首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   815篇
  免费   25篇
化学   563篇
力学   6篇
数学   187篇
物理学   84篇
  2023年   2篇
  2022年   4篇
  2021年   4篇
  2020年   4篇
  2019年   10篇
  2018年   12篇
  2017年   16篇
  2016年   17篇
  2015年   30篇
  2014年   22篇
  2013年   67篇
  2012年   45篇
  2011年   49篇
  2010年   34篇
  2009年   32篇
  2008年   58篇
  2007年   51篇
  2006年   57篇
  2005年   45篇
  2004年   34篇
  2003年   33篇
  2002年   21篇
  2001年   6篇
  2000年   25篇
  1999年   11篇
  1998年   9篇
  1997年   9篇
  1996年   11篇
  1995年   11篇
  1994年   9篇
  1993年   9篇
  1992年   8篇
  1991年   6篇
  1990年   9篇
  1989年   2篇
  1988年   3篇
  1987年   2篇
  1986年   2篇
  1985年   4篇
  1984年   7篇
  1983年   3篇
  1982年   6篇
  1981年   6篇
  1979年   6篇
  1978年   6篇
  1977年   6篇
  1976年   2篇
  1975年   6篇
  1974年   2篇
  1973年   3篇
排序方式: 共有840条查询结果,搜索用时 656 毫秒
1.
Book Review     
Structural Chemistry -  相似文献   
2.
3.
Book Reviews     
Unsigned book reviews are by the Book Review Editor.  相似文献   
4.
Twin Paradox and the Logical Foundation of Relativity Theory   总被引:3,自引:0,他引:3  
We study the foundation of space-time theory in the framework of first-order logic (FOL). Since the foundation of mathematics has been successfully carried through (via set theory) in FOL, it is not entirely impossible to do the same for space-time theory (or relativity). First we recall a simple and streamlined FOL-axiomatization Specrel of special relativity from the literature. Specrel is complete with respect to questions about inertial motion. Then we ask ourselves whether we can prove the usual relativistic properties of accelerated motion (e.g., clocks in acceleration) in Specrel. As it turns out, this is practically equivalent to asking whether Specrel is strong enough to “handle” (or treat) accelerated observers. We show that there is a mathematical principle called induction (IND) coming from real analysis which needs to be added to Specrel in order to handle situations involving relativistic acceleration. We present an extended version AccRel of Specrel which is strong enough to handle accelerated motion, in particular, accelerated observers. Among others, we show that~the Twin Paradox becomes provable in AccRel, but it is not provable without IND.  相似文献   
5.
Book reviews     
Please forward books for review to the book review editor: Magdolna Hargittai, Structural Chemistry Research Group of the Hungarian Academy of Sciences, Eötvös University, H-1431 Budapest, Pf. 117, Hungary  相似文献   
6.
We present two different approaches to detect and quantify phase synchronization in the case of coupled non-phase coherent oscillators. The first one is based on the general idea of curvature of an arbitrary curve. The second one is based on recurrences of the trajectory in phase space. We illustrate both methods in the paradigmatic example of the R?ssler system in the funnel regime. We show that the second method is applicable even in the case of noisy data. Furthermore, we extend the second approach to the application of chains of coupled systems, which allows us to detect easily clusters of synchronized oscillators. In order to illustrate the applicability of this approach, we show the results of the algorithm applied to experimental data from a population of 64 electrochemical oscillators.  相似文献   
7.
An imidazolate-bridged copper(II)-zinc(II) complex (Cu(II)-diethylenetriamino-μ-imidazolato-Zn(II)-tris(2-aminoethyl)amine perchlorate (denoted as “Cu,Zn complex”) and a simple copper(II) complex (Cu(II)-tris(2-aminoethyl) amine chloride (“Cu-tren”) were prepared and immobilised on silica gel (by hydrogen or covalent bonds) and montmorillonite (by ion exchange). The immobilised substances were characterised by FT-IR spectroscopy and their thermal characteristics were also studied. The obtained materials were tested in two probe reactions: catalytic oxidation of 3,5-di-tert-butyl catechol (DTBC) (catecholase activity) and the decomposition of hydrogen peroxide (catalase activity). It was found that the catecholase activity of the Cu,Zn complex increased considerably upon immobilization on silica gel via hydrogen bonds and intercalation by ion exchange among the layers of montmorillonite. The imidazolate-bridged copper(II)-zinc(II) complex and its immobilised versions were inactive in hydrogen peroxide decomposition. The Cu(II)-tris(2-aminoethyl)amine chloride complex displayed good catalase activity; however, immobilisation could not improve it.  相似文献   
8.
9.
10.
The theoretical investigation on the distribution of chemical species obtainable as a function of the temperature of the aqueous solutions of metal complexes containing a basic ligand, altogether with the solubility relationship of the compounds to be formed, offers a simple means of planning the preparation of various types of complexes, double and single salts of the central metal cation and onium type compounds of protonated ligand of the central ion and the anion.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号