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   7773篇
  免费   218篇
  国内免费   56篇
化学   4589篇
晶体学   57篇
力学   177篇
数学   1526篇
物理学   1698篇
  2023年   31篇
  2022年   148篇
  2021年   182篇
  2020年   137篇
  2019年   204篇
  2018年   222篇
  2017年   186篇
  2016年   271篇
  2015年   223篇
  2014年   235篇
  2013年   518篇
  2012年   459篇
  2011年   566篇
  2010年   398篇
  2009年   348篇
  2008年   474篇
  2007年   448篇
  2006年   399篇
  2005年   377篇
  2004年   330篇
  2003年   269篇
  2002年   217篇
  2001年   113篇
  2000年   107篇
  1999年   121篇
  1998年   92篇
  1997年   72篇
  1996年   93篇
  1995年   60篇
  1994年   48篇
  1993年   57篇
  1992年   52篇
  1991年   35篇
  1990年   26篇
  1989年   34篇
  1987年   19篇
  1986年   17篇
  1985年   29篇
  1984年   30篇
  1983年   34篇
  1982年   20篇
  1981年   27篇
  1978年   22篇
  1977年   28篇
  1976年   22篇
  1975年   26篇
  1974年   19篇
  1973年   18篇
  1972年   28篇
  1971年   16篇
排序方式: 共有8047条查询结果,搜索用时 0 毫秒
31.
32.
33.
34.
For the unsymmetrical title compound, 1‐bromo‐1′‐[(2S)‐N‐(1‐hydroxy‐3‐methylbutane‐2‐yl)]‐ferroceneamide, two independent molecules were found in the asymmetric unit. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
35.
36.
37.
This paper is a direct continuation of [1] where we began the study of the integrable structures in Conformal Field Theory. We show here how to construct the operators ${\bf Q}_{\pm}(\lambda)$ which act in the highest weight Virasoro module and commute for different values of the parameter λ. These operators appear to be the CFT analogs of the Q - matrix of Baxter [2], in particular they satisfy Baxter's famous T- Q equation. We also show that under natural assumptions about analytic properties of the operators as the functions of λ the Baxter's relation allows one to derive the nonlinear integral equations of Destri-de Vega (DDV) [3] for the eigenvalues of the Q-operators. We then use the DDV equation to obtain the asymptotic expansions of the Q - operators at large λ; it is remarkable that unlike the expansions of the T operators of [1], the asymptotic series for Q(λ) contains the “dual” nonlocal Integrals of Motion along with the local ones. We also discuss an intriguing relation between the vacuum eigenvalues of the Q - operators and the stationary transport properties in the boundary sine-Gordon model. On this basis we propose a number of new exact results about finite voltage charge transport through the point contact in the quantum Hall system. Received: 2 December 1996 / Accepted: 11 March 1997  相似文献   
38.
The properties of the Rankin convolutions of two eigenfunctions of different parities from the discrete part of the spectrum of the Laplace operator are studied. Analytical continuability of these convolutions into the left half-plane is proved and a functional equation of Riemann type is obtained. Applications to arithmetical convolutions are given. In particular the asymptotics of such convolutions is obtained by using the nonhomogeneous Rankin convolutions. Bibliography: 4 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 226, 1996, pp. 37–51.  相似文献   
39.
The problems of field evaporation (FE) and field desorption (FD) from surface of oxide high-temperature superconductors (HTSC) of 123, 2212 and 2223 type are discussed. Wide-angle atom probe, usual time-of-flight atom probe and field ionization magnet mass-spectrometer have been used in these experiments. The main purpose of the investigation was to search for effects connected with phase transition. Therefore, the experiments were carried out over a wide range of temperatures: from T of solid nitrogen to room T.

Composition of pure, contaminated and deep corroded surface and typical species of FE and FD spectra have been studied. The bond energies between some atoms (or clusters) and the surface have been estimated on the basis of experimental results and FE theory. From these estimations, and from discovering of correlated ion pairs, it was concluded that the redistribution of local bonds should be taken into consideration in this case. The increase of FE rate was observed at cryogenic temperatures. Various versions are discussed to explain these effects. Some of them are connected with phase transition.

A detailed study of FD of water protonized clusters is performed and the catalytic activity of HTSC crystal surfaces is discussed.  相似文献   

40.
The spectral decomposition for the square of the classical Riemann zeta function ζ2(s) is generalized to the case of the product of two such functions ζ(s1) · ζ(s2) of different arguments. Bibliography: 6 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 322, 2005, pp. 17–44.  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