全文获取类型
收费全文 | 15115篇 |
免费 | 999篇 |
国内免费 | 878篇 |
专业分类
化学 | 368篇 |
晶体学 | 5篇 |
力学 | 1473篇 |
综合类 | 194篇 |
数学 | 13772篇 |
物理学 | 1180篇 |
出版年
2024年 | 31篇 |
2023年 | 148篇 |
2022年 | 214篇 |
2021年 | 223篇 |
2020年 | 338篇 |
2019年 | 340篇 |
2018年 | 398篇 |
2017年 | 401篇 |
2016年 | 383篇 |
2015年 | 291篇 |
2014年 | 633篇 |
2013年 | 1195篇 |
2012年 | 682篇 |
2011年 | 798篇 |
2010年 | 712篇 |
2009年 | 978篇 |
2008年 | 1038篇 |
2007年 | 1065篇 |
2006年 | 924篇 |
2005年 | 724篇 |
2004年 | 641篇 |
2003年 | 701篇 |
2002年 | 598篇 |
2001年 | 452篇 |
2000年 | 462篇 |
1999年 | 413篇 |
1998年 | 378篇 |
1997年 | 335篇 |
1996年 | 256篇 |
1995年 | 210篇 |
1994年 | 144篇 |
1993年 | 127篇 |
1992年 | 123篇 |
1991年 | 105篇 |
1990年 | 81篇 |
1989年 | 39篇 |
1988年 | 42篇 |
1987年 | 39篇 |
1986年 | 41篇 |
1985年 | 55篇 |
1984年 | 55篇 |
1983年 | 29篇 |
1982年 | 29篇 |
1981年 | 25篇 |
1980年 | 18篇 |
1979年 | 22篇 |
1978年 | 14篇 |
1977年 | 17篇 |
1976年 | 10篇 |
1974年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
方程w"-w+f(t,w)=O的Dirichlet边值问题的正解存在性与多解性 总被引:1,自引:0,他引:1
姚庆六 《应用泛函分析学报》2002,4(1):4-9
考察了下列常微分方程的Dirichlet边值问题的正解[w″(t)-w(t) f(t,w(t))=0,0≤t≤1 w(0)=w(1)=0建立了n正解的存在性,其中n是一个任意的自然数。 相似文献
33.
Johannes Elschner Rainer Hinder Gunther Schmidt 《Advances in Computational Mathematics》2002,16(2-3):139-156
This paper is devoted to the numerical study of diffraction by periodic structures of plane waves under oblique incidence. For this situation Maxwell's equations can be reduced to a system of two Helmholtz equations in R
2 coupled via quasiperiodic transmission conditions on the piecewise smooth interfaces between different materials. The numerical analysis is based on a strongly elliptic variational formulation of the differential problem in a bounded periodic cell involving nonlocal boundary operators. We obtain existence and uniqueness results for discrete solutions and provide the corresponding error analysis. 相似文献
34.
35.
A. A. Abramov S. V. Kurochkin 《Computational Mathematics and Mathematical Physics》2006,46(6):949-954
A new method for calculating the radial spheroidal functions of the first kind is proposed for the arguments that are greater than unity in modulus. A well-known representation of these functions is refined and used for this purpose. The constructs and the software implementation proposed in the paper provide an efficient tool for the calculation of the functions with a desired accuracy in a wide range of parameters. 相似文献
36.
ON THE UNIQUENESS OF THE WEAK SOLUTIONS OF A QUASILINEAR HYPERBOLIC SYSTEM WITH A SINGULAR SOURCE TERM 下载免费PDF全文
This paper is a continuation of the authors'previous paper[1].In this paper the authorsprove,assuming additional conditions on the initial data,some results about the existence anduniqueness of the entropy weak solutions of the Cauchy problem for the singular hyperbolicsystem a_t+(au)_x_2au/x=0,u_t+1/2(a~2+u~2)_x=0,x>0,t≥0. 相似文献
37.
When an organization solves a portfolio problem with public projects evaluated by multiple criteria, in which the economic dimension is not essential or not well characterized, the classical methods are not useful. We propose a non-linear preference model developed from normative Value Theory and using fuzzy sets to model some sources of imprecision. This model can be considered as a generalization of the classical approaches. However, the optimization problem is very complex in order to be solved with non-linear programming techniques. Therefore, the model is exploited by an evolutionary algorithm, able to achieve a strong improvement of the quality of solution. 相似文献
38.
In this paper necessary and sufficient conditions of null-controllability and approximate null-controllability are obtained for the wave equation on a half-axis. Controls solving these problems are found explicitly. Moreover, bang-bang controls solving the approximate null-controllability problem are constructed with the aid of solutions of a frequency extinguishing problem in the restricted band (−a,a) for this equation and the Markov power moment problem. 相似文献
39.
L. T. Ashchepkov 《Computational Mathematics and Mathematical Physics》2006,46(7):1168-1175
A general nonlinear programming problem with interval functions is considered. Two reductions of this problem to the deterministic nonlinear programming problem are proposed, and illustrative examples are discussed. 相似文献
40.
An implicit quasi-monotone second-order accurate method is proposed for analyzing the spiral Couette flow of a rarefied gas between coaxial cylinders. The basic advantages of the method over the conventional method of stationry iterations are that the former is conservative with respect to the collision integral, has a simple software implementation for any types of boundary conditions, and applies to a wide range of Knudsen numbers. 相似文献