全文获取类型
收费全文 | 7319篇 |
免费 | 423篇 |
国内免费 | 596篇 |
专业分类
化学 | 2005篇 |
晶体学 | 76篇 |
力学 | 99篇 |
综合类 | 107篇 |
数学 | 4939篇 |
物理学 | 1112篇 |
出版年
2023年 | 61篇 |
2022年 | 127篇 |
2021年 | 163篇 |
2020年 | 145篇 |
2019年 | 241篇 |
2018年 | 258篇 |
2017年 | 183篇 |
2016年 | 206篇 |
2015年 | 144篇 |
2014年 | 296篇 |
2013年 | 590篇 |
2012年 | 287篇 |
2011年 | 386篇 |
2010年 | 325篇 |
2009年 | 425篇 |
2008年 | 478篇 |
2007年 | 496篇 |
2006年 | 445篇 |
2005年 | 366篇 |
2004年 | 327篇 |
2003年 | 293篇 |
2002年 | 268篇 |
2001年 | 179篇 |
2000年 | 183篇 |
1999年 | 185篇 |
1998年 | 187篇 |
1997年 | 115篇 |
1996年 | 162篇 |
1995年 | 130篇 |
1994年 | 107篇 |
1993年 | 95篇 |
1992年 | 77篇 |
1991年 | 58篇 |
1990年 | 24篇 |
1989年 | 42篇 |
1988年 | 31篇 |
1987年 | 23篇 |
1986年 | 13篇 |
1985年 | 43篇 |
1984年 | 25篇 |
1983年 | 12篇 |
1982年 | 16篇 |
1981年 | 15篇 |
1980年 | 20篇 |
1979年 | 15篇 |
1978年 | 14篇 |
1977年 | 13篇 |
1975年 | 9篇 |
1974年 | 7篇 |
1973年 | 12篇 |
排序方式: 共有8338条查询结果,搜索用时 15 毫秒
101.
We investigate Γ-monomials of positive characteristic Γ-functions in the global function fields by using Anderson's double complex method. The results are the generalizations of those in the rational function field case. 相似文献
102.
Nessan J. Kerrigan 《Tetrahedron letters》2004,45(49):9087-9090
The samarium(II) iodide-mediated coupling of ketones with β-alkoxyacrylates gives β-hydroxy-γ-butyrolactones in moderate yield. The process has been applied to the asymmetric synthesis of an antifungal, γ-butyrolactone natural product. 相似文献
103.
Nicolas Victoir 《Journal of Functional Analysis》2004,208(1):107-121
This note extends the work of Capitaine (J. Funct. Anal. 179 (1) (2001) 153) on the Levy area process for the free Brownian motion in two directions. First, we reprove that a Levy area for the Free Brownian motion exists in the Von Neumann tensor product, by exhibiting a non-commutative Burkholder-Davis-Gundy type inequality. Then, we show that there does not exist a Levy area in the projective tensor product. 相似文献
104.
We present here an improved version of the method introduced by the first author to derive
pointwise gradient estimates for the solutions of one-dimensional parabolic problems. After considering
a general qualinear equation in divergence form we apply the method to the case of a nonlinear
diffusion-convection equation. The conclusions are stated first for classical solutions and then for
generalized and mild solutions. In the case of unbounded initial datum we obtain several regularizing
effects for t > 0. Some unilateral pointwise gradient
estimates are also obtained. The case of
the Dirichlet problem is also considered. Finally, we collect, in the last section, several comments
showing the connections among these estimates and the study of the free boundaries
associated to the solutions of the diffusion-convection equation. 相似文献
105.
质子入射散裂产物理论研究方法探讨 总被引:1,自引:1,他引:0
简要介绍了几种关于中高能质子入射引起散裂反应产物理论计算的方法,以及这些方法的最新发展.比较了这些方法在理论计算中的特点,指出经典外推方法有局限性,量子分子动力学方法和改进后的M C方法的计算结果与实验数据有较好的符合,但是计算量大,而且量子分子动力学方法在与宏观输运理论连接上存在不少的困难.半经验计算方法已经取得了初步的成果,需要根据新的实验结果来对其进行发展. The analysis on spallation product of proton-induced reaction with intermediate energy has important applications, such as astrophysics, biophysics, spallation neutron source, and accelerator-driven system (ADS) etc. In recent year, some theoretical models have been developed to investigate this reaction processes. At present work, we introduce the extrapolated classic theory, the quantum molecule dynamic (QMD) plus statistical decay and fission models, the method of Mento-Carlo and Smiempirical method for... 相似文献
106.
F. Berthelin F. Bouchut 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2003,20(6):189-997
We consider isentropic gas dynamics equations with unilateral constraint on the density and mass loss. The γ and pressureless pressure laws are considered. We propose an entropy weak formulation of the system that incorporates the constraint and Lagrange multiplier, for which we prove weak stability and existence of solutions. The nonzero pressure model is approximated by a kinetic BGK relaxation model, while the pressureless model is approximated by a sticky-blocks dynamics with mass loss. 相似文献
107.
We give three formulas expressing the Smale invariant of an immersion f of a (4k−1)-sphere into (4k+1)-space. The terms of the formulas are geometric characteristics of any generic smooth map g of any oriented 4k-dimensional manifold, where g restricted to the boundary is an immersion regularly homotopic to f in (6k−1)-space.The formulas imply that if f and g are two non-regularly homotopic immersions of a (4k−1)-sphere into (4k+1)-space then they are also non-regularly homotopic as immersions into (6k−1)-space. Moreover, any generic homotopy in (6k−1)-space connecting f to g must have at least ak(2k−1)! cusps, where ak=2 if k is odd and ak=1 if k is even. 相似文献
108.
Tjalling J. Ypma 《Numerical Linear Algebra with Applications》1995,2(6):533-541
An algorithm for pre- or post-multiplication of a matrix by a plane rotation, using only three vector saxpy operations instead of the four vector operations usually considered necessary, is described. No auxiliary storage for overwriting is required. The method is shown to be numerically stable. 相似文献
109.
Michael Bildhauer 《manuscripta mathematica》1998,97(3):389-406
H?lder continuity up to the free boundary is proved for minimizing solutions if they meet the supporting surface in an angle
which is bounded away from zero. The problem is localized by proving the continuity of the distance function, a result which
is also true for stationary points.
Received: 14 April 1998 相似文献
110.