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   1411355篇
  免费   33390篇
  国内免费   10444篇
化学   688507篇
晶体学   21004篇
力学   82236篇
综合类   321篇
数学   264114篇
物理学   399007篇
  2021年   14162篇
  2020年   16674篇
  2019年   16842篇
  2018年   21056篇
  2017年   19975篇
  2016年   32314篇
  2015年   22386篇
  2014年   31576篇
  2013年   75820篇
  2012年   42207篇
  2011年   45604篇
  2010年   44212篇
  2009年   47013篇
  2008年   42698篇
  2007年   40806篇
  2006年   35056篇
  2005年   33074篇
  2004年   31705篇
  2003年   29973篇
  2002年   29550篇
  2001年   26736篇
  2000年   24050篇
  1999年   22452篇
  1998年   21280篇
  1997年   21299篇
  1996年   21562篇
  1995年   19561篇
  1994年   18894篇
  1993年   18372篇
  1992年   18033篇
  1991年   18325篇
  1990年   17569篇
  1989年   17612篇
  1988年   17104篇
  1987年   17115篇
  1986年   15996篇
  1985年   22441篇
  1984年   23714篇
  1983年   19926篇
  1982年   21641篇
  1981年   20856篇
  1980年   20197篇
  1979年   20269篇
  1978年   21655篇
  1977年   21191篇
  1976年   20928篇
  1975年   19331篇
  1974年   19000篇
  1973年   19561篇
  1972年   14070篇
排序方式: 共有10000条查询结果,搜索用时 15 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