全文获取类型
收费全文 | 10307篇 |
免费 | 819篇 |
国内免费 | 340篇 |
专业分类
化学 | 1747篇 |
晶体学 | 28篇 |
力学 | 1062篇 |
综合类 | 150篇 |
数学 | 7034篇 |
物理学 | 1445篇 |
出版年
2024年 | 12篇 |
2023年 | 98篇 |
2022年 | 203篇 |
2021年 | 317篇 |
2020年 | 216篇 |
2019年 | 226篇 |
2018年 | 251篇 |
2017年 | 333篇 |
2016年 | 331篇 |
2015年 | 250篇 |
2014年 | 486篇 |
2013年 | 601篇 |
2012年 | 640篇 |
2011年 | 497篇 |
2010年 | 481篇 |
2009年 | 597篇 |
2008年 | 596篇 |
2007年 | 648篇 |
2006年 | 546篇 |
2005年 | 497篇 |
2004年 | 415篇 |
2003年 | 390篇 |
2002年 | 315篇 |
2001年 | 293篇 |
2000年 | 278篇 |
1999年 | 193篇 |
1998年 | 224篇 |
1997年 | 215篇 |
1996年 | 145篇 |
1995年 | 171篇 |
1994年 | 132篇 |
1993年 | 115篇 |
1992年 | 102篇 |
1991年 | 85篇 |
1990年 | 78篇 |
1989年 | 61篇 |
1988年 | 48篇 |
1987年 | 40篇 |
1986年 | 38篇 |
1985年 | 57篇 |
1984年 | 51篇 |
1983年 | 14篇 |
1982年 | 22篇 |
1981年 | 22篇 |
1980年 | 18篇 |
1979年 | 31篇 |
1978年 | 20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 15 毫秒
991.
基于增广Lagrange函数的RQP方法 总被引:3,自引:0,他引:3
Recursive quadratic programming is a family of techniques developd by Bartholomew-Biggs and other authors for solving nonlinear programming problems.This paperdescribes a new method for constrained optimization which obtains its search di-rections from a quadratic programming subproblem based on the well-known aug-mented Lagrangian function.It avoids the penalty parameter to tend to infinity.We employ the Fletcher‘s exact penalty function as a merit function and the use of an approximate directional derivative of the function that avoids the need toevaluate the second order derivatives of the problem functions.We prove that thealgorithm possesses global and superlinear convergence properties.At the sametime, numerical results are reported. 相似文献
992.
993.
András Fási Péter Zsák István Pálinkó Klára Hernádi 《Reaction Kinetics and Catalysis Letters》2006,87(2):349-357
Summary Bimetallic (Fe-Co) catalyst samples prepared from different precursors over various supports were tested in carbon nanotube
(CNT) production. In order to quicken the evaluation of the performance of the catalysts a combinatorial arrangement was used.</o:p> 相似文献
994.
基于有限元仿真的东风11型救援小车支撑块结构优化 总被引:3,自引:0,他引:3
对东风11型救援小车支撑件进行了有限元分析.通过有限元计算。详细分析了有效应力分布情况;找出了应力集中较大的区域.并分析了其主要原因;观察了应力值最大区域并提出了改善应力集中的方法和措施。从而达到了结构优化的目的. 相似文献
995.
996.
In this paper, we provide theoretical analysis for a cubic regularization of Newton method as applied to unconstrained minimization problem. For this scheme, we prove general local convergence results. However, the main contribution of the paper is related to global worst-case complexity bounds for different problem classes including some nonconvex cases. It is shown that the search direction can be computed by standard linear algebra technique. 相似文献
997.
998.
We use the first and second order approximations of mappings to establish both necessary and sufficient optimality conditions for unconstrained and constrained nonsmooth vector optimization problems. Ideal solutions, efficient solutions, and weakly efficient solutions are considered. The data of the problems need not even be continuous. Some often imposed compactness assumptions are also relaxed. Examples are provided to compare our results and some known recent results.This work was partially supported by the National Basic Research Program in Natural Sciences of Vietnam. 相似文献
999.
This paper considers constrained and unconstrained parametric global optimization problems in a real Hilbert space. We assume that the gradient of the cost functional is Lipschitz continuous but not smooth. A suitable choice of parameters implies the linear or superlinear (supergeometric) convergence of the iterative method. From the numerical experiments, we conclude that our algorithm is faster than other existing algorithms for continuous but nonsmooth problems, when applied to unconstrained global optimization problems. However, because we solve 2n + 1 subproblems for a large number n of independent variables, our algorithm is somewhat slower than other algorithms, when applied to constrained global optimization.This work was partially supported by the NATO Outreach Fellowship - Mathematics 219.33.We thank Professor Hans D. Mittelmann, Arizona State University, for cooperation and support. 相似文献
1000.
F. Flores-Bazán C. Vera PhD Student 《Journal of Optimization Theory and Applications》2006,130(2):185-207
As a consequence of an abstract theorem proved elsewhere, a vector Weierstrass theorem for the existence of a weakly efficient solution without any convexity assumption is established. By using the notion (recently introduced in an earlier paper) of semistrict quasiconvexity for vector functions and assuming additional structure on the space, new existence results encompassing many results appearing in the literature are derived. Also, when the cone defining the preference relation satisfies some mild assumptions (but including the polyhedral and icecream cones), various characterizations for the nonemptiness and compactness of the weakly efficient solution set to convex vector optimization problems are given. Similar results for a class of nonconvex problems on the real line are established as well.Research supported in part by Conicyt-Chile through FONDECYT 104-0610 and FONDAP-Matemáticas Aplicadas II. 相似文献