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   1254330篇
  免费   30679篇
  国内免费   8911篇
化学   617066篇
晶体学   14860篇
力学   73693篇
综合类   214篇
数学   237512篇
物理学   350575篇
  2021年   13659篇
  2020年   16226篇
  2019年   16356篇
  2016年   27257篇
  2015年   20845篇
  2014年   30729篇
  2013年   74603篇
  2012年   34543篇
  2011年   28298篇
  2010年   35087篇
  2009年   38082篇
  2008年   28633篇
  2007年   23331篇
  2006年   31756篇
  2005年   22950篇
  2004年   25547篇
  2003年   24868篇
  2002年   26522篇
  2001年   24240篇
  2000年   22257篇
  1999年   21371篇
  1998年   20600篇
  1997年   20617篇
  1996年   20898篇
  1995年   19019篇
  1994年   17898篇
  1993年   17382篇
  1992年   16853篇
  1991年   17199篇
  1990年   16438篇
  1989年   16533篇
  1988年   16118篇
  1987年   16182篇
  1986年   15031篇
  1985年   21624篇
  1984年   23080篇
  1983年   19275篇
  1982年   21072篇
  1981年   20319篇
  1980年   19619篇
  1979年   19729篇
  1978年   21177篇
  1977年   20771篇
  1976年   20459篇
  1975年   19125篇
  1974年   18742篇
  1973年   19284篇
  1972年   13815篇
  1968年   11857篇
  1967年   12250篇
排序方式: 共有10000条查询结果,搜索用时 78 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