全文获取类型
收费全文 | 5254篇 |
免费 | 594篇 |
国内免费 | 420篇 |
专业分类
化学 | 507篇 |
晶体学 | 3篇 |
力学 | 922篇 |
综合类 | 94篇 |
数学 | 3443篇 |
物理学 | 1299篇 |
出版年
2024年 | 6篇 |
2023年 | 40篇 |
2022年 | 52篇 |
2021年 | 67篇 |
2020年 | 108篇 |
2019年 | 124篇 |
2018年 | 128篇 |
2017年 | 131篇 |
2016年 | 140篇 |
2015年 | 108篇 |
2014年 | 222篇 |
2013年 | 333篇 |
2012年 | 241篇 |
2011年 | 253篇 |
2010年 | 256篇 |
2009年 | 272篇 |
2008年 | 298篇 |
2007年 | 353篇 |
2006年 | 281篇 |
2005年 | 286篇 |
2004年 | 268篇 |
2003年 | 280篇 |
2002年 | 259篇 |
2001年 | 222篇 |
2000年 | 230篇 |
1999年 | 194篇 |
1998年 | 161篇 |
1997年 | 159篇 |
1996年 | 113篇 |
1995年 | 101篇 |
1994年 | 75篇 |
1993年 | 77篇 |
1992年 | 80篇 |
1991年 | 70篇 |
1990年 | 27篇 |
1989年 | 28篇 |
1988年 | 21篇 |
1987年 | 20篇 |
1986年 | 26篇 |
1985年 | 29篇 |
1984年 | 20篇 |
1983年 | 10篇 |
1982年 | 17篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 12篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1976年 | 6篇 |
1957年 | 4篇 |
排序方式: 共有6268条查询结果,搜索用时 187 毫秒
11.
Lance Nielsen 《Acta Appl Math》2002,74(3):265-292
Stability properties of Feynman's operational calculus are addressed in the setting of exponential functions of noncommuting operators. Applications of some of the stability results are presented. In particular, the time-dependent perturbation theory of nonrelativistic quantum mechanics is presented in the setting of the operational calculus and application of the stability results of this paper to the perturbation theory are discussed. 相似文献
12.
Constraint Programming and Operations Research: Comments from an Operations Researcher 总被引:4,自引:0,他引:4
Michel Gendreau 《Journal of Heuristics》2002,8(1):19-24
This paper relates the author's personal experience with constraint programming and gives a personal assessment of the relationships between constraint programming and operations research. 相似文献
13.
14.
15.
16.
James Murdock 《Journal of Differential Equations》2004,205(2):424-465
Hypernormal forms (unique normal forms, simplest normal forms) are investigated both from the standpoint of foundational theory and algorithms suitable for use with computer algebra. The Baider theory of the Campbell-Hausdorff group is refined, by a study of its subgroups, to determine the smallest substages into which the hypernormalization process can be divided. This leads to a linear algebra algorithm to compute the generators needed for each substage with the least amount of work. A concrete interpretation of Jan Sanders’ spectral sequence for hypernormal forms is presented. Examples are given, and a proof is given for a little-known theorem of Belitskii expressing the hypernormal form space (in the inner product style) as the kernel of a higher-order differential operator. 相似文献
17.
Geng Sheng WANG 《数学学报(英文版)》2005,21(5):1005-1014
This work is concerned with Pontryagin's maximum principle of optimal control problems governed by some non-well-posed semilinear heat equations. A type of approach to the non-well-posed optimal control problem is given. 相似文献
18.
Michael T. Jury David W. Kribs 《Proceedings of the American Mathematical Society》2005,133(1):213-222
Given a row contraction of operators on a Hilbert space and a family of projections on the space that stabilizes the operators, we show there is a unique minimal joint dilation to a row contraction of partial isometries that satisfy natural relations. For a fixed row contraction the set of all dilations forms a partially ordered set with a largest and smallest element. A key technical device in our analysis is a connection with directed graphs. We use a Wold decomposition for partial isometries to describe the models for these dilations, and we discuss how the basic properties of a dilation depend on the row contraction.
19.
We consider the plane-strain buckling of a cylindrical shellof arbitrary thickness which is made of a Varga material andis subjected to an external hydrostatic pressure on its outersurface. The WKB method is used to solve the eigenvalue problemthat results from the linear bifurcation analysis. We show thatthe circular cross-section buckles into a non-circular shapeat a value of µ1 which depends on A1/A2 and a mode number,where A1 and A2 are the undeformed inner and outer radii, andµ1 is the ratio of the deformed inner radius to A1. Inthe large mode number limit, we find that the dependence ofµ1 on A1/A2 has a boundary layer structure: it is constantover almost the entire region of 0 < A1/A2 < 1 and decreasessharply from this constant value to unity as A1/A2 tends tounity. Our asymptotic results for A1 1 = O(1) and A1 1 = O(1/n) are shown to agree with the numerical resultsobtained by using the compound matrix method. 相似文献
20.
考虑一个奇异摄动罗宾问题在Bakhvalov-Shishkin网格上的迎风差分策略,得到在改进的Shishkin网格上迎风策略是关于ε一致的一阶L∞模收敛的.数值实验证实了此理论结果,显示估计是稳健的. 相似文献