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   418366篇
  免费   2436篇
  国内免费   720篇
化学   197776篇
晶体学   6471篇
力学   23677篇
综合类   13篇
数学   58258篇
物理学   135327篇
  2021年   4075篇
  2020年   4411篇
  2019年   5339篇
  2018年   7785篇
  2017年   7916篇
  2016年   10253篇
  2015年   4835篇
  2014年   9105篇
  2013年   17417篇
  2012年   14168篇
  2011年   16625篇
  2010年   13561篇
  2009年   13841篇
  2008年   15933篇
  2007年   15681篇
  2006年   13976篇
  2005年   12202篇
  2004年   11736篇
  2003年   10757篇
  2002年   10891篇
  2001年   11166篇
  2000年   8654篇
  1999年   6526篇
  1998年   5946篇
  1997年   5853篇
  1996年   5368篇
  1995年   4693篇
  1994年   4851篇
  1993年   4825篇
  1992年   5034篇
  1991年   5457篇
  1990年   5328篇
  1989年   5340篇
  1988年   5104篇
  1987年   5104篇
  1986年   4786篇
  1985年   5803篇
  1984年   6070篇
  1983年   5131篇
  1982年   5331篇
  1981年   5004篇
  1980年   4629篇
  1979年   5334篇
  1978年   5355篇
  1977年   5623篇
  1976年   5672篇
  1975年   5327篇
  1974年   5161篇
  1973年   5365篇
  1972年   4377篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
The behavior of real disperse systems with organic impurities was examined under conditions of destabilization by inorganic coagulants. A number of physicochemical methods of analysis and a simulation method were used to identify the character and type of the complexes formed and to calculate their stability constants.  相似文献   
93.
A standard model Lagrangian is constructed making the pseudo-Finsleroid generalization of the Yang-Mills field equation by the conformal method. The Higgs field potential is suggested that ensures generation of particle masses caused by the spontaneous symmetry breaking. After transition to the conformal coordinates, the expressions obtained assume the standard form that in many cases allows the results of pseudo-Euclidean theory to be used in calculations of the Feynman diagrams. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 44–51, April, 2006.  相似文献   
94.
95.
The luminescence and scintillation properties of poly(methyl methacrylate) containing 1,1,3-trimethyl-3-phenylindan were studied.  相似文献   
96.
The structural change in the depth direction of a polyimide (UPILEX‐S) film treated in alkaline solution, which was a representative surface treatment used to form a seed layer for plating and to improve the adhesive strength, was analyzed by means of micro Fourier transform infrared attenuated total reflection (FTIR‐ATR) line analysis with gradient shaving preparation. The polyimide film was treated with KOH. The imide ring opened through the alkaline treatment, and the amide structure and carboxylic acid salt were formed. The attainment depth of this structural change was almost proportional to the treatment time, and it reached about 8 μm after a 30‐min treatment. The degree of structural change through the alkaline treatment was almost constant after it reached a considerably degraded stage, and the chemically changed region penetrated into the inner part of the film from the surface. An intermediate layer before the final degraded stage appeared in the treated layer, and its thickness increased with the treatment time. The region that was changed chemically by the alkaline treatment progressed to the inner part simultaneously and continuously as the treatment time increased. The combined use of gradient shaving preparation and micro FTIR‐ATR line analysis was found to be extremely effective for the depth profiling of organic materials. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2071–2078, 2003  相似文献   
97.
It is proved that a Galois extension of a field of characteristic p is completely determined by its Galois group and the endomorphism of the additive group of the group algebra that corresponds to the raising to the power p.  相似文献   
98.
99.
The generalized Hilbert symbol in a cyclotomic extension of an absolutely unramified higher local field of characteristic 0 with a perfect last residue field of characteristic p > 2 is considered. Generalized Artin–Hasse and Iwasawa formulas are derived from an explicit Kummer Type Vostokov formula. Bibliography: 13 titles.  相似文献   
100.
For a planar convex set K with C 2-smooth boundary, the area of the set of the points lying on a given number of affine diameters of K is estimated. As a corollary, it is proved that the area of K is at most pM2 /4\pi M^2 /4 , where M is the largest length of a chord of K halving the area of K. Bibliography: 2 titles.  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