全文获取类型
收费全文 | 12731篇 |
免费 | 1199篇 |
国内免费 | 541篇 |
专业分类
化学 | 1454篇 |
晶体学 | 32篇 |
力学 | 1335篇 |
综合类 | 241篇 |
数学 | 9713篇 |
物理学 | 1696篇 |
出版年
2024年 | 24篇 |
2023年 | 131篇 |
2022年 | 223篇 |
2021年 | 387篇 |
2020年 | 295篇 |
2019年 | 308篇 |
2018年 | 354篇 |
2017年 | 473篇 |
2016年 | 453篇 |
2015年 | 315篇 |
2014年 | 585篇 |
2013年 | 847篇 |
2012年 | 743篇 |
2011年 | 630篇 |
2010年 | 579篇 |
2009年 | 706篇 |
2008年 | 719篇 |
2007年 | 806篇 |
2006年 | 676篇 |
2005年 | 582篇 |
2004年 | 468篇 |
2003年 | 472篇 |
2002年 | 439篇 |
2001年 | 401篇 |
2000年 | 371篇 |
1999年 | 296篇 |
1998年 | 297篇 |
1997年 | 267篇 |
1996年 | 185篇 |
1995年 | 208篇 |
1994年 | 166篇 |
1993年 | 138篇 |
1992年 | 126篇 |
1991年 | 106篇 |
1990年 | 92篇 |
1989年 | 70篇 |
1988年 | 60篇 |
1987年 | 46篇 |
1986年 | 43篇 |
1985年 | 66篇 |
1984年 | 64篇 |
1983年 | 17篇 |
1982年 | 32篇 |
1981年 | 29篇 |
1980年 | 35篇 |
1979年 | 39篇 |
1978年 | 24篇 |
1977年 | 36篇 |
1976年 | 19篇 |
1957年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 150 毫秒
81.
Regina S. Burachik Rafail N. Gasimov Nergiz A. Ismayilova C. Yalçin. Kaya 《Journal of Global Optimization》2006,34(1):55-78
We study convergence properties of a modified subgradient algorithm, applied to the dual problem defined by the sharp augmented
Lagrangian. The primal problem we consider is nonconvex and nondifferentiable, with equality constraints. We obtain primal
and dual convergence results, as well as a condition for existence of a dual solution. Using a practical selection of the
step-size parameters, we demonstrate the algorithm and its advantages on test problems, including an integer programming and
an optimal control problem.
*Partially Supported by 2003 UniSA ITEE Small Research Grant Ero2.
Supported by CAPES, Brazil, Grant No. 0664-02/2, during her visit to the School of Mathematics and Statistics, UniSA. 相似文献
82.
In this paper, nonconvex multiobjective optimization problems are studied. New characterizations of a properly efficient solution in the sense of Geoffrion's are established in terms of the stability of one scalar optimization problem and the existence of an exact penalty function of a scalar constrained program, respectively. One of the characterizations is applied to derive necessary conditions for a properly efficient control-parameter pair of a nonconvex multiobjective discrete optimal control problem with linear constraints. 相似文献
83.
Hua Nie Jian-hua Wu 《应用数学学报(英文版)》2006,22(2):257-264
This paper is concerned with the unstirred chemostat model with two-species and one non-reproducingresource.The global attractivity of the positive steady-state solutions of the original system is established.Moreover,the effects of the growth rate on the unique positive equilibrium of the single population model arestudied. 相似文献
84.
This paper proposes a new method that extends the efficient global optimization to address stochastic black-box systems. The
method is based on a kriging meta-model that provides a global prediction of the objective values and a measure of prediction
uncertainty at every point. The criterion for the infill sample selection is an augmented expected improvement function with
desirable properties for stochastic responses. The method is empirically compared with the revised simplex search, the simultaneous
perturbation stochastic approximation, and the DIRECT methods using six test problems from the literature. An application
case study on an inventory system is also documented. The results suggest that the proposed method has excellent consistency
and efficiency in finding global optimal solutions, and is particularly useful for expensive systems. 相似文献
85.
M. A. Posypkin I. Kh. Sigal 《Computational Mathematics and Mathematical Physics》2006,46(12):2187-2202
The efficiency of parallel implementations of the branch-and-bound method in discrete optimization problems is considered. A theoretical analysis and comparison of two parallel implementations of this method is performed. A mathematical model of the computation process is constructed and used to obtain estimates of the maximum possible speedup. Examples of problems in which none of these two parallel implementations can speed up the computations are considered. 相似文献
86.
Silvia Vogel 《Annals of Operations Research》2006,142(1):269-282
The paper considers upper semicontinuous behavior in distribution of sequences of random closed sets. Semiconvergence in distribution
will be described via convergence in distribution of random variables with values in a suitable topological space. Convergence
statements for suitable functions of random sets are proved and the results are employed to derive stability statements for
random optimization problems where the objective function and the constraint set are approximated simultaneously.
The author is grateful to two anonymous referees for helpful suggestions. 相似文献
87.
88.
This article studies the inshore-offshore fishery model with impulsive diffusion. The existence and global asymptotic stability of both the trivial periodic solution and the positive periodic solution are obtained. The complexity of this system is also analyzed. Moreover, the optimal harvesting policy are given for the inshore subpopulation, which includes the maximum sustainable yield and the corresponding harvesting effort. 相似文献
89.
A nonclassical problem is considered for the transport equation with coefficients depending on the energy of radiation. The task is to find the discontinuity surfaces for the coefficients of the equation from measurements of the radiation flux leaving the medium. For this tomography problem, an optimization problem is stated and numerically analyzed. The latter consists in determining the radiation energy that ensures the best reconstruction of the unknown medium. A simplified optimization problem is solved analytically. 相似文献
90.
Piotr Szopa 《Mathematical Methods in the Applied Sciences》2007,30(3):331-346
In this paper, we prove the existence and uniqueness of a global solution for 2‐D micropolar fluid equation with periodic boundary conditions. Then we restrict ourselves to the autonomous case and show the existence of a global attractor. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献