检索结果-南通市图书馆

Relationships between bacterial-algal proliferating and mass extinction in the Late Devonian Frasnian-Famennian transition:Enlightening from carbon isotopes and molecular fossils

引用

science china Earth sciences 2005年第10期48卷 1656-1665页

作者： GONG Yiming1,2, XU Ran1, TANG Zhongdao1, SI Yuanlan3.& LI Baohua4 1. Faculty of Earth science and State Key Laboratory of Geological Processes and Mineral Resources, china university of Geosciences, wuhan 4.0074. china 2. Institute of Resources & Environments, Henan Polytechnic university, Jiaozuo 454003. china 3. department of computer science, south-central university for nationalities, wuhan 4.0074. china 4. Laboratory of Marine Geology, Tongji university, Shanghai 200092, china Faculty of Earth science and State Key Laboratory of Geological Processes and Mineral Resources china university of Geosciences wuhan china Institute of Resources & Environments Henan Polytechnic university Jiaozuo china department of computer science{3. wuhan china Laboratory of Marine Geology Tongji university Shanghai china

Studies show positive shifts of inorganic and organic carbon isotope values (δ 13.carb and δ 13.kerogen) from +0.43.(‰ V-PDB) to +3.54 (‰ V-PDB) and from ?29.3. (‰ V-PDB) to ?24.14 (‰ V-PDB), respectively, B* (Ba* = Ba/ (Al2O3.X 15%)) values from 0.015 to 0.144, TOC values from 0.02% to 0.21%, V/Cr values from 0.3.to 2.0, Sr/Ba values from 3.20 to 49.50 in the Late Devonian Frasnian Upper rhenana zone to the top linguiformis zone of the Yangdi sec-tion deposited in carbonate slope facies of Guilin, Guangxi, south china, which indicates that biomass, productivity, organic carbon burial and salinity increase and that oxygenation near the boundary between sediments and waters decreases from the Late Devonian Frasnian Upper rhenana zone to the top linguiformis zone. Abundance of molecular fossils increases and normal alkanes, isoprenoid hydrocarbon, terpanes and steranes are dominated from the Late Devonian Frasnian to the bottom of Famennian, which shows that the predecessors of molecular fossils of the Frasnian-Famennian (F-F) transition are dominated by marine phytoplankton, zooplankton and benthic bacteria with no photosynthesis. Therefore, it is considered that the F-F transitional mass extinction with a multistage, selection and global synchronizing was caused by bacte-rial-algal proliferating, continuing deterioration of the shallow marine ecoenvironment of the mid-dle-lower latitudes. A simple cause and effect chain can be expressed as: appearance of seed plants and multi-storied forests → enhanced chemical and biochemical weathering and pe-dogenesis → wide development of soils → increasing riverine nutrient fluxes in epicontinental sea → from superoligotrophic to eutrophic in epicontinental sea → proliferating of marine phyto-plankton and zooplankton → frequent red tide and anoxia → mass extinction of shallow marine organisms in the middle-lower latitudes. It is worth notice that the factor drawdown of atmos-pheric Pco2, climatic cooling and sea level falling c

关键词： mass extinction, bacteria-algae, carbon isotopes, molecular fossils, biodiversity, Late Devonian, Guangxi, south china.

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

Material basis for inhibition of Dragon's Blood on evoked discharges of wide dynamic range neurons in spinal dorsal horn of rats

引用

science china(Life sciences) 2008年第11期51卷 1025-1038页

作者： GUO Min, CHEN Su & LIU XiangMing department of Biological & Medical Engineering, south-central university for nationalities, wuhan 4.0074. china 1. department of Biological & Medical Engineering South-Central University for Nationalities Wuhan 430074 China

In vivo experiments were designed to verify the analgesic effect of Dragon’s Blood and the material basis for this effect. Extracellular microelectrode recordings were used to observe the effects of Dragon’s Blood and various combinations of the three components (cochinchinenin A, cochinchinenin B, and loureirin B) extracted from Dragon’s Blood on the discharge activities of wide dynamic range (WDR) neurons in spinal dorsal horn (SDH) of intact male Wistar rats evoked by electric stimulation at sciatic nerve. When the Hill's coefficients describing the dose-response relations of drugs were dif-ferent, based on the concept of dose equivalence, the equations of additivity surfaces which can be applied to assess the interaction between three drugs were derived. Adopting the equations and Tal-larida's isobole equations used to assess the interaction between two drugs with dissimilar dose-response relations, the effects produced by various combinations of the three components in modulating the evoked discharge activities of WDR neurons were evaluated. Results showed that Dragon’s Blood and its three components could inhibit the evoked discharge frequencies of WDR neurons in a concentration-dependent way. The Hill's coefficients describing dose-response relations of three components were different. Only the combined effect of cochinchinenin A, cochinchinenin B and loureirin B was similar to that of Dragons Blood. Furthermore, the combined effect was synergistic. This investigation demonstrated that through the synergistic interaction of the three components Dragon’s Blood could interfere with the transmission and processing of pain signals in spinal dorsal horn. All these further proved that the combination of cochinchinenin A, cochinchinenin B, and loureirin B was the material basis for the analgesic effect of Dragon’s Blood.

关键词： Dragon’s Blood material basis for the efficacy extracellular microelectrode recordings wide dynamic range neurons interaction between drugs

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

On the new results of global attractive set and positive invariant set of the Lorenz chaotic system and the applications to chaos control and synchronization

引用

science in china(Series F) 2005年第3期48卷 304-321页

作者： LIAO Xiaoxin 1, 2, 3., FU Yuli 4 & XIE Shengli 4 1. department of Control science & Control Engineering, Huazhong university of science & Technology, wuhan 4.0074. china 2. School of Automation, wuhan university of science & Technology, wuhan 43.070, china 3. School of Information, central south university of Economy, Politics and Law, wuhan 43.064, china 4. School of Electronics & Information Engineering, south china university of Technology, Guangzhou 510640, china Correspondence should be addressed to Liao Xiaoxin (email: xiaoxin_liao@***) 1. department of Control science & Control Engineering Huazhong University of Science & Technology 430074 Wuhan China 2. School of Automation Wuhan University of Science & Technology 430070 Wuhan China 3. School of Information Central South University of Economy Politics and Law 430064 Wuhan China 4. School of Electronics & Information Engineering South China University of Technology 510640 Guangzhou China

Constructing a family of generalized Lyapunov functions, a new method is proposed to obtain new global attractive set and positive invariant set of the Lorenz chaotic system. The method we proposed greatly simplifies the complex proofs of the two famous estimations presented by the Russian scholar Leonov. Our uniform formula can derive a series of the new estimations. Employing the idea of intersection in set theory, we extract a new Leonov formula-like estimation from the family of the estimations. With our method and the new estimation, one can confirm that there are no equilibrium, periodic solutions, almost periodic motions, wandering motions or other chaotic attractors outside the global attractive set. The Lorenz butterfly-like singular attractors are located in the global attractive set only. This result is applied to the chaos control and chaos synchronization. Some feedback control laws are obtained to guarantee that all the trajectories of the Lorenz systems track a periodic solution, or globally stabilize an unstable (or locally stable but not globally asymptotically stable) equilibrium. Further, some new global exponential chaos synchronization results are presented. Our new method and the new results are expected to be applied in real secure communication systems.

关键词： Lorenz chaotic system global attractive set positive invariant set globally exponential tracking globally exponential synchronization.

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

EXISTENCE OF GLOBAL SMOOTH SOLUTION TO INITIAL BOUNDARY VALUE PROBLEM FOR A VISCOELASTIC MODEL WITH RELAXATION

引用

Acta Mathematica Scientia 2004年第2期24卷 265-274页

作者：阮立志朱长江 LaboratoryofNonlinearAnalysis Dept.ofMath.CentralChinaNormalUniversityWuhan430079China

This paper is concerned with the initial boundary value problem for a viscoelastic model with relaxation. Under the only assumption that the C^0-norm of the initial data is small, without smallness hypothesis for the C^1-norm, the existence of the global smooth solution to the corresponding initial boundary value problem is proved. The analysis is based on some a priori estimates obtained by the 'maximum principle' of first-order quasilinear hyperbolic system.

关键词： Viscoelastic model relaxation a priori estimates maximum principle

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 low frequency piezoelectric power harvester using a spiral-shaped bimorph

引用

science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 649-659页

作者： HU Yuantai1,2,HU Hongping2 & YANG Jiashi3.1. Institute of Mechanics and Sensing Technology,central south university,Changsha 410083.{3. 2. department of Mechanics,Huazhong university of science and Technology,wuhan 4.0074.{3. 3. department of Engineering Mechanics,university of Nebraska,Lincoln,NE 68588-0526,USA 1. Institute of Mechanics and Sensing Technology Central South University Changsha 410083 China 2. department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China 3. department of Engineering Mechanics University of Nebraska Lincoln NE 68588-0526 USA

We propose a spiral-shaped piezoelectric bimorph power harvester operating with coupled flexural and extensional vibration modes for applications to low frequency energy sources. A theoretical analysis is performed and the computational results show that the spiral structure has relatively low operating frequency compared to beam power harvesters of the same size. It is found that to optimize the performance of a piezoelectric spiral-shaped harvester careful design is needed.

关键词： spiral-shaped bimorph,piezoelectric harvester,power density.

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 Heuristic Algorithm for QoS Multicast Routing

引用

Journal of Systems Engineering and Electronics 2002年第4期13卷 73-78页

作者： Li Layuan & Li Chunlin department of computer science, {3. university of Technology, {3. 43.063. P. R. china department of computer science Wuhan University of Technology Wuhan 430063 P. R. China

In recent years, QoS multicast routing has continued to be a very important research topic in the areas of networks. This paper presents a heuristic algorithm for the QoS multicast routing (HAQMR). This heuristic algorithm deals with delay and bandwidth constraints and has low cost. The HAQMR attempts to significantly reduce the overhead for constructing a multicast tree, the proof for correctness of the HAQMR is given, and the performance of the HAQMR is evaluated by simulations. The study shows that HAQMR provides an available approach to QoS multicast routing.

关键词： Heuristic QoS Multicast QoS constraints QoS routing.

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

Singular Integral Equations with Cosecant Kernel in Solutions with Singularities of High Order

引用

wuhan university Journal of Natural sciences 2005年第2期10卷 339-343页

作者： HAN Hui-li 1,2 ,DU Jin-yuan 1,3.1. School of Mathematics and Statistics, wuhan university, wuhan 43.072, Hubei, {3. 2. School of Mathematics and computer, Ningxia university, Yinchuan 750021, Ningxia, {3. 3. department of Mathematics, Hubei Institute for nationalities, Enshi 445000, Hubei, {3. wuhan university School of Mathematics and Statistics Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***) Ningxia university School of Mathematics and Computer Yinchuan Ningxia China (GRID:grid.260987.2) (ISNI:***) wuhan university School of Mathematics and Statistics Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***) Hubei Institute for nationalities Department of Mathematies Enshi Hubei China (GRID:grid.34418.3a) (ISNI:***)

We have discussed and solved the boundary value problem with period 2aπ and the singular integral equation with kernel csc t-tv/a in solution having singularities of high order, where the smooth contour of integratio... 详细信息

关键词： boundary value problem singular integral equation the singularities of high order

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

Ti/Al_2O_3.Functionally Gradient Material Prepared by the Explosive Compaction/SHS Process

引用

Journal of Materials science & Technology 1999年第3期15卷 271-275页

作者： Yimin LI(Powder Metallurgy Research Institute, central-south university of Technology, Changsha 410083. {3.)Ziqiao ZHENG(department of Materials science and Engineering, central-south university of Technology, Changsha 410083. {3.) Cent S Univ Technol Powder Met Res Inst Changsha 410083 Peoples R China Cent S Univ Technol Dept Mat Sci & Engn Changsha 410083 Peoples R China

Ti1Al2O3.Functionally Gradient Material (FGM) was prepared by an explosive compaction/SHS process. Ten sheets of the compounding powder were laminated and pressed to get a green body of FGM. It was then compacted explosively By burying the explosive compaction body into a stoichiometric Al/TiO2 mixture and igniting the combustion of the stoichiometric Al/TiO2 mixture, the SHS reaction of the explosive compaction body was initiated by the heat released from the combustion of the stoichiometric Al/TiO2 mixture. In this way, Ti/Al2O3.FGM was synthesized. The adiabatic temperatures of each gradient layer were calculated when the preheating temperatures were 298 K and 1173.K, respectively The microstructure, composition and properties of Ti/Al2O3.FGM and the reaction mechanism of each gradient layer were studied. It was found that Ti/Al2O3.FGM prepared by the explosive compaction/SHS process had a high density and a high microhardness. Its structure, composition and properties showed apparent gradient distribution. The structure of the standard stoichiometric ratio gradient layer of FGM was a network structure. Its reaction mode could be described as follows: Al powder melted first, then the molten Al penetrated into the TiO2 zone and reacted with TiO2, and big pores were left in the original positions of Al powder. The reaction of gradient layers with the addition of Al3.3.as diluents was similar to that of the standard stoichiometric ratio gradient layer, so were their structure and composition. However, the reaction of gradient layers with the addition of Ti as diluents was more complex and the composition deviated slightly from the designed one

关键词： Al SHS Ti/Al2O3.Functionally Gradient Material Prepared by the Explosive Compaction/SHS Process

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 Trace Sc and Zr on the Mechanical Properties and Microstructure of A1 Alloy 2618

引用

Journal of Materials science & Technology 2000年第4期16卷 416-420页

作者： Kun YU, Songrui LI and Wenxian LI (department of Materials science and Engineering, central {3. university of Technology, Changsha 410083. china) department of Materials science and Engineering Central South University of Technology Changsha 410083 China

An experimental 2618(Al-Cu-Mg-Fe-Ni) alloy added with trace Sc and Zr was prepared by ingot metallurgy (IM) method. The aging behavior of the alloy was studied by Vickers hardness measurement at 200℃ and 3.0℃. and the tensile properties of alloy specimens were measured at 20℃, 200℃, 250℃ and 3.0℃. The microstructure was observed by using optical microscope, SEM and TEM. It was found that the addition of Sc and Zr to 2618 alloy resulted in a primary Al_3.Sc,Zr) phase which could refine the grain because it acts as nuclei of heterogeneous crystallization in the melt during solidification. The secondary Al_3.Sc,Zr) particles were full coherent with matrix and had obvious precipitation hardening effect. They also made the S' phase precipitate more homogeneous. So the strength of alloy increases at both ambient and elevated temperatures without a decrease of ductility. The ductile fracture of alloy occurs by microvoid nucleation, growth and coalescence, so the microvoid coalescence is the dominant fracture mechanism.

关键词： Sc Zr Effect of Trace Sc and Zr on the Mechanical Properties and Microstructure of A1 Alloy 2618

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

Algorithm of graph isomorphism with threedimensional DNA graph structures

引用

Progress in Natural science:Materials International 2005年第2期15卷 86-89页

作者： LIU Guangwu 1,2*, YIN Zhixiang 1,3. XU Jin1 and DONG Yafei1(1. department of Control science and Engineering, Hua Zhong university of science and Technology, wuhan 4.0074. china 2. College of Transportation, wuhan university of Technology, wuhan 43.063. china 3. department of Mathematics and Physics, Anhui university of science and Technology, Huainan 23.001, china) department of Control science and Engineering Hua Zhong University of Science and Technology Wuhan 430074 China. College of Transportation Wuhan University of Technology Wuhan 430063 China. department of Mathematics and Physics Anhui University of Science and Technology Huainan 232001 China

An algorithm for solving the graph isomorphism problem with 3.D DNA structures is proposed in this paper. The k-armed branched junction molecules are used to code k-degree vertices. Double stranded molecules are used to code edges. Then the molecules are mixed in a tube to be ligated. The result can be detected by gel electrophoresis. The time complexity of the algorithm is O(n2), where n is the number of vertices of the graph.

关键词： DNA computing DNA graph structure graph isomorphism

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

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：