全文获取类型
收费全文 | 23417篇 |
免费 | 2022篇 |
国内免费 | 1349篇 |
专业分类
化学 | 1851篇 |
晶体学 | 34篇 |
力学 | 2724篇 |
综合类 | 217篇 |
数学 | 17709篇 |
物理学 | 4253篇 |
出版年
2024年 | 52篇 |
2023年 | 238篇 |
2022年 | 240篇 |
2021年 | 353篇 |
2020年 | 619篇 |
2019年 | 641篇 |
2018年 | 614篇 |
2017年 | 638篇 |
2016年 | 668篇 |
2015年 | 562篇 |
2014年 | 1004篇 |
2013年 | 2350篇 |
2012年 | 993篇 |
2011年 | 1293篇 |
2010年 | 1094篇 |
2009年 | 1495篇 |
2008年 | 1430篇 |
2007年 | 1457篇 |
2006年 | 1318篇 |
2005年 | 1058篇 |
2004年 | 978篇 |
2003年 | 935篇 |
2002年 | 923篇 |
2001年 | 731篇 |
2000年 | 757篇 |
1999年 | 684篇 |
1998年 | 570篇 |
1997年 | 537篇 |
1996年 | 385篇 |
1995年 | 268篇 |
1994年 | 251篇 |
1993年 | 180篇 |
1992年 | 175篇 |
1991年 | 127篇 |
1990年 | 116篇 |
1989年 | 85篇 |
1988年 | 72篇 |
1987年 | 59篇 |
1986年 | 59篇 |
1985年 | 88篇 |
1984年 | 120篇 |
1983年 | 57篇 |
1982年 | 87篇 |
1981年 | 87篇 |
1980年 | 79篇 |
1979年 | 69篇 |
1978年 | 62篇 |
1977年 | 42篇 |
1976年 | 38篇 |
1974年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
P. Q. Khanh 《Journal of Optimization Theory and Applications》1995,87(2):359-378
We prove the Kuhn-Tucker sufficient optimality condition, the Wolfe duality, and a modified Mond-Weir duality for vector optimization problems involving various types of invex-convexlike functions. The class of such functins contains many known generalized convex functions. As applications, we demonstrate that, under invex-convexlikeness assumptions, the Pontryagin maximum principle is a sufficient optimality condition for cooperative differential games. The Wolfe duality is established for these games.The author is indebted to the referees and Professor W. Stadler for valuable remarks and comments, which have been used to revise considerably the paper. 相似文献
92.
Ansgar Jüngel 《Mathematische Nachrichten》1997,185(1):85-110
A multi-dimensional transient drift-diffusion model for (at most) three charged particles, consisting of the continuity equations for the concentrations of the species and the Poisson equation for the electric potential, is considered. The diffusion terms depend on the concentrations. Such a system arises in electrophoretic modeling of three species (neutrally, positively and negatively charged) and in semiconductor theory for two species (positively charged holes and negatively charged electrons). Diffusion terms of degenerate type are also possible in semiconductor modeling. For the initial boundary value problem with mixed Dirichlet - Neumann boundary conditions and general reaction rates, a global existence result is proved. Uniqueness of solutions follows in the Dirichlet boundary case if the diffusion terms are uniformly parabolic or if the initial and boundary densities are strictly positive. Finally, we prove that solutions exist which are positive uniformly in time and globally bounded if the reaction rates satisfy appropriate growth conditions. 相似文献
93.
OSCILLATION OF A FORCED SECOND ORDER NONLINEAR EQUATION ¥KONGQINGKAI;ZHANGBINGGENAbstract:Thispapergivesseveralcriteriaontheo... 相似文献
94.
95.
李亚纯 《应用数学与计算数学学报》1994,8(1):47-54
本文采用整体迭代法证明了带小初值的一阶非线性耗散偏微分方程组的Cauchy问题的整体经典解的存在性及指数衰减性质。 相似文献
96.
Bernard Bialecki 《Numerical Algorithms》1994,8(2):167-184
Cyclic reduction and Fourier analysis-cyclic reduction (FACR) methods are presented for the solution of the linear systems which arise when orthogonal spline collocation with piecewise Hermite bicubics is applied to boundary value problems for certain separable partial differential equations on a rectangle. On anN×N uniform partition, the cyclic reduction and Fourier analysis-cyclic reduction methods requireO(N
2log2
N) andO(N
2log2log2
N) arithmetic operations, respectively. 相似文献
97.
We consider a spatially distributed hybrid system consisting of a convection/reaction system in which the reaction switches discontinuously in time between modes, independently at each spatial point on reaching “switching thresholds”. The model involves a novel formulation for evolution of the free boundary between the modal regions. 相似文献
98.
本针对P0函数互补问题,给出了一种微方程方法,并且证明了P0函数互补问题的解是微分方程系统的渐进稳定平衡点。在适当的假设条件下,证明了所给出的算法具有二次收敛速度。几个数值例子表明了该算法的有效性。 相似文献
99.
In this paper we analyse numerical models for time-dependent Boussinesq equations. These equations arise when so-called Boussinesq terms are introduced into the shallow water equations. We use the Boussinesq terms proposed by Katapodes and Dingemans. These terms generalize the constant depth terms given by Broer. The shallow water equations are discretized by using fourth-order finite difference formulae for the space derivatives and a fourth-order explicit time integrator. The effect on the stability and accuracy of various discrete Boussinesq terms is investigated. Numerical experiments are presented in the case of a fourth-order Runge-Kutta time integrator. 相似文献
100.
T. Van Cauteren J. Ryckebusch B. Metsch H. -R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):613-615
We present some of our results for the electromagnetic properties of excited Σ hyperons, computed within the framework of the Bonn constituent-quark model, which is based on the Bethe-Salpeter approach.
The seven parameters entering the model are fitted against the best-known baryon masses. Accordingly, the results for the
form factors and helicity amplitudes are genuine predictions. We compare with the scarce experimental data available and discuss
the processes in which Σ
*'s may play an important role. 相似文献