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   1419539篇
  免费   29862篇
  国内免费   7696篇
化学   719359篇
晶体学   16129篇
力学   76575篇
综合类   108篇
数学   248736篇
物理学   396190篇
  2021年   13518篇
  2020年   16017篇
  2019年   16170篇
  2018年   15553篇
  2017年   14049篇
  2016年   29367篇
  2015年   21223篇
  2014年   30693篇
  2013年   74881篇
  2012年   43007篇
  2011年   43854篇
  2010年   40197篇
  2009年   41836篇
  2008年   41537篇
  2007年   38403篇
  2006年   41322篇
  2005年   35021篇
  2004年   34969篇
  2003年   32148篇
  2002年   32390篇
  2001年   33358篇
  2000年   27701篇
  1999年   23922篇
  1998年   21599篇
  1997年   21558篇
  1996年   21425篇
  1995年   19403篇
  1994年   18881篇
  1993年   18451篇
  1992年   18962篇
  1991年   18539篇
  1990年   17748篇
  1989年   17778篇
  1988年   17378篇
  1987年   17274篇
  1986年   16292篇
  1985年   22746篇
  1984年   23838篇
  1983年   19855篇
  1982年   21473篇
  1981年   20652篇
  1980年   19996篇
  1979年   20542篇
  1978年   21676篇
  1977年   21378篇
  1976年   21247篇
  1975年   19927篇
  1974年   19631篇
  1973年   20164篇
  1972年   14591篇
排序方式: 共有10000条查询结果,搜索用时 221 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.
103.
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   
104.
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   
105.
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   
106.
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   
107.
David Hull     
Journal of Optimization Theory and Applications -  相似文献   
108.
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   
109.
110.
Journal of Applied Mechanics and Technical Physics - A refined model of viscoelastic-plastic deformation of flexible plates with spatial reinforcement structures has been developed. Strains of the...  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