全文获取类型
收费全文 | 11855篇 |
免费 | 863篇 |
国内免费 | 482篇 |
专业分类
化学 | 2350篇 |
晶体学 | 44篇 |
力学 | 1641篇 |
综合类 | 164篇 |
数学 | 6811篇 |
物理学 | 2190篇 |
出版年
2024年 | 28篇 |
2023年 | 118篇 |
2022年 | 375篇 |
2021年 | 372篇 |
2020年 | 256篇 |
2019年 | 262篇 |
2018年 | 307篇 |
2017年 | 379篇 |
2016年 | 387篇 |
2015年 | 287篇 |
2014年 | 553篇 |
2013年 | 744篇 |
2012年 | 714篇 |
2011年 | 576篇 |
2010年 | 532篇 |
2009年 | 667篇 |
2008年 | 646篇 |
2007年 | 710篇 |
2006年 | 589篇 |
2005年 | 528篇 |
2004年 | 443篇 |
2003年 | 396篇 |
2002年 | 352篇 |
2001年 | 352篇 |
2000年 | 328篇 |
1999年 | 260篇 |
1998年 | 287篇 |
1997年 | 226篇 |
1996年 | 175篇 |
1995年 | 190篇 |
1994年 | 155篇 |
1993年 | 129篇 |
1992年 | 119篇 |
1991年 | 99篇 |
1990年 | 88篇 |
1989年 | 68篇 |
1988年 | 63篇 |
1987年 | 53篇 |
1986年 | 44篇 |
1985年 | 60篇 |
1984年 | 56篇 |
1983年 | 16篇 |
1982年 | 30篇 |
1981年 | 27篇 |
1980年 | 21篇 |
1979年 | 36篇 |
1978年 | 21篇 |
1977年 | 29篇 |
1976年 | 18篇 |
1974年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Ivan Nunes da Silva Wagner Caradori do AmaralLucia Valeria de Arruda 《Applied Mathematical Modelling》2007
This paper presents an efficient approach based on recurrent neural network for solving nonlinear optimization. More specifically, a modified Hopfield network is developed and its internal parameters are computed using the valid subspace technique. These parameters guarantee the convergence of the network to the equilibrium points that represent an optimal feasible solution. The main advantage of the developed network is that it treats optimization and constraint terms in different stages with no interference with each other. Moreover, the proposed approach does not require specification of penalty and weighting parameters for its initialization. A study of the modified Hopfield model is also developed to analyze its stability and convergence. Simulation results are provided to demonstrate the performance of the proposed neural network. 相似文献
62.
63.
In this paper we characterize the local maxima of a continuous global optimization formulation for finding the independence
number of a graph. Classical Karush-Kuhn-Tucker conditions and simple combinatorial arguments are found sufficient to deduce
several interesting properties of the local and global maxima. These properties can be utilized in developing new approaches
to the maximum independent set problem. 相似文献
64.
Effect of the subdivision strategy on convergence and efficiency of some global optimization algorithms 总被引:2,自引:0,他引:2
Hoang Tuy 《Journal of Global Optimization》1991,1(1):23-36
We investigate subdivision strategies that can improve the convergence and efficiency of some branch and bound algorithms of global optimization. In particular, a general class of so called weakly exhaustive simplicial subdivision processes is introduced that subsumes all previously known radial exhaustive processes. This result provides the basis for constructing flexible subdivision strategies that can be adapted to take advantage of various problem conditions. 相似文献
65.
本主要介绍原木经销商在周期内原木变价销售情况下的最佳期初贮存量的决策方法,在建立期望机会成本的数学模型基础上,探讨原木随机存贮策略的最优化问题。 相似文献
66.
A domain partitioning algorithm for minimizing or maximizing a Lipschitz continuous function is enhanced to yield two new, more efficient algorithms. The use of interval arithmetic in the case of rational functions and the estimates of Lipschitz constants valid in subsets of the domain in the case of others and the addition of local optimization have resulted in an algorithm which, in tests on standard functions, performs well. 相似文献
67.
Dirk P. Kroese Sergey Porotsky Reuven Y. Rubinstein 《Methodology and Computing in Applied Probability》2006,8(3):383-407
In recent years, the cross-entropy method has been successfully applied to a wide range of discrete optimization tasks. In
this paper we consider the cross-entropy method in the context of continuous optimization. We demonstrate the effectiveness
of the cross-entropy method for solving difficult continuous multi-extremal optimization problems, including those with non-linear
constraints.
相似文献
68.
C. Zălinescu 《Mathematical Methods of Operations Research》1991,35(4):291-298
In this paper there is stated a result on sets in ordered linear spaces which can be used to show that some properties of the sets are inherited by their convex hulls under suitable conditions. As applications one gives a characterization of weakly efficient points and a duality result for nonconvex vector optimization problems. 相似文献
69.
We give a concise review and extension of S-procedure that is an instrumental tool in control theory and robust optimization analysis. We also discuss the approximate S-Lemma as well as its applications in robust optimization.The many suggestions and detailed corrections of an anonymous referee are gratefully acknowledged. 相似文献
70.
Some effective methods for unconstrained optimization based on the solution of systems of ordinary differential equations 总被引:5,自引:0,他引:5
A. A. Brown M. C. Bartholomew-Biggs 《Journal of Optimization Theory and Applications》1989,62(2):211-224
In this paper, we review briefly some methods for minimizing a functionF(x), which proceed by follwoing the solution curve of a system of ordinary differential equations. Such methods have often been thought to be unacceptably expensive; but we show, by means of extensive numerical tests, using a variety of algorithms, that the ODE approach can in fact be implemented in such a way as to be more than competitive with currently available conventional techniques.This work was supported by a SERC research studentship for the first author. Both authors are indebted to Dr. J. J. McKeown and Dr. K. D. Patel of SCICON Ltd, the collaborating establishment, for their advice and encouragement. 相似文献