检索结果-南通市图书馆

Formation and evolution mechanisms of large-clusters during rapid solidification process of liquid metal Al

Science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 101-112页

作者： LIU Rangsu, DONG Kejun, LIU Fengxiang, ZHENG Caixing, LIU Hairong & LI Jiyong Department of Applied Physics, hunan university, Changsha 410082. {2. college of Materials Science and engineering, hunan university, Changsha 410082. {2. college of chemistry and chemical engineering, hunan university, Changsha 410082. {2. Department of Applied Physics Hunan University Changsha 410082 China college of Materials Science and engineering Hunan University Changsha 410082 China college of chemistry and chemical engineering Hunan University Changsha 410082 China

A molecular dynamics simulation study has been performed for the formation and evolution characteristics of nano-clusters in a large-scale system consisting of 400000 atoms of liquid metal Al. The center-atom method combined with pair-bond analysis technique and cluster-type index method (CTIM) has been applied here to describe the structural configurations of various basic clusters. It is demonstrated that both the 1551 bond-type and the icosahedral cluster (12.0 12.0) constructed by 1551 bond-types are dominant among all the bond-types and cluster-types, respectively, in the system and play a critical role in the microstructure transitions of liquid metal Al. The nano-clusters (containing up to 150 atoms) are formed by the combination of some middle and small clusters with distinctly different sizes, through mutual competition by unceasing annex and evolution in a seesaw manner (in turn of obtaining and losing),which do not occur as the multi-shell structures accumulated with an atom as the center and the surrounding atoms are arranged according to a certain rule. This is the essential distinction of nano-cluster in liquid metal from those obtained by gaseous deposition, ionic spray methods, and so on. Though the nano-clusters differ from each other in shape and size, all of them possess protruding corners that could become the starting points of various dendrite structures in the solidification processes of liquid metals.

关键词： liquid metal, solidification process, large-cluster configuration, evolution mechanism, computer simulation.

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

Effect of static magnetic field on activity of immobilized α-amylase

引用

Chinese Science Bulletin 1997年第2期42卷 127-130页

作者： YAN Liushui, ZHU Yuanbao, HE-Shuang’e and CAO Zhixiang1 Department of chemical engineering, Nanchang Institute of Aeronautical Technology, Nanchang 330034, {2. 2. Department of chemistry and chemical engineering, hunan university, Changsha 410082. {2. Department of chemical engineering Nanchang Institute of Aenwututical Techndogy Nanchang China Department of chemistry and chemical {2. Hunan University Changsha China

BIOLOGICAL effect of magnetic field is one of the three major subjects of contemporary biomagnetism, and is also the basis of applied biomagnetism. In order to explore magnetic biological effects, the influence of various sorts of magnetic field on many living systems as well as their different constructural levels has been extensively studied. However, only a few studies with in vitro enzyme have been reported, and few researches concerning the influence of magnetic field on immobilized enzyme reactions have been published. This note describes

关键词： static magnetic field immobilized α-amylase enzyme activity oscillatory behaviour.

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

Study on H atoms diffusion and adsorption properties of MgH_2.V systems

引用

Science china(Technological Sciences) 2008年第7期51卷 979-988页

作者： ZHOU DianWu1,2. LIU JinShui3 & PENG Ping3 1 State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, hunan university, Changsha 410082. {2. 2.college of Mechanical and Automatic engineering, hunan university, Changsha 410082. {2. 3 college of Materials Science and engineering, hunan university, Changsha 410082. {2. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University college of Mechanical and Automatic engineering Hunan University college of Materials Science and engineering

Based on experimental results that VH0.81/MgH2.interface was found during the process of mechanically milling MgH2.5at.%V nanocomposite, H atoms diffusion and adsorption properties of MgH2.V systems have been investigated by using a first-principles plane-wave pseudopotential method based on the density functional theory. The results are as follows. When VH/MgH2.interface is formed due to V alloying MgH2.phase, the vacancy formed by H atoms near VH phase region is more stable than that without V alloying, while vacancy near MgH2.phase region is less stable than that without V alloying. During the process of H atoms diffusion after V alloying, the max migration barrier energy of H atoms in MgH2.V systems is reduced compared with that of MgH2.phase, which means that H atoms diffuse easily. When H diffuses into VH from MgH2.across VH/MgH2.interface, among three substitutions such as the replacement of H for V vacancy, or interstitial site or V atoms, the replacement of H for V vacancy has the strongest diffusion ability, next interstitial site, and finally V atoms site. As far as H adsorbed on different surfaces of VH phase is concerned, physical adsorption is carried out more easily than chemical adsorption, and the behavior of H atoms adsorbed on the surface near VH phase region can be found more easily than that near MgH2.phase region.

关键词： plane-wave pseudopotential theory magnesium hydride diffusion adsorption

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

Inductance-based sensing technique for wireless,remote-query measurement in liquid media

引用

Science china chemistry 2010年第6期53卷 1391-1397,1460页

作者： MA Lin,NIE Zhou,HUANG Yan & YAO ShouZhou State Key Laboratory of Chemo/Biosensing and Chemometrics,college of chemistry and chemical engineering,hunan {2.,Changsha 410082.china State Key Laboratory of Chemo/Biosensing and Chemometrics College of Chemistry and Chemical Engineering Hunan University Changsha China

A novel inductance-based sensing technique is presented for remote query measurement in different liquid media including organic solvents and inorganic *** inorganic solutions tested included salt solutions of different concentrations,and the organic solvents detected included 1,4-dioxane and *** extend the application of the sensor,bacterial culture media were also detected,and the growth of Escherichia coli (***) was *** influential factors which may affect the inductance responses were studied in *** was found that quantitative relationships exist between the sensor’s inductance response and the physico-chemical parameters of the liquid *** sensor’s inductance response (L) decreases with the increase of salt concentration (C) and its ionic valence (e) according to a semi-logarithmic equation LgL =-aeC + b,where a and b are constants,which is in accordance with the theoretically deduced *** inductance variation rate (ΔK) increases directly with the temperature (T): ΔK = a′ T + b′.As for organic solutions,the sensor’s inductance was found to increase with the increasing permittivity of the organic *** wireless sensor we designed is simple and easy to *** has the potential for remote determination of not only chemical substances but also microbiological species such as *** the newly developed inductance-based sensor,the pathogenic *** was monitored with a limit of detection of 10 cells/mL and a linear semi-logarithmic range of 1.0 × 101 to 2.5 × 109 cells/mL.

关键词： inductance sensor remote-query liquid medium wireless bacterial detection E. coli.

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

Piezoelectric transmission spectroelectrochemistry with a normal piezoelectric quartz crystal as an optically-transparent electrode

引用

Chinese Journal of chemistry 1994年第5期12卷 425-431页

作者： XIE, Qing-Ji PANG, Xiao-Yong NIE, Li-Hua YAO, Shou-Zhuo Department of chemistry and chemical {2., hunan university, Changsha, hunan 410082. china Department of chemistry and chemical {2. Hunan University Changsha Hunan 410082 China

Piezoelectric transmission spectroelectrochemistry (PTSEC), i.e., the combination of electrochemistry and spectroelectrochemistry (SEC) with electrochemical quartz crystal microbalance (EQCM) technique is reported by using a normal piezoelectric quartz crystal (PQC) as an optically-transparent electrode (OTE). A theoretical relationship between the PQC response and the spectroelectrochemical response is derived and used to estimate the apparent molar absorptivity of the absorbing species deposited on the OTE on the PQC surface. The complex of copper with aspartic acid is used to test this new PQC-SEC technique. Results show that the combination of three such diverse techniques provides a very useful methodology for studying electrode processes and electrode surface characteristics in situ.

关键词： Piezoelectronic transimission spectroelectrochemistry optically-transparent electrode electrochemical quartz crystal microbalance copper aspartic acid.

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 Series Piezoelectric Quartz Crystal Response Kinetics for *** Growth in the Presence of Cu(Ⅱ)

引用

Journal of Central South university 2000年第1期12卷 15-19页

作者： CHAI Li yuan 1,2.,WEI Wan zhi 2.YAO Shou zhuo 2.1. Department of Metallurgical Science and engineering, Central South university of Technology, Changsha 410083, {2. 2. college of chemistry and chemical engineering, hunan university, Changsha Department of Metallurgical Science and engineering Central South University of Technology Changsha China college of chemistry and chemical engineering Hunan University Changsha China

The kinetics on the growth of *** in the presence of Cu(Ⅱ) was studied using of series piezoelectric quartz crystal (SPQC). Arsenic ion inhibits the growth of *** , which is consistent with the previous results by other measuring methods. This further demonstrates that the SPQC can monitor the chemical activity of *** growth. Cupric ion accelerates the growth of *** . The mechanism was discussed, i. e., copper promotes the protein enzyme of *** , rusticyanin, to form over the range of cupric ion concentration studied. The reaction order of cupric ion in accelerating the bacterial growth is 0.067. The growth of *** is dependent on temperature, the apparent reaction activation energy decreases from 2..56 kJ/mol to 18.32.kJ/mol because of the addition of 10 mg/L Cu(Ⅱ) to the bacterial growth solution of pH 2.0 at initial inoculum of 10%.

关键词： series piezoelectric quartz crystal T.ferrooxidans growth kinetics sigmoid curve cupric ion

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

Cell-SELEX-based aptamer-conjugated nanomaterials for enhanced targeting of cancer cells

引用

Science china chemistry 2011年第8期54卷 1218-1226页

作者： KONG RongMei, CHEN Zhuo, YE Mao, ZHANG XiaoBing & TAN WeiHong State Key Laboratory for Chemo/Biosensing and Chemometrics college of chemistry and chemical engineering, hunan university, Changsha {2. china State Key Laboratory for Chemo/Biosensing and Chemometrics college of chemistry and chemical engineering Hunan University Changsha China

Early detection and treatment of cancer depends on developing highly sensitive and specific methods for targeting cancer cells. To do this, aptamers, which are generated by a novel technique caUed ceU-SELEX （systematic evolution of ligands by exponential enrichment）, have been widely applied in cancer cell targeting based on such merits as high target affinity and specificity, small size, minimal immunogenicity, and ease of chemical modification. Furthermore, aptamers can gain more flexibility as cancer cell targeting tools when conjugated to nanomaterials, including metallic nanoparticles, quantum dots, silica nanoparticles, and carbon nanomaterials, among others. In this review, we discuss the use of cell-SELEX-based aptamer-nanomaterials conjugates as novel molecular tools for enhanced targeting of cancer cells.

关键词： celI-SELEX aptamer nanomaterial cancer cells targeting

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

Silylated and acetylated β-cyclodextrins for gas chromatographic stationary phases

引用

Journal of Central South university of Technology 2001年第4期8卷 239-243页

作者： TANG Ke wen 1,2.,YI Jian ming 2.ZHOU Chun shan 1,ZHONG Shi an 1 (1. college of chemistry and chemical engineering, Central South university, Changsha 410083, {2. 2. college of chemistry and chemical engineering, Yueyang Normal university college of chemistry and chemical engineering Central South University Changsha China college of chemistry and chemical engineering Yueyang Normal University Yueyang China

Two new chiral stationary phases, 2.3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2.6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means of infrared and NMR spectra. Capillary columns were coated with the two stationary phases by dynamic method. The chromatographic properties, and enantiomers separation, such as ketone, esters, alcohols and olefines, were investigated on the silylated and acetylated β cyclodextrin stationary phases. The experimental results show that the silylated and acetylated β cyclodextrins are suitable to be used as capillary gas chromatographic stationary phases, the relative polarity of DATBCD and DTABCD stationary phases is respectively 4143 and 392., the column efficiencies are respectively 3084 and 4198, and DATBCD is of stronger enantioselectivity than DTABCD, capacity factor of the first eluted enantiomer ( k 1) and separation factor(α)of α phenylethanol on DATBCD stationary phase are respectively 8.2. and 1.019.

关键词： capillary gas chromatography silylated and acetylated β-cyclodextrins enantiomeric separation

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

Influence of steric and intramolecular inductive effects on the variable trends in R-X (R=Alkyl) bond dissociation energy

引用

Science china chemistry 2009年第7期52卷 943-951页

作者： CAO ChenZhong School of chemistry and chemical {2., hunan university of Science and Technology, Xiangtan 4112.1, china School of chemistry and chemical {2. Hunan University of Science and Technology Xiangtan China

The question "why are the variation trends of R-X bond dissociation energy different?" is answered. The R-X bond dissociation energy (BDE) may be influenced by three main factors: the C-X intrinsic bond energy, the 1,3 geminal repulsion, and the intramolecular charge-induced dipole. In the presence of atom X, the variation trend of BDE in R-X (R= Me, Et, i-Pr, t-Bu) is dominated by two factors, the 1,3 geminal repulsion and the intramolecular charge-induced dipole. The former decreases the R-X BDE, and the latter either increases or decreases the R-X BDE. For the series of R-X with the R-C bond (such as R-Me, R-CH == CH2. R-C≡CH, and R-CN), the 1,3 geminal repulsion decreases the R-X BDE, and the variation trends of R-C BDE decrease from Me to t-Bu. As regards the series of R-X (such as R-H, R-BH2. and R-SiH2. in which the electronegativity of atom X is smaller than that of the carbon atom, the above two factors decrease the R-X BDE, and the variation trends of the R-X BDE decrease from Me to t-Bu. As to the series of R-X (such as R-F, R-OH, R-Cl, R-Br, R-I, and R-NH2. in which the electronegativity of atom X is larger than that of the carbon atom, the 1,3 geminal repulsion decreases the R-X BDE, while the intramolecular charge-induced dipole increases the R-X BDE. In this case, the variation trends of R-X BDE depend on the competition of the two factors. As a result, some of them (e. g., R-F, R-OH) increase from Me to t-Bu, some (e. g., R-I) decrease from Me to t-Bu, and some (e. g., R-Br) change very little.

关键词： bond dissociation energy charge-induced dipole geminal repulsion ionic configuration

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

3D-QSAR studies on glycogen phosphorylase inhibitors by flexible comparative molecular field analysis

引用

Science china chemistry 2007年第4期50卷 568-573页

作者： ZHOU Peng1 & LI ZhiLiang1,2.1 college of chemistry and chemical engineering, Chongqing university, Chongqing 400044, {2. 2.State Key Laboratory of Chemo/Biosensing and Chemometrics, Changsha 410082. {2. college of chemistry and chemical engineering Chongqing UniversityChongqing 400044China State Key Laboratory of Chemo/Biosensing and Chemometrics Changsha 410082China

Canceling grids accommodating probes in comparative molecular field analysis (CoMFA), the idea of flexibleness is introduced into the CoMFA, and in combination with swarm intelligent algorithm which attempts to optimize distributions of diverse probes around drug molecules, a new 3D-QSAR method is proposed in this context as flexible comparative molecular field analysis (FCoMFA). In preliminary at-tempts to performing QSAR studies on 47 glycogen phosphorylase inhibitors, FCoMFA is employed and confirmed to be potent to exploring ligand-receptor interaction manners at active positions and thus to generating stable and predictable models. Simultaneously by an intuitive graphics regarding probe distribution patterns, impacts of different substituted groups on activities is also given an insight into.

关键词： flexible comparative molecular field analysis (FCoMFA) three-dimensional quantitative structure-activity relationship (3D-QSAR) particle swarm optimization algorithm (PSO) glycogen phosphorylase inhibitor probe distribution pattern

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：