全文获取类型
收费全文 | 8136篇 |
免费 | 323篇 |
国内免费 | 400篇 |
专业分类
化学 | 78篇 |
力学 | 451篇 |
综合类 | 44篇 |
数学 | 5544篇 |
物理学 | 338篇 |
综合类 | 2404篇 |
出版年
2024年 | 10篇 |
2023年 | 63篇 |
2022年 | 60篇 |
2021年 | 65篇 |
2020年 | 111篇 |
2019年 | 127篇 |
2018年 | 126篇 |
2017年 | 152篇 |
2016年 | 150篇 |
2015年 | 177篇 |
2014年 | 296篇 |
2013年 | 634篇 |
2012年 | 362篇 |
2011年 | 413篇 |
2010年 | 344篇 |
2009年 | 531篇 |
2008年 | 523篇 |
2007年 | 574篇 |
2006年 | 465篇 |
2005年 | 415篇 |
2004年 | 317篇 |
2003年 | 326篇 |
2002年 | 278篇 |
2001年 | 245篇 |
2000年 | 225篇 |
1999年 | 202篇 |
1998年 | 228篇 |
1997年 | 178篇 |
1996年 | 154篇 |
1995年 | 105篇 |
1994年 | 117篇 |
1993年 | 95篇 |
1992年 | 97篇 |
1991年 | 59篇 |
1990年 | 59篇 |
1989年 | 48篇 |
1988年 | 64篇 |
1987年 | 51篇 |
1986年 | 52篇 |
1985年 | 45篇 |
1984年 | 41篇 |
1983年 | 24篇 |
1982年 | 34篇 |
1981年 | 30篇 |
1980年 | 44篇 |
1979年 | 39篇 |
1978年 | 28篇 |
1977年 | 26篇 |
1976年 | 33篇 |
1974年 | 7篇 |
排序方式: 共有8859条查询结果,搜索用时 250 毫秒
991.
A general theory for the approximate solution of nonlinear operator equations where the solution lies in some real or complex Hilbert space is developed. It is shown that the techniques can be applied to a variety of problems taken from the theories of plasma physics, colloid theory, and the theory of current flow in nerve membranes. 相似文献
992.
The note demonstrates that modeling a nonlinear minimax problem as a nonlinear programming problem and applying a classical differentiable penalty function to attempt to solve the problem can lead to convergence to a stationary point of the penalty function which is not a feasible point of the nonlinear programming problem. This occurred naturally in an application from statistical reliability theory. The note resolves the problem through modification of both the problem formulation and the iterative penalty function method. 相似文献
993.
994.
E. J. Dean 《Journal of Optimization Theory and Applications》1992,75(3):471-486
The method of quasilinearization for nonlinear two-point boundary-value problems is an application of Newton's method to a nonlinear differential operator equation. Since the linear boundary-value problem to be solved at each iteration must be discretized, it is natural to consider quasilinearization in the framework of an inexact Newton method. More importantly, each linear problem is only a local model of the nonlinear problem, and so it is inefficient to try to solve the linear problems to full accuracy. Conditions on size of the relative residual of the linear differential equation can then be specified to guarantee rapid local convergence to the solution of the nonlinear continuous problem. If initial-value techniques are used to solve the linear boundary-value problems, then an integration step selection scheme is proposed so that the residual criteria are satisfied by the approximate solutions. Numerical results are presented that demonstrate substantial computational savings by this type of economizing on the intermediate problems.This work was supported in part by DOE Contract DE-AS05-82-ER13016 and NSF Grant RII-89-17691 and was part of the author's doctoral thesis at Rice University. It is a pleasure to thank the author's thesis advisors, Professor R. A. Tapia and Professor J. E. Dennis, Jr. 相似文献
995.
This paper solves a general continuous-time consumption and portfolio decision problem for a single agent for whom there exists, upon bankruptcy, a possibility of recovery from his bankruptcy. The main contribution of the paper is in the modeling of the recovery process. Moreover, it is shown that the model with recovery has a one-to-one correspondence with the model with terminal bankruptcy treated in the literature.This research was supported by Grants SSHRC-410-83-9888 and NSERC-A4619 to the first author and by Grants NSF-DMS-86-01510 and AFOSR-88-0183 to the second author. Comments from E. Presman are gratefully acknowledged. 相似文献
996.
Nonlinear singularly perturbed boundary-value problems are considered, with one or two boundary layers but no turning points. The theory of differential inequalities is used to obtain a numerical procedure for quasilinear and semilinear problems. The required solution is approximated by combining the solutions of suitable auxiliary initial-value problems easily deduced from the given problem. From the numerical results, the method seems accurate and solutions to problems with extremely thin layers can be obtained at reasonable cost.This work was supported by CNR, Rome, Italy (Progetto Finalizzato Sistemi Informatici e Calcolo Parallelo, Sottoprogetto 1). 相似文献
997.
J. P. Paymond 《Journal of Optimization Theory and Applications》1992,72(1):199-200
A correction in the statement of Proposition 4.1 of Ref. 1 is given. 相似文献
998.
柴国庆 《湖北师范学院学报(自然科学版)》2003,23(3):12-15
用上下解方法结合不动点定理,研究了带非线性边值条件的泛函微分方程,获得了解的存在性结果。 相似文献
999.
浅谈农村中学体育教学存在的问题及对策 总被引:2,自引:0,他引:2
李孟军 《达县师范高等专科学校学报》2004,14(2):94-95
通过调查分析了制约农村中学体育教学的主要因素,并提出相应对策,为农村中学体育教学的发展提供参考. 相似文献
1000.
Pseudo-monotone complementarity problems in Hilbert space 总被引:1,自引:0,他引:1
In this paper, some existence results for a nonlinear complementarity problem involving a pseudo-monotone mapping over an arbitrary closed convex cone in a real Hilbert space are established. In particular, some known existence results for a nonlinear complementarity problem in a finite-dimensional Hilbert space are generalized to an infinite-dimensional real Hilbert space. Applications to a class of nonlinear complementarity problems and the study of the post-critical equilibrium state of a thin elastic plate subjected to unilateral conditions are given.This research was partially supported by the National Science Foundation Grant DMS-89-13089, Department of Energy Grant DE-FG03-87-ER-25028, and Office of Naval Research Grant N00014-89-J-1659. The authors would like to express their sincere thanks to Professor S. Schaible, School of Administration, University of California, Riverside, for his helpful suggestions and comments. They also thank the referees for their comments and suggestions that improved this paper substantially. 相似文献