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   1990篇
  免费   11篇
  国内免费   1篇
化学   700篇
晶体学   67篇
力学   91篇
数学   246篇
物理学   898篇
  2022年   23篇
  2021年   28篇
  2020年   42篇
  2019年   51篇
  2018年   74篇
  2017年   55篇
  2016年   73篇
  2015年   24篇
  2014年   60篇
  2013年   71篇
  2012年   62篇
  2011年   85篇
  2010年   89篇
  2009年   77篇
  2008年   85篇
  2007年   94篇
  2006年   59篇
  2005年   61篇
  2004年   42篇
  2003年   60篇
  2002年   37篇
  2001年   41篇
  2000年   44篇
  1999年   28篇
  1998年   23篇
  1997年   20篇
  1996年   29篇
  1995年   15篇
  1994年   27篇
  1991年   28篇
  1990年   20篇
  1989年   25篇
  1988年   15篇
  1986年   16篇
  1984年   25篇
  1983年   19篇
  1982年   32篇
  1981年   15篇
  1980年   19篇
  1979年   19篇
  1978年   21篇
  1977年   24篇
  1976年   21篇
  1975年   23篇
  1974年   21篇
  1972年   20篇
  1971年   18篇
  1970年   19篇
  1969年   15篇
  1968年   18篇
排序方式: 共有2002条查询结果,搜索用时 9 毫秒
81.
82.
Russian Journal of Applied Chemistry - The influence of parameters of the dry-jet wet spinning process was studied on properties of porous polysulfone hollow fiber membranes. The air gap distance,...  相似文献   
83.
Crystallography Reports - Fluoride crystals K2(Ta0.9I0.1)F7 (sp. gr. Р21/c) complementary to the K2TaF7 and K2NbF7 fluoride family have been obtained by hydrothermal synthesis. Their...  相似文献   
84.
Crystallography Reports - A new polymer-inorganic nanocomposite composed of fibrous Na–Mg triple chain hydrosilicate with a poly(amide-imide) matrix was developed. Its structure, morphology,...  相似文献   
85.
Crystals of new indium iodate (K0.6Na0.4Ba)In[IO3]6 were prepared by the hydrothermal synthesis. The unit-cell parameters are a = 11.3984(3) Å, с = 11.3817(3) Å, sp. gr. R3?. The chemical formula of the compound was derived from the structure determination and refinement with anisotropic displacement parameters to R = 0.0284. In the structure the InO6 octahedra share vertices with six umbrella-like [IO3]–groups typical of iodates and form isolated 3?-symmetric charged \(\rm{In[IO_{3}]_6^{3-}}\) clusters. Large Ba, K, and Na cations occupy a common site on a threefold axis due to the isomorphous substitution and compensate the charge of the clusters. The new structure extends the family of the recently discovered alkali-metal and barium iodates containing Ti and Zr atoms in octahedral sites. The iodate K2Ge[IO3]6 containing Ge atoms in the centers of octahedra is the parent compound of this structural family.  相似文献   
86.
The possibility of fabricating focusators of infrared laser radiation, based on photolithographic technology, is analysed. The realizability of focusator fabrication is based on the possibility of producing a set of binary photomasks and achieving the necessary depth of etching the substrate of the pattern while forming the microrelief. The possibility of producing these photomasks is evaluated with regard to the focusator's extremal zone width and the appearance of photomasks displayed on the screen. Forming of step-by-step microrelief is achieved using plasma etching or wet etching and depends on the minimum element's dimension and the etching depth. Examples of the microrelief's profiles, of focusators fabricated using photolithography, and the result of the transformation of a focusator's radiation into a straight line segment, are discussed.  相似文献   
87.
Two absorption lines are observed over a wide temperature range below T c in the magnetic resonance spectrum of an La0.7Pb0.3MnO3 single crystal. These lines correspond to two magnetic phases in the sample. The frequency-field dependence of spectra obtained in the range of microwave radiation frequencies 10–77 GHz allows these phases to be interpreted as ferromagnetic and paramagnetic phases. The phase volume ratio depends on the temperature and the magnitude of the external magnetic field. Features in the temperature behavior of parameters of the magnetic absorption line are observed in the region of the highest magnetic resistance of the sample. The results are interpreted within the mechanism of electronic phase separation.  相似文献   
88.
The electromagnetic radius of a charged pion and the transition radius of a neutral pion are calculated in the framework of the nonlocal chiral quark model. It is shown in this model that the vector meson contributions to the pion radii are noticeably suppressed in comparison with a similar contribution in the local Nambu-Jona-Lasinio model. The form factor for the process is calculated for -1 GeV2< q 2 < 1.6 GeV2. Our results are in satisfactory agreement with experimental data.Received: 28 November 2003, Published online: 13 July 2004PACS: 14.40.-n Mesons - 11.10.Lm Nonlinear or nonlocal theories and models - 12.39.Ki Relativistic quark model  相似文献   
89.
Physics of the Solid State - Within the Hubbard model with allowance for Hund’s and spin–orbit interactions, the concepts of thermal spin fluctuations in a strongly correlated system of...  相似文献   
90.
Journal of Solid State Electrochemistry - Poly-3,4-ethylenedioxythiophene composite films with tungsten oxide (PEDOT/WO3) were obtained by potentiodynamic deposition of tungsten oxide from acidic...  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