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   1377472篇
  免费   30510篇
  国内免费   8450篇
化学   696049篇
晶体学   20510篇
力学   75364篇
综合类   161篇
数学   244168篇
物理学   380180篇
  2021年   13600篇
  2020年   16057篇
  2019年   16151篇
  2018年   13270篇
  2016年   28250篇
  2015年   21028篇
  2014年   30631篇
  2013年   74798篇
  2012年   40389篇
  2011年   38598篇
  2010年   38387篇
  2009年   40434篇
  2008年   37441篇
  2007年   33489篇
  2006年   38868篇
  2005年   31535篇
  2004年   32028篇
  2003年   29993篇
  2002年   30817篇
  2001年   30345篇
  2000年   26000篇
  1999年   23124篇
  1998年   21263篇
  1997年   21253篇
  1996年   21273篇
  1995年   19321篇
  1994年   18770篇
  1993年   18330篇
  1992年   18424篇
  1991年   18692篇
  1990年   17856篇
  1989年   17916篇
  1988年   17469篇
  1987年   17399篇
  1986年   16388篇
  1985年   22785篇
  1984年   23970篇
  1983年   20098篇
  1982年   21767篇
  1981年   20954篇
  1980年   20342篇
  1979年   20581篇
  1978年   21826篇
  1977年   21472篇
  1976年   21289篇
  1975年   19927篇
  1974年   19660篇
  1973年   20133篇
  1972年   14592篇
  1967年   12732篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Physics of Atomic Nuclei - The muon puzzle is an excess of muon bundles generated by primary cosmic rays (PCR) at energies above 10 $${}^{17}$$ eV compared to estimations that assume even a heavy...  相似文献   
82.
Taherian  A.  Toutounian  F. 《Numerical Algorithms》2021,88(4):1831-1850
Numerical Algorithms - In this paper, the block generalized product-type bi-conjugate gradient (GPBi-CG) method for solving large, sparse nonsymmetric linear systems of equations with multiple...  相似文献   
83.
Shavgulidze  N. E. 《Mathematical Notes》2021,110(1-2):297-300
Mathematical Notes -  相似文献   
84.
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   
85.
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   
86.
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   
87.
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   
88.
David Hull     
Journal of Optimization Theory and Applications -  相似文献   
89.
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   
90.
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