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   737154篇
  免费   5356篇
  国内免费   1885篇
化学   348758篇
晶体学   10237篇
力学   41808篇
综合类   19篇
数学   125396篇
物理学   218177篇
  2021年   6212篇
  2020年   6719篇
  2019年   7688篇
  2018年   20112篇
  2017年   20025篇
  2016年   20192篇
  2015年   8467篇
  2014年   13552篇
  2013年   29337篇
  2012年   26197篇
  2011年   36432篇
  2010年   25779篇
  2009年   26121篇
  2008年   31626篇
  2007年   33339篇
  2006年   23465篇
  2005年   21864篇
  2004年   20715篇
  2003年   19382篇
  2002年   18438篇
  2001年   18414篇
  2000年   14439篇
  1999年   11109篇
  1998年   9891篇
  1997年   9639篇
  1996年   9065篇
  1995年   8039篇
  1994年   8087篇
  1993年   7893篇
  1992年   8157篇
  1991年   8712篇
  1990年   8419篇
  1989年   8321篇
  1988年   8026篇
  1987年   7872篇
  1986年   7457篇
  1985年   9351篇
  1984年   9873篇
  1983年   8327篇
  1982年   8684篇
  1981年   8124篇
  1980年   7667篇
  1979年   8422篇
  1978年   8617篇
  1977年   8645篇
  1976年   8642篇
  1975年   8244篇
  1974年   8053篇
  1973年   8294篇
  1972年   6365篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
132.
The spin splitting caused by the terms linear in wavevector in the effective Hamiltonian containing can give rise to the new magneto-oscillation phenomena in two-dimensional systems. It is shown that the joint action of the spin-dependent contributions due to the heterostructure asymmetry and to the lack of inversion center in the bulk material suppresses beats that arise in the magneto-oscillation phenomena in the presence of the terms of only one of these types.  相似文献   
133.
The principal physics goals of the Compact Muon Solenoid experiment under construction at the Large Hadron Collider at CERN in Geneva are reviewed. Procedures to search for the Standard Model Higgs boson, supersymmetric Higgses and other supersymmetric particles are described.  相似文献   
134.
Properties of oxygenated carbon nitride films have attracted the attention of physics researchers due to their magnetic and physical properties, as well as for their usefulness in the industry. The free radicals were investigated using electron paramagnetic resonance applied in the study of spin concentration due to the different mechanism of preparation of carbon nitride films by RF-discharge with different kinds of plasma. Unpaired spin concentrations, in the order of 1020 per cm3, were measured and their time recombination dependency was important in those films. The films were grown by plasma enhanced chemical vapor deposition using mixtures of hydrocarbons, N2 and O2 in different proportions.  相似文献   
135.
An unusually high mobility of atoms under intensive impulse reactions is explained by the behavior of point defects at the shock wave front. It is shown that either a shock wave front or moving dislocations can capture the interstitials, or they can be thermally activated in the direction of the shock wave propagation.  相似文献   
136.
The scattering of heavy ion with a multilevel Rydberg atom in the presence of an electromagnetic field is studied. The interaction of Rydberg atom and the e.m field is explored using non-perturbative quasi-energy technique. Although the results are presented for selected excitations but in actual calculations we have included many levels of the atom. The effect of various parameters are shown on collisional excitation process. As an illustration detailed calculations are performed for the inelastic proton-Na Rydberg atom collision accompanied by the transfer of photons and the effects of dressing due to the field are considered. The emphasis of the present work is on collision induced transitions especially the case that involves change of orbital as well as principal quantum number. Received 26 December 2001 / Received in final form 8 April 2002 Published online 19 July 2002  相似文献   
137.
Ionic conductivity of dry quaternary ammonium polymer, polydiallyldimethylammonium with Cl and H2PO4 counter ions was studied in a wide range of frequencies (10−2-107 Hz) and temperatures (300-470 K). The data were analysed within the formalism of permittivity. WAXS, and thermal properties of this polymer were investigated prior to conductivity measurements.  相似文献   
138.
The diffraction efficiency and the recording and relaxation times of dynamic reflection holograms, recorded in CdF2 crystals with bistable centers are studied experimentally in the temperature range 20–100°C. In the model experiments which measured the quality of the wave reflected from the hologram, the dynamic wavefront distortions are demonstrated to be efficiently compensated using a holographic corrector based on these crystals. CdF2 crystals with bistable centers are likely to be useful in solving problems of correction of laser light wavefront and image correction in observation telescopes with nonideal primary mirrors.  相似文献   
139.
Translated fromProblemy Ustoichivosti Stokhasticheskikh Modelei. Trudy Seminara, 1988, pp. 115–120.  相似文献   
140.
We study properties of some linear and nonlinear operators which occur in the theory of stochastic differential and integral equations.Translated from Statisticheskie Metody Otsenivaniya i Proverki Gipotez, pp. 148–154, 1988.  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