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   1334253篇
  免费   29965篇
  国内免费   7708篇
化学   667698篇
晶体学   15679篇
力学   75068篇
综合类   103篇
数学   244766篇
物理学   368612篇
  2021年   13549篇
  2020年   16072篇
  2019年   16315篇
  2018年   13323篇
  2016年   28403篇
  2015年   21255篇
  2014年   30854篇
  2013年   75441篇
  2012年   39079篇
  2011年   35837篇
  2010年   37881篇
  2009年   39980篇
  2008年   35167篇
  2007年   30819篇
  2006年   36672篇
  2005年   29214篇
  2004年   30077篇
  2003年   28417篇
  2002年   29491篇
  2001年   27069篇
  2000年   24152篇
  1999年   22231篇
  1998年   20893篇
  1997年   20924篇
  1996年   21210篇
  1995年   19209篇
  1994年   18667篇
  1993年   18258篇
  1992年   18032篇
  1991年   17666篇
  1990年   16888篇
  1989年   16913篇
  1988年   16532篇
  1987年   16546篇
  1986年   15406篇
  1985年   22026篇
  1984年   23404篇
  1983年   19462篇
  1982年   21262篇
  1981年   20484篇
  1980年   19807篇
  1979年   20008篇
  1978年   21378篇
  1977年   20971篇
  1976年   20724篇
  1975年   19435篇
  1974年   19037篇
  1973年   19630篇
  1972年   14092篇
  1967年   12496篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
101.
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   
102.

In this paper, we design a Branch and Bound algorithm based on interval arithmetic to address nonconvex robust optimization problems. This algorithm provides the exact global solution of such difficult problems arising in many real life applications. A code was developed in MatLab and was used to solve some robust nonconvex problems with few variables. This first numerical study shows the interest of this approach providing the global solution of such difficult robust nonconvex optimization problems.

  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