学观察,并在注射后7天进行T1WI及T2WI序列扫描。根据MRI异常信号部位进行大鼠脑组织Gd-DTDAS染色(n=6)以及浸泡(n=6),评估Gd-DTDAS与髓鞘部位的结合情况,其中,染色实验分组命名为对照组3与实验组3,浸泡实验分组命名为对照组4与实验组4;通过尾静脉注射Gd-DTDAS,MR评估实验组(n=6)注射Gd-DTDAS前后大脑髓鞘变化。结果细胞毒性实验中,当Gd-DTDAS浓度增加到400μM时,OLN-93细胞的存活率约为95%,细胞存活率差异无统计学意义(t=4.20,P>0.05)。细胞摄取实验中,两组细胞均能摄取Gd-DTDAS,LPC组摄取量显著低于对照组2,差异具有统计学意义(t=31.75,P<0.01)。动物体外实验中,与对照组3比较,Gd-DTDAS染色的实验组3脑组织切片荧光强度显著下降,差异有统计学意义(U=9,P<0.01);Gd-DTDAS浸泡中,对照组4(n=6)与实验组4(n=6)脑组织切片浸泡后MRI分辨率显著升高,差异有统计学意义(对照组4,t=8.76,P<0.01)(实验组4,t=2.89,P<0.01)。体内实验中,与尾静脉注射前比较,注射后胼胝体区域MRI T1maps弛豫性显著降低(t=14.46,P<0.01)。结论髓鞘探针Gd-DTDAS能够更好地结合髓磷脂丰富的区域,髓鞘靶向MRI显像更佳,能特异性显示多发性硬化髓鞘损伤部位。

关键词：自身免疫性疾病多发性硬化髓鞘探针分子成像磁共振成像

Identification of petroleum aromatic fraction by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2010年第19期55卷 2039-2045页

作者： WANG HuiTong weng na ZHANG ShuiChang ZHU GuangYou CHEN JianPing WEI CaiYun Petroleum Geology Research and Laboratory Center Institute of Petroleum Exploration&DevelopmentPetroChinaBeijing 100083China Key Laboratory of Petroleum Geochemistry of PetroChina Beijing 100083China State key laboratory of enhanced oil recovery RIPEDPetroChinaBeijing 100083China

Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry(GC×GC-TOFMS) is commercially available in the 1990s,with the characteristics of large peak capacity,high resolution,high sensitivity,***,its application to the petroleum and geological analyses is just emerging in China and *** this research,the analytical method for petroleum aromatic fraction using GC×GC-TOFMS is set up,via the choice of the column system and optimization of setting parameters,such as temperature programming,modulation time,hot pulse time,flow rate of carrier gas,data acquisition rate and data *** results indicate that different polar compounds of aromatic fraction distribute as bands on structured GC×GC *** each band,homologous compounds appear as a roof-tile structure based on the number of substituent *** aromatic compounds are identified and characterized according to the GC×GC chromatogram and mass *** to the polarity and the number of rings,aromatic compounds are spatially present on one chromatogram,which directly reflects the distribution characteristics of complex compounds of aromatic *** addition,quantitative analysis is favored as some overlapped peaks on traditional GC-MS chromatogram have been separated completely on GC×*** heterocyclic atom aromatic compounds at trace level can be clearly identified using this method,for polarity differences from other interfered aromatic *** development of this method and chromatogram recognition offer petroleum geologists a practical example for the application performance of GC×GC-TOFMS.

关键词： comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry aromatic compounds heterocycliccompounds petroleum geological experiments

Technetium-99m-labeled macroaggregated albumin lung perfusion scan for diagnosis of hepatopulmonary syndrome: A prospective study comparing brain uptake and whole-body uptake

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2020年第10期26卷 1088-1097页

作者： He Zhao Jiaywei Tsauo Xiao-Wu Zhang Huai-Yuan Ma Ning-na weng Gong-Shun Tang Xiao Li Department of Interventional Therapy National Cancer Center/National Clinical Research Center/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100021China Department of Gastroenterology West China HospitalSichuan UniversityChengdu 610041Sichuan ProvinceChina Department of Nuclear Medicine West China HospitalSichuan UniversityChengdu 610041Sichuan ProvinceChina

BACKGROUND Hepatopulmonary syndrome (HPS) is an arterial oxygenation defect induced by intrapulmonary vascular dilatation (IPVD) in the setting of liver disease and/or portal *** syndrome occurs most often in cirrhotic patients(4%-32%) and has been shown to be detrimental to functional status,quality of life,and *** diagnosis of HPS in the setting of liver disease and/or portal hypertension requires the demonstration of IPVD (i.e.,diffuse or localized abnormally dilated pulmonary capillaries and pulmonary and pleural arteriovenous communications) and arterial oxygenation defects,preferably by contrast-enhanced echocardiography and measurement of the alveolar-arterial oxygen gradient,*** To compare brain and whole-body uptake of technetium for diagnosing *** Sixty-nine patients with chronic liver disease and/or portal hypertension were prospectively *** uptake and whole-body uptake were calculated using the geometric mean of technetium counts in the brain and lungs and in the entire body and lungs,*** Thirty-two (46%) patients had IPVD as detected by *** demographics and clinical characteristics of the patients with and without IPVD were not significantly different with the exception of the creatinine level (0.71±0.18 mg/dL vs 0.83±0.23 mg/dL;P=0.041),alveolararterial oxygen gradient (23.2±13.3 mmHg vs 16.4±14.1 mmHg;P=0.043),and arterial partial pressure of oxygen (81.0±12.1 mmHg vs 90.1±12.8 mmHg;P=0.004).Whole-body uptake was significantly higher in patients with IPVD than in patients without IPVD (48.0%±6.1%vs 40.1%±8.1%;P=0.001).The area under the curve of whole-body uptake for detecting IPVD was significantly higher than that of brain uptake (0.75 vs 0.54;P=0.025).The optimal cut-off values of brain uptake and whole-body uptake for detecting IPVD were 5.7%and 42.5%,respectively,based on Youden’s *** sensitivity,specificity,and accuracy of brain uptake

关键词： Portal hypertension Intrapulmonary vascular dilations Radionuclide imaging Technetium-99m-labeled macroaggregated albumin lung perfusion scan Diagnostic tests Sensitivity and specificity

Impact of formation water on the generation of H2S in condensate reservoirs： a case study from the deep Ordovician in the Tazhong Uplift of the Tarim Basin, NW China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum Science 2017年第3期14卷 507-519页

作者： Jin Su Yu Wang Xiao-Mei Wang Kun He Hai-Jun Yang Hui-Tong Wang Hua-Jian Wang Bin Zhang Ling Huang na weng Li-na Bi Zhi-Hua Xiao Key Laboratory of Petroleum Geochemistry CNPCBeijing 100083 China State Key Laboratory for Enhancing Oil Recovery Research Institute of Petroleum Exploration and Development PetroChina Beijing 100083 China Research Institute of Tarim Oilfield Company PetroChinaKorla 841000 Xinjiang China PetroChina Coalbed Methane Company Limited Beijing 100028 China

A number of condensate reservoirs with high concentrations of H2S have been discovered in the deep dolomite reservoirs of the lower Ordovician Yingshan Formation（O1y） in the Tazhong Uplift, where the formation water has a high p H value. In the O1y reservoir, the concentrations of Mg^2＋ and SO4^2-in the formation water are higher than those in the upper Ordovician *** concentration of H2 S in the condensate reservoirs and the concentration of Mg^2＋in the formation water correlate well in the O1y reservoirs of the Tazhong Uplift, which indicates a presumed thermochemical sulfate reduction（TSR） origin of H2S according to the oxidation theory of contact ion-pairs（CIPs）. Besides, the p H values of the formation water are positively correlated with the concentration of H2S in the condensate reservoirs, which may indicate that high p H might be another factor to promote and maintain TSR. Oil–source correlation of biomarkers in the sulfuretted condensates indicates the Cambrian source rocks could be the origin of condensates. The formation water in the condensate reservoirs of O1y is similar to that in the Cambrian; therefore, the TSR of sulfate-CIPs likelyoccurred in the Cambrian. High H2S-bearing condensates are mainly located near the No. 1 Fault and NE-SW strikeslip faults, which are the major migration pathway of deep fluids in the Tazhong Uplift. The redox between sulfateCIPs and hydrocarbons is the generation mechanism of H2S in the deep dolomite condensate reservoirs of the Tazhong Uplift. This finding should be helpful to predict the fluid properties of deep dolomite reservoirs.

关键词： Formation water Sulfate-CIPs - TSR -Condensates Dolomite reservoir Tarim basin

Performance analysis and simulation of TH-PPM UWB system in image transmission

在线全文

学校读者我要写书评

暂无评论

通讯和计算机（中英文版） 2007年第3期4卷 60-62页

作者： YANG Jie weng Li-na Institute of Information Engineering Wuhan University of Technology Wuhan 430070 China

TH-PPM-UWB system of image transmission is presented in this paper. And then the performance analysis over an ideal AWGN (Additive White Gaussian Noise) channel is given. The studies indicate that the selection of parameters has a great influence on BER (Bit Error Rate) of the system, especially the number of pulses per information bit. The simulation results of image transmission demonstrate that a larger number of pulses per information bit will lead to better BER performance.

关键词：仿真图象传输 TH-PPM-UWB系统性能附加怀特高斯噪音通道误比特率超频

兆瓦级锂冷空间核反应堆电源方案设计与研发进展

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国科学：技术科学 2024年第3期54卷 365-376页

作者：吴宜灿刘超金鸣陈建伟张勇吴庆生洒荣园柏云清李春京蒋洁琼宋勇胡丽琴王芳谈鹏翁娜江新标高扬周新贵郑友琦鹿鹏张智刚郝祖龙殷园中子科学国际研究院青岛266199 中子科学(重庆)研究院有限公司重庆401331 中子科学研究院(合肥)有限公司合肥230001 安徽中科超核科技有限公司合肥230001 中国科学院合肥物质科学研究院合肥230001 中国科学技术大学合肥230026 上海核工程研究设计院有限公司上海200233 西北核技术研究院西安710024 中国科学院空间应用工程与技术中心北京100094 国防科技大学新型陶瓷纤维及其复合材料重点实验室长沙410073 西安交通大学核科学与技术学院西安710049 南京航空航天大学能源与动力学院南京210016 哈尔滨工程大学核安全与仿真技术国防重点学科实验室哈尔滨150001 华北电力大学核科学与工程学院北京102206 深圳大学物理与光电工程学院深圳518060 山东大学核科学技术研究院济南250012

空间核反应堆电源因具有能量密度大、输出功率高、持续时间长、环境适应性强等优势,是未来大功率长寿期航天任务及深空探测任务能源供应的优选路线.本文在分析兆瓦级空间堆电源研发需求与选型特点的基础上,提出并设计了一套兆瓦级小型... 详细信息

空间核反应堆电源因具有能量密度大、输出功率高、持续时间长、环境适应性强等优势,是未来大功率长寿期航天任务及深空探测任务能源供应的优选路线.本文在分析兆瓦级空间堆电源研发需求与选型特点的基础上,提出并设计了一套兆瓦级小型锂冷空间堆电源技术方案,该方案采用锂冷反应堆与布雷顿发电系统耦合,具有轻量化、长寿命等特点.本文针对该方案梳理了所涉及的关键技术,介绍了在技术分析论证、相关验证样机和实验平台研制的进展情况,并在此基础上提出我国未来发展大功率空间堆电源的建议.

关键词：空间核反应堆锂冷反应堆布雷顿发电

基于Kalman滤波技术的捷联惯导系统水平阻尼算法

在线全文

学校读者我要写书评

暂无评论

中国惯性技术学报 2013年第3期21卷 285-288页

作者：刘飞刘超翁海娜胡小毛天津航海仪器研究所天津300131

立足现代控制理论,探索一种应用Kalman滤波技术估计出系统状态,通过反馈校正实现惯导系统水平阻尼的方法。当外速度存在常值误差时,惯导系统水平姿态误差和加表零偏的耦合量A/g经Kalman滤波,能够被快速准确地估计出来,在最优时刻反馈此... 详细信息

立足现代控制理论,探索一种应用Kalman滤波技术估计出系统状态,通过反馈校正实现惯导系统水平阻尼的方法。当外速度存在常值误差时,惯导系统水平姿态误差和加表零偏的耦合量A/g经Kalman滤波,能够被快速准确地估计出来,在最优时刻反馈此估计量对系统进行校正,可以对舒勒振荡进行阻尼,实现传统水平阻尼网络的作用。仿真试验表明,与传统阻尼网络相比,Kalman滤波阻尼不仅能够有效地消除舒勒周期振荡误差,而且在导航状态切换过程中能有效抑制超调的产生,改善系统的性能。

关键词：捷联惯性导航 Kalman滤波水平阻尼反馈校正

基于时间序列分析的链路质量预测和稳定路由算法研究

在线全文

学校读者我要写书评

暂无评论

电子与信息学报 2011年第4期33卷 885-890页

作者：翁丽娜杨杰柯海舟张良俊武汉理工大学信息工程学院武汉430063

针对现有链路质量预测算法不适用于实际通信场景的问题,该文提出一个不依赖于任何特定信号传输模型和节点移动模型、低复杂度的实时链路质量预测算法,并将其应用于稳定路由协议设计。通信节点存储并更新其邻节点的接收信号强度集合以构... 详细信息

针对现有链路质量预测算法不适用于实际通信场景的问题,该文提出一个不依赖于任何特定信号传输模型和节点移动模型、低复杂度的实时链路质量预测算法,并将其应用于稳定路由协议设计。通信节点存储并更新其邻节点的接收信号强度集合以构成时间序列,将时间序列分析中的局部线性核平滑方法和滑动窗口局部多项式预测方法引入链路质量判断及预测。在此基础上,结合跨层协作思想,提出了节点移动自适应的提前路由修复机制。仿真结果表明,该预测算法具有较高的预测准确度,并能显著增强路由稳定性,提高网络性能。

关键词：无线网络链路质量预测时间序列分析稳定路由跨层协作自适应提前路由修复