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Periodic solutions of a 2.th-order nonlinear difference equation

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Science China mathematics 2010年第1期53卷 41-50页

作者： ZHOU Zhan 1, YU JianShe 1 & CHEN YuMing 2. School of mathematics and Information Science, guangzhou {2., guangzhou 510006, China 2.department of mathematics, Wilfrid Laurier {2., Waterloo N2. 3C5, Canada 1. School of mathematics and Information Science Guangzhou University Guangzhou 510006 China2. Department of Mathematics Wilfrid Laurier University Waterloo N2L 3C5 Canada

In this paper, a 2.nth-order nonlinear difference equation is *** the critical point theory, we establish various sets of sufficient conditions of the nonexistence and existence of periodic *** obtained complement or ... 详细信息

关键词： periodic solution nonlinear difference equation critical point theory

THE CHARACTERISTIC OF MARINE ENVIRONMENT IN LINGDINGYANG ESTUARY

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Chinese Geographical Science 2001年第2期11卷 155-162页

作者： CHEN Bing-lu1, ZHANG Yun-ni2. CHEN Xin-geng1, WANG Zhi-gang1, YANG Guang-xing1 (1.Institute of Environmental Science, zhongshan university, guangzhou 51.2.5, P. R. China 2. {2. of Environmental Science, zhongshan university, guangzhou 51.2.5 Institute of Environmental Science Zhongshan University Guangzhou P. R. China department of Environmental Science Zhongshan University Guangzhou P. R. China

Hydrologic features, load of main pollutants and current condition of water quality in Lingdingyang Estuary are discussed by references and monitoring data. Affected by topography, runoff and tide, its dynamic condition is very complicated. Different water areas have different hydrologic features. The topography under the water of Lingdingyang Estuary is higher in the northwest than that in the southeast. The shoal alternates with the deep trough within the bay .The distribution of the salinity and the contents of the mud and the main pollutants tally with the topography tendency. Change in water quality goes through four stages. Current condition of water quality is fairly good. Inorganic nitrogen is the primary pollutant, and then phosphorus. Rich in nutrition of nitrogen and phosphorus become a more and more prominent problem.

关键词： Lingdingyang Estuary hydrologic features load of pollutant water quantity

Microwave peak absorption frequency of liquid

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Science China(Physics,Mechanics & Astronomy) 2008年第9期51卷 1254-1263页

作者： HAN GuangZe1 & CHEN MingDong2.1 department of Physics,South China university of Technology,{2. 510640,China 2.{2. Auto College,South China university of Technology,{2. 510800,China 1. department of Physics South China University of Technology Guangzhou 510640 China 2. guangzhou Auto College South China University of Technology Guangzhou 510800 China

Microwave-assisted extraction is a new effective method which has practical ap-plications in many fields. Microwave heating is one of its physical mechanisms,and it also has the characteristic of selectivity. When the applied microwave fre-quency equals a certain absorption frequency of the material (or specific compo-nent),the material will intensively absorb microwave energy. This is also known as resonant absorption,and the frequency is called the peak absorption frequency which depends on the physical structure of the material. In this work,dynamic hy-drogen bond energy was included in molecular activation energy; with the liquid cell model,the expression of interaction energy between dipolar molecules was derived. The rotational relaxation time was gotten from the Eyring viscosity formula. Then based on the relationship between dielectric dissipation coefficient and re-laxation time,the expression of microwave peak absorption frequency as a func-tion of the material physical structure,rotational inertia and electrical dipole mo-ment of molecules was established. These theoretical formulas were applied to water and benzene,and the calculated results agree fairly well with the experi-mental data. This work can not only deepen the study of the interaction between microwave and material,but also provide a possible guide for the experiment of microwave-assisted extraction.

关键词： microwave-assisted extraction microwave heating relaxation time liquid viscosity peak absorption fre-quency

Geochemical behavior of elements at fossil sea floor water/sediment interface

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Chinese Science Bulletin 1999年第S2期44卷 232-233页

作者： ZHANG Haihua~1, XIA Yu~1, WANG Zuwei~2.and ZHOU Yongzhang~3 1. guangzhou Institute of Geochemistry, Chinese Academy of Science, guangzhou 510640, China 2. {2. of Geography, Tianjin Normal university, Tianjin 300071, China 3. {2. of Earth Sciences, zhongshan university, guangzhou 51.2.5, China guangzhou Institute of Geochemistry Chinese Academy of Science Guangzhou 510640 China department of Geography Tianjin Normal University Tianjin 300071 China department of Earth Sciences Zhongshan University Guangzhou 510275 China

THIS note deals with the geochemical behavior of elements near the water/sediment interface of a fossil seafloor. The Nandan-Hechi basin, located in northwest Guangxi, Southern China, is selected for exemplified study. It is an elongated basin, and developed on a Caledonian basement. Its Devonian strata hosthydrtothermally sedimentary formations, and are typical of the intra-platformal basin facies sediments oversouthern China. A steady sedimentary sequence may be observed, commonly going from carboniferouspelite at bottom, upward through bedded chert, thickly banded argillaceous limestone, thinly bandedsiliceous limestone and small lensiod argillaceous limestone in the middle, to coarse lensoid siliceousand/or argillaceous limestone at the top. The chert and some argillaceous limestone are related to hydrothermally sedimentary origin. The present study focuses on the lensoid argillaceous limestone formation. This formation contains the following characteristic sedimentary structures: small lensoid structure,vermiform structure, wave-shaped banded structure, massive structure, white framboid structure, andcage netting structure.

关键词： water/sediment interface sedimentation periodicity sedimentary geochemistry basin.

On Some Species Extinction in the Nonautonomous n -Competing Pecies Systems

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Systems Science and Systems Engineering 1999年第3期9卷 267-276页

作者： CHEN Bo\|shan\+1\ \ LIU Yong\|qing\+2.1. department of mathematics, Hubei Normal {2., Huangshi 435002. China 2. department of Automatic Control Engineering South China {2. of Technology guangzhou 510641

We generalize and unify some recent results about extinction in nonautonomous n \|species competitive Lotka\|Volterra system. We exhibit new algebraic criteria which guarantee that any solution with strictly initial values that is positive has the property that some of its components vanishes while other approaches a certain solution of their isolate subsystem.

关键词： lotka\|volterra system asymptotic behaviors extinction coexistence

ON CLASSIFICATION OF PROJECTIVE VARIETIES WITH NON-INTEGRAL NEF VALUES

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Chinese Annals of mathematics,Series B 2001年第2期22卷 255-262页

作者： ZHAO YICAI department of mathematics, Jinan {2., guangzhou 510632. China. department of mathematics Jinan University Guangzhou 510632 China

Let M be an n-dimensional normal projective variety with only Gorenstein, terminal, Qfactorial singularities. Let L be an ample line bundle on M. Let r denote the nef value of (M, L). The classification of (M, L) via ... 详细信息

关键词： Nef value morphism Ample line bundle Projective variety

The Stamping Formability of AZ31 Magnesium Alloy Sheet Improved by Equal-channel Angular Pressing

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Journal of Wuhan university of Technology(Materials Science) 2010年第2期25卷 234-237页

作者：刘英 department of Material Science and Engineering Jinan University

Equal channel angular pressing （ECAP） processing and annealing were applied to the AZ31 magnesium alloy sheets to evaluate the potential improvement in the mechanical properties and formability. The ECAP experiment was conducted at 300 ℃ in a die having an included angle of 90o between two channels by the BCZ route with the sheets rotated by 90°about the normal axis of plate plane. The tensile tests and conical cup tests were conducted at various temperatures from 2. to 2.0 ℃. The experimental results indicated that improving the working temperatures could lead to the soft in the material and the enhancement of ductility. Comparatively, the ECAPed AZ31 alloy sheets showed the lower yield strength and smaller conical cup value （CCV） than the unECAPed counterpart in the room temperature. The difference in yield strength between them became small in the elevated temperature, but the ECAPed samples still had the smaller CCV value, implying the improved formability. The texture of the AZ31 alloy sheets could be modified by ECAP and the decrease in the yield strength and more uniform deformation realized in the material, so the formability of AZ31 alloy sheets was improved.

关键词： AZ31 magnesium alloy sheets equal-channel angular pressing mechanical properties conical cup value (CCV)

Deformation of Isolated Hypersurface Singularities and Their Moduli Algebras

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Acta Mathematica Sinica,English Series 1997年第3期13卷 357-362页

作者： Chen Hao (department of mathematics,{2. university,guangzhou,51.2.5,China) department of mathematics Zhongshan University

By the using of determinantal varieties from moduli algebras of hypersurface singularites the relation of the deformation of hypersurface singularities and the deformation of their moduli algebras is *** a type of hypersufface singularities a weak Torelli type result is *** weak Torelli type result showes that for families of hypersurface singularities the moduli algebras can be used to distinguish the complex structures of singularities at least in some weak sence.

关键词： Hypersurface singularities Moduli algebra Deformation

EXISTENCE AND NONEXISTENCE OF GLOBAL CONTINUOUS SOLUTIONS OF RIEMANN PROBLEM FOR QUASILINEAR HYPERBOLIC SYSTEMS^(**)

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Chinese Annals of mathematics,Series B 1991年第1期12卷 13-25页

作者：林龙威 department of mathematics Zhongshan UniversityGuangzhouGuangdongChina.

Consider Riemann problem(E),(R)under the condition(M).It is proved that,as0 详细信息

Consider Riemann problem(E),(R)under the condition(M).It is proved that,as0

关键词： Riemann breakdown sufficiently proof vertex 切二成子 inequal implies belongs