检索结果-南通市图书馆

Microwave-assisted reaction of peptide formation by amino acid with phosphate:Exploration of the most possible channels for the origin of life

引用

Science china Chemistry 2006年第4期49卷 351-356页

作者： HU Rong1, TIAN Jinping2 & YIN Yingwu2,3 1. College of Chemistry & environment Protection Engineering, Southwest University for Nationalities, Chengdu 610041, china 2. TH-UNIS Insight Co., Ltd., Beijing 100085, china 3. key laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, ministry of education, Department of Chemistry, Tsinghua University, Beijing 100084, china 1. College of Chemistry & environment Protection Engineering Southwest University for Nationalities Chengdu 610041 China 2. TH-UNIS Insight Co. Ltd. Beijing 100085 China 3. key laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology Ministry of Education Department of Chemistry Tsinghua University Beijing 100084 China

Microwave-assisted reaction of peptide formation by amino acids with phosphate was studied. The results showed that the products were a mixture of peptides containing dipeptide, oc- tapeptides and cyclic peptides, which could be obtained in a short time. Polyphosphate was also produced synchronously by the intermolecular condensation of phosphate. The polymerization de- gree reached 99% (pyrophosphate 64%, trimetaphosphate 35%) after 2 h at 200℃ under microwave irradiation. The intermediates of the mixed anhydrides formed by the intermolecular condensation of phosphates and glycin were determined by ESI-MS. Peptides were also produced by the reaction of amino acids with trimetaphosphate in aqueous solution. The conversion degree of valine reached 46.5% even at room temperature. The cyclic process of peptide formation and phosphate polymeri- zation, regeneration and utilization in amino acids-phosphate system under microwave irradiation was detected and proved. Peptides could be continually formed only by inputting energy into this system. The above recycle may be the most possible process for primitive peptide formation in the origin of life.

关键词： microwave, phosphate, amino acid, peptide, origin of life.

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

Nature of the Precambrian metamorphic blocks in the eastern segment of Central Tianshan:Constraint from geochronology and Nd isotopic geochemistry

引用

Science china Earth Sciences 2004年第12期47卷 1085-1094页

作者： LIU Shuwen,GUO Zhaojie,ZHANG Zhicheng,LI Qiugen & ZHENG Haifei The key laboratory of Orogenic Belts and Crustal Evolution,ministry of education,china School of Earth and Space Sciences,Peking University,Beijing 100871,china 1. The key laboratory of Orogenic Belts and Crustal Evolution Ministry of Education China 2. School of Earth and Space Sciences Peking University 100871 Beijing China

Granitoid gneisses are widespread in Precambrian metamorphic blocks of eastern segment of the Central Tianshan Tectonic Zone, and they have intrusive contact relationships with their metamorphic sedimentary country rocks of Proterozoic Xingxingxia and Kawabulag groups. Zircon U-Pb ages from a granodioritic gneiss (IW11-1) and a parametamorphic schist (W05-9) are determined at the Weiya area. Euhedral prismatic zircons from the granodioritic gneiss (IW11-1) provide U-Pb isotopic discordia intercept ages of 1218±17 Ma and 426±26 Ma, respectively, and euhedral prismatic zircons from the parametamorphic schist (W05-9) display U-Pb isotopic discordia intercept ages of 1216±74 Ma and 290±15 Ma, respectively. A whole-rock Sm-Nd isotopic isochron is determined in augen granitoid gneiss samples at the Gang- gou-Kumishi area and we obtain the isochron age of 1142±120 Ma, and its ε Nd (t) = -4.3. These geochronological data suggest that these Precambrian metamorphic basement blocks within eastern segment of the Central Tianshan Tectonic Zone can be produced during 1140—1220 Ma, and occur a nearly homochronous metamorphism. Integrated to these geochronological data, Nd depleted mantle model ages (T DM ) and epsilon Nd(t) values of these granitoid gneiss samples indicate that they can derive from mixing in various scales both magmas from mantle and crust sources at a late Mesoproterozoic active continental margin tectonic environment. Similarity in geochronology, Sm-Nd isotopic geochemistry between Weiya-Xingxingxia, Pargangtag and Ganggou-Kumishi areas suggests that they could be a bigger uniform metamorphic basement block, which could be formed by the assembly of the supercontinent Rodinia and be separated by late geological processes.

关键词： Central Tianshan Tectonic Zone, Precambrian metamorphic blocks, granitoid gneisses, isotopic chronolo-gy, active continental margin, supercontinent Rodinia.

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

Quenched moderate deviations principle for random walk in random environment

引用

Science china Mathematics 2010年第8期53卷 1947-1956页

作者： HONG WenMing 1 & WANG HuaMing 1,2 1 key laboratory of Mathematics and Complex Systems of ministry of education & School of Mathematical Sciences,Beijing Normal University,Beijing 100875,china 2 Department of Basic Courses,Business College,Beijing Union University,Beijing 100025,china 1. key laboratory of Mathematics and Complex Systems of ministry of education & School of Mathematical Sciences Beijing Normal University Beijing 100875 China2. Department of Basic Courses Business College Beijing Union University Beijing 100025 China

We derive a quenched moderate deviations principle for the one-dimensional nearest random walk in random environment,where the environment is assumed to be stationary and *** approach is based on hitting time decompos... 详细信息

关键词： random walk in random environment moderate deviations principle hitting time

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 community-centric approach to automated service composition

引用

Science china(Information Sciences) 2010年第1期53卷 50-63页

作者： LIU XuanZhe1,2, HUANG Gang1,2 & MEI Hong1,2 1School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, china 2key laboratory of High Confidence Software Technologies, ministry of education, Peking University, Beijing 100871, china 1. School of Electronics Engineering and Computer Science Peking University Beijing 100871 China2. Key Laboratory of High Confidence Software Technologies Ministry of Education Peking University Beijing 100871 China

In the recent years, the web has kept growing rapidly and undergone tremendous changes towards a user-centric environment. With the proliferation of services available on the Internet, millions of users are able to voluntarily participate in and collaborate for their own interests and benefits by means of service composition. However, due to the ever increasing number of services, it then becomes a challenging issue to enable the users to rapidly select and compose the proper services. In this paper, we propose an approach which utilizes service communities for automated service composition. This paper makes three contributions. Firstly, we propose the service community architecture and identify two key components to facilitate service discovery and composition. Secondly, assisted by the service community, we provide two composition types to help users explore the space of potential composition opportunities without having to understand too many details of individual candidate services. Finally, we evaluate our approach by performance analysis and provide a web-based prototype that lowers the entry barrier for the users.

关键词： services computing service composition service community

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

Biomimetic preparation of elastomeric fibers with micro/nano structures on the surfaces

引用

Progress in Natural Science:Materials International 2012年第5期22卷 493-501页

作者： Quanyong Liu a,Liqun Zhang c,Lei Jiang a,b a key laboratory of Bio-Inspired Smart Interfacial Science and Technology of ministry of education,School of Chemistry and environment,Beihang University,Beijing 100191,PR china b Beijing National laboratory for Molecular Sciences(MNLMS),key laboratory of Organic Solids,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,PR china c State key laboratory of Organic-Inorganic Composites,Beijing University of Chemical Technology,Beijing 100029,PR china [a] key laboratory of Bio-Inspired Smart Interfacial Science and Technology of ministry of education School of Chemistry and Environment Beihang University Beijing 100191 PR China [b] Beijing National laboratory for Molecular Sciences (MNLMS) Key Laboratory of Organic Solids Institute of Chemistry Chinese Academy of Sciences Beijing 100190 PR China [c] State key laboratory of Organic–Inorganic Composites Beijing University of Chemical Technology Beijing 100029 PR China

Bioinspired by the spinning of spider silks,the biomimetic preparation of elastomeric fibers with micro/nano structures on the surfaces was attempted,and as a result,three types of ultrafine fullvulcanized powdered nitrile-butadiene rubber(UFPNBR)/thermoplastic polyurethane(TPU) fibers were *** first fiber was only decorated by the micron-sized grooves on the surface,and the second fiber was dotted by both the micron-sized grooves and nanometer-sized spheres on the surface,while the third fiber was helical and with a concave-convex *** biomimetic preparation mainly consisted of four steps,and the formation mechanism was described as an integrated mechanism of diffusion,coagulation,self assembly,and microphase *** micro/nano structures on the fibers were controlled by changing the mass ratio of UFPNBR to TPU and environment of vertical *** UFPNBR/TPU elastomeric fibers were hoped to have an integrated function of superhydrophobicity,self cleaning,and mechanical improvement of toughness or strength.

关键词： Biomimetic preparation Elastomeric fiber Micro/nano structure Self assembly Spider silk

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

Evolution of windblown sand flux and dune field——Trans-scale modeling and simulation

引用

Theoretical & Applied Mechanics Letters 2011年第4期1卷 3-10页

作者： Xiaojing Zheng a) key laboratory of Mechanics on Western Disaster & environment,ministry of education,Lanzhou 730000,china key laboratory of Mechanics on Western Disaster & environment Ministry of Education Lanzhou 730000 China

Windblown sand flux and dune field evolving toward the oasis have been a common ecological and environmental threat confronted by many ***,it is also a kind of complex dynamical process involving multiple temporal and spatial scales which is still out of accurate description through current field *** models and reliable quantitative simulations are of significant value to predict the spreading rate of desertification and provide an optimal design for sand *** paper presents a 'triple-jump' method to realize quantitative simulations to the formation and evolution of an aeolian dune field from an arbitrary initial *** results achieve a satisfactory agreement with observations qualitatively and quantitatively,which also reveal the characteristics and dynamical behaviors of dunes and dune *** a paradigm is of a good level of generality,which provides an exploratory probe into the subject of multi-scale physics.

关键词： dune field complex dynamical process quantitative simulation windblown sand environment

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 the double-logarithmic profile of tidal flow velocity in the near-bed layers

引用

Acta Oceanologica Sinica 2009年第6期28卷 84-92页

作者： NI Zhihui SONG Zhiyao WU Lichun Southwestern Research Institute of Water Transport Engineering Chongqing Jiaotong UniversityChongqing 400016 China key laboratory of Virtual Geographic environment （ministry of education） Nanjing NormMUniversity Nanjing 210097 China State key laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098 China Chongqing education College Chongqing 400067 China

Tidal current velocity profile in the near-bed layers has been widely studied. The results showed that velocity profile in the near-bed layer obviously departure from the traditional logarithmic profile, due to the acceleration or deceleration. Although the logarithmic linear profile can reduce the rate of deviation from this, only it is a lower-order approximate solution. In this paper, considering the unsteady and non-linear features of tidal motion, the double logarithmic profile near-bed layers in estuarine and coastal waters is established on the assumption that the turbulent shear stress along the water depth was parabolic distribution, and on the basis of Prandtl＇s mixing length theory and yon Karman＇s self-similar theory. Having been verified the data observed at the West Solent in the south of England, and comparison of the logarithmic linear profile, it found that the double logarithmic profile is more precious than the latter. At last, the discussed results showed that：（1） The parabolic distribution of the tidal shear stresses verified good by the field data and experimental data, can be better reflected the basic features of the tidal shear stress deviating from linear distribution that is downward when to accelerate, upward when to decelerate. （2） The traditional logarithmic velocity profile is the zero-order approximation solution of the double logarithmic profile, the logarithmic linear profile is the first order, and the logarithmic parabolic profile is the second order. （3） Ignoring the conditions of diffusion and convection in the tida movement, the double logarithmic profile can reflect the tidal properties of acceleration or deceleration, so that the calculation of the friction velocity and roughness length are more reasonable. When the acceleration or the deceleration is about zero, the double logarithmic profile becomes the logarithmic profile.

关键词： turbulence shear stress tidal current double logarithmic profile near-bed layers friction velocity roughness length

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

Preparation of anatase TiO_2 with assistance of surfactant OP-10 and its electrochemical properties as an anode material for lithium ion batteries

引用

Rare Metals 2010年第5期29卷 505-510页

作者： YI Jin,TAN Chunlin,LI Weishan,LEI Jianfei,and HAO Liansheng School of Chemistry and environment & key laboratory of Electrochemical Technology on Energy Storage and Power Generation of Guangdong Higher education Institutes,South china Normal University,Guangzhou 510006,china School of Chemistry and environment & key laboratory of Electrochemical Technology on Energy Storage and Power Generation of Guangdong Higher education Institutes South China Normal University Guangzhou China

With the assistance of nonionic surfactant （OP-10） and surface-selective surfactant （CH3COOH）, anatase TiO2 was prepared as an anode material for lithium ion batteries. The morphology, the crystal structure, and the electrochemical properties of the prepared anatase TiO2 were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, electrochemical impedance spectroscopy （EIS）, and galvanostatic charge and discharge test. The result shows that the prepared anatase TiO2 has high discharge capacity and good cyclic stability. The maximum discharge capacity is 313 mAh.g^-1, and there is no significant capacity decay from the second cycle.

关键词： lithium ion batteries titanium dioxide sol-gel process electrochemical properties sttrfactants

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

Growth of Carbon Encapsulated Long Nickel Nanorods on Bulk Nickel Substrate

引用

Journal of wuhan University of Technology(Materials Science) 2011年第1期26卷 28-32页

作者：宾晓蓓 College of Resources & environment Engineering Wuhan University of Technology

Carbon nanotube encapsulated nickel nanorods were catalytic grown via pyrolysis of oil on a bulk nickel wire substrate. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy were employed to characterize the as-prepared sample. The results show that, carbon nanotubes possess several microns in length, the filled metallic nickel nanorods with a uniform diameter of 35 nm were tightly encapsulated by the carbon capsules. The detailed formation mechanism for the carbon nanotubes encapsulated nickel nanorods were discussed briefly.

关键词： carbon nanotube nickel nanorod pyrolysis core-shell

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 decision-making model of development intensity based on similarity relationship between land attributes intervened by urban design

引用

Science china(Technological Sciences) 2010年第7期53卷 1743-1754页

作者： WANG JianGuo1, ZHANG Yu2 & FENG Han3 1 School of Architecture, Southeast University key laboratory for Urban and Architectural Heritage Conservation, ministry of education, Nanjing 210096, china 2 School of Architecture, Southeast University, Nanjing 210096, china 3 Faculty of Architecture, Delft University of Technology, 2628 CR Delft, Netherlands 1. key laboratory for Urban and Architectural Heritage Conservation Ministry of Education Nanjing 210096 China2. School of Architecture Southeast University Nanjing 210096 China3. Faculty of Architecture Delft University of Technology 2628 CR Delft Netherlands

The paper presents a dynamic model intervened by urban design for the decision-making of land development intensity, which expresses the inherent interaction mechanism between lands based on the evaluation of land attributes and their similarity relationship. Each land unit is described with several factors according to their condition and potential for development, such as land function, accessibility, historical site control, landscape control, and so on. Then, the dynamic reference relationship between land units is established according to the similarity relationship between their factors. That means lands with similar conditions tend to have similar development intensities, which expresses the rule of the spontaneous urban development. Therefore, the development intensities of the pending lands can be calculated by the confirmed ones. Furthermore, the system can be actively intervened by adjusting the parameters according to urban design or planning intentions. And the reaction of the system offers effective support and reference for reasonable decision. The system with multiple intervention input is not only a credible tool for deriving development intensities, but also a platform to activate urban design conception. Above all, the system as a socio-technical tool integrates the optimization of form, function and environment, and embodies the principle of impersonality, justice and flexibility in the decision of land development intensity.

关键词： land development intensity urban design land attribute similarity relationship complex system FAR

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：