全文获取类型
收费全文 | 1196篇 |
免费 | 156篇 |
国内免费 | 85篇 |
专业分类
化学 | 14篇 |
晶体学 | 3篇 |
力学 | 236篇 |
综合类 | 46篇 |
数学 | 817篇 |
物理学 | 321篇 |
出版年
2024年 | 7篇 |
2023年 | 29篇 |
2022年 | 42篇 |
2021年 | 36篇 |
2020年 | 26篇 |
2019年 | 14篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 33篇 |
2015年 | 30篇 |
2014年 | 79篇 |
2013年 | 80篇 |
2012年 | 86篇 |
2011年 | 91篇 |
2010年 | 95篇 |
2009年 | 112篇 |
2008年 | 66篇 |
2007年 | 55篇 |
2006年 | 40篇 |
2005年 | 58篇 |
2004年 | 74篇 |
2003年 | 60篇 |
2002年 | 35篇 |
2001年 | 35篇 |
2000年 | 33篇 |
1999年 | 23篇 |
1998年 | 35篇 |
1997年 | 28篇 |
1996年 | 18篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 7篇 |
1992年 | 14篇 |
1991年 | 12篇 |
1990年 | 16篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有1437条查询结果,搜索用时 15 毫秒
41.
RADIATION BOUNDARY CONDITIONS FOR MAXWELL'S EQUATIONS: A REVIEW OF ACCURATE TIME-DOMAIN FORMULATIONS
Thomas Hagstrom Stephen Lau 《计算数学(英文版)》2007,25(3):305-336
We review time-domain formulations of radiation boundary conditions for Maxwell's equations, focusing on methods which can deliver arbitrary accuracy at acceptable compu-tational cost. Examples include fast evaluations of nonlocal conditions on symmetric and general boundaries, methods based on identifying and evaluating equivalent sources, and local approximations such as the perfectly matched layer and sequences of local boundary conditions. Complexity estimates are derived to assess work and storage requirements as a function of wavelength and simulation time. 相似文献
42.
<正>数学是人们对客观世界定性把握、定量刻画、逐渐抽象概括而形成的方法和理论,并进行广泛应用的过程。数学可以帮助人们更好地探究客观的规律,并对现代社会中大量纷繁复杂的信息作出恰当的选择和判 相似文献
43.
Based on the low-order conforming finite element subspace (Vh, Mh) such as the P1-P0 triangle element or the Q1-P0 quadrilateral element, the locally stabilized finite element method for the Stokes problem with nonlinear slip boundary conditions is investigated in this paper. For this class of nonlinear slip boundary conditions including the subdifferential property, the weak variational formulation associated with the Stokes problem is an variational inequality. Since (Vh, Mh) does not satisfy the discrete inf-sup conditions, a macroelement condition is introduced for constructing the locally stabilized formulation such that the stability of (Vh, Mh) is established. Under these conditions, we obtain the H1 and L2 error estimates for the numerical solutions. 相似文献
44.
This article considers a Markov-dependent risk model with a constant dividend barrier. A system of integro-differential equations with boundary conditions satisfied by the expected discounted penalty function, with given initial environment state, is derived and solved. Explicit formulas for the discounted penalty function are obtained when the initial surplus is zero or when all the claim amount distributions are from rational family. In two state model, numerical illustrations with exponential claim amounts are given. 相似文献
45.
HUANGJIANJUN 《高校应用数学学报(英文版)》1998,13(2):135-140
In this paper, tile existence of coexistence states in the Voterra-Lotka competition model under Dirichlet boundary conditions is the major concern. Attention will be focused on the logistic equation. With a comparison theorem an inequality satistisfied by the solution of logistic equation is established. Some improved sufficient conditions for the existence of coexistence states are obtained. 相似文献
46.
Wen-junSun 《应用数学学报(英文版)》2003,19(1):143-156
This paper deals with the existence and nonexistence of global positive solution to a semilinear reaction-diffusion system with nonlinear boundary conditions.For the heat diffusion case,the necessary and sufficient conditions on the global existence of all positive solutions are obtained.For the general fast diffusion case,we get some conditions on the global existence and nonexistence of positive solutions.The results of this paper fill the some gaps which were left in this field. 相似文献
47.
48.
49.
CAO Zhen-Bin DUAN Yi-Shi 《理论物理通讯》2009,51(1):110-114
Generally, open string boundary conditions play a nontrivial role in string theory. For example, in the presence of an antisymmetric tensor background field, they will lead the spacetime coordinates noncommutative. In this paper, we mainly discuss how to build up a generalized Dirichlet normal ordered product of open bosonic string embedding operators that satisfies both the equations of motion and the generalized Dirichlet boundary conditions at the quantum level in the presence of an antisymmetric background field, as the generalized Neumann case has already been discussed in the literature. Further, we also give a brief check of the consistency of the theory under the newly introduced normal ordering. 相似文献
50.
一类二阶奇异微分方程正解的存在唯一性 总被引:2,自引:1,他引:1
利用上下解方法,不动点理论研究奇异微分方程u" f(t,u)=0,t∈(0,1)在边界条件au(0)-βu'(0)=0,γu(1) δu'(1)=0下C[0,1]正解和C1[0,1]正解的存在性与唯一性.其中非线性项f(t,u)关于u是减的,仅满足较弱的要求. 相似文献