检索结果-南通市图书馆

Theoretical analysis and experimental investigation on flexural performance of steel reinforced ultrahigh toughness cementitious composite (RUHTCC) beams

引用

Science China(Technological Sciences) 2009年第4期52卷 1068-1089页

作者： XU ShiLang zhang xiufang State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

UHTCC (ultrahigh toughness cementitious composite), which is a kind of ultrahigh toughness cemen- titious composites material, exhibits pseudo strain hardening feature when subjected to tension load, and has enormous ductility and prominent crack dispersal ability. Accordingly, UHTCC can improve mechanical behavior of ordinary concrete structure especially its durability, and has been regarded as historical breakthrough to traditional cementitious materials. In this paper, the study focuses on flexure behavior of steel reinforced beam made of UHTCC. Based on the plane section assumption, along with two equilibrium equations of force and moment, the formulae to calculate the flexural load capability for the reinforced ultrahigh toughness cementitious composite (RUHTCC) beam were developed under the assumption that the compression stress- strain relationship in the UHTCC material is a bilinear model. Following this, the simplified formulae were further evolved by effective rectangle stress distribution approach in order to facilitate design of practical engineering. Two effective parameters introduced in effective rectangle approach were determined. The mathematical expressions to evaluate limited rein- forcement ratio, flexural stiffness as well as ductility index were proposed, too. Last, two series of dif- ferent reinforcement ratios of the RUHTCC beams were tested in four-point flexure loading. For com- parison purposes, ordinary RC (reinforced concrete) beams also were prepared. Both moment curva- ture curves and load mid-span displacement curves were recorded and compared with the theoretical calculations. A good agreement between them was found, which validates the proposed theoretical formulae. For ductility index, a slightly big difference between the experimental values and the calcu- lated ones exists. The experimental results show that, compared to control RC beams, the RUHTCC beam can improve both flexural capacity and ductility index, and the degree of i

关键词： ultrahigh toughness cementitious composites (UHTCC) RUHTCC beam flexural capacity crack width ductility index reinforcement ratio

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

Profiling biotoxicities of hexafluoropropylene oxide trimer acid with human embryonic stem cell-based assays

引用

Journal of Environmental Sciences 2022年第6期34卷 34-42页

作者： Shengxian Liang Guoqiang Liang Yue zhang xiufang zhang Li Zhong Institute of Life Sciences and Green Development College of Life SciencesHebei UniversityBaoding 071000China Western University of Health Sciences PomonaCalifornia 91766USA

Hexafluoropropylene oxide trimer acid(HFPO-TA), an emerging replacement of perfluorooctanoic acid(PFOA), has recently been reported to be a potential environmental *** to the similar structure to PFOA, HFPO-TA may cause comparable adverse effects on human health. Therefore, evaluating the toxic profiles of HFPO-TA has become an urgent *** this study, we investigated the cytotoxicity and hepatoxicity of HFPO-TA using human embryonic stem cell(h ESC)-based assays. Results showed that HFPO-TA reduced h ESCs’ viability in a dose dependent manner, and the calculated IC50 for 24, 48 and 72 hr were 222.8,167.4, and 80.6 μmol/L, respectively. Significant intracellular ROS accumulation and mitochondrion membrane potential reduction were detected with HFPO-TA exposure, and increased apoptotic/necrotic cells were also observed in high dose of HFPO-TA treated ***, HFPO-TA at noncytotoxic concentrations also significantly impaired the functions of induced hepatocytes by diminishing cell glycogen storage ability and deregulating specific functional genes. Transcriptome sequencing analysis identified a set of hepatic associated biological processes responding to HFPO-TA exposure. PPAR was the most significantly enriched pathway. Genes including FGA, FGB, FGG, AHSG, HRG, ITIH2, ALB were characterized as hub genes by cyto Hubba plug-in. These data indicated that HFPO-TA is a potential hepatotoxicant, and may not be a safe replacement for PFOA.

关键词： Hexafluoropropylene oxide trimer acid(HFPO-TA) Stem cell toxicology Hepatoxicity Transcriptional analysis

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

tructure and Composition of Crystalline Carbon Nitride Films Synthesized by Microwave Plasma Chemical Vapor Deposition

引用

International Journal of Minerals,Metallurgy and Materials 2000年第4期14卷 282-285页

作者： Yongping zhang Yousong Gu Xiangrong Chang Zhongzhuo Tian xiufang zhang Material Science and Engineering School University of Science and Technology BeijingBeijing 100083China Beijing Laboratory of Vacuum Physics Institute of physicsChinese

Crystalline carbon nitride thin films were prepared on Si (100) substrates by a microwave plasma chemical vapor deposition method, using CH4/N2 as precursor gases. The surface morphologies of the carbon nitride films deposited on Si substrate at 830℃ are consisted of hexagonal crystalline rods. The effect of substrate temperature on the formation of carbon nitrides was investigated. X-ray photoelectron spectroscopy analysis indicated that the maximum value of N/C in atomic ratio in the films deposited at a substrate temperature of 830℃ is 1 .20, which is close to the stoichiometric value of C3N4. The X-ray diffraction pattern of the films deposited at 830℃ indicates no amorphous phase in the films, which are composed of β- and α-C3N4 phase containing an unidentified C-N phase. Fourier transform infrared spectroscopy supports the existence of C-N covalent bond.

关键词： Crystalline materials

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

Correlation between tension softening relation and crack extension resistance in concrete

引用

Frontiers of Structural and Civil Engineering 2009年第3期3卷 323-329页

作者： xiufang zhang Shilang XU Department of Civil and Hydraulic Engineering Dalian University of TechnologyDalian 116024China

Changes of the material fracture toughness with crack propagation can be described by a crack extension resistance curve,one of the fundamental fracture criteria in crack ***,experimental observation of the fracture behavior in concrete was used to develop a new fracture criterion,the crack extension GR resistance curve,to analyze crack propagation during the entire concrete fracture *** variation of the crack extension resistance is mainly associated with the energy consumption in the fracture process zone ahead of the stress-free crack *** crack extension resistance is then a function of the softening curve,which is a basic mechanical property in the fracture process *** relationship between the softening curve and the crack extension GR resistance curve is then analyzed based on results of three-point bending beams *** results indicate that the characteristic points of the crack extension resistance GR curve is closely related to the characteristic point on used tension softening curve.

关键词： concrete fracture process zone crack exten-sion GR resistance tension softening curve

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

Diamond Polycrystal Powder Formation Directly from Gas Phase in a Plasma Jet System

引用

Chinese Physics Letters 1993年第6期10卷 359-361页

作者： JIANG Xiangliu QIN Sizhan zhang xiufang XUE Zengquan PANG Shijin Beijing Laboratory of Vacuum Physics Academia SinicaBeijing 100080

Diamond polycrystal powder has been produced directly from gas phase in an arc discharge plasma jet *** diluted in argon was used as hydrocarbon source *** product was the mixture of diamond polycrystal powders and *** 3C cubic phase diamond which is dominant,and the mixture phases of cubic and 6H hexagonal diamond are identified in the produced diamond polycrystal powders by electron diffraction patterns.

关键词： powders cubic Diamond

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

ESTIMATION OF DOPPLER CENTROID FREQUENCY IN SPACEBORNE SCANSAR

引用

Journal of Electronics(China) 2008年第6期25卷 822-826页

作者： Zou xiufang zhang Qunying Lab 10 Institute of Electronics Chinese Academy of Sciences Beijing 100190 China

Doppler centroid frequency is an essential parameter in the imaging processing of the Scanning mode Synthetic Aperture Radar (ScanSAR). Inaccurate Doppler centroid frequency will result in ghost images in imaging result. In this letter, the principle and algorithms of Doppler centroid frequency estimation are introduced. Then the echo data of ScanSAR system is analyzed. Based on the algorithms of energy balancing and correlation Doppler estimator in the estimation of Doppler centroid frequency in strip mode SAR, an improved method for Doppler centroid frequency estimation in ScanSAR is proposed. The method has improved the accuracy of Doppler centroid frequency estimation in ScanSAR by zero padding between burst data. Finally, the proposed method is validated with the processing of ENVIronment SATellite Advanced Synthetic Aperture Radar (ENVISAT ASAR) wide swath raw data.

关键词： Spaceborne the Scanning mode Synthetic Aperture Radar (ScanSAR) Doppler centroid frequency Energy balancing Correlation Doppler estimator

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

Cylindrotheca closterium Is a Species Complex as Was Evidenced by the Variations of rbcL Gene and SSU rDNA

引用

Journal of Ocean University of China 2007年第2期6卷 167-174页

作者： LI Haitao YANG Guanpin SUN Ying WU Suihan zhang xiufang College of Marine Life Sciences Ocean University of China Qingdao 266003 P. R. China

The genus Cylindrotheca consists of a small group of marine diatoms with a few species described. Eleven isolates of diatoms identified as Cylindrotheca closterium morphologically were obtained from Jiaozhou Bay with their nuclear-encoded small-subunit ribosomal RNA （SSU rDNA） and chloroplast-encoded rbcL gene sequences determined in this study. Interestingly, very high sequence divergences of SSU rDNA and rbcL gene were found among these isolates, and numerous nucleotide variation of rbcL gene caused relatively few variation of deduced amino acid sequence. Phylogenetic analyses based on SSU rDNA and rbcL gene, respectively, grouped the isolates into 6 clades. Phylogenetic tree of SSU rDNA placed all the Cylindrotheca isolates together, separating them into two lineages clearly. LineageⅠ was composed of the eleven C. closterium isolates obtained in this study together with another C. closterium isolate, but some clades were not well supported. LineageⅠwas contained two C. closterium isolates and one C. fusiformis isolate. Phylogenetic analysis of rbcL gene also separated the Cylindrotheca isolates into two well-defined lineages. The eleven C. closterium isolates formed a lineage and all clades were supported strongly. Statistical comparisons of SSU rDNA indicated that the average distance within lineageⅠwas significantly higher than that of other microalgae species （P 〈0.01）. These results suggested the existence of cryptic species within C. closterium.

关键词： Cylindrotheca closterium species complex rbcL gene, SSU rDNA

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

Endogenously generated amyloid β increases membrane fluidity in neural 2a cells

引用

Chinese Science Bulletin 2009年第3期54卷 394-398页

作者： NIU Ying SHENG BaiYang SONG Bo LIU LingLing zhang xiufang ZHAO NanMing GONG YanDao State Key Laboratory of Biomembrane and Membrane Biotechnology Department of Biological Sciences and Biotechnology Tsinghua University Beijing 100084 China Medical School Tsinghua University Beijing 100084 China

The effect of endogenously generated amyloid β on membrane fluidity was investigated in Neural 2a cells stably expressing Swedish mutant amyloid precursor protein (APPswe). Membrane fluidity was studied by fluorescence polarizability using 1,6-Diphenyl-1,3,5-Hexatriene (DPH) as the fluorescence probe. It was found that the membrane fluidity in APPswe cells was significantly higher than that in its wild type counterparts. Alleviating the effect of amyloid β either by γ secretase activity inhibition or by amyloid antibody treatment decreased membrane fluidity, which indicated an important role of amyloid β in increasing membrane fluidity. Treatment using amyloid β channel blocker, tromethamine and NA4 suggested that channel formed by amyloid β on the cell membrane is a way through which amyloid β takes its membrane fluidizing effect.

关键词：膜流动性荧光极化老年痴呆症淀粉

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

The mitochondrial function was impaired in APP knockout mouse embryo fibroblast cells

引用

Chinese Science Bulletin 2009年第10期54卷 1725-1731页

作者： SHENG BaiYang NIU Ying ZHOU Hui ZHOU Hui YAN JiaXin ZHAO NanMing zhang xiufang GONG YanDao State Key Laboratory of Biomembrane and Membrane Biotechnology Department of Biological Sciences and Biotechnology Tsinghua University Beijing 100084 China Wuhan Institute of-Biological Products Wuhan 430060 China Medical School Tsinghua University Beijing 100084 China

The amyloid precursor protein (APP) is recognized as the source of Aβ, which plays an important role in Alzheimer’s disease. However, the biological function of APP is obscure. Previous studies showed that mitochondria could be a target of APP. In this work, APP knockout mouse embryo fibroblast (MEF) cells were used to test if APP plays any role in maintaining the mitochondrial function. As the result, APP knockout MEF cells (APP-/- cells) showed the abnormal mitochondrial function, including slower cell proliferation, lower mitochondrial membrane potential, lower intracellular ROS, higher mitochondrial membrane fluidity and lower cytochrome c oxidase activity than their wild-type counterparts. However, no change was found in the amount of mitochondria in MEF APP-/-cells.

关键词：胚胎成纤维细胞线粒体膜电位亚洲功能障碍小鼠细胞色素C氧化酶阿尔茨海默氏病应用程序

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

Amyloid precursor protein-mediated modulation of capacitive calcium entry

引用

Chinese Science Bulletin 2012年第35期57卷 4552-4559页

作者： MA Tuo NIU Ying ZHAO Chang SU ZuQi AO Qiang zhang xiufang ZHAO NanMing GONG YanDao State Key Laboratory of Biomembrane and Membrane Biotechnology School of Life SciencesTsinghua UniversityBeijing 100084China Institute of Neurological Disorders Yuquan HospitalTsinghua UniversityBeijing 100084China

Alzheimer's disease(AD) is a progressive neurodegenerative *** the present study,the function of amyloid precursor protein(APP) in modulating capacitive calcium entry(CCE),a refilling mechanism for depleted intracellular calcium stores,was *** in neural 2a(N2a) cells stably expressing wild-type human APP was lower than in wild-type N2a cells,while CCE in APP knockout mouse embryonic fibroblast(MEF) cells was higher than in their wild-type *** demonstrate that wild-type APP depresses ***,using N2a cells transfected with C-terminal APP fragments,we show that these fragments anchored in the cell membrane play an important role in CCE depression.

关键词：淀粉样前体蛋白细胞内钙库电容调制蛋白质神经变性疾病阿尔茨海默氏病胚胎成纤维细胞

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：