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   114057篇
  免费   62篇
  国内免费   30篇
化学   39865篇
晶体学   1719篇
力学   7707篇
综合类   3篇
数学   26370篇
物理学   38485篇
  2018年   9796篇
  2017年   10768篇
  2016年   4551篇
  2015年   1027篇
  2014年   218篇
  2013年   348篇
  2012年   4950篇
  2011年   14035篇
  2010年   8018篇
  2009年   8167篇
  2008年   11937篇
  2007年   15901篇
  2006年   365篇
  2005年   7712篇
  2004年   3976篇
  2003年   3907篇
  2002年   1699篇
  2001年   287篇
  2000年   451篇
  1999年   137篇
  1998年   109篇
  1997年   77篇
  1996年   263篇
  1995年   173篇
  1994年   167篇
  1993年   141篇
  1992年   148篇
  1991年   156篇
  1990年   161篇
  1989年   146篇
  1988年   142篇
  1987年   153篇
  1986年   148篇
  1985年   159篇
  1984年   197篇
  1983年   188篇
  1982年   177篇
  1981年   186篇
  1980年   196篇
  1979年   187篇
  1978年   215篇
  1977年   129篇
  1976年   141篇
  1975年   110篇
  1974年   104篇
  1973年   143篇
  1972年   76篇
  1969年   112篇
  1968年   129篇
  1966年   86篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The paper outlines a procedure to identify the space-and time-dependent external nonstationary load acting on a closed circular cylindrical shell of medium thickness. Time-dependent deflections at several points of the shell are used as input data to solve the inverse problem. Examples of numerical identification of various nonstationary loads, including moving ones are presented. The relationship between the external load and the stress-strain state of the shell is described by the Volterra equation of the first kind. The identification problem is solved using Tikhonov's regularization method and Apartsin's h-regularization method __________ Translated from Prikladnaya Mekhanika, Vol. 44, No. 7, pp. 91–100, July 2008.  相似文献   
992.
The shock structure problem is one of the classical problems of fluid mechanics and at least for non-reacting dilute gases it has been considered essentially solved. Here we present a few recent findings, to show that this is not the case. There are still new physical effects to be discovered provided that the numerical technique is general enough to not rule them out a priori. While the results have been obtained for dense fluids, some of the effects might also be observable for shocks in dilute gases.  相似文献   
993.
Reduction of tetranuclear heterometallic complex Mo2Mg2 was simulated using the B3LYP and PBE density functional methods. The results of geometry calculations of the initial complex [MoVIO2Mg(MeOH)2(OMe)4]2 and a partially reduced MoV complex are in good agreement with experimental data. The reduced MoIII complex is characterized by a decrease in the binding energy of aqua ligands. Structural rearrangement of the complex with release of a coordination position at the Mo atoms requires small energy expenditure. One can assume that the reduction of the polynuclear complex causes overcrowding of its coordination sphere, which favors formation of dinitrogen complexes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 441–457, March, 2008.  相似文献   
994.
Organic-inorganic composites of poly(methyl methacrylate) with alkoxysilane hydrolyzates form transparent films. Their thermal and oxidative thermal degradation were studied by differential scanning calorimetry and thermogravimetric analysis.  相似文献   
995.
996.
997.
998.
999.
The images of magnetic and nonmagnetic nanoparticles obtained by scanning near-field microscopy in the photon collection mode are numerically simulated. A theoretical approach that uses tensor electrodynamic Green’s functions to find the optical near field in a given observation scheme is considered. Typicalimages of nanoparticles with various shapes are obtained by numerical simulation. Subject to boundary conditions, the plane of polarization is shown to change at topographic features (edges and angles) of objects studied. This makes the observation of the magnetic structure of a nanoparticle with a magnetooptic method difficult. The near-field study of the magnetization distribution in homogeneous thin films appears to be more effective, since the rotation of plane of polarization is associated primarily with the magnetic properties of the sample in this case.  相似文献   
1000.
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