全文获取类型
收费全文 | 12774篇 |
免费 | 333篇 |
国内免费 | 303篇 |
专业分类
化学 | 1229篇 |
晶体学 | 33篇 |
力学 | 99篇 |
综合类 | 25篇 |
数学 | 10888篇 |
物理学 | 1136篇 |
出版年
2023年 | 36篇 |
2022年 | 43篇 |
2021年 | 65篇 |
2020年 | 88篇 |
2019年 | 351篇 |
2018年 | 345篇 |
2017年 | 221篇 |
2016年 | 173篇 |
2015年 | 165篇 |
2014年 | 331篇 |
2013年 | 863篇 |
2012年 | 334篇 |
2011年 | 743篇 |
2010年 | 662篇 |
2009年 | 865篇 |
2008年 | 973篇 |
2007年 | 1021篇 |
2006年 | 781篇 |
2005年 | 512篇 |
2004年 | 446篇 |
2003年 | 404篇 |
2002年 | 345篇 |
2001年 | 250篇 |
2000年 | 248篇 |
1999年 | 286篇 |
1998年 | 276篇 |
1997年 | 189篇 |
1996年 | 303篇 |
1995年 | 266篇 |
1994年 | 252篇 |
1993年 | 203篇 |
1992年 | 155篇 |
1991年 | 118篇 |
1990年 | 104篇 |
1989年 | 102篇 |
1988年 | 72篇 |
1987年 | 77篇 |
1986年 | 72篇 |
1985年 | 103篇 |
1984年 | 70篇 |
1983年 | 56篇 |
1982年 | 72篇 |
1981年 | 72篇 |
1980年 | 63篇 |
1979年 | 45篇 |
1978年 | 53篇 |
1977年 | 42篇 |
1976年 | 42篇 |
1974年 | 12篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Denis V. Osin 《Archiv der Mathematik》2007,88(5):403-412
The aim of this paper is to show that free Burnside groups of sufficiently large odd exponent are non-amenable in a certain
strong sense. More precisely their left regular representations are isolated from the trivial representation uniformly on
finite generating sets. It follows that free Burnside groups are of uniform exponential growth. This answers a question of
de la Harpe.
This work has been partially supported by the NSF grant DMS-0605093 and by the RFBR Grant # 05-01-00892.
Received: 25 April 2006 相似文献
142.
Suppose F is a field of characteristic p?5, and that B is a p-block of the symmetric group Sn of defect 3. We prove that the Ext1-quiver of B is bipartite, with the bipartition being described in a simple way using the leg-lengths of p-hooks of partitions. 相似文献
143.
We give a small functorial algebraic model for the 2-stage Postnikov section of the K-theory spectrum of a Waldhausen category and use our presentation to describe the multiplicative structure with respect to biexact functors. 相似文献
144.
Let X be a Tychonoff space, C(X) be the space of all continuous real-valued functions defined on X and CL(X×R) be the hyperspace of all nonempty closed subsets of X×R. We prove the following result. Let X be a countably paracompact normal space. The following are equivalent: (a) dimX=0; (b) the closure of C(X) in CL(X×R) with the Vietoris topology consists of all F∈CL(X×R) such that F(x)≠∅ for every x∈X and F maps isolated points into singletons; (c) each usco map which maps isolated points into singletons can be approximated by continuous functions in CL(X×R) with the locally finite topology. From the mentioned result we can also obtain the answer to Problem 5.5 in [L'. Holá, R.A. McCoy, Relations approximated by continuous functions, Proc. Amer. Math. Soc. 133 (2005) 2173-2182] and to Question 5.5 in [R.A. McCoy, Comparison of hyperspace and function space topologies, Quad. Mat. 3 (1998) 243-258] in the realm of normal, countably paracompact, strongly zero-dimensional spaces. Generalizations of some results from [L'. Holá, R.A. McCoy, Relations approximated by continuous functions, Proc. Amer. Math. Soc. 133 (2005) 2173-2182] are also given. 相似文献
145.
Ronald Ortner 《Operations Research Letters》2007,35(5):619-626
In ergodic MDPs we consider stationary distributions of policies that coincide in all but n states, in which one of two possible actions is chosen. We give conditions and formulas for linear dependence of the stationary distributions of n+2 such policies, and show some results about combinations and mixtures of policies. 相似文献
146.
This paper examines the steady state behaviour of a batch arrival queue with two phases of heterogeneous service along and Bernoulli schedule vacation under multiple vacation policy, where after two successive phases service or first vacation the server may go for further vacations until it finds a new batch of customer in the system. We carry out an extensive stationary analysis of the system, including existence of stationary regime, queue size distribution of idle period process, embedded Markov chain steady state distribution of stationary queue size, busy period distribution along with some system characteristics. 相似文献
147.
Michael J. Puls 《Archiv der Mathematik》2007,88(6):500-506
Let p be a real number greater than one. In this paper we study the vanishing and nonvanishing of the first L
p
-cohomology space of some groups that have one end. We also make a connection between the first L
p
-cohomolgy space and the Floyd boundary of the Cayley graph of a group. We apply the result about Floyd boundaries to show
that there exists a real number p such that the first L
p
-cohomology space of a nonelementary hyperbolic group does not vanish.
Received: 4 August 2006 Revised: 2 November 2006 相似文献
148.
149.
David Swanson William P. Ziemer 《Calculus of Variations and Partial Differential Equations》2002,14(1):69-84
Let be a connected open set, . We give a sufficient condition for a mapping , , to have the property that sgn is almost everywhere of one sign. Following the work of Müller, Spector, and Tang [MST], we give an application of our results
to the theory of non-linear elasticity.
Received: 13 October 2000 / Accepted: 23 January 2001 / Published online: 4 May 2001 相似文献
150.
Vahid Karimipour 《Letters in Mathematical Physics》1994,30(2):87-98
Quantum de Rham complexes on the quantum plane and the quantum group itself are constructed for the nonstandard deformation of Fun(SL(2)). It is shown that in contrast to the standardq-deformation of SL(2), the above complexes are unique for SL
h
(2). Also, as a byproduct, a new deformation of the two-dimensional Heisenberg algebra is obtained which can be used to construct models ofh-deformed quantum mechanics. 相似文献