全文获取类型
收费全文 | 2273篇 |
免费 | 245篇 |
国内免费 | 220篇 |
专业分类
化学 | 61篇 |
力学 | 190篇 |
综合类 | 43篇 |
数学 | 2121篇 |
物理学 | 323篇 |
出版年
2023年 | 29篇 |
2022年 | 24篇 |
2021年 | 29篇 |
2020年 | 52篇 |
2019年 | 52篇 |
2018年 | 47篇 |
2017年 | 69篇 |
2016年 | 69篇 |
2015年 | 55篇 |
2014年 | 92篇 |
2013年 | 204篇 |
2012年 | 93篇 |
2011年 | 103篇 |
2010年 | 111篇 |
2009年 | 141篇 |
2008年 | 137篇 |
2007年 | 146篇 |
2006年 | 167篇 |
2005年 | 145篇 |
2004年 | 109篇 |
2003年 | 121篇 |
2002年 | 140篇 |
2001年 | 102篇 |
2000年 | 101篇 |
1999年 | 66篇 |
1998年 | 71篇 |
1997年 | 72篇 |
1996年 | 47篇 |
1995年 | 29篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 14篇 |
1983年 | 1篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有2738条查询结果,搜索用时 15 毫秒
61.
For a fundamental group of a compact orientable manifold, a condition is specified that is sufficient to guarantee the presence
of a “virtual” epimorphism onto a free non-Abelian group. A consequence is deriving a strong Tits alternative. An arbitrary
noncompact finitely generated discrete subgroup in PO(3, 1) either is large or is virtually Abelian. An application is provided
to the problem of uniform exponential growth for lattices in a 3-dimensional hyperbolic space and of growth of Betti numbers
for lattices in a hyperbolic n-dimensional space, where n is an odd number.
Supported by RFBR (project No. 08-01-00067), by DFG grant Gr 627-11, and by Forschergruppe “Spektrale Analysis, asymptotical
Verteilungen und stochastische Dynamiken,” Billfold University. (G. A. Noskov)
Translated from Algebra i Logika, Vol. 48, No. 2, pp. 174–189, March–April, 2009. 相似文献
62.
We study the geometry of homogeneous hypersurfaces and their focal sets in complex hyperbolic spaces. In particular, we provide
a characterization of the focal set in terms of its second fundamental form and determine the principal curvatures of the
homogeneous hypersurfaces together with their multiplicities.
相似文献
63.
Larry Ericksen 《Mathematica Slovaca》2009,59(3):261-274
The divisibility of numbers is obtained by iteration of the weighted sum of their integer digits. Then evaluation of the related
congruences yields information about the primality of numbers in certain recursive sequences. From the row elements in generalized
Delannoy triangles, we can verify the primality of any constellation of numbers. When a number set is not a prime constellation,
we can identify factors of their composite numbers. The constellation primality test is proven in all generality, and examples
are given for twin primes, prime triplets, and Sophie Germain primes.
相似文献
64.
Taeko Yamazaki 《Mathematical Methods in the Applied Sciences》2009,32(15):1893-1918
We consider a hyperbolic–parabolic singular perturbation problem for a quasilinear hyperbolic equation of Kirchhoff type with dissipation weak in time. The purpose of this paper is to give time‐decay convergence estimates of the difference between the solutions of the hyperbolic equation above and those of the corresponding parabolic equation, together with the unique existence of the global solutions of the hyperbolic equation above. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
65.
广义KPP(Kolmogorov-Petrovskii-Piskunov)方程是一个积分微分方程.为了要研究其数值解,我们首先将该方程转化为一个非线性双曲型方程,然后构造了一个线性化的差分格式,得到了差分格式解的存在唯一性,利用能量不等式证明了差分格式二阶收敛性和关于初值的无条件稳定性,数值结果验证了本文提出的方法. 相似文献
66.
Viviane Baladi Sbastien Gouëzel 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2009,26(4):1453-1481
We introduce a weak transversality condition for piecewise C1+α and piecewise hyperbolic maps which admit a C1+α stable distribution. We show bounds on the essential spectral radius of the associated transfer operators acting on classical anisotropic Sobolev spaces of Triebel–Lizorkin type which are better than previously known estimates (when our assumption on the stable distribution holds). In many cases, we obtain a spectral gap from which we deduce the existence of finitely many physical measures with basin of total measure. The analysis relies on standard techniques (in particular complex interpolation) but gives a new result on bounded multipliers. Our method applies also to piecewise expanding maps and to Anosov diffeomorphisms, giving a unifying picture of several previous results on a simpler scale of Banach spaces. 相似文献
67.
A meshless method is proposed for the numerical solution of the two space dimensional linear hyperbolic equation subject to appropriate initial and Dirichlet boundary conditions. The new developed scheme uses collocation points and approximates the solution employing thin plate splines radial basis functions. Numerical results are obtained for various cases involving variable, singular and constant coefficients, and are compared with analytical solutions to confirm the good accuracy of the presented scheme. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009 相似文献
68.
ZHU HUI-LIN 《东北数学》2009,25(3):282-288
By using algebraic number theory and p-adic analysis method, we give a new and simple proof of Diophantine equation (^n2) = (^m4) 相似文献
69.
We study the defocusing nonlinear Schrödinger (NLS) equation written in hydrodynamic form through the Madelung transform. From the mathematical point of view, the hydrodynamic form can be seen as the Euler–Lagrange equations for a Lagrangian submitted to a differential constraint corresponding to the mass conservation law. The dispersive nature of the NLS equation poses some major numerical challenges. The idea is to introduce a two‐parameter family of extended Lagrangians, depending on a greater number of variables, whose Euler–Lagrange equations are hyperbolic and accurately approximate NLS equation in a certain limit. The corresponding hyperbolic equations are studied and solved numerically using Godunov‐type methods. Comparison of exact and asymptotic solutions to the one‐dimensional cubic NLS equation (“gray” solitons and dispersive shocks) and the corresponding numerical solutions to the extended system was performed. A very good accuracy of such a hyperbolic approximation was observed. 相似文献
70.
Fei Teng Zhengdong Luo Jing Yang 《Mathematical Methods in the Applied Sciences》2019,42(12):4273-4291
In this article, we primarily focuses to study the order‐reduction for the classical natural boundary element (NBE) method for the two‐dimensional (2D) hyperbolic equation in unbounded domain. To this end, we first build a semi‐discretized format about time for the hyperbolic equation and discuss the existence, stability, and convergence of the time semi‐discretized solutions. We then establish the classical fully discretized NBE format from the time semi‐discretized one and analyze the existence, stability, and convergence of the classical NBE solutions. Next, using proper orthogonal decomposition method, we build a reduced‐order extrapolated NBE (ROENBE) format containing very few unknowns but having adequately high accuracy, and we also discuss the existence, stability, and convergence of the ROENBE solutions. Finally, we use some numerical examples to show that the ROENBE method is far superior to the classical NBE one. It shows that the ROENBE method is reliable and effective for solving the 2D hyperbolic equation with the unbounded domain. 相似文献