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   1381825篇
  免费   29606篇
  国内免费   10518篇
化学   698051篇
晶体学   20275篇
力学   76352篇
综合类   320篇
数学   245483篇
物理学   381468篇
  2021年   14423篇
  2020年   16761篇
  2019年   16951篇
  2016年   28585篇
  2015年   21770篇
  2014年   31761篇
  2013年   76289篇
  2012年   41322篇
  2011年   38221篇
  2010年   38212篇
  2009年   40335篇
  2008年   36880篇
  2007年   32199篇
  2006年   39529篇
  2005年   30621篇
  2004年   31874篇
  2003年   29896篇
  2002年   31072篇
  2001年   30527篇
  2000年   26254篇
  1999年   23591篇
  1998年   21750篇
  1997年   21667篇
  1996年   21639篇
  1995年   19674篇
  1994年   19021篇
  1993年   18526篇
  1992年   18624篇
  1991年   18838篇
  1990年   18038篇
  1989年   18013篇
  1988年   17567篇
  1987年   17428篇
  1986年   16404篇
  1985年   22799篇
  1984年   23949篇
  1983年   20096篇
  1982年   21805篇
  1981年   20979篇
  1980年   20290篇
  1979年   20513篇
  1978年   21796篇
  1977年   21395篇
  1976年   21146篇
  1975年   19876篇
  1974年   19577篇
  1973年   20040篇
  1972年   14512篇
  1968年   12344篇
  1967年   12671篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Experimental Techniques - MDRMIN consists of k numbers of identical N/k multistage networks in k planes having k × 1 multiplexers and 1 × k demultiplexers at input and output,...  相似文献   
992.
The synergetic effect of corrosion and corrosion induced hydrogen embrittlement damage processes which occur at local scale has been found to result in a dramatic macroscopic tensile ductility loss of the 2024 aluminum alloy. In the present work, the tensile behaviour of corroded 2024 T351 specimens has been estimated on the basis of FE analysis by taking into account the local material properties in the damaged areas. A parametric study is involved to account for the effect of thickness in the results. Calculated tensile properties obtained with the analysis agree well with experimental data.  相似文献   
993.
Crystalline materials that are transparent in the vacuum UV spectral region and currently used have been reviewed. Transmission of crystals of solid solutions with the fluorite structure Ca1?x R xF2+x (R = Sc, Y, La, Yb, Lu) in the UV and vacuum UV spectral regions has been investigated. It is shown that application of different methods of purification of fluorides from some impurities can significantly improve the optical quality of fluoride multicomponent crystals in the short-wavelength spectral region.  相似文献   
994.
Summary Three weak variants of compactness which lie strictly between compactness and quasicompactness, are introduced. Their basic properties are studied. The interplay with mapping and their direct and inverse preservation under mappings are investigated. In the process three decompositions of compactness are observed.  相似文献   
995.
996.
997.
998.
The semi‐iterative method (SIM) is applied to the hyper‐power (HP) iteration, and necessary and sufficient conditions are given for the convergence of the semi‐iterative–hyper‐power (SIM–HP) iteration. The root convergence rate is computed for both the HP and SIM–HP methods, and the quotient convergence rate is given for the HP iteration. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
999.
We show that the Hardy-Littlewood maximal operator and a class of Calderón-Zygmund singular integrals satisfy the strong type modular inequality in variable Lp spaces if and only if the variable exponent p(x) ∼ const. Received: 15 September 2004  相似文献   
1000.
Basic principles of the generalized lattice model of multicomponent condensed systems are formulated. Short-range parts of interatomic interactions are taken into account by means of the geometric constraints method. Long-range parts of the interactions are taken into account in mean field approximation. The expression for Helmholtz free energy is obtained. A system of integral equations for the equilibrium distributions of components is derived. The asymptotic properties of its solutions are investigated. Moment expansion of interatomic interactions and localization of integral terms in free energy is obtained. A Ginzburg–Landau-like functional of free energy is derived.  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