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Birkhoff's theorem and viscosity solutions of Hamilton-Jacobi equations

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Science china mathematics 2009年第8期52卷 1796-1800页

作者： chenG wei department of mathematics, nanjing university, nanjing 210093, china department of mathematics Nanjing University Nanjing 210093 China

We obtain a partial generalization of Birkhoff's theorem of invariant curve to higher dimesional case in the context of viscosity solutions of Hamilton-Jacobi equations, or weak KAM theory. This is a new approach afte... 详细信息

关键词： Hamilton-Jacobi equation viscosity solution semiconcave function

Completely regular paracompact reflection of locales

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Science china mathematics 2006年第6期49卷 820-826页

作者： HE wei & LUO Maokang department of mathematics, nanjing Normal university, nanjing 210097, china department of mathematics, Sichuan university, chengdu 610064, china department of mathematics Nanjing Normal University Nanjing 210097 China department of mathematics Sichuan University Chengdu 610064 China

We give an explicit construction of the completely regular paracompact reflection pL of a completely regular locale L described as a sublocale of the Stone-tech compactification βL of L.

关键词： completely regular paracompact locale, nucleus.

Existence of Invariant Tori for Certain Weakly Reversible Mappings

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Acta Mathematica Sinica,English Series 2002年第4期18卷 701-718页

作者： Bao She wei department of mathematics, nanjing university. nanjing 210093. P. R. china department of mathematics Nanjing University Nanjing 210093 P. R. China

In this paper, we consider certain mappings. M, sufficiently close to an integrable one, which is weakly reversible with respect to the mappings G sufficiently close to an involution of type (m.n). where m, n∈Z_+ are arbitrary. Under some weak non-degeneracy condition, we construct a uniform KAM iteration for proving the existence of a Cantor family of m-tori invariant under the reversible mappings M and the reversing mapping G.

关键词： Weakly reversible mappings Weakly undegenerate condition Invariant tori

On the Conditions of a Center and General Integrals of Quadratic Differential Systems

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Acta Mathematica Sinica,English Series 2001年第2期17卷 229-236页

作者： wei yin YE department of mathematics. nanjing Normal university. nanjing 210097, P. R. china Yan Qian YE department of mathematics. nanjing university, nanjing 210093, P. R. china department of mathematics Nanjing Normal University Nanjing 210097 P. R. China department of mathematics Nanjing University Nanjing 210093 P. R. China

We give the general integral of quadratic differential system with center in two cases under the Chinese classification.

关键词： Quadratic differential system Center General integral

ITERATIVE METHODS WITH PRECONDITIONERS FOR INDEFINITE SYSTEMS

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Journal of Computational mathematics 1999年第1期17卷 89-96页

作者： wei-qing Ren Jin-xi Zhao(department of mathematics, Naming university, nanjing 210008, china) nanjing Univ Dept Math Nanjing 210008 Peoples R China

For the sparse linear equations K x = b, where K arising from optimization and discretization of some PDEs is symmetric and indefinite, it is shown that the L (L) over bar(T) factorization can be used to provide an 'exact' preconditioner for SYMMLQ and UZAWA algorithms. 'Inexact' preconditioner derived from approximate factorization is used in the numerical experiments.

关键词： generalized condition number indefinite systems factorization method

Dynamic damage and stress-strain relations of ultra-high performance cementitious composites subjected to repeated impact

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Science china(Technological Sciences) 2010年第6期53卷 1520-1525页

作者： LAI JianZhong1 & suN wei2 1 department of Materials Science and Engineering,nanjing university of Science and Technology,nanjing 210094,china.2 College of Materials Science and Engineering,Southeast university,nanjing 211189,china 1. department of Materials Science and Engineering Nanjing University of Science and Technology Nanjing 210094 China2. College of Materials Science and Engineering Southeast University Nanjing 211189 China

Ultra-high performance cementitious composites (UHPCC) were prepared by replacing 60% of cement with ultra-fine industrial waste *** dynamic damage and compressive stress-strain relations of UHPCC were studied using split Hopkinson pressure bar (SHPB).The damage of UHPCC subjected to repeated impact was measured by the ultrasonic pulse velocity *** show that the dynamic damage of UHPCC increases linearly with impact times and the abilities of repeated impact resistance of UHPCC are improved with increasing fiber volume *** stress waves on impact were recorded and the average stress,strain and strain rate of UHPCC were calculated based on the wave propagation *** effects of strain rate,fibers volume fraction and impact times on the stress-strain relations of UHPCC were *** show that the peak stress and elastic modulus decrease while the strain rate and peak strain increase gradually with increasing impact times.

关键词： ultra-high performance cementitious composites (UHPCC) split Hopkinson pressure bar (SHPB) repeated impact damage stress-strain

Regioselective aminohalogenation of β-nitrostyrenes using NCS and NBS as nitrogen/halogen sources

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Science china Chemistry 2010年第1期53卷 140-146页

作者： ZHI SanJun1,2,suN Hao2,LIN chen2,ZHANG GuangQian2,LI GuiGen4 & PAN yi2,3 1 department of Chemistry,Huaiyin Normal university,Huai’an 221003,china.2 School of Chemistry and Chemical Engineering,nanjing university,nanjing 210093,china 3 State Key Lab of Coordination Chemistry,nanjing university,nanjing 210093,china 4 department of Chemistry and Biochemistry,Texas Tech university,Lubbock,Texas 79409-1061,USA 1. department of Chemistry Huaiyin Normal University Huai’an 221003 China2. School of Chemistry and Chemical Engineering Nanjing University Nanjing 210093 China4. Department of Chemistry and Biochemistry Texas Tech University Lubbock Texas 79409-1061 USA3. State Key Lab of Coordination Chemistry Nanjing University Nanjing 210093 China

Aminohalogenation reaction of β-nitrostyrenes with N-halosuccinimides(N-chloro and N-bromosuccinimides) has been successfully conducted by using nickel acetate as a catalyst in the presence of potassium carbonate and succinimide as *** reaction was easily performed at room temperature under nitrogen gas protection to give dihalorinaed haloamino products in good to excellent yields(60%-98%).The structure has been confirmed by X-ray crystal structure analysis.

关键词： aminohalogenation vicinal haloamines β-nitrostyrenes NBS NCS

Polymer-assisted nanoparticulate contrast-enhancing materials

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Science china Chemistry 2010年第3期53卷 479-486页

作者： DING yin1,3,HU Yong2,WU wei1 & JIANG XiQun1 1Laboratory of Mesoscopic Chemistry and department of Polymer Science and Engineering,College of Chemistry & Chemical Engineering,nanjing university,nanjing 210093,china.2National Laboratory of Solid State Microstructure,department of Material Science and Engineering,nanjing university,nanjing 210093,china 3Key Laboratory of Analytical Chemistry for Life Science,Ministry of Education,School of Chemistry and Chemical Engineering,nanjing university,nanjing 210093,china 1. Laboratory of Mesoscopic Chemistry and department of Polymer Science and Engineering College of Chemistry & Chemical Engineering Nanjing University Nanjing 210093 China3. Key Laboratory of Analytical Chemistry for Life Science Ministry of Education School of Chemistry and Chemical Engineering Nanjing University Nanjing 210093 China2. National Laboratory of Solid State Microstructure Department of Material Science and Engineering Nanjing University Nanjing 210093 China

The application of nanotechnology in medicine research has significant potential in modern biomedical research,disease diagnosis and *** fluorophore-based detection techniques have been widely used as imaging and signal transduction tools for the detection of trace levels of *** photosensitivity of the fluorophores,however,limits their application in such complex environments as living bio-systems where degradation or photobleaching *** nanoparticles have unique and stable optical,electrical,magnetic and catalytic properties because of their various shapes,sizes and *** potential of the nanoparticles as novel imaging agents has been studied as a possible solution to this *** modification of inorganic nanoparticles could enhance their biostability in physiological conditions and ability of targeting bioactive molecules.

关键词： contrast agent cell image gold nanoparticles iron oxide nanoparticles carbon nanotubes polymeric-inorganic hybrid nanoparticles

A local spin evaluation into the active site models of [2Fe2S] ferrodoxin [Fe_2S_2(SR)_4]^(2-) (R=-H, -CH_3)

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Science china Chemistry 2007年第3期50卷 327-334页

作者： wei JiChong1,2, WANG Yan3 & JU GuanZhi2,3 1 department of Chemistry, Hainan Normal university, Haikou 571158, china.2 State Key Laboratory of Theoretical and Computational Chemistry, Jilin university, Changchun 130023, china 3 department of Chemistry, nanjing university, nanjing 210093, china 1. department of Chemistry Hainan Normal University Haikou 571158 China 2. State Key Laboratory of Theoretical and Computational Chemistry Jilin University Changchun 130023 China 3. department of Chemistry Nanjing University Nanjing 210093 China

To test the feasibility of local spin theory of Davidson and Clark for ferrodoxin clusters, the models [Fe2S2(SR)4]2- (R=-H, -CH3) are chosen for evaluation. This purpose is realized by calculating the local spin expectation values , 2 >, and mA and discussing the connection between these expected values and the Heisenberg spin model (HSM) and the Noodleman broken-symmetry approach. In practical calculation, the spin-unrestricted Hartree-Fock (UHF) and spin-polarized density functional theory (DFT) are used and the calculational qualities of these two methods are also discussed. In addition, the theoretical magnetic coupling constants JAB of these models are calculated by various computational schemes for comparison with both theoretical and experimental results previously reported.

关键词： local spin iron-sulfur protein model density function theory magnetic coupling constant