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   3476篇
  免费   166篇
  国内免费   14篇
化学   2710篇
晶体学   24篇
力学   53篇
数学   429篇
物理学   440篇
  2023年   48篇
  2022年   112篇
  2021年   106篇
  2020年   100篇
  2019年   98篇
  2018年   74篇
  2017年   59篇
  2016年   188篇
  2015年   160篇
  2014年   137篇
  2013年   243篇
  2012年   262篇
  2011年   278篇
  2010年   197篇
  2009年   134篇
  2008年   205篇
  2007年   194篇
  2006年   175篇
  2005年   153篇
  2004年   99篇
  2003年   93篇
  2002年   75篇
  2001年   40篇
  2000年   31篇
  1999年   25篇
  1998年   22篇
  1997年   14篇
  1996年   20篇
  1995年   16篇
  1994年   15篇
  1993年   21篇
  1992年   20篇
  1991年   14篇
  1990年   17篇
  1989年   16篇
  1988年   15篇
  1987年   8篇
  1986年   8篇
  1985年   14篇
  1984年   12篇
  1983年   9篇
  1982年   11篇
  1981年   8篇
  1978年   6篇
  1976年   6篇
  1963年   5篇
  1959年   11篇
  1958年   8篇
  1957年   11篇
  1956年   9篇
排序方式: 共有3656条查询结果,搜索用时 0 毫秒
1.
 The main result of this paper is a normalizing system of natural deduction for the full language of intuitionistic linear logic. No explicit weakening or contraction rules for -formulas are needed. By the systematic use of general elimination rules a correspondence between normal derivations and cut-free derivations in sequent calculus is obtained. Normalization and the subformula property for normal derivations follow through translation to sequent calculus and cut-elimination. Received: 10 October 2000 / Revised version: 26 July 2001 / Published online: 2 September 2002 Mathematics Subject Classification (2000): 03F52, 03F05 Keywords or phrases: Linear logic – Natural deduction – General elimination rules  相似文献   
2.
A novel dinitroxide mediating agent that was suitable for stable free‐radical polymerization was synthesized and used in the block copolymerization of styrene and t‐butyl styrene. Quantitative yields of a novel dinitroxide based on 1,6‐hexamethylene diisocyanate and 4‐hydroxy‐2,2,6,6‐tetramethyl‐1‐piperidinyloxy were obtained. Various experimental parameters, including the nitroxide‐to‐initiator molar ratio, were examined, and it was determined that the polymerization was most controlled under conditions similar to those of conventional 2,2,6,6‐tetramethyl‐1‐piperidinyloxy‐mediated stable free‐radical polymerization. Moreover, the dinitroxide mediator proved to be a viable route for the facile two‐step synthesis of triblock copolymers of styrene and t‐butyl styrene. However, the dinitroxide mediation process resulted in a higher than expected level of nitroxide decomposition, which resulted in polymers possessing a terminal alkoxyamine and an adjacent hydroxylamine rather than a preferred internal bisalkoxyamine. This decomposition resulted in the formation of diblock copolymer species during the triblock copolymer synthesis. Gel permeation chromatography was used to monitor the chain‐end decomposition kinetics, and the determined observed rate constant (5.89 × 10?5 s?1) for decomposition agreed well with previous studies for other dinitroxide mediating agents. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1547–1556, 2004  相似文献   
3.
This paper uses dualities between facet ideal theory and Stanley–Reisner theory to show that the facet ideal of a simplicial tree is sequentially Cohen–Macaulay. The proof involves showing that the Alexander dual (or the cover dual, as we call it here) of a simplicial tree is a componentwise linear ideal. We conclude with additional combinatorial properties of simplicial trees.  相似文献   
4.
We introduce fractional monodromy in order to characterize certain non-isolated critical values of the energy–momentum map of integrable Hamiltonian dynamical systems represented by nonlinear resonant two-dimensional oscillators. We give the formal mathematical definition of fractional monodromy, which is a generalization of the definition of monodromy used by other authors before. We prove that the 1:( − 2) resonant oscillator system has monodromy matrix with half-integer coefficients and discuss manifestations of this monodromy in quantum systems. Communicated by Eduard Zehnder Submitted: February 25, 2005; Accepted: November 17, 2005  相似文献   
5.
Dr. Miroslav Kyrš, DrSc. passed away prematurely and unexpectedly in August 2006 at age of 75. He was a leading person of the Czech radiochemistry during the second half of the 20th century and his results have of world-wide impact. His diligence, intelligence and permanent activity led him to be at first a laboratory chief and subsequently for about 25 years to be a chief of the Radiochemical Department of Czech Nuclear Research Institute (NRI) at Řež near Prague.  相似文献   
6.
7.
The validity of local parton-hadron duality within the framework of HERWIG and JETSET event generators is investigated. We concentrate one + e annihilations in LEP 2 energy range as these interactions provide theoretically the cleanest condition for the discussion of this concept. We conclude that the concept of local parton-hadron duality is not valid in either of the two generators considered.  相似文献   
8.
9.
10.
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