全文获取类型
收费全文 | 1957篇 |
免费 | 33篇 |
国内免费 | 91篇 |
专业分类
化学 | 107篇 |
晶体学 | 1篇 |
力学 | 38篇 |
综合类 | 3篇 |
数学 | 1504篇 |
物理学 | 140篇 |
无线电 | 288篇 |
出版年
2023年 | 20篇 |
2022年 | 27篇 |
2021年 | 35篇 |
2020年 | 30篇 |
2019年 | 30篇 |
2018年 | 31篇 |
2017年 | 27篇 |
2016年 | 32篇 |
2015年 | 31篇 |
2014年 | 75篇 |
2013年 | 149篇 |
2012年 | 136篇 |
2011年 | 83篇 |
2010年 | 63篇 |
2009年 | 130篇 |
2008年 | 118篇 |
2007年 | 101篇 |
2006年 | 78篇 |
2005年 | 75篇 |
2004年 | 66篇 |
2003年 | 41篇 |
2002年 | 61篇 |
2001年 | 50篇 |
2000年 | 47篇 |
1999年 | 38篇 |
1998年 | 39篇 |
1997年 | 40篇 |
1996年 | 42篇 |
1995年 | 34篇 |
1994年 | 30篇 |
1993年 | 17篇 |
1992年 | 18篇 |
1991年 | 10篇 |
1990年 | 12篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 24篇 |
1985年 | 29篇 |
1984年 | 27篇 |
1983年 | 19篇 |
1982年 | 29篇 |
1981年 | 16篇 |
1980年 | 31篇 |
1979年 | 25篇 |
1978年 | 32篇 |
1977年 | 5篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有2081条查询结果,搜索用时 11 毫秒
101.
本文得到:具有细链双曲无穷远鞍点和一个细焦点的二次系统至多存在一个极限环,若有细无穷远分界线环S,则其内部不存在极限环,其稳定性与它包围的奇点的稳定性相反. 相似文献
102.
本文把稳健统计的影响函数概念引入到了概率约束下的随机规划模型中.在一定条件下,得到了三个模型最优解的影响函数表达式. 相似文献
103.
In this paper we motivate and describe an algorithm to solve the nonlinear programming problem. The method is based on an exact penalty function and possesses both global and superlinear convergence properties. We establish the global qualities here (the superlinear nature is proven in [7]). The numerical implementation techniques are briefly discussed and preliminary numerical results are given.This work is supported in part by NSERC Grant No. A8639 and the U.S. Dept. of Energy. 相似文献
104.
L. McLinden 《Mathematical Programming》1982,24(1):162-176
Three theorems of linear programming form our starting point: Tucker's theorem (1956) concerning the existence of optimal solutions satisfying the complementary slackness conditions strictly, and Williams' two theorems (1970) concerning the coordinatewise complementary behavior of feasible and optimal solutions. Here, we establish that the same phenomena hold in another, more versatile framework involving general polyhedral convexity. As one main application, the results are transferred into the context of the monotone complementarity problem. Several other theoretical applications are indicated.Research supported in part by the National Science Foundation under grant number MCS 79-05793 at the University of Illinois at Urbana-Champaign. 相似文献
105.
J. E. Spingarn 《Mathematical Programming》1982,22(1):82-92
Optimality conditions for families of nonlinear programming problems inR
n
are studied from a generic point of view. The objective function and some of the constraints are assumed to depend on a parameter, while others are held fixed. Techniques of differential topology are used to show that under suitable conditions, certain strong second-order conditions are necessary for optimality except possibly for parameter values lying in a negligible set.Research sponsored, in part, by the Air Force Office of Scientific Research, under grants number 77-3204 and 79-0120. 相似文献
106.
107.
Solving the subproblem in the lagrangian dual of separable discrete programs with linear constraints
This note presents an efficient method for the routine solution of the subproblem associated with the Lagrangian dual of discrete programming problems having separable non-linear objective function and linear constraints. An additional advantage for subgradient methods is described. 相似文献
108.
The definition of random polytope adopted in this paper restricts consideration to those probability measures satisfying two properties. First, the measure must induce an absolutely continuous distribution over the positions of the bounding hyperplanes of the random polytope; and second, it must result in every point in the space being equally as likely as any other point of lying within the random polytope. An efficient Monte Carlo method for their computer generation is presented together with analytical formulas characterizing their aggregate properties. In particular, it is shown that the expected number of extreme points for such random polytopes increases monotonically in the number of constraints to the limiting case of a polytope topologically equivalent to a hypercube. The implied upper bound of 2
n
wheren is the dimensionality of the space is significantly less than McMullen's attainable bound on the maximal number of vertices even for a moderate number of constraints. 相似文献
109.
In this paper we consider an initial boundary value problem for a reaction-diffusion equation under nonlinear and nonlocal Robin type boundary condition. Assuming the existence of an ordered pair of upper and lower solutions we establish a generalized quasilinearization method for the problem under consideration whose characteristic feature consists in the construction of monotone sequences converging to the unique solution within the interval of upper and lower solutions, and whose convergence rate is quadratic. Thus this method provides an efficient iteration technique that produces not only improved approximations due to the monotonicity of its iterates, but yields also a measure of the convergence rate. 相似文献
110.
We complete A. Klapper's work on the invariant of a one-term trace form over a finite field of odd characteristic. We apply this to computing the probability of a successful impersonation attack on an authentication code proposed by C. Ding et al. (2005). 相似文献