全文获取类型
收费全文 | 21628篇 |
免费 | 1290篇 |
国内免费 | 836篇 |
专业分类
化学 | 1839篇 |
晶体学 | 67篇 |
力学 | 2283篇 |
综合类 | 200篇 |
数学 | 15544篇 |
物理学 | 3821篇 |
出版年
2024年 | 21篇 |
2023年 | 215篇 |
2022年 | 287篇 |
2021年 | 425篇 |
2020年 | 422篇 |
2019年 | 441篇 |
2018年 | 469篇 |
2017年 | 591篇 |
2016年 | 575篇 |
2015年 | 496篇 |
2014年 | 996篇 |
2013年 | 1582篇 |
2012年 | 1113篇 |
2011年 | 1228篇 |
2010年 | 1083篇 |
2009年 | 1333篇 |
2008年 | 1408篇 |
2007年 | 1459篇 |
2006年 | 1073篇 |
2005年 | 926篇 |
2004年 | 771篇 |
2003年 | 739篇 |
2002年 | 653篇 |
2001年 | 571篇 |
2000年 | 571篇 |
1999年 | 449篇 |
1998年 | 489篇 |
1997年 | 424篇 |
1996年 | 338篇 |
1995年 | 339篇 |
1994年 | 291篇 |
1993年 | 225篇 |
1992年 | 209篇 |
1991年 | 149篇 |
1990年 | 140篇 |
1989年 | 102篇 |
1988年 | 96篇 |
1987年 | 91篇 |
1986年 | 105篇 |
1985年 | 126篇 |
1984年 | 112篇 |
1983年 | 56篇 |
1982年 | 80篇 |
1981年 | 67篇 |
1980年 | 89篇 |
1979年 | 100篇 |
1978年 | 66篇 |
1977年 | 67篇 |
1976年 | 52篇 |
1974年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2021,38(5):1337-1371
In this paper we consider minimizers of the functional where is a bounded open set and where are the first k eigenvalues on Ω of an operator in divergence form with Dirichlet boundary condition and with Hölder continuous coefficients. We prove that the optimal sets have finite perimeter and that their free boundary is composed of a regular part, which is locally the graph of a -regular function, and a singular part, which is empty if , discrete if and of Hausdorff dimension at most if , for some . 相似文献
2.
In this article, we construct and analyze a residual-based a posteriori error estimator for a quadratic finite volume method (FVM) for solving nonlinear elliptic partial differential equations with homogeneous Dirichlet boundary conditions. We shall prove that the a posteriori error estimator yields the global upper and local lower bounds for the norm error of the FVM. So that the a posteriori error estimator is equivalent to the true error in a certain sense. Numerical experiments are performed to illustrate the theoretical results. 相似文献
3.
This paper is concerned with the Cauchy problem on the Boltzmann equation without angular cutoff assumption for hard potential in the whole space. When the initial data is a small perturbation of a global Maxwellian, the global existence of solution to this problem is proved in unweighted Sobolev spaces with . But if we want to obtain the optimal temporal decay estimates, we need to add the velocity weight function, in this case the global existence and the optimal temporal decay estimate of the Boltzmann equation are all established. Meanwhile, we further gain a more accurate energy estimate, which can guarantee the validity of the assumption in Chen et al. (0000). 相似文献
4.
5.
利用标量化方法建立对称向量拟均衡问题有效解的存在性定理。作为标量化方法的应用,利用这一方法得到向量变分不等式和拟向量变分不等式有效解的存在性定理。 相似文献
6.
7.
《Operations Research Letters》2021,49(6):855-861
This letter studies the problem of minimizing increasing set functions, equivalently, maximizing decreasing set functions, over the base matroid. This setting has received great interest, since it generalizes several applied problems including actuator and sensor placement problems in control, task allocation problems, video summarization, and many others. We study two greedy heuristics, namely, the forward and reverse greedy. We provide two novel performance guarantees for the approximate solutions obtained by them depending on both submodularity ratio and curvature. 相似文献
8.
9.
《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2021,38(6):1943-1959
This paper studies the asymptotic behavior of coexistence steady-states of the Shigesada-Kawasaki-Teramoto model as both cross-diffusion coefficients tend to infinity at the same rate. In the case when either one of two cross-diffusion coefficients tends to infinity, Lou and Ni [18] derived a couple of limiting systems, which characterize the asymptotic behavior of coexistence steady-states. Recently, a formal observation by Kan-on [10] implied the existence of a limiting system including the nonstationary problem as both cross-diffusion coefficients tend to infinity at the same rate. This paper gives a rigorous proof of his observation as far as the stationary problem. As a key ingredient of the proof, we establish a uniform estimate for all steady-states. Thanks to this a priori estimate, we show that the asymptotic profile of coexistence steady-states can be characterized by a solution of the limiting system. 相似文献
10.