全文获取类型
收费全文 | 5075篇 |
免费 | 588篇 |
国内免费 | 544篇 |
专业分类
化学 | 604篇 |
晶体学 | 31篇 |
力学 | 373篇 |
综合类 | 144篇 |
数学 | 3882篇 |
物理学 | 1173篇 |
出版年
2024年 | 4篇 |
2023年 | 61篇 |
2022年 | 58篇 |
2021年 | 81篇 |
2020年 | 138篇 |
2019年 | 124篇 |
2018年 | 155篇 |
2017年 | 165篇 |
2016年 | 172篇 |
2015年 | 132篇 |
2014年 | 208篇 |
2013年 | 374篇 |
2012年 | 236篇 |
2011年 | 223篇 |
2010年 | 254篇 |
2009年 | 307篇 |
2008年 | 324篇 |
2007年 | 351篇 |
2006年 | 279篇 |
2005年 | 288篇 |
2004年 | 258篇 |
2003年 | 252篇 |
2002年 | 252篇 |
2001年 | 229篇 |
2000年 | 209篇 |
1999年 | 167篇 |
1998年 | 144篇 |
1997年 | 120篇 |
1996年 | 128篇 |
1995年 | 76篇 |
1994年 | 75篇 |
1993年 | 34篇 |
1992年 | 41篇 |
1991年 | 35篇 |
1990年 | 31篇 |
1989年 | 16篇 |
1988年 | 22篇 |
1987年 | 22篇 |
1986年 | 13篇 |
1985年 | 20篇 |
1984年 | 18篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 8篇 |
1980年 | 17篇 |
1979年 | 14篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1974年 | 4篇 |
排序方式: 共有6207条查询结果,搜索用时 31 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.
Natalia L. Calvo Sebastian O. SimonettiRubén M. Maggio Teodoro S. Kaufman 《Analytica chimica acta》2015
Exposure of cimetidine (CIM) to dry heat (160–180 °C) afforded, upon cooling, a glassy solid containing new and hitherto unknown products. The kinetics of this process was studied by a second order chemometrics-assisted multi-spectroscopic approach. Proton and carbon-13 nuclear magnetic resonance (NMR), as well as ultraviolet and infrared spectroscopic data were jointly used, whereas multivariate curve resolution with alternating least squares (MCR-ALS) was employed as the chemometrics method to extract process information. It was established that drug degradation follows a first order kinetics. 相似文献
3.
Ieva
Dauickait Amos S. Lawless Jennifer A. Scott Peter Jan van Leeuwen 《Numerical Linear Algebra with Applications》2020,27(5)
We consider the large sparse symmetric linear systems of equations that arise in the solution of weak constraint four‐dimensional variational data assimilation, a method of high interest for numerical weather prediction. These systems can be written as saddle point systems with a 3 × 3 block structure but block eliminations can be performed to reduce them to saddle point systems with a 2 × 2 block structure, or further to symmetric positive definite systems. In this article, we analyse how sensitive the spectra of these matrices are to the number of observations of the underlying dynamical system. We also obtain bounds on the eigenvalues of the matrices. Numerical experiments are used to confirm the theoretical analysis and bounds. 相似文献
4.
5.
本文定义了二阶微分方程的弱 Carathéodory解 ,在不涉及紧型条件的情形下 ,直接用迭代法证明了 Banach空间二阶非线性常微分方程两点边值问题存在唯一解 ,并给出逼近解迭代序列的误差估计 ,对周期边值问题得到类似的结果 相似文献
6.
Xuguang Lu 《Journal of statistical physics》2006,124(2-4):517-547
The paper considers macroscopic behavior of a Fermi–Dirac particle system. We prove the L
1-compactness of velocity averages of weak solutions of the Boltzmann equation for Fermi–Dirac particles in a periodic box with the collision kernel b(cos θ)|ρ−ρ
*|γ, which corresponds to very soft potentials: −5 < γ ≤ −3 with a weak angular cutoff: ∫0
π
b(cos θ)sin 3θ dθ < ∞. Our proof for the averaging compactness is based on the entropy inequality, Hausdorff–Young inequality, the L
∞-bounds of the solutions, and a specific property of the value-range of the exponent γ. Once such an averaging compactness is proven, the proof of the existence of weak solutions will be relatively easy. 相似文献
7.
8.
Robert S. Strichartz 《Proceedings of the American Mathematical Society》2002,130(3):805-817
Harmonic mappings from the Sierpinski gasket to the circle are described explicitly in terms of boundary values and topological data. In particular, all such mappings minimize energy within a given homotopy class. Explicit formulas are also given for the energy of the mapping and its normal derivatives at boundary points.
9.
10.
Agnieszka Kaamajska 《Mathematical Methods in the Applied Sciences》2006,29(11):1307-1325
The weak limits of sequences {f(uν)}ν∈? where uν's are vector‐valued µ‐measurable functions defined on a compact set Ω and f is (possibly) discontinuous are investigated. As shown by the author (J. Conv. Anal. (to appear)), they are described in terms of integral formulae involving parametrized measures independent of f, similarly as in the classical theorem by Young and its generalization due to DiPerna and Majda. In the present paper we describe the supports of the involved parametrized measures. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献