检索结果-南通市图书馆

Low-temperature magnetic properties of horse spleen ferritin

chinese Science Bulletin 2010年第27期55卷 3174-3180页

作者： TIAN LanXiang 1,2,CAO ChangQian 1,2,LIU QingSong 1,2 &PAN YongXin 1,2 1key laboratory of the Earth’s Deep Interior,Institute of Geology and Geophysics,chinese {3. of Sciences,{3. 100029,China 2Franco-chinese Biomineralization and Nano-structures laboratory,{3. 100029,China key laboratory of the Earth''s Deep Interior Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Franco-chinese Biomineralization and Nano-structures laboratory Beijing 100029 China

The magnetic properties of the antiferromagnetic cores in ferritin are of importance in the construction and improvement of ferritin-based magnetic resonance imaging systems and their application to environmental *** this study,we carry out integrated magnetic and transmission electron microscopy analyses of horse spleen ferritin(HoSF)to understand the relationships between the magnetic behavior of HoSF and temperature,applied field and grain-size *** R-value from the Wohlfarth-Cisowski test for the investigated sample at 5 K was 0.46,indicating very weak magnetostatic interactions among the nanoparticles of *** nanoparticles of HoSF show superparamagnetic properties at room temperature,while below the blocking temperature of Tb≈12 K it has a net magnetic moment that comes from the uncompensated spins of the nanoparticle surface or *** thermal relaxation process of HoSF follows the Néel-Arrhenius *** low-temperature AC susceptibility data,we calculated the effective magnetic anisotropy energy Ea=(5.52±0.16)×10-21 J;the effective magnetic anisotropy energy constant Keff=(4.65±0.14)×10 4 J/m3.and the pre-exponential frequency factor f0 =(4.52±2.93.×1011 *** values are useful in understanding the magnetic behavior of the antiferromagnetic nanoparticles and their potential application in biomedical technology.

关键词：马脾铁蛋白低温度磁性质透射电子显微镜磁各向异性常数纳米粒子生物医学技术交流磁化率

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

MODIFICATION OF EPOXY RESIN WITH POLYSILOXANE BEARING PENDANT QUATERNARY AMMONIUM GROUPS

引用

chinese Journal of Polymer Science 2002年第6期20卷 537-541页

作者： Zuo-xin Huang Ying Huang Yun-zhao Yu The State key laboratory of Engineering Plastics, Institute of Chemistry chinese {3. of Sciences, {3. 100080 China chinese Acad Sci Inst Chem State Key Lab Engn Plast Beijing 100080 Peoples R China

Polysiloxane bearing pendant quaternary ammonium groups (PSI) was used to modify the surface properties of epoxy resins. In the cured resin, PSI formed the dispersed phase. Remarkable enrichment and gradient distribution of polysiloxane on the surface region of the epoxy resins were demonstrated by XPS analysis. The composition and properties of the surface of PSI-modified epoxy resin, which is in contact with the mold, are dependent on the material of the mold. Through the incorporation. of PSI, epoxy resins with low surface energy and low friction coefficient were obtained. Polysiloxane with lower ionic group content shows a higher degree of enrichment on the resin surface and leads to a higher contact angle against water, while the polysiloxane having optimum compatibility with the epoxy resin shows a greater effect in reducing the static friction coefficient of the resin against glass.

关键词： polysiloxane epoxy resin surface composition friction coefficient

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

Ecological hydraulic radius model to calculate instream flow requirements for transporting sediment in the western water transfer region

引用

Science China(Technological Sciences) 2009年第11期52卷 3401-3405页

作者： MEN BaoHui1 & LIU ChangMing2 1 Renewable energy Institute, North China Electric Power University, beijing 102206, China 2 key {3. of Water Cycle and Related Land Surface Process, Institute of Geographical Sciences and Natural Resources Research, {3. academy of Sciences, beijing 100101, China 1. Renewable energy Institute North China Electric Power University Beijing 102206 China 2. key laboratory of Water Cycle and Related Land Surface Process Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

Transporting sediment is a natural function of the river. To maintain the normal evolution of the river certain amount of water flow is required, which is called the instream flow requirements for transporting sediment (IFRTS). We defined the permitting flow velocity by the conception of IFRTS, and also put forward the ecological hydraulic radius model (EHRM) to estimate IFRTS. The calculating process of EHRM is explained by the example of Daofu Hydrological Station on Xianshui branch of Yalong River in the west line first-stage construction of South-North Water Transfer Project. The result shows that the IFRTS occupied 29.7%―59.5% of annual mean discharge in flood season, the average of IFRTS was about 100.2 m3.s during 1966―1987, it is close to the IFRTS 90 m3.s calculated by IFRTS conception. Hence, it is feasible to use EHRM to calculate IFRTS.

关键词： ecological hydraulic radius model (EHRM) instream flow requirements for transporting sediment (IFRTS) permitting flow velocity ecological hydraulic radius for transporting sediment

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

Bifurcation timescales in power spectra of black hole binaries and ultraluminous X-ray sources

引用

Science China(Physics,Mechanics & Astronomy) 2010年第S1期53卷 177-182页

作者： WANG TaiShan1 & LI TiPei1,2 1 Department of Physics & Center for Astrophysics,Tsinghua University,beijing 100084,China 2 key laboratory of Particle Astrophysics,Institute of High {3. Physics,{3. academy of Sciences,beijing 100049,China Tsinghua Univ Dept Phys Beijing 100084 Peoples R China Tsinghua Univ Ctr Astrophys Beijing 100084 Peoples R China chinese Acad Sci Inst High Energy Phys Key Lab Particle Astrophys Beijing 100049 Peoples R China

For black hole binaries(BHBs) and active galactic nuclei(AGNs),bifurcation timescales(BTs) Δtb exist,below which time-domain power is significantly higher than the corresponding Fourier ***-periodic oscillations(QPOs) are removed from the Fourier spectra of BHBs.A relationship between BT,black hole mass and bolometric luminosity is *** anti-correlation between BT and luminosity of Cyg X-1 is *** removing the QPOs,BTs are also obtained for two ultraluminous X-ray sources(ULXs),M82 X-1 and NGC5408 *** results support that they harbor intermediate mass black holes(IMBHs).

关键词： black hole binary ultraluminous X-ray source power spectral density data analysis

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

Diagnostics for the structure of AGNs'broad line regions with reverberation mapping data:confirmation of the two-component broad line region model

引用

Science China(Physics,Mechanics & Astronomy) 2010年第S1期53卷 196-201页

作者： ZHU Ling1 & ZHANG ShuangNan2 1 Department of Physics and Tsinghua Center for Astrophysics,Tsinghua University,beijing 100084,China 2 key laboratory of Particle Astrophysics,Institute of High {3. Physics,{3. academy of Sciences,beijing 100049,China 1. Department of Physics and Tsinghua Center for Astrophysics Tsinghua University Beijing 100084 China 2. key laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

We re-examine the ten Reverberation Mapping(RM) sources with public data based on the two-component model of the Broad Line Region(BLR).In fitting their broad Hβ Mlines,six of them only need one Gaussian component,one of them has a double-peak profile,one has an irregular profile,and only two of them need two components,i.e.,a Very Broad Gaussian Component(VBGC) and an Inter-Mediate Gaussian Component(IMGC).The Gaussian components are assumed to come from two distinct regions in the two-component model;they are the Very Broad Line Region(VBLR) and the Inter-Mediate Line region(IMLR).The two sources with a two-component profile are Mrk 509 and NGC *** time lags of the two components of both sources satisfy tIMLR/tVBLR=V 2VBLR/V 2IMLR,where tIMLR and tVBLR are the lags of the two components while VIMLR and VVBLR represent the mean gas velocities of the two regions,supporting the two-component model of the BLR of Active Galactic Nuclei(AGNs).The fact that most of these ten sources only have the VBGC confirms the assumption that RM mainly measures the radius of the VBLR;consequently,the radius obtained from the R-L relationship mainly represents the radius of ***,NGC 4051,with a lag of about 5 days in the one component model,is an outlier on the R-L relationship as shown in Kaspi et al.(2005);however this problem disappears in our two-component model with lags of about 2 and 6 days for the VBGC and IMGC,respectively.

关键词： broad line region AGN Reverberation Mapping cross correlation

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

Second mode unstable disturbance measurement of hypersonic boundary layer on cone by wavelet transform

引用

Acta Mechanica Sinica 2011年第4期27卷 488-493页

作者： Jian Han.Nan Jiang.Yan Tian Department of Mathematics,Tianjin University,3.0072 Tianjin,China Department of Mechanics,Tianjin University,3.0072 Tianjin,China Tianjin key laboratory of Modern Engineering Mechanics,3.0072 Tianjin,China State key laboratory of Nonlinear Mechanics,Institute of Mechanics,chinese {3. of Sciences,100190 beijing,China Department of Mathematics Tianjin University Tianjin China Department of Mechanics Tianjin University Tianjin China Tianjin key laboratory of Modern Engineering Mechanics Tianjin China State key laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing China

Experimental investigation of hypersonic boundary layer instability on a cone is performed at Mach number 6 in a hypersonic wind tunnel. Time series signals of instantaneous fluctuating surface-thermal-flux are measured by Pt-thin-film thermocouple temperature sensors mounted at 28 stations on the cone surface in the streamwise direction to investigate the development of the unstable disturbance. Wavelet transform is employed as a mathematical tool to obtain the multi-scale characteristics of fluctuating surfacethermal-flux both in the temporal and spectrum space. The conditional sampling algorithm using wavelet coefficient as an index is put forward to extract the unstable disturbance waveform from the fluctuating surface-thermal-flux *** generic waveform for the second mode unstable disturbance is obtained by a phase-averaging technique. The development of the unstable disturbance in the streamwise direction is assessed both in the temporal and spectrum space. Our study shows that the local unstable disturbance detection method based on wavelet transformation offers an alternative powerful tool in studying the hypersonic unstable mode of laminar-turbulent transition. It is demonstrated that, at hypersonic speeds, the dominant flow instability is the second mode, which governs the course of laminar-turbulent transition of sharp cone boundary layer.

关键词： Hypersonic boundary layer. Sharp cone Insta-bility Wavelet transform

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 Explicit Function Expression for dc Bias and Temperature Dependence of Magnetoresistances in Magnetic Tunnel Junctions

引用

Journal of Materials Science & Technology 2002年第6期18卷 497-501页

作者： Xiufeng HANState key laboratory of Magnetism, Institute of Physics and Center of Condensed Matter Physics, chinese {3. of Sciences, {3. 100080, China chinese Acad Sci Inst Phys State Key Lab Magnetism Beijing 100080 Peoples R China chinese Acad Sci Ctr Condensed Matter Phys Beijing 100080 Peoples R China

An explicit function expression for the bias voltage or/and temperature dependences of tunnel magnetoresistance ratio and resistances were obtained with a unique set of intrinsic parameters. Two of these intrinsic parameters are the Curie temperature TC and the density of state (DOS) for itinerant majority and minority electrons ξ(ρM/ρm), which are the eigen parameters of ferromagnetic electrodes. Others are the spin-dependent matrix-element ratio (i.e., |Td|2/|TJ|2 ) and the anisotropic-wavelength-cutoff energy ECγ of spin-wave spectrum in magnetic tunnel junction (MTJ), which are the structure parameters of an MTJ. These intrinsic parameters can be predetermined using the experimental measurement or, in principle, using the first-principle calculation method for an MTJ with the three key layers of FM/I/FM. Furthermore, a series of experimental data for an MTJ, for example, a spin-valve-type MTJ of Ta (5 nm)/Ni79Fe21(25 nm)/lr22Mn78(12 nm)/Co75Fe25(4 nm)/AI(0.8 nm)-oxide/Co75Fe25(4 nm)/Ni79Fe21(20 nm)/Ta (5 nm) in this work, can be self-consistently evaluated and explained using such concise explicit function formulations.

关键词： Magnetic tunnel junction TMR Spin-electron transport Magnon excitation Spin-polarization Magnetotransport

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

Characteristics of energy dissipation in hyperconcentrated flows

引用

International Journal of Sediment Research 2008年第4期23卷 387-397页

作者： An-ping SHU 1,Qing-quan LIU2,Yu-jun YI 3.and Zhi-dong ZHANG 41 Assoc.Prof.,School of Environment,key laboratory of Water and Sediment Sciences of Ministry of Education,beijing Normal University,beijing 100875,China2 Prof.,Institute of Mechanics,{3. academy of Sciences,beijing 100080,China3.Lecturer,Dr.,School of Environment,beijing Normal University,beijing 100875,China4 Graduate student,School of Environment,beijing Normal University,beijing 100875,China [a]Assoc. Prof. School of Environment key laboratory of Water and Sediment Sciences of Ministry of Education beijing Normal University beijing 100875 China [b]Prof. Institute of Mechanics chinese academy of Sciences beijing 100080 China [c]Lecturer Dr. School of Environment beijing Normal University beijing 100875 China. The project is supported by the National Natural Science Foundation of China (Grant No. 10672024) [d]Graduate student School of Environment beijing Normal University beijing 100875 China

An equilibrium equation for the turbulence energy in sediment-laden flows was derived on the basis of solid–liquid two-phase flow theory. The equation was simplified for two-dimensional, uniform, steady and fully developed turbulent hyperconcentrated flows. An energy efficiency coefficient of suspended-load motion was obtained from the turbulence energy equation, which is defined as the ratio of the sediment suspension energy to the turbulence energy of the sediment-laden flows. laboratory experiments were conducted to investigate the characteristics of energy dissipation in hyperconcentrated flows. A total of 115 experimental runs were carried out, comprising 70 runs with natural sediments and 45 runs with cinder powder. Effects of sediment concentration on sediment suspension energy and flow resistance were analyzed and the relation between the energy efficiency coefficient of suspended-load motion and sediment concentration was established on the basis of experimental data. Furthermore, the characteristics of energy dissipation in hyperconcentrated flows were identified and described. It was found that the high sediment concentration does not increase the energy dissipation; on the contrary, it decreases flow resistance.

关键词： Hyperconcentrated flows Turbulence energy Efficiency coefficient energy dissipation

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

Observation of the Turbulent Burst near ASheared Air-Water Interface

引用

Communications in Nonlinear Science and Numerical Simulation 1999年第2期4卷 94-99页

作者： Shuangfeng WANG Fu JIA Zhennan NIU Zhangzhi WU(Institute of Mechanics, chinese academy of Sciences, beijing 100080, China)(State {3. {3. for Turbulence Research, Peking University, beijing 100871,China) Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

The turbulent burst under a sheared air-water interface was experimentally investigated using hydrogen bubble visualization technique. The surface shear wasimposed by an airflow over the water flow which was kept free from surface waves. Resultsshow that the wind shear has the main influence on the bursting events. At relativelyhigh shear rates, the flow near the interface is dominated primarily by intermittent bursting events. The general features of bursting processes are described in some detail. Theobserved bursting events show qualitative similarities with those occurring in near-wallturbulence. However, a few distinctive phenomena were also observed, including the existence of vertical vortices and thickening process of the boundary layer, which appear tobe associated with the Characteristics of air-water interface.

关键词： air-water interface turbulent burst flow-visualization

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

Numerical exploration of new features on three-dimensional transition of a cylinder wake

引用

Science China Mathematics 2004年第z1期47卷 69-80页

作者： LING Guocan, XIONG Jun & ZHU KeqinState key laboratory of Nonlinear Mechanics, Institute of Mechanics, chinese {3. of Sciences, {3. 100080, China Department of Engineering Mechanics, Tsinghua University, {3. 100084, China chinese Acad Sci Inst Mech State Key Lab Nonlinear Mech Beijing 100080 Peoples R China Tsing Hua Univ Dept Engn Mech Beijing 100084 Peoples R China

The three-dimensional transition of the wake flow behind a circular cylinder is studied in detail by direct numerical simulations using 3. incompressible N-S equations for Reynolds number ranging from 200 to 3.0. New features and vortex dynamics of the 3. transition of the wake are found and investigated. At Re = 200, the flow pattern is characterized by mode A instability. However, the spanwise characteristic length of the cylinder determines the transition features. Particularly for the specific spanwise characteristic length linear stable mode may dominate the wake in place of mode A and determine the spanwise phase difference of the primary vortices shedding. At Re = 250 and 3.0 it is found that the streamwise vortices evolve into a new type of mode "dual vortex pair mode" downstream. The streamwise vortex structures switch among mode A, mode B and dual vortex pair mode from near wake to downstream wake. At Re = 250, an independent low frequency fm in addition to the vortex shedding frequency fs is identified. Frequency coupling between fm and fs occurs. These result in the irregularity of the temporal signals and become a key feature in the transition of the wake. Based on the formation analysis of the streamwise vorticity in the vicinity of cylinder, it is suggested that mode A is caused by the emergence of the spanwise velocity due to three dimensionality of the incoming flow past the cylinder. energy distribution on various wave numbers and the frequency variation in the wake are also described.

关键词： cylinder, wake, 3. transition, Fourier-spectral-spectral-element method, direct numerical simulation (DNS).

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：