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   207159篇
  免费   3224篇
  国内免费   544篇
化学   115567篇
晶体学   2360篇
力学   7543篇
综合类   12篇
数学   25888篇
物理学   59557篇
  2021年   1756篇
  2020年   1923篇
  2019年   2027篇
  2018年   2524篇
  2017年   2441篇
  2016年   4295篇
  2015年   3115篇
  2014年   3994篇
  2013年   9703篇
  2012年   8220篇
  2011年   9509篇
  2010年   6490篇
  2009年   6264篇
  2008年   8563篇
  2007年   8454篇
  2006年   7833篇
  2005年   7356篇
  2004年   6404篇
  2003年   5573篇
  2002年   5347篇
  2001年   5425篇
  2000年   4377篇
  1999年   3345篇
  1998年   2866篇
  1997年   2765篇
  1996年   2707篇
  1995年   2425篇
  1994年   2469篇
  1993年   2282篇
  1992年   2549篇
  1991年   2567篇
  1990年   2409篇
  1989年   2331篇
  1988年   2247篇
  1987年   2143篇
  1986年   2065篇
  1985年   2669篇
  1984年   2778篇
  1983年   2249篇
  1982年   2425篇
  1981年   2332篇
  1980年   2207篇
  1979年   2323篇
  1978年   2466篇
  1977年   2358篇
  1976年   2391篇
  1975年   2260篇
  1974年   2327篇
  1973年   2335篇
  1972年   1511篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Nienhaus  G. U.  Hartmann  H.  Parak  F.  Heinzl  J.  Huenges  E. 《Hyperfine Interactions》1989,47(1-4):299-310

RSMR experiments with57Fe radiation were performed on myoglobin. An areasensitive detector was employed for simultaneous angular dependent collection of the scattered quanta up to a maximum angle 2θ of 17‡. Experimental data of polycrystalline and lyophilized myoglobin are compared with computer calculations of the scattering which are based on the atomic coordinates determined by X-ray structure analysis. Special attention has been paid to the influence of coherence effects from collectively moving parts of the protein. A simple model is introduced in order to take into account these segmental motions. Our first results indicate that the sizes of collectively moving segments are comparable with spheres of about 6 å in diameter in dry myoglobin. In myoglobin crystals, where the molecules are surrounded by large hydration shells, the movements appear to be correlated in segments with sizes comparable to helices.

  相似文献   
102.
The general structure of the pureSU(2) gauge potentials is calculated in detail. It is shown that the expansion of the gauge potentials about nonvanishing pure gauge potentials gives rise to new effects with confinement character.  相似文献   
103.
104.
Some remarks to problems of point and interval estimation, testing and problems of outliers are presented in the case of multivariate regression model. This work was supported by the Council of Czech Government J14/98:153100011.  相似文献   
105.
On Quantum Team Games   总被引:2,自引:0,他引:2  
Recently Liu and Simaan (2004) convex static multi-team classical games have been introduced. Here they are generalized to both nonconvex, dynamic and quantum games. Puu's incomplete information dynamical systems are modified and applied to Cournot team game. The replicator dynamics of the quantum prisoner's dilemma game is also studied.  相似文献   
106.
The influence of processing parameters on the electrical characteristics of RuO2/LaAlO3/Si metal-oxide-semiconductor structures was investigated. In particular, the sputtering regime during deposition of LaAlO3 on Si and the atmosphere used in the post-deposition annealing step were addressed by determining capacitance-voltage and gate current-voltage characteristics. These results were correlated with compositional information obtained by Rutherford backscattering spectrometry and nuclear reaction analysis. A post-deposition annealing step in oxygen at 600 °C resulted in better electrical characteristics of the final structure as compared to the same treatment performed in nitrogen. This result is explained by oxygen ability to heal oxygen vacancies in the LaAlO3 film, especially at the dielectric/semiconductor interface region. A thermalized sputtering regime during deposition of LaAlO3 on Si leads to capacitors with electrical characteristics superior to those deposited in ballistic regime. PACS 77.84.Dy; 81.15.Cd; 81.40.Gh; 73.40.Qv; 82.80.Yc  相似文献   
107.
108.
109.
We consider Ising-spin systems starting from an initial Gibbs measure ν and evolving under a spin-flip dynamics towards a reversible Gibbs measure μ≠ν. Both ν and μ are assumed to have a translation-invariant finite-range interaction. We study the Gibbsian character of the measure νS(t) at time t and show the following: (1) For all ν and μ, νS(t) is Gibbs for small t. (2) If both ν and μ have a high or infinite temperature, then νS(t) is Gibbs for all t > 0. (3) If ν has a low non-zero temperature and a zero magnetic field and μ has a high or infinite temperature, then νS(t) is Gibbs for small t and non-Gibbs for large t. (4) If ν has a low non-zero temperature and a non-zero magnetic field and μ has a high or infinite temperature, then νS(t) is Gibbs for small t, non-Gibbs for intermediate t, and Gibbs for large t. The regime where μ has a low or zero temperature and t is not small remains open. This regime presumably allows for many different scenarios. Received: 26 April 2001 / Accepted: 10 October 2001  相似文献   
110.
Algebraic methods in quantum mechanics: from molecules to polymers   总被引:2,自引:0,他引:2  
We present a brief review of algebraic techniques developed and applied in molecular spectroscopy in the last five years. We also outline perspectives for new applications of the Lie algebraic method in the first decade of the new century. Received 21 November 2001  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