全文获取类型
收费全文 | 4947篇 |
免费 | 311篇 |
国内免费 | 215篇 |
专业分类
化学 | 961篇 |
晶体学 | 17篇 |
力学 | 537篇 |
综合类 | 70篇 |
数学 | 3260篇 |
物理学 | 628篇 |
出版年
2024年 | 12篇 |
2023年 | 59篇 |
2022年 | 72篇 |
2021年 | 89篇 |
2020年 | 114篇 |
2019年 | 138篇 |
2018年 | 121篇 |
2017年 | 132篇 |
2016年 | 142篇 |
2015年 | 125篇 |
2014年 | 188篇 |
2013年 | 477篇 |
2012年 | 224篇 |
2011年 | 242篇 |
2010年 | 191篇 |
2009年 | 284篇 |
2008年 | 312篇 |
2007年 | 303篇 |
2006年 | 267篇 |
2005年 | 217篇 |
2004年 | 210篇 |
2003年 | 154篇 |
2002年 | 150篇 |
2001年 | 125篇 |
2000年 | 127篇 |
1999年 | 115篇 |
1998年 | 116篇 |
1997年 | 103篇 |
1996年 | 78篇 |
1995年 | 56篇 |
1994年 | 61篇 |
1993年 | 46篇 |
1992年 | 51篇 |
1991年 | 34篇 |
1990年 | 30篇 |
1989年 | 35篇 |
1988年 | 18篇 |
1987年 | 26篇 |
1986年 | 26篇 |
1985年 | 15篇 |
1984年 | 27篇 |
1983年 | 18篇 |
1982年 | 19篇 |
1981年 | 19篇 |
1980年 | 19篇 |
1979年 | 22篇 |
1978年 | 15篇 |
1977年 | 17篇 |
1976年 | 15篇 |
1973年 | 6篇 |
排序方式: 共有5473条查询结果,搜索用时 15 毫秒
41.
Bilal Chanane. 《Mathematics of Computation》2005,74(252):1793-1801
The purpose in this paper is to compute the eigenvalues of Sturm-Liouville problems with quite general separated boundary conditions nonlinear in the eigenvalue parameter using the regularized sampling method, an improvement on the method based on Shannon sampling theory, which does not involve any multiple integration and provides higher order estimates of the eigenvalues at a very low cost. A few examples shall be presented to illustrate the power of the method and a comparison made with the the exact eigenvalues obtained as squares of the zeros of the exact characteristic functions.
42.
基于错误概率达到最小的原则,该文在罐子模型序贯试验中构造了一种渐近最优设计。在这种设计下,不仅能使病员以较多机会分配到较好的处理,而且能使估计量的统计效率在一定意义下达到最优。 相似文献
43.
This study investigates the robust output tracking problem for a class of uncertain linear systems. The uncertainties are assumed to be time invariant and to satisfy the matching conditions. According to the selected nominal parameters, an optimal solution with a prescribed degree of stability is determined. Then, an auxiliary input via the use of an adapting factor, connected to the nominal optimal control, is introduced to guarantee the robustness and prescribed degree of stability for the output tracking control of the uncertain linear systems. This method is very simple and effective and can reject bounded uncertainties imposed on the states. A maglev vehicle model example is given to show its effectiveness. 相似文献
44.
We first state a uniform convergence theorem for finite-part integrals which are derivatives of weighted Cauchy principal value integrals. We then give a two-stage process to modify approximating splines and optimal nodal splines in such a way that the conditions of this theorem are satisfied. Consequently, these modified splines can be used in the numerical evaluation of these finite-part integrals. 相似文献
45.
Stan J. Surma 《Logica Universalis》2007,1(1):209-219
The connection presented in this paper mirror-links two metamathematical structures, the finitary closure operators, and the
compact consistency properties, in such a way that a specification of one structure induces a provably equivalent specification
of the other.
Mathematics Subject Classification (2000): Primary 06A15, Secondary 28E10 03B22 相似文献
46.
The line search method incorporating the Wolfe conditions is modified to ensure that a descent algorithm terminates in a finite number of steps at an approximate stationary point where the second-order conditions of optimality are satisfied. A simple procedure based on conjugate directions is proposed to determine directions of negative curvature. 相似文献
47.
CONE-DIRECTED CONTINGENT DERIVATIVES AND GENERALIZED PREINVEX SET-VALUED OPTIMIZATION 总被引:2,自引:0,他引:2
丘京辉 《数学物理学报(B辑英文版)》2007,27(1):211-218
By using cone-directed contingent derivatives, the unified necessary and suffi-cient optimality conditions are given for weakly and strongly minimal elements respectively in generalized preinvex set valued optimization. 相似文献
48.
Contingent epiderivatives and set-valued optimization 总被引:24,自引:0,他引:24
In this paper we introduce the concept of the contingent epiderivative for a set-valued map which modifies a notion introduced by Aubin [2] as upper contingent derivative. It is shown that this kind of a derivative has important properties and is one possible generalization of directional derivatives in the single-valued convex case. For optimization problems with a set-valued objective function optimality conditions based on the concept of the contingent epiderivative are proved which are necessary and sufficient under suitable assumptions. 相似文献
49.
林支桂 《数学物理学报(B辑英文版)》1998,(3)
1IntroductionInthispaper,weconsidertheinitial-boundaryvalueproblem,where"o(x)isnon-negativesmoothfunctionsatisfying"o.(0)=0,"o.(1)=1'Whenconsideringtheblow-upofsolution,thefollowingproblemarisenaturally:Doesblow-upoccur?Howdoesthesolutionapproachtheblow-uptime'!Andwilersisthehotspotlocated(blow-upset)?WelookattheheatequationwithanonlillearboundaryconditiollHerefiisaboundeddomaininR",p>1isarealnumber.IthasbeenknownforalongtimethattheDroblelil(1.1).(1.2)withAL(~,0)--'no(x)doesnothaveaglobals… 相似文献
50.
本文讨论定义于Banach空间的多目标数学规划,得到一些ε-最优解和(弱)有效解的必要条件,充分条件和必要充分条件。 相似文献