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   3851篇
  免费   140篇
  国内免费   2篇
化学   2590篇
晶体学   42篇
力学   86篇
数学   269篇
物理学   1006篇
  2023年   41篇
  2022年   66篇
  2021年   63篇
  2020年   90篇
  2019年   113篇
  2018年   74篇
  2017年   61篇
  2016年   142篇
  2015年   78篇
  2014年   140篇
  2013年   255篇
  2012年   259篇
  2011年   316篇
  2010年   192篇
  2009年   161篇
  2008年   233篇
  2007年   191篇
  2006年   179篇
  2005年   154篇
  2004年   117篇
  2003年   79篇
  2002年   78篇
  2001年   64篇
  2000年   57篇
  1999年   46篇
  1998年   30篇
  1997年   25篇
  1996年   40篇
  1995年   33篇
  1994年   36篇
  1993年   46篇
  1992年   30篇
  1991年   27篇
  1990年   13篇
  1989年   24篇
  1988年   22篇
  1987年   30篇
  1986年   21篇
  1985年   20篇
  1984年   32篇
  1983年   20篇
  1982年   23篇
  1981年   33篇
  1980年   20篇
  1979年   27篇
  1978年   17篇
  1977年   19篇
  1976年   16篇
  1975年   15篇
  1957年   13篇
排序方式: 共有3993条查询结果,搜索用时 0 毫秒
1.
It is explicitly shown that if phase transition occurs at the core of a newborn neutron star with moderately strong magnetic field strength, which populates only the electron’s Landau levels, then in the β -equilibrium condition, the quark core is energetically much more unstable than the neutron matter of identical physical condition.  相似文献   
2.
An exact formalism for the relativistic version of Landau theory of Fermi liquid in presence of strong quantizing magnetic field is developed. Both direct and exchange type interactions with scalar and vector coupling cases are considered.  相似文献   
3.
To describe the long time asymptotic behaviour of weakly nonlinear plasma waves propagating in a strongly magnetized plasmafilled cylindrical waveguide the usual KDV equation which is first order in wave amplitude is extended to second order including the effects of finite temperature, mobile ions and giving a proper treatment to the radial co-ordinate for all possible modes of propagation. The second-order effects on the first-order solitary wave profile, phase speed and first order correction to the wavelength are all determined and discussed.  相似文献   
4.
The study of the angular distribution of slow particles during high energy hadron-nucleus interaction indicates that emission of slow particles takes place from a thermally non-equilibrated system. This evidence has come out from the presence of intermittency - a phenomenon that reveals a fractal structure and represents a self-similarity in the particle production process. Hence, this study highlights inadequacy of cascade-evaporation model and advocates the need of its refinement.  相似文献   
5.
6.
A convenient and enantioselective synthesis of ethyl (8RS, 15R)-8-acetoxy-15-hydroxyhexadecanoate15 via a chemoenzymatic approach has been described. The salient features of the synthesis were operational simplicity, use of easily accessible materials, and excellent enantiocontrol via lipase catalyzed acetylation of 2-alkanol.  相似文献   
7.
The non-commutative (NC) CP(1) model is studied from field theory perspective. Our formalism and definition of the NC CP(1) model differs crucially from the existing one [Phys. Lett. B 498 (2001) 277, hep-th/0203125, hep-th/0303090].

Due to the U(1) gauge invariance, the Seiberg–Witten map is used to convert the NC action to an action in terms of ordinary spacetime degrees of freedom and the subsequent theory is studied. The NC effects appear as (NC parameter) θ-dependent interaction terms. The expressions for static energy, obtained from both the symmetric and canonical forms of the energy momentum tensor, are identical, when only spatial noncommutativity is present. Bogomolny analysis reveals a lower bound in the energy in an unambiguous way, suggesting the presence of a new soliton. However, the BPS equations saturating the bound are not compatible to the full variational equation of motion. This indicates that the definitions of the energy momentum tensor for this particular NC theory (the NC theory is otherwise consistent and well defined), are inadequate, thus leading to the “energy crisis”.

A collective coordinate analysis corroborates the above observations. It also shows that the above mentioned mismatch between the BPS equations and the variational equation of motion is small.  相似文献   

8.
Preface     
Rupamanjari Ghosh 《Pramana》2002,58(2):148-148
  相似文献   
9.
A four-noded rectangular element with seven degrees of freedom at each node is developed for buckling analysis of laminated plate structures having any number of layers with a constant thickness of individual layers. The displacement model is so chosen that it can explain adequately the parabolic distribution of transverse shear stresses and the non-linearity of in-plane displacements across the thickness. A geometrical stiffness matrix is developed using in-plane stresses. A wide range of plates from thick to thin are examined under uniaxial loading conditions. The results are compared with the existing analytical and numerical solutions. The present formulations confirm its applicability for buckling analysis of a wide range of plates.  相似文献   
10.
We investigate the change in the calculated value of asymptotic normalization constant (ANC) by the hyperspherical harmonics expansion method with the inclusion of three nucleon force (3BF) in addition to two nucleon force. We see that ANC does not change very much with the inclusion of 3BF indicating that the 3BF does not alter the asymptotic behaviours of HHE wavefunction significantly.  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