全文获取类型
收费全文 | 23706篇 |
免费 | 1323篇 |
国内免费 | 243篇 |
专业分类
化学 | 14998篇 |
晶体学 | 103篇 |
力学 | 494篇 |
综合类 | 19篇 |
数学 | 4461篇 |
物理学 | 5197篇 |
出版年
2023年 | 192篇 |
2022年 | 178篇 |
2021年 | 348篇 |
2020年 | 458篇 |
2019年 | 409篇 |
2018年 | 476篇 |
2017年 | 443篇 |
2016年 | 1021篇 |
2015年 | 833篇 |
2014年 | 948篇 |
2013年 | 1623篇 |
2012年 | 1419篇 |
2011年 | 1660篇 |
2010年 | 1082篇 |
2009年 | 886篇 |
2008年 | 1303篇 |
2007年 | 1150篇 |
2006年 | 1067篇 |
2005年 | 941篇 |
2004年 | 812篇 |
2003年 | 615篇 |
2002年 | 606篇 |
2001年 | 385篇 |
2000年 | 319篇 |
1999年 | 319篇 |
1998年 | 275篇 |
1997年 | 312篇 |
1996年 | 248篇 |
1995年 | 240篇 |
1994年 | 215篇 |
1993年 | 206篇 |
1992年 | 222篇 |
1991年 | 166篇 |
1990年 | 149篇 |
1989年 | 176篇 |
1988年 | 162篇 |
1987年 | 148篇 |
1986年 | 139篇 |
1985年 | 190篇 |
1984年 | 180篇 |
1983年 | 153篇 |
1982年 | 171篇 |
1981年 | 139篇 |
1980年 | 155篇 |
1979年 | 133篇 |
1978年 | 162篇 |
1977年 | 137篇 |
1976年 | 122篇 |
1974年 | 123篇 |
1973年 | 127篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
41.
We investigate some topological properties of a normal functorH introduced earlier by Radul which is some functorial compactification of the Hartman-Mycielski construction HM. We prove
that the pair (H X, HMY) is homeomorphic to the pair (Q, σ) for each nondegenerated metrizable compactumX and each denseσ-compact subsetY. 相似文献
42.
Veličković Jelena Đ. Andrić Deana Roglić Goran Tešic Živoslav Lj. Milojković-Opsenica Dušanka M. 《平面色谱法杂志一现代薄层色谱法》2004,17(4):255-260
JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of fourteen 1-arylpiperazine derivatives has been studied by thin-layer chromatography on both silica... 相似文献
43.
44.
Selecting, modifying or creating appropriate problems for mathematics class has become an activity of increaing importance in the professional development of German mathematics teachers. But rather than asking in general: “What is a good problem?” there should be a stronger emphasis on considering the specific goal of a problem, e.g.: “What are the ingredients that make a problem appropriate for initiating a learning process” or “What are the characteristics that make a problem appropriate for its use in a central test?” We propose a guiding scheme for teachers that turns out to be especially helpful, since the newly introduced orientation on outcome standards a) leads to a critical predominance of test items and b) expects teachers to design adequate problems for specific learning processes (e.g. problem solving, reasoning and modelling activities). 相似文献
45.
We study condensation of ethanol-hexanol vapour by numerical solution of kinetic equations. The number of droplets formed
in unit volume is computed within self-consistent classical model. It is shown that formation of ethanol-rich droplets prevails
at the initial stage of nucleation process, but in the stationary state formation of droplets near the saddle point (on cluster
formation energy surface) plays the dominant role.
Presented at the 6th Joint Seminar “Development of Materials Science in Research and Education”, Karlštejn, Czech Republic,
17–19 September 1996.
This work was supported by Grant No. A1010615 of the Grant Agency of the Academy of Sciences of the Czech Republic. 相似文献
46.
Arno Jüschke Johannes Jahn Andreas Kirsch 《Computational Optimization and Applications》1997,7(3):261-276
In this paper we consider a special optimization problem withtwo objectives which arises in antenna theory. It is shown that thisabstract bicriterial optimization problem has at least one solution.Discretized versions of this problem are also discussed, and therelationships between these finite dimensional problems and the infinitedimensional problem are investigated. Moreover, we presentnumerical results for special parameters using a multiobjectiveoptimization method. 相似文献
47.
The purpose of this paper is to give the Reid ``Roundabout Theorem' for quadratic functionals with general boundary conditions.
In particular, we describe the so-called coupled point and regularity condition introduced in [16] in terms of Riccati equation
solutions.
Accepted 27 February 1996 相似文献
48.
The new techniques and ideas in quantum interferometry with neutrons, photons, atoms, electrons, and Bose condensates that fluorished in the last two decades have influenced in a decisive way the thinking and the research in the foundations and interpretation of quantum mechanics. The controversies existing among different schools on the reality of matter waves of quantum theory, the postulates of quantum measurement theory, and the (in)completeness of quantum mechanics have to be approached now in a new way. Our argumentation follows the spirit of the Paris school. 相似文献
49.
50.