全文获取类型
收费全文 | 7944篇 |
免费 | 173篇 |
国内免费 | 24篇 |
专业分类
化学 | 5901篇 |
晶体学 | 50篇 |
力学 | 77篇 |
数学 | 1153篇 |
物理学 | 960篇 |
出版年
2020年 | 78篇 |
2019年 | 75篇 |
2016年 | 149篇 |
2015年 | 152篇 |
2014年 | 118篇 |
2013年 | 265篇 |
2012年 | 254篇 |
2011年 | 330篇 |
2010年 | 190篇 |
2009年 | 197篇 |
2008年 | 301篇 |
2007年 | 316篇 |
2006年 | 285篇 |
2005年 | 314篇 |
2004年 | 295篇 |
2003年 | 241篇 |
2002年 | 212篇 |
2001年 | 118篇 |
2000年 | 114篇 |
1999年 | 117篇 |
1998年 | 112篇 |
1997年 | 135篇 |
1996年 | 136篇 |
1995年 | 130篇 |
1994年 | 115篇 |
1993年 | 125篇 |
1992年 | 113篇 |
1991年 | 110篇 |
1990年 | 86篇 |
1989年 | 112篇 |
1988年 | 120篇 |
1987年 | 106篇 |
1986年 | 116篇 |
1985年 | 140篇 |
1984年 | 108篇 |
1983年 | 111篇 |
1982年 | 114篇 |
1981年 | 100篇 |
1980年 | 107篇 |
1979年 | 97篇 |
1978年 | 96篇 |
1977年 | 87篇 |
1976年 | 84篇 |
1974年 | 100篇 |
1973年 | 88篇 |
1971年 | 77篇 |
1961年 | 141篇 |
1960年 | 195篇 |
1959年 | 102篇 |
1958年 | 115篇 |
排序方式: 共有8141条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Summary We study a countable system of interacting diffusions on the interval [0,1], indexed by a hierarchical group. A particular choice of the interaction guaranties, we are in the diffusive clustering regime. This means clusters of components with values either close to 0 or close to 1 grow on various different scales. However, single components oscillate infinitely often between values close to 0 and close to 1 in such a way that they spend fraction one of their time together and close to the boundary. The processes in the whole class considered and starting with a shift-ergodic initial law have the same qualitative properties (universality). 相似文献
5.
6.
Christoph Elschenbroich Jrn Plackmeyer Klaus Harms Olaf Burghaus Jürgen Pebler 《无机化学与普通化学杂志》2006,632(5):819-827
Trovacene Chemistry. 13 [1] On Being Lead and Mislead in the Synthesis of Di([5]trovacenyl)ketone Di([5]trovacenyl)ketone ( 3¨ ) has been prepared from lithio‐[5]trovacene and dimethylcarbamoyl chloride and studied by X‐ray diffraction, cyclic voltammetry, magnetic susceptometry and EPR spectroscopy. Slight variation of the synthetic protocol affords an unusual trinuclear complex 5 ? that is also fully characterized. Spin‐spin exchange interaction is smaller in 3¨ than in 1,1‐di([5]trovacenylethene ( 2¨ ), which differs from 3¨ by a replacement of O for CH2. The novel trinuclear complex 5 ? , however, displays exchange coupling very similar to that observed in 1‐methoxy‐2,5,6‐tri([5]trovacenyl)benzene ( 7 ? ). In both cases, an unsymmetrical triangular arrangement of S = 1/2 centers is encountered. These findings are discussed in terms of the nature of the respective spacers. 相似文献
7.
Andrzej Dabrowski Erich Robens Peter Klobes Klaus Meyer Przemyslaw Podkocielny 《Particle & Particle Systems Characterization》2003,20(5):311-322
Since a comprehensive survey published in 1999 [1] much work was done in standardizing measuring methods to characterize the surface geometry of dispersed and/or porous solids and to certify reference materials. The present paper is an extension of a short communication [2]. It gives a survey on existing standards and reports on new drafts and proposals. 相似文献
8.
9.
A Variable Neighborhood Search for the Multi Depot Vehicle Routing Problem with Time Windows 总被引:6,自引:0,他引:6
Michael Polacek Richard F. Hartl Karl Doerner Marc Reimann 《Journal of Heuristics》2004,10(6):613-627
The aim of this paper is to propose an algorithm based on the philosophy of the Variable Neighborhood Search (VNS) to solve Multi Depot Vehicle Routing Problems with Time Windows. The paper has two main contributions. First, from a technical point of view, it presents the first application of a VNS for this problem and several design issues of VNS algorithms are discussed. Second, from a problem oriented point of view the computational results show that the approach is competitive with an existing Tabu Search algorithm with respect to both solution quality and computation times. 相似文献
10.