全文获取类型
收费全文 | 5937篇 |
免费 | 449篇 |
国内免费 | 521篇 |
专业分类
化学 | 73篇 |
力学 | 315篇 |
综合类 | 125篇 |
数学 | 5915篇 |
物理学 | 479篇 |
出版年
2024年 | 8篇 |
2023年 | 59篇 |
2022年 | 64篇 |
2021年 | 106篇 |
2020年 | 125篇 |
2019年 | 151篇 |
2018年 | 145篇 |
2017年 | 164篇 |
2016年 | 188篇 |
2015年 | 121篇 |
2014年 | 308篇 |
2013年 | 491篇 |
2012年 | 304篇 |
2011年 | 391篇 |
2010年 | 330篇 |
2009年 | 473篇 |
2008年 | 486篇 |
2007年 | 411篇 |
2006年 | 358篇 |
2005年 | 311篇 |
2004年 | 227篇 |
2003年 | 232篇 |
2002年 | 234篇 |
2001年 | 158篇 |
2000年 | 176篇 |
1999年 | 154篇 |
1998年 | 136篇 |
1997年 | 112篇 |
1996年 | 80篇 |
1995年 | 62篇 |
1994年 | 54篇 |
1993年 | 42篇 |
1992年 | 32篇 |
1991年 | 26篇 |
1990年 | 23篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 15篇 |
1985年 | 15篇 |
1984年 | 19篇 |
1983年 | 7篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1976年 | 8篇 |
1936年 | 5篇 |
排序方式: 共有6907条查询结果,搜索用时 15 毫秒
951.
Matthieu Felsinger 《偏微分方程通讯》2013,38(9):1539-1573
Weak solutions to parabolic integro-differential operators of order α ∈ (α0, 2) are studied. Local a priori estimates of Hölder norms and a weak Harnack inequality are proved. These results are robust with respect to α↗2. In this sense, the presentation is an extension of Moser's result from [20]. 相似文献
952.
We show that a class of divergence-form elliptic problems with quadratic growth in the gradient and non-coercive zero order terms are solvable, under essentially optimal hypotheses on the coefficients in the equation. In addition, we prove that the solutions are in general not unique. The case where the zero order term has the opposite sign was already intensively studied and the uniqueness is the rule. 相似文献
953.
Sami Mustapha 《偏微分方程通讯》2013,38(1-2):245-275
Abstract We study the regularity of the free boundary in the two membranes problem. We prove that around any point the free boundary is either a C 1, α surface or a cusp, as in the obstacle problem. We also prove C 1, 1 regularity for the pair of functions solving the problem. 相似文献
954.
V. Iftimie 《偏微分方程通讯》2013,38(3-4):651-686
We study here the problem of geometry optimization for a crystal in the Thomas–Fermi–Von Weizsäcker (TFW) solid-state setting, i.e., the problem of minimizing the TFW energy with respect to the periodic lattice defining the positions of the nuclei. We show the existence of such a minimum, and use for that purpose the TFW models of polymers and thin films defined in a previous work (X. Blanc and C. Le Bris, Adv. Differential Equations, 5, 977–1032, 2000). 相似文献
955.
《偏微分方程通讯》2013,38(9-10):1281-1303
Abstract We give here a class of counterexamples to the Fefferman–Phong inequality for systems of pseudodifferential operators, which contains Brummelhuis’ one as a particular case. The main ingredient in the proof is the use of “localized operators” associated with the system, and Hörmander's example of a positive-semidefinite matrix whose Weyl quantization is not nonnegative. For the considered class, in the “isotropic” case, the Sharp Gårding inequality cannot be improved. 相似文献
956.
In this paper, we use the variational iteration method (VIM) for optimal control problems. First, optimal control problems are transferred to Hamilton–Jacobi–Bellman (HJB) equation as a nonlinear first order hyperbolic partial differential equation. Then, the basic VIM is applied to construct a nonlinear optimal feedback control law. By this method, the control and state variables can be approximated as a function of time. Also, the numerical value of the performance index is obtained readily. In view of the convergence of the method, some illustrative examples are presented to show the efficiency and reliability of the presented method. 相似文献
957.
The flow through porous media can be better described by fractional models than the classical ones since they include inherently memory effects caused by obstacles in the structures. The variational iteration method was extended to find approximate solutions of fractional differential equations with the Caputo derivatives, but the Lagrange multipliers of the method were not identified explicitly. In this paper, the Lagrange multiplier is determined in a more accurate way and some new variational iteration formulae are presented. 相似文献
958.
Regarding the generalizations of the Bessel inequality in Hilbert spaces which are due to Bombieri and Boas–Bellman, we obtain a version of the Bessel inequality and some generalizations of this inequality in the framework of Hilbert C *-modules. 相似文献
959.
The mean transformations M(A,?B) are linear mappings and they are analogues of the matrix means of A,?B?≥?0. They are defined by operator monotone functions. In this article several properties are described and a part of them characterize the concept. 相似文献
960.