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   1856篇
  免费   24篇
  国内免费   7篇
化学   1076篇
晶体学   10篇
力学   42篇
数学   270篇
物理学   489篇
  2020年   14篇
  2019年   14篇
  2016年   26篇
  2015年   19篇
  2014年   31篇
  2013年   56篇
  2012年   66篇
  2011年   79篇
  2010年   49篇
  2009年   42篇
  2008年   81篇
  2007年   68篇
  2006年   69篇
  2005年   68篇
  2004年   46篇
  2003年   57篇
  2002年   63篇
  2001年   46篇
  2000年   42篇
  1999年   32篇
  1998年   30篇
  1997年   32篇
  1996年   28篇
  1995年   32篇
  1994年   31篇
  1993年   31篇
  1992年   31篇
  1991年   18篇
  1990年   24篇
  1989年   21篇
  1988年   25篇
  1987年   21篇
  1986年   25篇
  1985年   33篇
  1984年   21篇
  1983年   32篇
  1982年   30篇
  1981年   22篇
  1980年   39篇
  1979年   25篇
  1978年   25篇
  1977年   23篇
  1976年   23篇
  1975年   28篇
  1974年   32篇
  1973年   23篇
  1972年   18篇
  1971年   13篇
  1970年   16篇
  1968年   17篇
排序方式: 共有1887条查询结果,搜索用时 31 毫秒
1.
Journal of Thermal Analysis and Calorimetry - Buckwheat starch is an alternative source to supply the high global demand for starch. The properties of starch can be modified through chemical and...  相似文献   
2.
3.
Many of the striking similarities which occur for the adjoint representation of groups in the exceptional series (cf. [1–3]) also occur for certain representations of specific reductive subgroups. The tensor algebras on these representations are easier to describe (cf. [4,5,7]), and may offer clues to the original situation.The subgroups which occur form a Magic Triangle, which extends Freudenthal's Magic Square of Lie algebras. We describe these groups from the perspective of dual pairs, and their representations from the action of the dual pair on an exceptional Lie algebra. To cite this article: P. Deligne, B.H. Gross, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 877–881.  相似文献   
4.
5.
Controlled precipitation of the diagnostic imaging agent ethyl 3,5-di(acetylamino)-2,4,6-triiodobenzoate has been used to produce fine particles of various sizes, morphologies, and degrees of crystallinity, which depended on experimental conditions. In addition, two distinct polymorphic forms of the drug have been fully characterized by single crystal X-ray diffraction studies, and evidence for a third polymorph was also observed. Some of the so prepared dry particles were coated with a thin layer of silica.  相似文献   
6.
7.
A new scheme for controlling photodissociation through preparation of a variationally optimized linear superposition of field free vibrational eigenstates is applied for selective control of IBr and HI dissociation. The dependence of photodissociation on various field parameters and initial conditions is examined to investigate the mechanistic basis of selective control. The parametric equations of motion approach for determining vibrational dynamics as a function of field parameters without having to solve the time dependent Schrödinger equation explicitly for each field parameter separately is outlined and its use to identify field characteristics which will provide the requisite population mix represented by the optimal linear superposition of vibrational states is advocated.  相似文献   
8.
9.
The chemical mechanism of the precipitation of lead titanium peroxohydroxide particles in a solution of nitrilotriacetate (NTA) complexes of lead and titanium peroxo-hydroxide is envisioned as the interaction between cations of lead hydroxide and anions of polymeric titanium peroxo-hydroxide.  相似文献   
10.
The propagation of partially coherent beams through optical systems is computed numerically in one transverse dimension. The optical system is divided into different elementary segments, through which the propagation of light can be calculated by appropriate operators, working on the coherence function or the Wigner distribution function respectively. For the necessary changes between these two functions describing the partially coherent beams, the use of the remarkable z-transform seems to be an advantage. With this algorithm the grid and the resolution in the spatial frequency domain can be arbitrarily chosen in contrast to the usual Fourier transform, the influence of phase aberrations on the focusability of Gauss-Schell model beams is discussed as an application example of the numerical model. With the help of this tool, practical beam guiding systems can be simulated for use with multimode laser radiation.  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