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   6687篇
  免费   210篇
  国内免费   38篇
化学   4845篇
晶体学   37篇
力学   158篇
数学   993篇
物理学   902篇
  2023年   35篇
  2022年   42篇
  2021年   59篇
  2020年   91篇
  2019年   87篇
  2018年   59篇
  2017年   51篇
  2016年   155篇
  2015年   133篇
  2014年   145篇
  2013年   303篇
  2012年   387篇
  2011年   448篇
  2010年   225篇
  2009年   198篇
  2008年   407篇
  2007年   438篇
  2006年   483篇
  2005年   392篇
  2004年   360篇
  2003年   322篇
  2002年   290篇
  2001年   116篇
  2000年   69篇
  1999年   62篇
  1998年   67篇
  1997年   85篇
  1996年   96篇
  1995年   79篇
  1994年   73篇
  1993年   114篇
  1992年   65篇
  1991年   63篇
  1990年   77篇
  1989年   52篇
  1988年   44篇
  1987年   45篇
  1986年   36篇
  1985年   74篇
  1984年   62篇
  1983年   45篇
  1982年   74篇
  1981年   66篇
  1980年   54篇
  1979年   50篇
  1978年   48篇
  1977年   33篇
  1976年   47篇
  1975年   27篇
  1974年   26篇
排序方式: 共有6935条查询结果,搜索用时 546 毫秒
111.
Copper reagents react with secondary and tertiary aldehyde tosylhydrazones to give unique, hindered cuprates which are alkylated in a one-flask procedure.  相似文献   
112.
The differential pulse-polarographic (DPP) determination of both CS2 and COS gases, after their absorption in a methanolic piperidine reagent and the subsequent application of this technique to the residue analysis of dithiocarbamate fungicides is described. Rectilinear calibration curves for both CS2 and COS in the respective regions of 1.5–9.2 and 2.1–12.6 mol/l were obtained. The DPP method has been successfully applied to the determination of thiram residues on apples after a hot acid hydrolysis of the fruits.  相似文献   
113.
For all oddv 3 the complete graph onvK v vertices can be decomposed intov – 2 edge disjoint cycles whose lengths are 3, 3, 4, 5,...,v – 1. Also, for all oddv 7,K v can be decomposed intov – 3 edge disjoint cycles whose lengths are 3, 4,...,v – 4,v – 2,v – 1,v. Research supported by Australian Research Council grant A49130102  相似文献   
114.
We give a simple proof of ergodicity of eigenfunctions of the Laplacian with Dirichlet boundary conditions on compact Riemannian manifolds with piecewise smooth boundaries and ergodic billiards. Examples include the Bunimovich stadium, the Sinai billiard and the generic polygonal billiard tables of Kerckhoff, Masur and Smillie.  相似文献   
115.
Reichenbach proposed a three-valued logic to describe quantum mechanics. In his development, Reichenbach presented three different negation operators without providing any criteria for choosing among them. In this paper we develop two three-valuedderived logics for classical systems. These logics are derived in that they are based on a theory of physical measurement. In this regard they have some of the characteristics of the quantum logic developed by Birkhoff and von Neumann. The theory of measurement used in the present development is the one used previously in developingbivalent derived logics for classical systems. As these systems are derived logics, many of the ambiguities possessed by systems such as Reichenbach's are avoided.  相似文献   
116.
We consider a nonstandard odd reduction of supermatrices (as compared with the standard even reduction) which arises in connection with the possible extension of manifold structure group reductions. The study was initiated by consideration of generalized noninvertible superconformal-like transformations. The features of even- and odd-reduced supermatrices are investigated together. They can be unified into some kind of sandwich semigroups. We also define a special module over even- and odd-reduced supermatrix sets, and the generalized Cayley-Hamilton theorem is proved for them. It is shown that the odd-reduced supermatrices represent semigroup bands and Rees matrix semigroups over a unit group.Alexander von Humboldt Fellow. On leave of absence from Theory Division, Nuclear Physics Laboratory, Kharkov State University, Kharkov 310077, Ukraine  相似文献   
117.
118.
119.
120.
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