全文获取类型
收费全文 | 3092篇 |
免费 | 461篇 |
国内免费 | 103篇 |
专业分类
化学 | 293篇 |
晶体学 | 4篇 |
力学 | 343篇 |
综合类 | 82篇 |
数学 | 747篇 |
物理学 | 627篇 |
无线电 | 1560篇 |
出版年
2024年 | 5篇 |
2023年 | 29篇 |
2022年 | 42篇 |
2021年 | 51篇 |
2020年 | 70篇 |
2019年 | 54篇 |
2018年 | 54篇 |
2017年 | 102篇 |
2016年 | 116篇 |
2015年 | 137篇 |
2014年 | 168篇 |
2013年 | 183篇 |
2012年 | 231篇 |
2011年 | 228篇 |
2010年 | 141篇 |
2009年 | 134篇 |
2008年 | 182篇 |
2007年 | 193篇 |
2006年 | 168篇 |
2005年 | 169篇 |
2004年 | 176篇 |
2003年 | 163篇 |
2002年 | 128篇 |
2001年 | 105篇 |
2000年 | 78篇 |
1999年 | 80篇 |
1998年 | 77篇 |
1997年 | 79篇 |
1996年 | 47篇 |
1995年 | 56篇 |
1994年 | 41篇 |
1993年 | 45篇 |
1992年 | 39篇 |
1991年 | 18篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 15篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有3656条查询结果,搜索用时 137 毫秒
51.
旋转带电体磁矩计算的若干法则与算例 总被引:2,自引:0,他引:2
本文在文献 [1]、[2 ]等的基础上给出关于旋转带电体的磁矩计算的若干法则 ,均以定理形式表达 ,并列表枚举其相关算例 相似文献
52.
In this work we consider computing and continuing connecting orbits in parameter dependent dynamical systems. We give details
of algorithms for computing connections between equilibria and periodic orbits, and between periodic orbits. The theoretical
foundation for these techniques is given by the seminal work of Beyn in 1994, “On well-posed problems for connecting orbits
in dynamical systems”, where a numerical technique is also proposed. Our algorithms consist of splitting the computation of
the connection from that of the periodic orbit(s). To set up appropriate boundary conditions, we follow the algorithmic approach
used by Demmel, Dieci, and Friedman, for the case of connecting orbits between equilibria, and we construct and exploit the
smooth block Schur decomposition of the monodromy matrices associated to the periodic orbits. Numerical examples illustrate
the performance of the algorithms.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
53.
Multiple-zero multiple-pole optical filter transfer functions may be implemented more efficiently in an integrated optics architecture if higher order N × M optical couplers are utilized. For example, a coherent ring resonator made from two 3×3 couplers offers some advantages over the three mirror Fabry-Perot etalon, which is its analog. To this end we develop the formalism for obtaining the transfer functions and scattering matrices of ring resonators made from two N × M couplers. We then present a methodology for analyzing serial and parallel systems of N × M optical coupler ring resonators. 相似文献
54.
55.
朱方生 《武汉大学学报(理学版)》1995,(3)
构造了线性二次型最优控制的并行算法,介绍了这个并行算法在武汉大学“WUDP91”并行分布式处理系统上试算的数值应用软件的框图.本软件适用于既定动态系统的平衡问题.对于经济系统,可通过政策控制变量来调节和改善其状态和响应.对于自治系统可找出最优控制使得消耗函数达到最小值.通过对一系列例子进行试算,结果证实,所构造的并行算法和相应的数值软件是有效的,其加速比约为7. 相似文献
56.
57.
Yi-rang Yuan 《应用数学学报(英文版)》2007,23(2):255-268
For a coupled system of multiplayer dynamics of fluids in porous media,the characteristic finiteelement domain decomposition procedures applicable to parallel arithmetic are put forward.Techniques suchas calculus of variations,domain decomposition,characteristic method,negative norm estimate,energy methodand the theory of prior estimates are adopted.Optimal order estimates in L~2 norm are derived for the error inthe approximate solution. 相似文献
58.
文中给出了二维网络结构的计算机上求平面上一组不相交简单物体平行视图的算法,并分析了算法的正确性和时间复杂性。 相似文献
59.
Generalizations of prophet inequalities for single sequences are obtained for optimal stopping of several parallel sequences of independent random variables. For example, if {Xi, j, 1 ≤ i ≤ n, 1 ≤ j < ∞} are independent non-negative random variables, then
and this bound is best possible. Applications are made to comparisons of the optimal expected returns of various alternative methods of stopping of parallel processes. 相似文献
Full-size image
60.
T. Katsuki 《Russian Chemical Bulletin》2004,53(9):1859-1870
The recent development of asymmetric Baeyer—Villiger oxidation of prochiral and racemic ketones is briefly summarized, focusing on the regio- and stereocontrol of the oxidation attained by regulating the stereoelectronic demand in the step of rearrangement of the Criegee intermediate.Based on the report presented at the International Conference Modern Trends in Organoelement and Polymer Chemistry dedicated to the 50th anniversary of the A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences (Moscow, May 30–June 4, 2004).Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1784–1794, September, 2004. 相似文献