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   1322640篇
  免费   29983篇
  国内免费   7660篇
化学   658863篇
晶体学   15245篇
力学   74940篇
综合类   102篇
数学   244669篇
物理学   366464篇
  2021年   13579篇
  2020年   16113篇
  2019年   16358篇
  2018年   12432篇
  2016年   28273篇
  2015年   21212篇
  2014年   30957篇
  2013年   75598篇
  2012年   38740篇
  2011年   34777篇
  2010年   37314篇
  2009年   39576篇
  2008年   34174篇
  2007年   29447篇
  2006年   36220篇
  2005年   28095篇
  2004年   29575篇
  2003年   28036篇
  2002年   29127篇
  2001年   27182篇
  2000年   23987篇
  1999年   22144篇
  1998年   20939篇
  1997年   20956篇
  1996年   21249篇
  1995年   19242篇
  1994年   18437篇
  1993年   17703篇
  1992年   17397篇
  1991年   17632篇
  1990年   16858篇
  1989年   16900篇
  1988年   16489篇
  1987年   16504篇
  1986年   15351篇
  1985年   21964篇
  1984年   23368篇
  1983年   19494篇
  1982年   21273篇
  1981年   20482篇
  1980年   19798篇
  1979年   19979篇
  1978年   21401篇
  1977年   20956篇
  1976年   20697篇
  1975年   19385篇
  1974年   19039篇
  1973年   19568篇
  1972年   14044篇
  1967年   12442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.

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   
104.
105.
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   
106.
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   
107.
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   
108.
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   
109.
David Hull     
Journal of Optimization Theory and Applications -  相似文献   
110.
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   
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