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   1269654篇
  免费   31090篇
  国内免费   9143篇
化学   625486篇
晶体学   20082篇
力学   74008篇
综合类   252篇
数学   237987篇
物理学   352072篇
  2021年   13668篇
  2020年   16231篇
  2019年   16361篇
  2016年   27281篇
  2015年   20932篇
  2014年   30765篇
  2013年   74765篇
  2012年   34813篇
  2011年   28575篇
  2010年   35323篇
  2009年   38370篇
  2008年   28947篇
  2007年   23577篇
  2006年   31955篇
  2005年   23180篇
  2004年   25685篇
  2003年   25024篇
  2002年   26616篇
  2001年   24264篇
  2000年   22315篇
  1999年   21403篇
  1998年   20601篇
  1997年   20665篇
  1996年   20932篇
  1995年   19077篇
  1994年   18473篇
  1993年   18001篇
  1992年   17479篇
  1991年   17829篇
  1990年   17058篇
  1989年   17164篇
  1988年   16708篇
  1987年   16738篇
  1986年   15631篇
  1985年   22100篇
  1984年   23486篇
  1983年   19759篇
  1982年   21509篇
  1981年   20756篇
  1980年   20088篇
  1979年   20095篇
  1978年   21521篇
  1977年   21062篇
  1976年   20717篇
  1975年   19386篇
  1974年   19015篇
  1973年   19493篇
  1972年   14019篇
  1968年   11892篇
  1967年   12270篇
排序方式: 共有10000条查询结果,搜索用时 421 毫秒
101.
Shavgulidze  N. E. 《Mathematical Notes》2021,110(1-2):297-300
Mathematical Notes -  相似文献   
102.
Russian Physics Journal - The specific features of the sorption activity of silver nanoparticles (AgNPs) on biodegradable polymers of natural (collagen) and artificial (polyamide 6.6) origin have...  相似文献   
103.
104.
A formal computation proving a new operator identity from known ones is, in principle, restricted by domains and codomains of linear operators involved, since not any two operators can be added or composed. Algebraically, identities can be modelled by noncommutative polynomials and such a formal computation proves that the polynomial corresponding to the new identity lies in the ideal generated by the polynomials corresponding to the known identities. In order to prove an operator identity, however, just proving membership of the polynomial in the ideal is not enough, since the ring of noncommutative polynomials ignores domains and codomains. We show that it suffices to additionally verify compatibility of this polynomial and of the generators of the ideal with the labelled quiver that encodes which polynomials can be realized as linear operators. Then, for every consistent representation of such a quiver in a linear category, there exists a computation in the category that proves the corresponding instance of the identity. Moreover, by assigning the same label to several edges of the quiver, the algebraic framework developed allows to model different versions of an operator by the same indeterminate in the noncommutative polynomials.  相似文献   
105.
Crystallography Reports - The crystal and molecular structures of Cl–C6H4–O–C16H33 (I) have been studied, and its differential scanning calorimetry (DSC) study is performed....  相似文献   
106.
Gawad  Dina A.  Elnaggar  Mai M.  Belal  Tarek S. 《Chromatographia》2022,85(7):617-628
Chromatographia - The present work deals with the optimization, validation and application of a versatile HPLC–DAD method for concurrent estimation of nine antimicrobials and proton pump...  相似文献   
107.
We investigate the possibility of phantom crossing in the dark energy sector and the solution for the Hubble tension between early and late universe observations. We use robust combinations of different cosmological observations, namely the Cosmic Microwave Background (CMB), local measurement of Hubble constant (H0), Baryon Acoustic Oscillation (BAO) and SnIa for this purpose. For a combination of CMB+BAO data that is related to early universe physics, phantom crossing in the dark energy sector was confirmed at a 95% confidence level and we obtained the constraint H0=71.03.8+2.9 km/s/Mpc at a 68% confidence level, which is in perfect agreement with the local measurement by Riess et al. We show that constraints from different combinations of data are consistent with each other and all of them are consistent with phantom crossing in the dark energy sector. For the combination of all data considered, we obtained the constraint H0=70.25±0.78 km/s/Mpc at a 68% confidence level and the phantom crossing happening at the scale factor am=0.8510.031+0.048 at a 68% confidence level.  相似文献   
108.
David Hull     
Journal of Optimization Theory and Applications -  相似文献   
109.
Algebra and Logic - Unary functions definable in o-stable ordered groups of nonvaluational type are studied. Such functions are proved to be piecewise monotone and continuous.  相似文献   
110.
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