检索结果-南通市图书馆

[Determination of eight phthalate metabolites in urine of pregnant women and evaluation of neonatal birth outcomes based on solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry]

引用

Se pu = Chinese journal of chromatography 2025年第1期43卷 60-67页

作者： Zi-Hao Wang Meng-fei xu Bei-Ni Li Ping Wu Wei Wu Hubei University of Chinese Medicine Wuhan 430065 China.

Phthalates (PAEs) are endocrine-disrupting chemicals that are widely present in everyday life and enter the human body through various pathways. The release of PAEs into the environment through pathways that include leaching, evaporation, abrasion, and the use of personal care products exposes humans to PAEs via ingestion, inhalation, and dermal absorption. Pregnant women, as a particularly vulnerable population, risk adverse newborn growth and development when exposed to PAEs. While the concentrations of PAEs in urine reflect recent exposure levels in humans, urinary levels of phthalate metabolites (mPAEs) are commonly used as biomarkers of internal exposure owing to the relatively short biological half-lives of PAEs (<24 h). In this study, we developed a solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS) method for simultaneously detecting eight mPAEs in the urine of pregnant women. Urine samples were enzymatically hydrolyzed with -glucosidase and then purified using the Bond Elut Plexa SPE column, with subsequent elution, concentration, and redissolved performed prior to HPLC-MS/MS. Separation was achieved using an Agilent Eclipse Plus C18 column (100 mm×3 mm, 3.5 μm), with gradient elution performed using 0.1% acetic acid aqueous solution and 0.1% acetic acid acetonitrile as mobile phases. Multiple reaction monitoring (MRM) mode was used for detection, with quantification performed using the internal-standard method. Good linearities were obtained in the range of 0.1-200 ng/mL for the eight mPAEs, with limits of detection (LODs) and quantification (LOQs) of 0.015-0.048 and 0.050-0.160 ng/mL, respectively. The eight mPAEs exhibited recoveries of 80.2%-99.7% at three spiked levels (1, 10, and 50 ng/mL). This method was subsequently used to analyze the eight mPAEs levels in urine samples of 497 pregnant women from the Ezhou Maternity and Child Health Care Hospital. The participants exhibited widespread exposure t

关键词： birth outcomes high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) phthalate metabolites (mPAEs) urine samples of pregnant women

来源：

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

机械应力调控血管平滑肌细胞的凋亡

引用

中国组织工程研究 2025年第5期29卷 1064-1072页

作者：徐飞闫金强柴守栋北京航空航天大学生物与医学工程学院北京市100083 聊城市人民医院中心实验室山东省聊城市252000 聊城市人民医院病理科山东省聊城市252000 聊城市人民医院心外科山东省聊城市252000

背景:随着生物力学的发展,其在心血管疾病中的研究也日益广泛,通过研究血管的力学特性可以有效地揭示动脉粥样硬化、再狭窄等心血管疾病的发病机制,开发心血管疾病治疗的新思路和新方法。目的:综述机械应力刺激对血管平滑肌细胞凋亡的... 详细信息

背景:随着生物力学的发展,其在心血管疾病中的研究也日益广泛,通过研究血管的力学特性可以有效地揭示动脉粥样硬化、再狭窄等心血管疾病的发病机制,开发心血管疾病治疗的新思路和新方法。目的:综述机械应力刺激对血管平滑肌细胞凋亡的研究现状,寻找临床治疗潜在靶分子和信号通路,以期改善临床动脉粥样硬化及再狭窄等心血管疾病的临床治疗效果。方法:检索1992年1月至2023年5月在中国知网、PubMed及ScienceDirect数据库收录的文献。中文检索词为“血管平滑肌细胞,机械应力,剪切力,牵张力,凋亡”;英文检索词为“vascular smooth muscle cell,mechanical stress,shear stress,stretch stress,apoptosis”,最终纳入63篇文献进行综述分析。结果与结论:①血管平滑肌细胞的生理性和病理性凋亡都是为了适应血管力学变化而发生的适应性重构。不同部位的平滑肌细胞承受不同的力学刺激,其发病机制也不同。②低剪切力、生理剪切力和高剪切力可通过直接与平滑肌细胞表面分子、受体及蛋白等作用调控凋亡信号分子和抑制增殖实现对血管平滑肌细胞凋亡的调控,该部分未对促进增殖的研究进行综述。③低牵张力、生理牵张力和高牵张力可导致平滑肌细胞凋亡,但仍存在争议。平滑肌表面存在多种力学感受分子(如整合素及受体络氨酸激酶等)可以将力学信号转导为细胞内的化学信号(如Hippo通路),启动平滑肌细胞的凋亡信号,调控平滑肌细胞的凋亡。④总之,不同力学刺激通过多种信号分子,启动多个信号通路共同作用,调控平滑肌细胞的凋亡,例如剪切力主要通过刺激分泌前列腺素、转化生长因子等影响Fas/FasL、Akt通路;而牵张力主要通过Yes相关蛋白等调控YAP通路和Notch通路等。这些分子在不同的作用时间,或不同作用强度下可能发挥相反的双向作用,比如,小鼠血管平滑肌细胞受到10%生理牵张1 h时,其增殖增加;然而,人的血管平滑肌细胞牵张12 h后可以减少其增殖。临床可以通过寻找其关键作用时间点干扰力学转导关键分子,达到预防和治疗临床心血管疾病的目的。

关键词：血管平滑肌细胞机械应力凋亡牵张力剪切应力整合素受体络氨酸激酶 G蛋白偶联受体和G蛋白离子通道

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Deciphering fungal metabolon coupling tandem inverse-electrondemand Diels-Alder reaction and semipinacol rearrangement for the biosynthesis of spiro polycyclic alkaloids

引用

Science China Chemistry 2025年第01期 288-296页

作者： Shuai Liu Wen-Qiang xu Ying-Tong Di Man-Cheng Tang Ding-Kang Chen Ming-Ming Cao Yao-Wen Chang Hong-Yu Tang Chun-Mao Yuan Jun-Bo Yang Zhi-Li Zuo Han Guo Zi-fei xu Ying Zeng Yun-Dong Wu Xiao-Jiang Hao Key Laboratory of Phytochemistry and Natural Medicines (Chinese Academy of Sciences) Kunming Institute of Botany Chinese Academy of Sciences University of Chinese Academy of Sciences Lab of Computational Chemistry and Drug Design State Key Laboratory of Chemical Oncogenomics Peking University Shenzhen Graduate School Shenzhen Bay Laboratory State Key Laboratory of Microbial Metabolism School of Life Sciences & Biotechnology Shanghai Jiao Tong University State Key Laboratory of Functions and Applications of Medicinal Plants Guizhou Medical University Molecular Biology Experimental Center Germplasm Bank of Wild Species in Southwest China Kunming Institute of Botany Chinese Academy of Sciences Yunnan Key Laboratory for Wild Plant Resources Kunming Institute of Botany Chinese Academy of Sciences Research Unit of Chemical Biology of Natural Anti-Virus Products Chinese Academy of Medical Sciences

In the intricate process of natural product biosynthesis, a metabolon can enhance metabolic flux by associating sequential enzymes. A fungal metabolon, comprising of flavin-dependent monooxygenase Spe F and P450 monooxygenase Spe G, is identified in the biosynthesis of spiro polycyclic alkaloids(+)-notoamide B and its diastereomer(+)-versicolamide B. Using notoamide E as a substance, Spe F/Spe G metabolon can control the stereoselectivity of its 2,3-epoxidation, followed by hydrogen atom ion at C-17 to generate reactive epoxide tau-m A with dienyl iminium unit. Subsequently,(+)-notoamide B and(+)-versicolamide B are produced via tandem nonenzymatic inverse-electron-demand Diels-Alder reaction and semipinacol rearrangement. This provides the first example of metabolon in the biosynthesis of spiro-prenylated indole alkaloids.

关键词：

来源：

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Surface Polarization Effects on Collapse Transition of Polyelectrolyte Brushes

引用

Chinese Journal of Polymer Science 2024年第9期42卷 1313-1320,I0006页

作者： Xiao-fei xu State Key Laboratory of Chemical Engineering and School of Chemical Engineering East China University of Science and TechnologyShanghai200237China

Polyelectrolyte brushes(PEBs)are commonly used to modify surface that have attracted great research *** dielectric permittivity of the grafted surface is typically significantly different from that of solution,which results in surface polarization(SP)effect with a jump of electric *** is thus important to study how SP alters the PEB’s structure and *** this work,the SP effects on PEB structure was studied using a statistical thermodynamic *** free energy functional to describe SP effect was constructed by using the image-charge ***,the electrostatic potential was solved from a modified Poisson-Boltzmann equation taking the ion solvation effect into *** the absence of SP,the thickness of PEB exhibited a continuous collapse transition when decreasing the solvent *** the presence of SP,the collapse became a jump-like *** energy analysis showed that the long-range Coulombic interaction dominated the transition because of the enhanced counterion condensation in the presence of *** theory provides an effective tool to study SP effect on PEBs,and the results explain the underlying physics in PEB collapse transition.

关键词： Surface polarization Polyelectrolyte brush Image charge Ion solvation Polyelectrolyte collapse transition

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

An accurate a posteriori error estimator for the Steklov eigenvalue problem and its applications

引用

Science China Mathematics 2021年第3期64卷 623-638页

作者： fei xu Qiumei Huang Beijing Institute for Scientific and Engineering Computing Faculty of ScienceBeijing University of TechnologyBeijing 100124China

In this paper, a type of accurate a posteriori error estimator is proposed for the Steklov eigenvalue problem based on the complementary approach, which provides an asymptotic exact estimate for the approximate eigenpair. Besides, we design a type of cascadic adaptive finite element method for the Steklov eigenvalue problem based on the proposed a posteriori error estimator. In this new cascadic adaptive scheme, instead of solving the Steklov eigenvalue problem in each adaptive space directly, we only need to do some smoothing steps for linearized boundary value problems on a series of adaptive spaces and solve some Steklov eigenvalue problems on a low dimensional space. Furthermore, the proposed a posteriori error estimator provides the way to refine meshes and control the number of smoothing steps for the cascadic adaptive method. Some numerical examples are presented to validate the efficiency of the algorithm in this paper.

关键词： Steklov eigenvalue problem a posteriori error estimator cascadic multigrid method adaptive finite element method complementary method

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A CASCADIC MULTIGRID METHOD FOR SEMILINEAR ELLIPTIC EQUATIONS

引用

Journal of Computational Mathematics 2019年第1期37卷 112-129页

作者： fei xu Fusheng Luo Beijing Institute for Scientific and Engineering Computing Beijing University of Technology Beijing 100124China The Third Institute of Oceanography SOAXiamen 361005China

This paper introduce a cascadic multigrid method for solving semilinear elliptic equations based on a multilevel correction *** of the common costly way of directly solving semilinear elliptic equation on a very fine space,the new method contains some smoothing steps on a series of multilevel finite element spaces and some solving steps to semilinear elliptic equations on a very coarse *** prove the efficiency of the new method,we derive two results,one of the optimal convergence rate by choosing the appro- priate sequence of finite element spaces and the number of smoothing steps,and the other of the optimal computational work by applying the parallel computing ***,the requirement of bounded second order derivatives of nonlinear term in the existing multigrid methods is reduced to a bounded first order derivative in the new *** numerical experiments are presented to validate our theoretical analysis.

关键词： Sernilinear elliptic equation Parallel computing Cascadic multigrid Multilevel correction Finite element method

来源：

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

Protection zone in a diffusive predator-prey model with Ivlev-type functional response

引用

Applied Mathematics(A Journal of Chinese Universities) 2020年第4期35卷 437-451页

作者： ZHANG Li-na xu fei Department of Mathematics and statistics Northwest Normal UniversityLanzhou 730070China

The effect of a protection zone on a diffusion predator-prey model with Ivlev-type functional response is *** discuss the existence and non-existence of positive steady state solutions by using the bifurcation *** is shown that the protection zone for prey has beneficial effects on the coexistence of the two species when the growth rate of predator is ***,we examine the dependence of the coexistence region on the efficiency of the predator capture of the prey and the protection zone.

关键词： Ivlev-type functional response protection zone bifurcation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Optimal production lot size with process deterioration under an extended inspection policy

引用

Journal of Systems Engineering and Electronics 2009年第4期20卷 768-776页

作者： Hu fei xu Genqi Ma Lixia Dept. of Mathematics Tianjin Univ. Tianjin 300072 P. R. China

A mathematical model to determine the optimal production lot size for a deteriorating production system under an extended product inspection policy is developed. The last-K product inspection policy is considered so that the nonconforming items can be reduced, under which the last K products in a production lot are inspected and the nonconforming items from those inspected are reworked. Consider that the products produced towards the end of a production lot are more likely to be nonconforming, is proposed an extended product inspection policy for a deteriorating production system. That is, in a production lot, product inspections are performed among the middle K1 items and after inspections, all of the last K2 products are directly reworked without inspections. Our objective here is the joint optimization of the production lot size and the corresponding extended inspection policy such that the expected total cost per unit time is minimized. Since there is no closed form expression for our optimal policy, the existence for the optimal production inspection policy and an upper bound for the optimal lot size are obtained. Furthermore, an efficient solution procedure is provided to search for the optimal policy. Finally, numerical examples are given to illustrate the proposed model and indicate that the expected total cost per unit time of our product inspection model is less than that of the last-K inspection policy.

关键词： production lot size product inspection policy deteriorating production system economic manufacturing quantity.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Some topics on the smooth particle hydrodynamics method

引用

Acta Mechanica Sinica 2023年第2期39卷 1-2页

作者： fei xu Renato Vacondio School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China Department of Engineering and Architecture University of ParmaParmaItaly

The smooth particle hydrodynamics(SPH)method is one of the earliest meshfree methods,first proposed in 1977[1,2],to solve astrophysical *** the past years,as a Lagrangian,particle method,the SPH method has been widely applied in computational engineering *** provides novel insights for solving complex problems in fluid dynamics and solid mechanics involving large deformations.

关键词： problems. particle hydrodynamics

来源：

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

Realization of Numbers As the Degrees of Maps between Manifolds

引用

Acta Mathematica Sinica,English Series 2010年第8期26卷 1413-1424页

作者： Young Min LEE fei xu Department of Mathematics Seoul National University Seoul 151747 Republic of Korea School of Mathematics Capital Normal University Beijing 100048 P. R. China

We determine the set of degrees between some classes of oriented closed （n - 1）-connected 2n-manifolds by using the arithmetic theory of quadratic forms.

关键词： Oriented closed manifold degree of a map integral quadratic form

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：