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   436793篇
  免费   4868篇
  国内免费   1233篇
化学   234307篇
晶体学   6504篇
力学   18771篇
综合类   13篇
数学   49964篇
物理学   133335篇
  2021年   3774篇
  2020年   4194篇
  2019年   4528篇
  2018年   5861篇
  2017年   5748篇
  2016年   8837篇
  2015年   5569篇
  2014年   8563篇
  2013年   20211篇
  2012年   15693篇
  2011年   19304篇
  2010年   13513篇
  2009年   13373篇
  2008年   17705篇
  2007年   17569篇
  2006年   16286篇
  2005年   14582篇
  2004年   13560篇
  2003年   11926篇
  2002年   11759篇
  2001年   13451篇
  2000年   10096篇
  1999年   7923篇
  1998年   6579篇
  1997年   6323篇
  1996年   6093篇
  1995年   5485篇
  1994年   5400篇
  1993年   5208篇
  1992年   5839篇
  1991年   5934篇
  1990年   5670篇
  1989年   5479篇
  1988年   5501篇
  1987年   5385篇
  1986年   5102篇
  1985年   6571篇
  1984年   6702篇
  1983年   5312篇
  1982年   5393篇
  1981年   5372篇
  1980年   4961篇
  1979年   5363篇
  1978年   5497篇
  1977年   5393篇
  1976年   5337篇
  1975年   4923篇
  1974年   4891篇
  1973年   4891篇
  1972年   3456篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
211.
We prove some new evaluations for multiple polylogarithms of arbitrary depth. The simplest of our results is a multiple zeta evaluation one order of complexity beyond the well-known Broadhurst–Zagier formula. Other results we provide settle three of the remaining outstanding conjectures of Borwein, Bradley, and Broadhurst. A complete treatment of a certain arbitrary depth class of periodic alternating unit Euler sums is also given.  相似文献   
212.
Chemisorption is a well-known phenomenon for many interfaces between organic semiconductors and metals. It is shown that many published data indicate that the occurrence of chemisorption can be rationalized upon the consideration of the metal work function versus the electron affinity of the organic semiconductor.  相似文献   
213.
We give a surprisingly short proof that in any planar arrangement of n curves where each pair intersects at most a fixed number (s) of times, the k-level has subquadratic (O(n2-1/2s) complexity. This answers one of the main open problems from the author’s previous paper [DCG 29, 375-393 (2003)], which provided a weaker upper bound for a restricted class of curves only (graphs of degree-s polynomials). When combined with existing tools (cutting curves, sampling, etc.), the new idea generates a slew of improved k-level results for most of the curve families studied earlier, including a near-O(n3/2 bound for parabolas.  相似文献   
214.
215.
216.
The PARRNe facility has been used to produce neutron-rich isotopes 83,84Gaby the ISOL method. Their decay has been studied, and β-γ coincidence and γ-γ coincidence data were collected as a function of time. The first two excited levels in 83Ge and the first excited level in 84Ge have been measured for the first time.  相似文献   
217.
218.
A self-consistent, completely quantum calculation of the structure of the inner crust of neutron stars is carried out in the Wigner-Seitz approximation with a realistic phenomenological nuclear energy functional, where pair correlations of neutrons and protons are included in the explicit form. It has been shown that the superfluidity of neutrons and protons affects the structure of the ground state of the crust.  相似文献   
219.
We examine several interesting relationships and expressions involving Fourier-Feynman transform, convolution product and first variation for functionals in the Fresnel class F(B) of an abstract Wiener space B. We also prove a translation theorem and Parseval's identity for the analytic Feynman integral. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   
220.
In this paper we analyze the bottom of the energy-momentum spectrum of the translation invariant Nelson model, describing one electron linearly coupled to a second quantized massive scalar field. Our results are valid for all values of the coupling constant and include an HVZ theorem, non-degeneracy of ground states, existence of isolated groundstates in dimensions 1 and 2, non-existence of ground states embedded in the bottom of the essential spectrum in dimensions 3 and 4, (i.e., at total momenta where no isolated groundstate eigenvalue exists), and we study regularity and monotonicity properties of the bottom of the essential spectrum, as a function of total momentum. Communicated by Joel Feldman submitted 04/11/04, accepted 17/02/05  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