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   1334951篇
  免费   32923篇
  国内免费   10315篇
化学   669213篇
晶体学   20192篇
力学   75608篇
综合类   376篇
数学   241667篇
物理学   371133篇
  2021年   14146篇
  2020年   16644篇
  2019年   16921篇
  2016年   28176篇
  2015年   21415篇
  2014年   31511篇
  2013年   75761篇
  2012年   38987篇
  2011年   34735篇
  2010年   37029篇
  2009年   39621篇
  2008年   33692篇
  2007年   28746篇
  2006年   36498篇
  2005年   27653篇
  2004年   29414篇
  2003年   27874篇
  2002年   29216篇
  2001年   28213篇
  2000年   24868篇
  1999年   22857篇
  1998年   21402篇
  1997年   21399篇
  1996年   21561篇
  1995年   19537篇
  1994年   18939篇
  1993年   18398篇
  1992年   18272篇
  1991年   18535篇
  1990年   17652篇
  1989年   17713篇
  1988年   17187篇
  1987年   17193篇
  1986年   16122篇
  1985年   22501篇
  1984年   23754篇
  1983年   19944篇
  1982年   21624篇
  1981年   20864篇
  1980年   20171篇
  1979年   20283篇
  1978年   21652篇
  1977年   21232篇
  1976年   20939篇
  1975年   19652篇
  1974年   19275篇
  1973年   19787篇
  1972年   14276篇
  1968年   12094篇
  1967年   12482篇
排序方式: 共有10000条查询结果,搜索用时 31 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