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   486667篇
  免费   3237篇
  国内免费   1167篇
化学   236994篇
晶体学   7709篇
力学   23754篇
综合类   17篇
数学   56903篇
物理学   165694篇
  2021年   4598篇
  2020年   5043篇
  2019年   5738篇
  2018年   7425篇
  2017年   7598篇
  2016年   10503篇
  2015年   5789篇
  2014年   9878篇
  2013年   21856篇
  2012年   17003篇
  2011年   20310篇
  2010年   15368篇
  2009年   15486篇
  2008年   18625篇
  2007年   18586篇
  2006年   16991篇
  2005年   14830篇
  2004年   14046篇
  2003年   12560篇
  2002年   12707篇
  2001年   14638篇
  2000年   10844篇
  1999年   8518篇
  1998年   7116篇
  1997年   7021篇
  1996年   6501篇
  1995年   5744篇
  1994年   5775篇
  1993年   5539篇
  1992年   6199篇
  1991年   6515篇
  1990年   6209篇
  1989年   6300篇
  1988年   5943篇
  1987年   6026篇
  1986年   5723篇
  1985年   7169篇
  1984年   7359篇
  1983年   6148篇
  1982年   6211篇
  1981年   5971篇
  1980年   5697篇
  1979年   6237篇
  1978年   6174篇
  1977年   6328篇
  1976年   6313篇
  1975年   5937篇
  1974年   5838篇
  1973年   5928篇
  1972年   4408篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
An arbitrary operator-valued function from the generalized Shur class is realized as the transfer function of a minimal optimal and minimal *-optimal dissipative scattering system with the Pontryagin state space. These results generalize Arov's results for the case of the Hilbert state space. Bibliography: 11 titles.  相似文献   
102.
103.
The generalized Hilbert symbol in a cyclotomic extension of an absolutely unramified higher local field of characteristic 0 with a perfect last residue field of characteristic p > 2 is considered. Generalized Artin–Hasse and Iwasawa formulas are derived from an explicit Kummer Type Vostokov formula. Bibliography: 13 titles.  相似文献   
104.
Journal of Nanoparticle Research - It was shown that the thermoelastic martensite transformation B2 ? B19 inside nanoparticles surrounded by amorphous matrix in Ni–Ti–Cu alloys as...  相似文献   
105.
106.
107.
108.
In the present paper, the notion of norm series with respect to the norm residue symbol is generalized to high-dimensional local fields. Necessary and sufficient conditions for the existence of norm series are obtained. Bibliography: 12 titles.__________Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 305, 2003, pp. 60–83.  相似文献   
109.
The results of optical study and quantum-chemical simulation of a conjugated organic system, 2-cyclooctylamino-5-nitropyridine (COANP)-fullerene, performed to determine its potential for application as a limiter of visible and near-IR laser radiation and as a material for diffraction elements in systems for reversible recording of optical information, are presented. Complexation between a COANP molecule and fullerene is considered as one of the main mechanisms responsible for the corresponding properties of this system. For the first time, nonlinear optical characteristics of COANP-C60 and COANP-C70 systems are comparatively studied and the intermolecular interaction between a COANP molecule and fullerene is analyzed on the quantum-chemical level.  相似文献   
110.
We report on the effect of commercially important polysaccharides (maltodextrins with variable dextrose equivalent (Paselli SA-2, MD-6 and MD-10) on the surface activity at the air–water interface of small-molecule surfactants (sms), possessing different hydrophobic–lipophilic balance ((SSL (Na+), the main component is a sodium salt of stearol–lactoyl lactic acid, and PGE (080), polyglycerol ester of C18 fatty acid), and widely used in food products. A marked change of the surface activity of sms was found in the presence of maltodextrins by tensiometry. The combined data of laser multiangle light scattering and mixing calorimetry have suggested that this result is governed by specific complex formation between maltodextrins and sms in aqueous medium. Measurements have been made of the molar mass, the second virial coefficient and the enthalpy of intermolecular interactions in aqueous solutions. The implication of a degree of polymerization of maltodextrins in this phenomenon was shown. The interrelation between the molecular parameters of the formed complexes and their surface activity at the air–water interface has been revealed and discussed.  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