全文获取类型
收费全文 | 8614篇 |
免费 | 725篇 |
国内免费 | 1164篇 |
专业分类
化学 | 84篇 |
力学 | 224篇 |
综合类 | 195篇 |
数学 | 8781篇 |
物理学 | 1219篇 |
出版年
2024年 | 15篇 |
2023年 | 86篇 |
2022年 | 91篇 |
2021年 | 129篇 |
2020年 | 179篇 |
2019年 | 236篇 |
2018年 | 235篇 |
2017年 | 240篇 |
2016年 | 275篇 |
2015年 | 185篇 |
2014年 | 402篇 |
2013年 | 663篇 |
2012年 | 374篇 |
2011年 | 497篇 |
2010年 | 472篇 |
2009年 | 676篇 |
2008年 | 648篇 |
2007年 | 693篇 |
2006年 | 572篇 |
2005年 | 517篇 |
2004年 | 421篇 |
2003年 | 446篇 |
2002年 | 423篇 |
2001年 | 275篇 |
2000年 | 301篇 |
1999年 | 309篇 |
1998年 | 247篇 |
1997年 | 229篇 |
1996年 | 154篇 |
1995年 | 83篇 |
1994年 | 70篇 |
1993年 | 41篇 |
1992年 | 44篇 |
1991年 | 29篇 |
1990年 | 21篇 |
1989年 | 19篇 |
1988年 | 21篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 19篇 |
1984年 | 31篇 |
1983年 | 15篇 |
1982年 | 27篇 |
1981年 | 15篇 |
1980年 | 24篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1936年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Decio Levi Piergiulio Tempesta 《Journal of Mathematical Analysis and Applications》2011,376(1):247-258
We propose a new approach to the multiple-scale analysis of difference equations, in the context of the finite operator calculus. We derive the transformation formulae that map any given dynamical system, continuous or discrete, into a rescaled discrete system, by generalizing a classical result due to Jordan. Under suitable analytical hypotheses on the function space we consider, the rescaled equations are of finite order. Our results are applied to the study of multiple-scale reductions of dynamical systems, and in particular to the case of a discrete nonlinear harmonic oscillator. 相似文献
992.
Jorge Cossio Sigifredo Herrón 《Journal of Mathematical Analysis and Applications》2011,376(2):741-749
We prove the existence of infinitely many radial solutions for a p-Laplacian Dirichlet problem which is p-superlinear at the origin. The main tool that we use is the shooting method. We extend for more general nonlinearities the results of J. Iaia in [J. Iaia, Radial solutions to a p-Laplacian Dirichlet problem, Appl. Anal. 58 (1995) 335-350]. Previous developments require a behavior of the nonlinearity at zero and infinity, while our main result only needs a condition of the nonlinearity at zero. 相似文献
993.
C.J. Read 《Journal of Mathematical Analysis and Applications》2011,381(1):202-217
We show that in every nonzero operator algebra with a contractive approximate identity (or c.a.i.), there is a nonzero operator T such that ‖I−T‖?1. In fact, there is a c.a.i. consisting of operators T with ‖I−2T‖?1. So, the numerical range of the elements of our contractive approximate identity is contained in the closed disk center and radius . This is the necessarily weakened form of the result for C?-algebras, where there is always a contractive approximate identity consisting of operators with 0?T?1 - the numerical range is contained in the real interval [0,1]. So, if an operator algebra has a c.a.i., it must have operators with a “certain amount” of positivity. 相似文献
994.
Zhongying Chen 《Journal of Mathematical Analysis and Applications》2011,383(2):522-1258
In this paper, we generalize the complex shifted Laplacian preconditioner to the complex shifted Laplacian-PML preconditioner for the Helmholtz equation with perfectly matched layer (Helmholtz-PML equation). The Helmholtz-PML equation is discretized by an optimal 9-point difference scheme, and the preconditioned linear system is solved by the Krylov subspace method, especially by the biconjugate gradient stabilized method (Bi-CGSTAB). The spectral analysis of the linear system is given, and a new matrix-based interpolation operator is proposed for the multigrid method, which is used to approximately invert the preconditioner. The numerical experiments are presented to illustrate the efficiency of the preconditioned Bi-CGSTAB method with the multigrid based on the new interpolation operator, also, numerical results are given for comparing the performance of the new interpolation operator with that of classic bilinear interpolation operator and the one suggested in Erlangga et al. (2006) [10]. 相似文献
995.
Thomas Ryan Harris Michael Mazzella David Renfrew Ilya M. Spitkovsky 《Linear algebra and its applications》2011,435(11):2639-2657
The numerical range of a bounded linear operator T on a Hilbert space H is defined to be the subset W(T)={〈Tv,v〉:v∈H,∥v∥=1} of the complex plane. For operators on a finite-dimensional Hilbert space, it is known that if W(T) is a circular disk then the center of the disk must be a multiple eigenvalue of T. In particular, if T has minimal polynomial z3-1, then W(T) cannot be a circular disk. In this paper we show that this is no longer the case when H is infinite dimensional. The collection of 3×3 matrices with three-fold symmetry about the origin are also classified. 相似文献
996.
We consider some functional Banach algebras with multiplications as the usual convolution product * and the so‐called Duhamel product ?. We study the structure of generators of the Banach algebras (C(n)[0, 1], *) and (C(n)[0, 1], ?). We also use the Banach algebra techniques in the calculation of spectral multiplicities and extended eigenvectors of some operators. Moreover, we give in terms of extended eigenvectors a new characterization of a special class of composition operators acting in the Lebesgue space Lp[0, 1] by the formula (Cφf)(x) = f(φ(x)). 相似文献
997.
998.
Xing-Hua ZhuJian-Zhong Xiao 《Applied mathematics and computation》2011,217(12):6004-6010
A new continuity theorem of minimum selection is presented for a continuous set-valued operator from a topological space into a Banach space with some uniform convexity. As applications, some problems concerning minimum right inverses for linear operators and minimum fixed points for condensing set-valued nonlinear operators are discussed. Also, the existence of minimum solutions for an integral inclusion is proved. 相似文献
999.
In this paper, a singularly perturbed delay differential equation of first order has been considered. The problem is solved by using a hybrid scheme on a Shishkin mesh. The difference scheme is shown to converge to the continuous solution uniformly with respect to the perturbation parameter. Truncation errors are obtained. Finally, numerical experiments are carried out on a test problem, confirming the effectiveness of the proposed technique. 相似文献
1000.
In this paper, a new iterative scheme by hybrid method is constructed. Strong convergence of the scheme to a common element of the set of common fixed points of finite family of relatively quasi-nonexpansive mappings and set of common solutions of a system of equilibrium problems in a uniformly convex and uniformly smooth real Banach space is proved using the properties of generalized f-projection operator. Our results extend important recent results. 相似文献