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   310694篇
  免费   2118篇
  国内免费   326篇
化学   144064篇
晶体学   4686篇
力学   17126篇
综合类   3篇
数学   43784篇
物理学   103475篇
  2021年   3198篇
  2020年   3577篇
  2019年   4287篇
  2018年   6365篇
  2017年   6585篇
  2016年   8278篇
  2015年   3833篇
  2014年   7174篇
  2013年   12685篇
  2012年   10684篇
  2011年   12475篇
  2010年   10263篇
  2009年   10386篇
  2008年   12037篇
  2007年   11805篇
  2006年   10553篇
  2005年   9083篇
  2004年   8720篇
  2003年   8128篇
  2002年   8373篇
  2001年   7955篇
  2000年   6297篇
  1999年   4685篇
  1998年   4435篇
  1997年   4300篇
  1996年   3918篇
  1995年   3474篇
  1994年   3518篇
  1993年   3558篇
  1992年   3567篇
  1991年   3934篇
  1990年   3907篇
  1989年   3913篇
  1988年   3646篇
  1987年   3746篇
  1986年   3449篇
  1985年   3988篇
  1984年   4253篇
  1983年   3636篇
  1982年   3846篇
  1981年   3544篇
  1980年   3278篇
  1979年   3761篇
  1978年   3843篇
  1977年   4001篇
  1976年   4056篇
  1975年   3793篇
  1974年   3641篇
  1973年   3794篇
  1972年   3225篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
Methods of silicon planar technology and pulsed laser deposition were applied to fabricate fully solid-state chemical sensors for determining ions of copper, lead, cadmium, thallium, and also sulfide and chloride ions on the basis of thin chalcogenide films as ion-sensitive membranes.  相似文献   
992.
In this paper, we consider questions related to the structure of inverse matrices of linear bounded operators acting in infinite-dimensional complex Banach spaces. We obtain specific estimates of elements of inverse matrices for bounded operators whose matrices have a special structure. Matrices are introduced as special operator-valued functions on an index set. The matrix structure is described by the behavior of the given function on elements of a special partition of the index set. The method used for deriving the estimates is based on an analysis of Fourier series of strongly continuous periodic functions.  相似文献   
993.
994.
This work deals with the polymer latexes synthesized using zinc-containing monomers. The effect of the ligand environment of the zinc-containing monomers on the colloidal and rheological properties of the latexes, as well as on mechanical properties of their films is studied. Mixed zinc salts containing the residues of saturated and unsaturated carboxylic acids are shown to be more efficient cross-linking agents than the symmetric salts of this metal.  相似文献   
995.
 This paper presents a study on affine similitude for the force coefficients of an arbitrary body oscillating in a uniformly stratified fluid. A simple formula is derived that gives a relation between the force coefficients for a body oscillating in homogeneous and uniformly stratified ideal fluids. In particular, it implies the existence of a universal nondimensional similitude criterion for a family of affinely similar bodies, namely, the bodies that can be transformed into each other by vertical dilation of the initial coordinate system. Theoretical results are verified by experiments with a set of spheroids having different length-to-diameter ratios. The experimental technique for evaluation of the frequency-dependent force coefficients is based on Fourier analysis of the time-history of damped oscillation tests. Received: 25 September 2000 / Accepted: 6 July 2001 Published online: 29 November 2001  相似文献   
996.
Differentiation of functions w.r.t. finite atomless measures with compact support on the real line is introduced. The related harmonic calculus is similar to that of the classical Lebesgue case. As an application we obtain the Weyl exponent for the spectral asymptotics of the Laplacians w.r.t. linear Cantor-type measures with arbitrary weights.  相似文献   
997.
998.
This paper proposes a model for the parametric representation of linguistic hedges in Zadeh’s fuzzy logic. In this model each linguistic truth-value, which is generated from a primary term of the linguistic truth variable, is identified by a real number r depending on the primary term. It is shown that the model yields a method of efficiently computing linguistic truth expressions accompanied with a rich algebraic structure of the linguistic truth domain, namely De Morgan algebra. Also, a fuzzy logic based on the parametric representation of linguistic truth-values is introduced.  相似文献   
999.
A modernized conception of hierarchical structure of reality is proposed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 3–6, December, 1980.  相似文献   
1000.
Biographical information on the eminent Soviet geometer Boris Lukich Laptev (4/23/05–1/15-89) is given as well as a survey of his research in the areas of differential geometry and history of mathematics.Translated from Itogi Nauki i Tekhniki, Seriya Problemy Geometrii, Vol. 21, pp.27–42, 1989.  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