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   1377360篇
  免费   29668篇
  国内免费   7733篇
化学   689411篇
晶体学   15853篇
力学   76154篇
综合类   113篇
数学   246743篇
物理学   386487篇
  2021年   13432篇
  2020年   15930篇
  2019年   16046篇
  2018年   15872篇
  2017年   14502篇
  2016年   29239篇
  2015年   21056篇
  2014年   30395篇
  2013年   74288篇
  2012年   40890篇
  2011年   40961篇
  2010年   39776篇
  2009年   41728篇
  2008年   39446篇
  2007年   36210篇
  2006年   38387篇
  2005年   33367篇
  2004年   33109篇
  2003年   30532篇
  2002年   30867篇
  2001年   29728篇
  2000年   25504篇
  1999年   22888篇
  1998年   21175篇
  1997年   21090篇
  1996年   21188篇
  1995年   19187篇
  1994年   18338篇
  1993年   17618篇
  1992年   17635篇
  1991年   17886篇
  1990年   17096篇
  1989年   17170篇
  1988年   16835篇
  1987年   16757篇
  1986年   15635篇
  1985年   22167篇
  1984年   23480篇
  1983年   19597篇
  1982年   21249篇
  1981年   20487篇
  1980年   19780篇
  1979年   20127篇
  1978年   21458篇
  1977年   21099篇
  1976年   20820篇
  1975年   19536篇
  1974年   19186篇
  1973年   19724篇
  1972年   14202篇
排序方式: 共有10000条查询结果,搜索用时 15 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