检索结果-南通市图书馆

Mesomechanism of steel fiber reinforcement and toughening of reactive powder concrete

Science China(Technological Sciences) 2007年第6期50卷 815-832页

作者： JU Yang jia yudan LIU HongBin CHEN jian State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China

Reactive powder concrete (RPC) is a novel cement-based composite material with ultra-high strength. Embedding a certain amount of short steel fibers in the matrix can improve the RPC’s toughness and overcome the disadvantage of high brittle- ness. In this paper, a number of direct uniaxial tension tests have been carried out with ‘8-shape’ RPC200 specimens. The bond-slip process, mesoscopic structural variation and mechanical characteristics of a fiber pullout of the matrix have been investigated using the real-time SEM loading system and CCD observation tech- niques. The influence of the volume of embedded short steel fibers in matrix on the mesoscopic morphology of attachments on the surface of a pulled individual fiber, the initial cracking force, the ultimate pullout force, interfacial bond strength and the pullout rupture energy have been analyzed. A general formulation relating these quantities to the volume of fibers in matrix has been proposed. The components comprising the interfacial bond strength have been outlined. In addition, the con- tribution that fibers make to enhance and toughen the reactive powder concrete has been discussed. It is shown that there exists an optimal threshold of fiber volume ρv, opt =1.5% at which the bond performance of a fiber pullout of RPC be- haves best.

关键词： reactive powder concrete, steel fiber, interfacial bond strength, reinforcement and toughening, mesomechanism

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

Toughness and characterization of reactive powder concrete with ultra-high strength

引用

Science China(Technological Sciences) 2009年第4期52卷 1000-1018页

作者： Yang Ju HongBin Liu jian Chen yudan jia PeiHuo Peng State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China Department of Mechanical & Manufacturing Engineering The University of Calgary 2500 University Drive NW Calgary AB T2N 1N4 Canada The University of Illinois at Urbana-Champaign 1110 West Green Street Urbana IL 61801 USA Building Design Division China Nuclear Power Engineering Co. Ltd Beijing 100840 China School of Civil Engineering University of Nottingham University Park Nottingham NG7 2RD UK

A number of three-point bending and fracture tests of 200 MPa-level reactive powder concrete (RPC) with the various fiber contents have been conducted to probe the nature and characteristics of toughness of RPC200. The contribution of the embedded fibers to improving the crack-resistant capacity, energy absorption capacity and toughness with various deformation mechanisms has been analyzed. Taking account of that the first-crack deformation, peak-load deformation and their improvement varied with the fiber contents and that the deformation mechanism affected differently the performance at the first crack and the peak load, we took the peak-load deformation of plain RPC200 as the reference deformation to measure the toughness of fibered RPC200. Two toughness indices T 2(n−1)(n) and FT 2(n−1)(n) have been formulated based on P-δ responses and P-CMOD responses. The indices quantify the toughness of RPC200 with the various deformation mechanisms relative to perfectly elastoplastic materials by setting the toughness level 2(n−1) as the initial reference. It is shown that the toughness index T 2(n−1)(n) reflects the function of fibers to improve the toughness of RPC with the deformation throughout specimens, but overestimates the contribution to enhancing the toughness in post-peak periods. It underestimates, on other hands, the contribution to improving the toughness in the period from the first crack to the peak load. In contrast, the toughness index FT 2(n−1)(n) properly presents the capability that fibers absorb energy and constrain crack propagation in the matrix when the deformation is concentrated on the open crack. The proposed index unveils the contribution of fibers to toughening RPC200 both in the period from the first-crack to the peak load and in the period of post peak. This characterization method not only reveals the nature of toughness but also levels the toughness of RPC200. I

关键词： reactive powder concrete toughness characterization index deformation mechanism flexure fracture

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

旋流场中PP单球颗粒力学行为实验测试分析

引用

应用力学学报 2020年第3期37卷 999-1006,I0006页

作者：贾玉丹伍开松况雨春陈柯杰西南石油大学机电工程学院成都610500 西南石油大学油气藏地质与开发国家重点实验室成都610500

研究PP(Polypropylene)球形颗粒在旋流场中的力学行为,需要一个比较理想的、稳定的旋流场,为此采用了特殊尺寸的实验转鼓。根据PP球形颗粒在这种强制旋流场中的实验现象、测试数据和颗粒受力平衡分析可知:PP颗粒在雷诺数为180~230范围... 详细信息

研究PP(Polypropylene)球形颗粒在旋流场中的力学行为,需要一个比较理想的、稳定的旋流场,为此采用了特殊尺寸的实验转鼓。根据PP球形颗粒在这种强制旋流场中的实验现象、测试数据和颗粒受力平衡分析可知:PP颗粒在雷诺数为180~230范围内的强制旋流场中达到稳定运动状态时,几乎静止在中心水平线附近的某一点,只有颗粒的自转运动;且转鼓转速越高,颗粒的质心位置越靠近旋转中心。依据切向受力平衡条件,利用现有的曳力公式对实验数据进行处理,发现颗粒不能达到受力平衡,且最大误差超过22%。为此,利用实验数据拟合方法,得到了旋流场中颗粒曳力系数的新经验公式,其受力平衡误差均小于0.5%。依据径向受力平衡条件,以径向压力梯度力、附加质量力、浮力与重力之差在径向上的分力之和为基准,与低雷诺数下的Saffman升力和Magnus升力的理论计算结果之和相比较,发现二者也不能达到力平衡条件,最大误差超过了55%。本文根据球形颗粒在旋流场中的升力特征,通过直观的力学分析和量纲分析,定义了颗粒旋流场升力概念,导出了相应的升力系数公式;并利用实验数据拟合得到了升力系数与颗粒雷诺数的经验公式;利用经验公式处理实验数据,其力平衡误差不超过7%。

关键词： PP颗粒旋流场曳力系数升力系数

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

等离子体电脉冲钻井破岩机理的电击穿实验与数值模拟方法

引用

石油学报 2020年第9期41卷 1146-1162页

作者：祝效华罗云旭刘伟吉高锐贾玉丹刘呈君西南石油大学机电工程学院四川成都610500 新奥科技发展有限公司(新奥能源研究院) 河北廊坊065000 中国石油西南油气田公司工程技术研究院四川成都610017

等离子体电脉冲钻井技术为一种高效破岩钻井技术。对4种岩石在80 kV固定输出电压、重频率为2.5 Hz下进行了电脉冲击穿实验。实验发现,电脉冲破碎结果中存在贯穿破碎和未贯穿破碎2种状貌,并针对产生这两种状貌的原因进行了分析。从电击... 详细信息

等离子体电脉冲钻井技术为一种高效破岩钻井技术。对4种岩石在80 kV固定输出电压、重频率为2.5 Hz下进行了电脉冲击穿实验。实验发现,电脉冲破碎结果中存在贯穿破碎和未贯穿破碎2种状貌,并针对产生这两种状貌的原因进行了分析。从电击穿角度明确了单次脉冲破岩效率的评价指标——能量转换效率η_e,并提出了一种新的岩石介质击穿模型——概率发展模型(PDM),借助PDM和简化的电击穿电路研究了单脉冲击穿时电路结构参数对破岩能耗分配的影响规律。基于电脉冲击穿实验参数和PDM生成的等离子体通道轨迹提出了等离子体电脉冲钻井破岩机理研究的数值模拟方法,利用该数值模拟方法研究了在地层压力为0~30 MPa下、直径为41 mm的电极钻具在加载峰值电压为60 kV时的破岩规律。

关键词：等离子通道钻井高压电脉冲破岩机理电击穿数值模拟方法电脉冲钻具

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

等离子炬破岩效果室内试验及现场应用建议

引用

石油钻探技术 2022年第4期50卷 59-63页

作者：于岩高锐贾玉丹乔磊周伟新奥科技发展有限公司河北廊坊065001 河北省深层地热技术创新中心河北廊坊065001 中国石油大学(华东)石油工程学院山东青岛266580

油气资源和深层地热能开发钻井过程中会遇到岩石硬度大、可钻性差等问题,采用传统钻井技术难以提高钻井效率。针对这一问题,分析了等离子炬的破岩原理,认为等离子炬破岩主要有岩石破碎、熔化和蒸发等方式;利用不同厚度的玄武岩和花岗岩... 详细信息

油气资源和深层地热能开发钻井过程中会遇到岩石硬度大、可钻性差等问题,采用传统钻井技术难以提高钻井效率。针对这一问题,分析了等离子炬的破岩原理,认为等离子炬破岩主要有岩石破碎、熔化和蒸发等方式;利用不同厚度的玄武岩和花岗岩岩样,进行了等离子炬破岩效果室内试验,证明等离子炬可以烧穿50 mm厚的玄武岩岩样和30 mm厚的花岗岩岩样,但不能烧穿更厚的岩样。结合试验结果,分析了现场应用等离子炬钻井技术存在的问题,提出了研发建议。研究结果为深层硬地层等离子炬钻井技术的研究与应用提供了技术借鉴。

关键词：等离子炬破岩实验室试验高温射流应用建议

来源：

维普期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Chronic spinal cord injury repair by NT3-chitosan only occurs after clearance of the lesion scar

引用

Signal Transduction and Targeted Therapy 2022年第7期7卷 2568-2580页

作者： Can Zhao jia-Sheng Rao Hongmei Duan Peng Hao Junkui Shang Yubo Fan Wen Zhao yudan Gao Zhaoyang Yang Yi Eve Sun Xiaoguang Li Beijing Key Laboratory for Biomaterials and Neural Regeneration Beijing Advanced Innovation Center for Biomedical EngineeringSchool of Biological Science and Medical EngineeringBeihang UniversityBeijing 100083China Institute of Rehabilitation Engineering China Rehabilitation Science InstituteBeijing 100068China Department of Neurobiology School of Basic Medical SciencesCapital Medical UniversityBeijing 100069China Beijing Advanced Innovation Centre for Biomedical Engineering Key Laboratory for Biomechanics and Mechanobiology of Chinese Education MinistrySchool of Biological Science and Medical EngineeringBeihang UniversityBeijing 10083China School of Engineering Medicine Beihang UniversityBeijing 10083China Shanghai Institute of Stem Cell Research and Clinical Translation Shanghai East HospitalTongji University School of MedicineShanghai 200120China Department of Psychiatry and Biobehavioral Sciences UCLA Medical SchoolLos AngelesCA 90095USA

Spinal cord injury(SCI)is a severe damage usually leading to limb dysesthesia,motor dysfunction,and other physiological *** have previously shown that NT3-chitosan could trigger an acute SCI repairment in rats and non-human *** to the negative effect of inhibitory molecules in glial scar on axonal regeneration,however,the role of NT3-chitosan in the treatment of chronic SCI remains *** with the fresh wound of acute SCI,how to handle the lesion core and glial scars is a major issue related to chronic-SCI *** we report,in a chronic complete SCI rat model,establishment of magnetic resonancediffusion tensor imaging(MR-DTI)methods to monitor spatial and temporal changes of the lesion area,which matched well with anatomical *** of the lesion core via suction of cystic tissues and trimming of solid scar tissues before introducing NT3-chitosan using either a rigid tubular scaffold or a soft gel form led to robust neural regeneration,which interconnected the severed ascending and descending axons and accompanied with electrophysiological and motor functional *** contrast,cystic tissue extraction without scar trimming followed by NT3-chitosan injection,resulted in little,if any *** together,after lesion core clearance,NT3-chitosan can be used to enable chronic-SCI repair and MR-DTI-based mapping of lesion area and monitoring of ongoing regeneration can potentially be implemented in clinical studies for subacute/chronic-SCI repair.

关键词： scar NT3 wound

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

A highly sensitive bio-barcode immunoassay for multi-residue detection of organophosphate pesticides based on fluorescence antiquenching

引用

Journal of Pharmaceutical Analysis 2022年第4期12卷 637-644页

作者： Lingyuan Xu Xiuyuan Zhang A.M.Abd El-Aty Yuanshang Wang Zhen Cao Huiyan jia J.-Pablo Salvador Ahmet Hacimuftuoglu Xueyan Cui yudan Zhang Kun Wang Yongxin She Fen Jin Lufei Zheng Baima Pujia Jing Wang Maojun Jin Bruce D.Hammock Institute of Quality Standard and Testing Technology for Agro-Products Chinese Academy of Agricultural SciencesBeijing100081China Department of Pharmacology Faculty of Veterinary MedicineCairo UniversityGiza12211Egypt Department of Medical Pharmacology Medical FacultyAtaturk UniversityErzurum25240Türkiye Institute of Livestock and Poultry Ningbo Academy of Agricultural SciencesNingboZhejiang315040China Nanobiotechnology for Diagnostics Group Instituto de Química Avanzada de CatalunaIQAC-CSICBarcelona08034Spain CIBER de Bioingeniería Biomateriales y Nanomedicina(CIBER-BBN)Madrid28029Spain Inspection and Testing Center of Agricultural and Livestock Products of Tibet Department of Agriculture and Rural Affairs of Tibet Autonomous RegionLhasa850000China Department of Entomology&Nematology and the UC Davis Comprehensive Cancer Center University of CaliforniaDavisCA95616USA

Balancing the risks and benefits of organophosphate pesticides(OPs)on human and environmental health relies partly on their accurate measurement.A highly sensitive fluorescence anti-quenching multi-residue bio-barcode immunoassay was developed to detect OPs(triazophos,parathion,and chlorpyrifos)in apples,turnips,cabbages,and *** nanoparticles were functionalized with monoclonal antibodies against the tested *** oligonucleotides were complementarily hybridized with an RNA fluorescent label for signal *** detection signals were generated by DNA-RNA hybridization and ribonuclease H dissociation of the *** resulting fluorescence signal enables multiplexed quantification of triazophos,parathion,and chlorpyrifos residues over the concentration range of 0.01-25,0.01-50,and 0.1-50 ng/mL with limits of detection of 0.014,0.011,and 0.126 ng/mL,*** mean recovery ranged between 80.3% and 110.8% with relative standard deviations of 7.3%-17.6%,which correlate well with results obtained by liquid chromatography-tandem mass spectrometry(LC-MS/MS).The proposed bio-barcode immunoassay is stable,reproducible and reliable,and is able to detect low residual levels of multi-residue OPs in agricultural products.

关键词： Organophosphate pesticides Fluorescence anti-quenching Gold nanoparticles DNA-RNA hybridization DNA oligonucleotides Ribonuclease H

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

Effect of HS2 and HS3 elements on erythroid-specific expression in transgenic mice

引用

Progress in Natural Science:Materials International 2003年第9期 34-39+83页

作者： jia Chunping, YAN Jingbin, XIAO Yanping, FANG yudan, HUANG Shuzheng and ZENG Yitao(Institute of Medical Genetics, Shanghai jiaotong University, Shanghai 200040, China)

The expression plasmids CMV/GFP, HS2ALL, HS3ALL and HS23ALL were selected to investigate the effect of HS2and HS3 element on erythroid-specific expression in transgenic mice. These plasmids were digested with restriction enzymes and *** five DNA fragments, CMV/GFP, HS2/GFP, CMV/HS2/GFP, HS23/GFP and HS3/GFP were obtained. After purification, theabove DNA fragments were microinjected into the pre-nuclei of the mice fertilized eggs and transgenic mice were generated, with an inte-gration rate of 10.89%. The green fluorescence protein(GFP) expression in many transgenic mouse tissues was determined by FACSanalysis. The results showed that the HS2 and 1.7 kb of β-globin gene promoter were sufficient for the erythroid-specific expression of β-globin gene. The GFP expression of different recombinant constructs was also analyzed in blood of all the transgenic mice with FACS. Theresults indicated that HS2 and HS3 had the same enhancement activity on the requlation of β-globin gene expression. Moreove

关键词： β-globin gene locus control region GFP transgenic mouse.

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Thickness dependence of microstructure and properties in Be2C coatings as a promising ablation material

引用

Matter and Radiation at Extremes 2019年第4期4卷 23-29页

作者： yudan He Lei Jin Jiqiang Zhang Bingchi Luo Kai Li Weidong Wu jiangshan Luo Research Center of Laser Fusion Chinese Academy of Engineering PhysicsMianyang 621900China Science and Technology on Plasma Physics Laboratory Mianyang 621900China IFSA Collaborative Innovation Center Shanghai Jiao Tong UniversityShanghai 200240China

Beryllium carbide(Be2C)thin films have proven to be promising ablation materials,but the properties of Be2C coatings of the greater thickness required for inertial confinement fusion capsules are still *** this work,Be2Ccoatings of various thicknesses(0.3–32.9μm)are prepared byDC reactive magnetron *** influence of thickness on crystal properties,microstructure,and optical properties is *** results indicate that the crystallinity of polycrystalline Be2C films improves with increasing thickness,while the grain size(∼5 nm)and texture properties(without a preferred orientation)have only a weak dependence on *** featureless microstructure and smooth surface(root mean square roughness∼8 nm)are observed even in thick(32.9μm)films,despite the presence of defects induced by *** densities(2.19–2.31 g/cm3)and high deposition rates(∼270 nm/h)are realized,with the latter corresponding to the upper limit for the fabrication of Be2Ccoatings by magnetron *** transmittance of the films in the near-infrared region remains at a high level(>80%)and has only a weak dependence on thickness,while the transmittance in the visible region decreases with increasing *** addition,the optical bandgap is estimated to be about 1.9 eV and decreases with increasing thickness owing to the presence of defects.

关键词： microstructure carbide properties

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

细鳞鱼温和气单胞菌LAMP检测方法的建立

引用

畜牧与兽医 2021年第1期53卷 101-105页

作者：郭玉丹杜迎春何亚鹏时晓贾斌石河子大学动物科技学院新疆石河子832003 北京市水生野生动植物救护中心北京102100

在对野生细鳞鱼保护和驯养繁育工作中发现其出现厌食独居、水中打转、体表溃疡和肝肾脏出血症状,从患病鱼体内分离得到1株细菌,经过生理生化鉴定和16S rRNA测序确定该菌株为温和气单胞菌(Aeromonas sobria),在此基础上利用环介导恒温扩... 详细信息

在对野生细鳞鱼保护和驯养繁育工作中发现其出现厌食独居、水中打转、体表溃疡和肝肾脏出血症状,从患病鱼体内分离得到1株细菌,经过生理生化鉴定和16S rRNA测序确定该菌株为温和气单胞菌(Aeromonas sobria),在此基础上利用环介导恒温扩增技术(LAMP)建立该菌的快速检测方法。选用管家基因zipA作为靶基因,设计筛选出一套最佳引物,使用25μL的优化体系,提取几种常见水产致病菌株DNA进行特异性分析,以10倍稀释法进行LAMP灵敏性试验,确定最低检测DNA浓度为1.663×10^(-9) ng/μL。试验表明建立的温和气单胞菌LAMP检测方法可及早发现感染细菌,为阻止细鳞鱼疫情暴发和细鳞鱼驯化带来保障。

关键词：温和气单胞菌细菌鉴定环介导恒温扩增技术(LAMP)

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：