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   1427673篇
  免费   36916篇
  国内免费   13200篇
化学   733254篇
晶体学   20652篇
力学   77738篇
综合类   431篇
数学   249492篇
物理学   396222篇
  2021年   15099篇
  2020年   17594篇
  2019年   17900篇
  2018年   13309篇
  2016年   29766篇
  2015年   22837篇
  2014年   33112篇
  2013年   77826篇
  2012年   45313篇
  2011年   43464篇
  2010年   40321篇
  2009年   42039篇
  2008年   40949篇
  2007年   36409篇
  2006年   43145篇
  2005年   34095篇
  2004年   34762篇
  2003年   32105篇
  2002年   33075篇
  2001年   32925篇
  2000年   27868篇
  1999年   24564篇
  1998年   22222篇
  1997年   22094篇
  1996年   22001篇
  1995年   19958篇
  1994年   19305篇
  1993年   18759篇
  1992年   19036篇
  1991年   19261篇
  1990年   18367篇
  1989年   18311篇
  1988年   17833篇
  1987年   17668篇
  1986年   16716篇
  1985年   23043篇
  1984年   24120篇
  1983年   20234篇
  1982年   21871篇
  1981年   21058篇
  1980年   20367篇
  1979年   20667篇
  1978年   21909篇
  1977年   21537篇
  1976年   21299篇
  1975年   20062篇
  1974年   19758篇
  1973年   20240篇
  1972年   14690篇
  1967年   12797篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
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   
103.
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   
104.
Shavgulidze  N. E. 《Mathematical Notes》2021,110(1-2):297-300
Mathematical Notes -  相似文献   
105.
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   
106.
107.
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   
108.
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   
109.
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   
110.
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   
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