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   1285478篇
  免费   29659篇
  国内免费   7620篇
化学   630756篇
晶体学   13894篇
力学   73819篇
综合类   104篇
数学   238622篇
物理学   365562篇
  2021年   12624篇
  2020年   15890篇
  2019年   16046篇
  2018年   12294篇
  2016年   27683篇
  2015年   20708篇
  2014年   30358篇
  2013年   74215篇
  2012年   36982篇
  2011年   33200篇
  2010年   36403篇
  2009年   38870篇
  2008年   32714篇
  2007年   28228篇
  2006年   34957篇
  2005年   27063篇
  2004年   28727篇
  2003年   26576篇
  2002年   24540篇
  2001年   25386篇
  2000年   21720篇
  1999年   19714篇
  1998年   18542篇
  1997年   19176篇
  1996年   19113篇
  1995年   18489篇
  1994年   17993篇
  1993年   17519篇
  1992年   17291篇
  1991年   17634篇
  1990年   16833篇
  1989年   16895篇
  1988年   16504篇
  1987年   16508篇
  1986年   15396篇
  1985年   21955篇
  1984年   23285篇
  1983年   19430篇
  1982年   21193篇
  1981年   20410篇
  1980年   19731篇
  1979年   19940篇
  1978年   21307篇
  1977年   20940篇
  1976年   20689篇
  1975年   19390篇
  1974年   19010篇
  1973年   19567篇
  1972年   14076篇
  1967年   12438篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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   
72.
Integrated information theory (IIT) provides a mathematical framework to characterize the cause-effect structure of a physical system and its amount of integrated information (Φ). An accompanying Python software package (“PyPhi”) was recently introduced to implement this framework for the causal analysis of discrete dynamical systems of binary elements. Here, we present an update to PyPhi that extends its applicability to systems constituted of discrete, but multi-valued elements. This allows us to analyze and compare general causal properties of random networks made up of binary, ternary, quaternary, and mixed nodes. Moreover, we apply the developed tools for causal analysis to a simple non-binary regulatory network model (p53-Mdm2) and discuss commonly used binarization methods in light of their capacity to preserve the causal structure of the original system with multi-valued elements.  相似文献   
73.
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   
74.
Ivanov  D. V. 《Mathematical Notes》2021,110(3-4):311-321
Mathematical Notes - The paper is devoted to the study of conditional bounds for the expectation of the maximum of independent identically distributed standardized random variables for which the...  相似文献   
75.
Mathematical Notes - We consider the problem of the approximation of functions, continuous on the semiaxis $$[0,\infty)$$ and for which the derivatives $$f^{(\nu)}(0)$$ , $$\nu=0,\dots,r-1$$ exist...  相似文献   
76.
Mathematical Notes - In the present paper, we propose a new method of derivation of number-theoretic identities which is applied to the proof of the multidimensional analogue of one of the...  相似文献   
77.
Fomenko  T. N. 《Mathematical Notes》2021,110(3-4):583-591
Mathematical Notes - The notion of a $$\lambda$$ -generalized-search multivalued functional on an $$f$$ -quasimetric space is introduced. An existence theorem for zeros of such functionals is...  相似文献   
78.
Rozovsky  L. V. 《Mathematical Notes》2021,110(1-2):118-125
Mathematical Notes - The main purpose of the paper is to strengthen the results of P. R. Mercer (2003) concerning the comparison of arithmetic, geometric, and harmonic weighted means.  相似文献   
79.
Ferrarini  A.  Finotello  A.  Salsano  G.  Auricchio  F.  Palombo  D.  Spinella  G.  Pane  B.  Conti  M. 《Acta Mechanica Sinica》2021,37(7):1192-1192
Acta Mechanica Sinica - A Correction to this paper has been published: https://doi.org/10.1007/s10409-021-01066-2  相似文献   
80.
Siberian Mathematical Journal - We obtain some new estimates that show the extremality of the Rademacher system in the set of sequences of independent functions considered in rearrangement...  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