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Jackson’s theorem in Q_p spaces

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Science China mathematics 2010年第2期53卷 367-372页

作者： CHEN YingWei 1 & REN GuangBin 1, 2, 1 department of mathematics, university of Science and Technology of China, Hefei 230026, China 2.department of mathematics, university of aveiro, p-3810-193 aveiro, portugal 1. department of mathematics University of Science and Technology of China Hefei 230026 China2. Department of Mathematics University of Aveiro P-3810-193 Aveiro Portugal

A Jackson type inequality in Q p spaces is established, i.e., for any f (z) = Σ∞ j=0 ajzj ∈ Qp , 0≤p 1, and k-1 ∈ N,where ω(1/k, f, Q p ) is the modulus of continuity in Q p spaces and C(a) is an absolute const... 详细信息

关键词： Q p space BMOA polynomial approximation

The realization and structure of complete Lie algebras whose nilpotent radicals are Heisenberg algebras

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Chinese Science Bulletin 1998年第5期43卷 383-385页

作者： JIANG Cuibo 1 and MENG Daoji 2 1.department of mathematics,Yantai Teachers university, Yantai 264025, China 2.department of mathematics,Nankai university,Tianjin 300071, China. department of mathematics Yantai Teachers University Yantai China department of mathematics Nankai University Tianjin China

The realization and structure of complete Lie algebras whose nilpotent radicals are Heisenberg algebras over the complex field C are given.

关键词： complete Lie algebra Heisenberg algebra nilpotent radical.

NONOSCILLATION RESULTS FOR A CLASS OF THIRD ORDER NONLINEAR DIFFERENTIAL EQUATIONS

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Applied mathematics and Mechanics(English Edition) 2002年第10期23卷 1170-1175页

作者： pakize Temtek 1, Aydn Tiryaki 2 (1 department of mathematics, Faculty of Arts and Science, Erciyes university, 38039, Kayseri, Turkey 2.department of mathematics, Faculty of Arts and Science, Gazi university, Teknikokullar 06500 Ankara, Turke department of mathematics Faculty of Arts and Science Erciyes University 38039 Kayseri Turkey department of mathematics Faculty of Arts and Science Gazi University Teknikokullar 06500 Ankara Turkey

Sufficient conditions for the nonoscillatory solutions of a class of third order nonlinear differential equations are presented. The results obtained generalize some criteria given by parhi. In some special cases, som... 详细信息

关键词： differential equation nonlinear nonoscillatory solution parhi criteria

Comparative efficiency analysis of different nonlinear modelling strategies to simulate the biaxial response of RC columns

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Earthquake Engineering and Engineering Vibration 2012年第4期11卷 553-566页

作者： Hugo Rodrigues Humberto Varum António Arêde Aníbal Costa university of aveiro Civil Engineering Department Faculty of Natural Sciences Engineering and Technology-Oporto Lusophone University Civil Engineering department Faculty of Engineering University of Porto

The performance of different nonlinear modelling strategies to simulate the response of RC columns subjected to axial load combined with cyclic biaxial horizontal loading is compared. The models studied are classified into two categories according to the nonlinearity distribution assumed in the elements： lumped-plasticity and distributed inelasticity. For this study, results of tests on 24 columns subjected to cyclic uniaxial and biaxial lateral displacements were numerically reproduced. The analyses show that the global envelope response is satisfactorily represented with the three modelling strategies, but significant differences were found in the strength degradation for higher drift demands and energy dissipation.

关键词： RC columns non-linear behaviour biaxial bending fibre modelling

Effect of lead chloride on spermatogenesis and sperm parameters in mice

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Asian Journal of Andrology 2004年第3期6卷 237-241页

作者： António Graca Joao Ramalho-Santos Maria de Lourdes pereira department of Zoology University of CoimbraCoimbraPortugal Department of BiologyUniversity of Aveiro3810 AveiroPortugalDepartment of ZoologyUniversity of CoimbraCoimbraPortugalDepartment of BiologyUniversity of Aveiro3810 AveiroPortugal

Aim: To evaluate the effect of acute lead chloride exposure on testis and sperm parameters in mice. Methods: pbCl2, 74 mg/kg, was daily administered to sexually mature male mice for 3 days and the effects on the testicular histology and ultrastructure as well as the motility and density of spermatozoa in cauda epididymis were observed. An additional group of mice were treated for 1-3 days and were allowed to recover for 32 days to determine the reversibility of lead-induced changes. Results: The testicular weight, seminiferous tubular diameter and sperm counts were significantly decreased following 3 days of pbCl2 treatment, but were unaffected by shorter-term exposures. The changes caused by lead are mostly reversible. Conclusion: Acute lead chloride exposure injures the fertility parameters of male mice and the effects are partially reversible.

关键词： lead chloride seminiferous tubules epididymis semen analysis

OpTIMIZATION OF ADApTIVE DIRECT METHOD FOR AppROXIMATE SOLUTION OF INTEGRAL EQUATIONS OF SEVERAL VARIABLES

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Acta Mathematica Scientia 2004年第2期24卷 228-234页

作者：马万房艮孙 departmentofmathematics BeijingNormalUniversityBeijing100875China

This paper determines the exact error order on optimization of adaptive direct methods of approximate solution of the class of Fredholm integral equations of the second kind with kernel belonging to the anisotropic So... 详细信息

关键词： Integral equations direct methods anisotropic sobolev classes

On the generalized Busemann-petty problem

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Science China mathematics 2007年第8期50卷 1103-1116页

作者： Song-jun L~(1,2+) Gang-song LENG~1 1.College of mathematics and Computer Science,Chongqing Normal university,Chongqin 400047,China 2.department of mathematics,Shanghai university,Shanghai 200444,China College of mathematics Computer Science Chongqing Normal University Chongqin 400047 China department of mathematics Shanghai University Shanghai 200444 China

The generalized Busemann-petty problem asks whether the origin-symmetric convex bodies in ? n with a larger volume of all i-dimensional sections necessarily have a larger volume. As proved by Bourgain and Zhang, the answer to this question is negative if i > 3. The problem is still open for i = 2, 3. In this article we prove two specific affirmative answers to the generalized Busemann-petty problem if the body with a smaller i-dimensional volume belongs to given classes. Our results generalize Zhang’s specific affirmative answer to the generalized Busemann-petty problem.

关键词： star body cross i-section dual mixed volume Radon transform 52A30 52A40

EXISTENCE AND NONEXISTENCE OF GLOBAL pOSITIVE SOLUTIONS FOR DEGENERATE pARABOLIC EQUATIONS IN EXTERIOR DOMAINS

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Acta Mathematica Scientia 2010年第3期30卷 713-725页

作者：曾宪忠刘振海 department of mathematics and Computational Science Hunan University of Science and Technology department of mathematics Central South University

This article deals with the degenerate parabolic equations in exterior domains and with inhomogeneous Dirichlet boundary conditions. We obtain that pc = （σ ＋ m ）n / （ n-σ- 2 ） is its critical exponent provided max{-1, [ （1- m ）n- 2] / （ n ＋ l ） } 〈 σ 〈 n- 2. This critical exponent is not the same as that for the corresponding equations with the boundary value 0, but is more closely tied to the critical exponent of the elliptic type degenerate equations. Futhermore, we demonstrate that if max（1, σ ＋ m）〈 p 〈 pc, then every positive solution of the equations blows up in finite time; whereas for p 〉 pc, the equations admit global positive solutions for some boundary values and initial data. Meantime, we also demonstrate that its positive solutions blow up in finite time provided n〈σ＋2.

关键词： Degenerate parabolic equations exterior domains -inhomogeneous dirichlet boundary conditions critical exponent blow-up global existence

population-size-dependent branching processes in Markovian random environments

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Chinese Science Bulletin 1998年第8期43卷 635-638页

作者： WANG Hanxing 1 and DAI Yonglong 2 1. department of mathematics, Shanghai university, Shanghai 201800, China 2. department of mathematics, Zhongshan university, Guangzhou 510275, China department of mathematics Shanghai University Shanghai China department of mathematics Zhongshan University Gunngzhou China

A branching model {Z n} n≥0is considered where the offspring distribution of the population’s evolution is not only dependent on the population size, but also controlled by a Markovian environmental process {ξ n} n≥0. For this model, asymptotic behaviour is studied such as limn→∞Z n and limn→∞Z n/m n in the case that the mean m k, θof the offspring distribution converges to m>1 as the population size k grows to ∞. In the case that {ξ n} n≥0is an irreducible positive recurrent Markov chain, certain extinction (i.e. p(Z n=0 for some n)=1) and noncertain extinction (i.e. p(Z n=0 for some n)<1) are studied.

关键词： Markov chains in random environments stochastic population models branching processes.