检索结果-南通市图书馆

EMPIRICAL LIKELIHOOD CONFIDENCE REGION FOR PARAMETERS IN LINEAR ERRORS-IN-VARIABLES MODELS WITH MISSING DATA

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2011年第3期24卷 540-553页

作者： juan zhang Hengjian CUI Department of Statistics Capital University of Economics and Business Beijing 100070 China. Department of Statistics and Financial MatheTnatics School of Mathematical Sciences Beijing Normal University Beijing 100875 China School of Mathematical Sciences Capital Normal University Beijing 100048 China

The multivariate linear errors-in-variables model when the regressors are missing at random in the sense of Rubin （1976） is considered in this paper. A constrained empirical likelihood confidence region for a parameter β0 in this model is proposed, which is constructed by combining the score function corresponding to the weighted squared orthogonal distance based on inverse probability with a constrained region of β0. It is shown that the empirical log-likelihood ratio at the true parameter converges to the standard chi-square distribution. Simulations show that the coverage rate of the proposed confidence region is closer to the nominal level and the length of confidence interval is narrower than those of the normal approximation of inverse probability weighted adjusted least square estimator in most cases. A real example is studied and the result supports the theory and simulation＇s conclusion.

关键词： Confidence region coverage rate empirical likelihood ratio multivariate linear errors-in- variables model weighted adjusted LS estimation.

锆基金属有机框架捕获黄连中的生物碱类药物活性成分

在线全文

学校读者我要写书评

暂无评论

分析测试学报 2025年第1期44卷 188-194页

作者：司甜甜赵薇王慧张红玉刘小烨容蓉冯娟娟山东中医药大学药学院济南大学化学化工学院

采用溶剂热法制备了锆基MOF-808，利用其结构优势实现了中药黄连中生物碱类药物活性成分的富集与捕获，并结合其结构特点探讨了其协同低共熔溶剂捕获生物碱类活性成分过程中的相互作用。通过优化孵育捕获等条件，对黄连粗提液中药根碱... 详细信息

采用溶剂热法制备了锆基MOF-808，利用其结构优势实现了中药黄连中生物碱类药物活性成分的富集与捕获，并结合其结构特点探讨了其协同低共熔溶剂捕获生物碱类活性成分过程中的相互作用。通过优化孵育捕获等条件，对黄连粗提液中药根碱的回收率达到85.78%，结合高效液相色谱技术建立了检测黄连粗提液中5种生物碱类活性成分的方法。方法的线性范围为0.1～300μg·L-1，检出限为0.02～0.05μg·L-1，相对标准偏差为0.40%～4.7%，加标回收率达到69.7%～128%。该研究实现了中药黄连中生物碱类活性成分的高效、快速富集与捕获，为MOFs材料在选择性捕获与富集中药有效成分等领域的研究提供了新思路。

关键词：金属有机框架选择性富集色谱分离生物碱活性成分黄连

Large Deviations for Hitting Times of a Random Walk in Random Environment on a Strip

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2014年第3期30卷 395-410页

作者： Mei juan zhang School of Statistics and Mathematics Central University of Finance and Economics

We consider a random walk in random environment on a strip, which is transient to the right. The random environment is stationary and ergodic. By the constructed enlarged random environment which was first introduced by Goldsheid （2008）, we obtain the large deviations conditioned on the environment （in the quenched case） for the hitting times of the random walk.

关键词： Random walk in random environment strip large deviations quenched enlarged randomenvironment

尿NAG、RBP的变化在肾功能正常的肾病患者中的应用

在线全文

学校读者我要写书评

暂无评论

现代检验医学杂志 2004年第5期19卷 48-49页

作者：金磊孟伟龚学忠石娟娟张珏上海中医药大学附属曙光医院检验科上海200021

目的　探讨肾功能正常的肾小球和肾血管疾病患者尿 NAG、RBP的变化 ,以确定在上述患者中尿 NAG和 RBP的应用价值。方法　选择肾功能正常的慢性肾小球肾炎患者 ( CGN) 2 0例、原发性肾病综合征 ( NS)未缓解期患者 1 8例、高血压肾损害患... 详细信息

目的　探讨肾功能正常的肾小球和肾血管疾病患者尿 NAG、RBP的变化 ,以确定在上述患者中尿 NAG和 RBP的应用价值。方法　选择肾功能正常的慢性肾小球肾炎患者 ( CGN) 2 0例、原发性肾病综合征 ( NS)未缓解期患者 1 8例、高血压肾损害患者 ( HN) 1 0例、糖尿病性肾病患者 ( DN) 2 0例 ,分别进行尿NAG/尿肌酐、RBP检测 ,并与 1 2例正常人对照。结果　与正常组相比 ,各肾脏病组尿 NAG/尿肌酐、RBP均有不同程度升高 ,以 NS组最明显。结论　肾小球和肾血管疾病在出现肾功能减退之前 ,即可能存在一定程度的肾小管 -间质损伤 ,从而在尿 NAG和 RBP的变化中反映出来。

关键词：肾病尿N-乙酰-β-D氨基葡萄糖酐酶尿视黄醇结合蛋白

在线全文

学校读者我要写书评

暂无评论

翅果油树愈伤组织的继代培养

山西师范大学学报（自然科学版） 2002年第4期16卷 71-73页

作者：卢英梅程小丽侯娟娟宋安平张育盛山西师范大学生命科学学院山西临汾041004

本文对翅果油树 (Elaeagnus mollis Diels)实生苗的初代培养和愈伤组织的继代培养及种子的灭菌方法和时间进行了探索 .结果表明 :初代培养最佳培养基为 1 /2 MS(基本培养基MS中的大量元素减半 ) .继代培养中的最佳培养基为 N2 (MS+BA0 .... 详细信息

本文对翅果油树 (Elaeagnus mollis Diels)实生苗的初代培养和愈伤组织的继代培养及种子的灭菌方法和时间进行了探索 .结果表明 :初代培养最佳培养基为 1 /2 MS(基本培养基MS中的大量元素减半 ) .继代培养中的最佳培养基为 N2 (MS+BA0 .5+NAA0 .0 2 ) ,N4(MS+BA0 .5+NAA0 .0 4)

关键词：继代培养翅果油树组织培养愈伤组织培养基胡颓子科油料树种

MECHANISM FOR VISCOELASTIC POLYMER SOLUTION PERCOLATING THROUGH POROUS MEDIA

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2007年第2期19卷 241-248页

作者： zhang Li-juan YUE Xiang-an Ministry of Education Key Laboratory of Petroleum Engineering China University of Petroleum Beijing 102249 China

The pore throat of porous media is modeled as a constricted channel or expanded channel. The flow of viscoelastic polymer solution in pore throat model is studied by numerical method. Relationship between pressure drop and flow rate is developed, viscoelasticity and throat size are found to be two main factors in high flow resistance. According to pore throat model, 2-D stochastic channel bundle is put forward to model porous media, which is composed of pore throat models in series - parallel connection with size and length accord to Hating Greenkorn stochastic distribution. Percolation model of viscoelastic fluid is developed on the basis of Darcy equation and pressure drop vs. flow rate relation in 2-D stochastic channel bundle. Results indicate that the seepage ability of viscoelastic polymer solution decreases with the increase of viscoelasticity, injection rate, and heterogeneity as well as the decrease of mean pore size of porous media. The high pressure drop of viscoelastic fluid at the connection of pore to throat plays a great role in its anomalous high flow resistance through porous media.

关键词： polymer flooding viscoelastic fluid,flow resistance percolation pore throat

在线全文

学校读者我要写书评

暂无评论

彗星实验方法学的改进用于DNA损伤检测

临床和实验医学杂志 2018年第14期17卷 1480-1484页

作者：崔丽娟张娟程宇刘娟李玲梁超陈忠傅廷娇宁夏医科大学总医院血液内科宁夏银川750004 北京海思特医学检验实验室北京100176

目的对国际公认的经典彗星实验(单细胞凝胶电泳实验)进行方法学改进,使之更方便于临床检测。方法选用5例范可尼贫血的阳性标本作为阳性对照,30例初生婴儿的脐带血作为阴性对照,同时应用经典彗星实验以及改进版彗星实验进行比对,验证两... 详细信息

目的对国际公认的经典彗星实验(单细胞凝胶电泳实验)进行方法学改进,使之更方便于临床检测。方法选用5例范可尼贫血的阳性标本作为阳性对照,30例初生婴儿的脐带血作为阴性对照,同时应用经典彗星实验以及改进版彗星实验进行比对,验证两种方法的可行性。选用15例临床标本与中国医学科学院放射医学研究所同步进行实验,然后实验结果进行对比对,验证改进版彗星实验的准确度以及符合度。结果与经典彗星实验相比,改进版彗星实验检测结果的准确度达到100%,符合度达到100%。结论与经典的彗星实验相比,改进版彗星实验操作更加简单、省时;结果客观、准确、稳定,且重现性和准确性好,图像清晰,容易判读;成本更加低廉,操作安全,更加环保,推荐使用该方法作为DNA损伤的检测方法。

关键词：单细胞凝胶电泳实验经典彗星实验 DNA损伤碱性电泳

Structural and functional analysis of an asymmetric bidirectional promoter in Arabidopsis thaliana

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2015年第2期57卷 162-170页

作者： Shi-juan Liu Qiu-juan Yue Wei zhang Key Laboratory of Plant Cell Engineering and Germplasm Innovation Ministry of Education School of Life Sciences Shandong University College of Life Science Qufu Normal University

Bidirectional promoters are relatively abundant in eukaryotic genomes, suggesting that they have an important biological significance. As yet, few of these promoters have been characterized in detail. Here, using a promoter：：GUS transgene approach has revealed that the intergenic region of Arabidopsis thaliana divergent genes At1g71850 and At1g71860 is an asymmetric bidirectional promoter, which exhibits an orientation-dependent expression profile. The strength of the forward promoter was greater than that of the reverse promoter, and their tissue specificities were not identical. Deletion analyses revealed that this bidirectional promoter could be divided into three functional regions. The basal level and tissue specificity of the promoter in the reverse orientation were regulated positively by region II and negatively by region III, whereas promoter activity in the forward orientation was regulated negatively by region II and positively by region I. Thus the 52-bp stretch of region II had a dual function, enhancing expression in the reverse orientation and suppressing it in the forward orientation. These results demonstrated that the activity of the At1g71850-At1g71860 bidirectional promoter was modulated by complex interactions between both positive and negative cis-acting elements. These findings will enhance our understanding of the regulatory mechanisms of plant bidirectional promoters.

关键词： GUS (β-glucuronidase) positive and negative regulatoryelement promoter strength tissue-specific expression

Synergistic effect of Ni^(Ⅱ)and Co/Fe^(Ⅲ)in doped mixed-valence phosphonate for enhancing electrocatalytic oxygen evolution

在线全文

学校读者我要写书评

暂无评论

Green Energy & Environment 2022年第3期7卷 432-439页

作者： juan-juan Hou Jian-Tao Yuan Wei zhang Ying-Xia Wang Xian-Ming zhang Key Laboratory of Magnetic Molecules and Magnetic Information Materials(Ministry of Education) School of Chemistry and Material ScienceShanxi Normal UniversityLinfen041004China

Metal organophosphonates have been explored in energy-related fields due to their high chemical and thermal stability as a type of uniformly precursor,but only few of pristine metal organophosphonate are directly used for oxygen evolution reaction(OER)***,a mixedvalence iron phosphonate(Fe_(3)-ppat)has been constructed and applied to OER catalysis considered the potential active sites in pillars Fe^(Ⅱ)(-H_(2)O)_(4)(COO)_(2)and inorganic layers Fe^(Ⅲ)(μ_(2)–OH)PO_(3).Specifically,isostructural trimetallic framework Fe_(1.7)Co_(0.3)Ni_(1.0)-ppat possesses a minimum overpotential(291 mV),small Tafel slope(91.65 mV dec^(-1)),and high stability up to 83 *** enhanced catalytic performance could be mainly ascribed to the synergistic effect of Ni^(Ⅱ)equivalent occupancy in pillars and Co/Fe^(Ⅲ)in layers.

关键词： phosphonate stability organo