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   1405765篇
  免费   31309篇
  国内免费   9106篇
化学   708035篇
晶体学   20831篇
力学   76822篇
综合类   205篇
数学   248311篇
物理学   391976篇
  2021年   13792篇
  2020年   16275篇
  2019年   16414篇
  2018年   15323篇
  2017年   13798篇
  2016年   29468篇
  2015年   21489篇
  2014年   31150篇
  2013年   75566篇
  2012年   41777篇
  2011年   41558篇
  2010年   39988篇
  2009年   42001篇
  2008年   39568篇
  2007年   36162篇
  2006年   39352篇
  2005年   33204篇
  2004年   33151篇
  2003年   30639篇
  2002年   31229篇
  2001年   31377篇
  2000年   26610篇
  1999年   23534篇
  1998年   21652篇
  1997年   21611篇
  1996年   21545篇
  1995年   19531篇
  1994年   19015篇
  1993年   18505篇
  1992年   18743篇
  1991年   19013篇
  1990年   18164篇
  1989年   18127篇
  1988年   17710篇
  1987年   17699篇
  1986年   16652篇
  1985年   23023篇
  1984年   24157篇
  1983年   20235篇
  1982年   21852篇
  1981年   21062篇
  1980年   20435篇
  1979年   20743篇
  1978年   21933篇
  1977年   21556篇
  1976年   21313篇
  1975年   19963篇
  1974年   19645篇
  1973年   20069篇
  1972年   14538篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
International Journal of Theoretical Physics - Quantum coherence, coming from quantum superposition, occupies a significant position in the field of physics. We put forward a lower bound of the...  相似文献   
102.
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   
103.
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   
104.
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   
105.
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   
106.
David Hull     
Journal of Optimization Theory and Applications -  相似文献   
107.
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   
108.
109.
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   
110.
General Relativity and Gravitation - In previous work, we established theoretical results concerning the effect of matter shells surrounding a gravitational wave (GW) source, and we now apply these...  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