全文获取类型
收费全文 | 2885篇 |
免费 | 261篇 |
国内免费 | 220篇 |
专业分类
化学 | 443篇 |
晶体学 | 2篇 |
力学 | 293篇 |
综合类 | 35篇 |
数学 | 1859篇 |
物理学 | 734篇 |
出版年
2024年 | 3篇 |
2023年 | 24篇 |
2022年 | 35篇 |
2021年 | 58篇 |
2020年 | 83篇 |
2019年 | 75篇 |
2018年 | 75篇 |
2017年 | 99篇 |
2016年 | 79篇 |
2015年 | 79篇 |
2014年 | 111篇 |
2013年 | 344篇 |
2012年 | 102篇 |
2011年 | 147篇 |
2010年 | 130篇 |
2009年 | 170篇 |
2008年 | 192篇 |
2007年 | 184篇 |
2006年 | 161篇 |
2005年 | 137篇 |
2004年 | 118篇 |
2003年 | 123篇 |
2002年 | 98篇 |
2001年 | 92篇 |
2000年 | 88篇 |
1999年 | 84篇 |
1998年 | 68篇 |
1997年 | 61篇 |
1996年 | 39篇 |
1995年 | 32篇 |
1994年 | 42篇 |
1993年 | 26篇 |
1992年 | 31篇 |
1991年 | 20篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 14篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 5篇 |
排序方式: 共有3366条查询结果,搜索用时 406 毫秒
1.
2.
3.
4.
5.
Joseph Krasil'shchik 《Acta Appl Math》2002,72(1-2):1-17
A short introduction to geometrical theory of nonlinear differential equations is given to provide a unified overview to the collection 'Symmetries of differential equations and related topics'. 相似文献
6.
Annegret K. Wagler 《Mathematical Methods of Operations Research》2002,56(1):127-149
An edge e of a perfect graph G is critical if G−e is imperfect. We would like to decide whether G−e is still “almost perfect” or already “very imperfect”. Via relaxations of the stable set polytope of a graph, we define two
superclasses of perfect graphs: rank-perfect and weakly rank-perfect graphs. Membership in those two classes indicates how
far an imperfect graph is away from being perfect. We study the cases, when a critical edge is removed from the line graph
of a bipartite graph or from the complement of such a graph. 相似文献
7.
In this paper we introduce a generalization of stable sets: stable multi-sets. A stable multi-set is an assignment of integers
to the vertices of a graph, such that specified bounds on vertices and edges are not exceeded. In case all vertex and edge
bounds equal one, stable multi-sets are equivalent to stable sets.
For the stable multi-set problem, we derive reduction rules and study the associated polytope. We state necessary and sufficient
conditions for the extreme points of the linear relaxation to be integer. These conditions generalize the conditions for the
stable set polytope. Moreover, the classes of odd cycle and clique inequalities for stable sets are generalized to stable
multi-sets and conditions for them to be facet defining are determined.
The study of stable multi-sets is initiated by optimization problems in the field of telecommunication networks. Stable multi-sets
emerge as an important substructure in the design of optical networks.
Received: February 14, 2001/Revised version: September 7, 2001 相似文献
8.
Haifeng Yang Guangming XieTianguang Chu Long Wang 《Nonlinear Analysis: Theory, Methods & Applications》2006
In the paper, commuting and stable feedback design for switched linear systems is investigated. This problem is formulated as to build up suitable state feedback controller for each subsystem such that the closed-loop systems are not only asymptotically stable but also commuting each other. A new concept, common admissible eigenvector set (CAES), is introduced to establish necessary/sufficient conditions for commuting and stable feedback controllers. For second-order systems, a necessary and sufficient condition is established. Moreover, a parametrization of the CAES is also obtained. The motivation comes from stabilization of switched linear systems which consist of a family of LTI systems and a switching law specifying the switching between them, where if all the subsystems are stable and commuting each other, then the total system is stable under arbitrary switching. 相似文献
9.
Laurent Gosse. 《Mathematics of Computation》2002,71(238):553-582
This paper investigates the behavior of numerical schemes for nonlinear conservation laws with source terms. We concentrate on two significant examples: relaxation approximations and genuinely nonhomogeneous scalar laws. The main tool in our analysis is the extensive use of weak limits and nonconservative products which allow us to describe accurately the operations achieved in practice when using Riemann-based numerical schemes. Some illustrative and relevant computational results are provided.
10.
We establish a relation between stable distributions in probability theory and the fractional integral. Moreover, it turns out that the parameter of the stable distribution coincides with the exponent of the fractional integral. It follows from an analysis of the obtained results that equations with the fractional time derivative describe the evolution of some physical system whose time degree of freedom becomes stochastic, i.e., presents a sum of random time intervals subject to a stable probability distribution. We discuss relations between the fractal Cantor set (Cantor strips) and the fractional integral. We show that the possibility to use this relation as an approximation of the fractional integral is rather limited. 相似文献