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   99481篇
  免费   5438篇
  国内免费   4632篇
化学   56533篇
晶体学   1337篇
力学   5594篇
综合类   322篇
数学   11861篇
物理学   33904篇
  2023年   750篇
  2022年   1713篇
  2021年   2120篇
  2020年   2315篇
  2019年   2511篇
  2018年   2896篇
  2017年   2831篇
  2016年   3497篇
  2015年   2426篇
  2014年   3492篇
  2013年   4944篇
  2012年   5079篇
  2011年   5393篇
  2010年   4268篇
  2009年   4271篇
  2008年   4478篇
  2007年   4197篇
  2006年   3819篇
  2005年   3387篇
  2004年   3049篇
  2003年   2729篇
  2002年   2847篇
  2001年   2558篇
  2000年   2004篇
  1999年   1610篇
  1998年   1537篇
  1997年   1331篇
  1996年   1299篇
  1995年   1079篇
  1994年   1158篇
  1993年   1099篇
  1992年   1064篇
  1991年   1129篇
  1990年   1118篇
  1989年   1043篇
  1988年   918篇
  1987年   914篇
  1986年   884篇
  1985年   922篇
  1984年   916篇
  1983年   823篇
  1982年   800篇
  1979年   803篇
  1978年   814篇
  1977年   809篇
  1976年   921篇
  1975年   813篇
  1974年   846篇
  1973年   849篇
  1972年   755篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
The experimental data on the 180 MeV proton and 50, 180 MeV antiproton scattering by the nuclei12C,40Ca and208Pb have been analysed on the basis of the phenomenological diffraction theory. The optical properties of the nuclei with regards to the incident protons and antiprotons are investigated. Various limiting cases of the proton- and antiproton-nucleus scattering are considered. The contribution of the Coulomb and the spin-orbit interactions to the differential cross sections of these processes has been also analysed.The authors are indebted to D.M. Skrypnik for assistance in preparing the English version of this paper.  相似文献   
963.
We propose a method of obtaining homogeneous and isotropic cosmological models satisfying physical conditions for 0 and . The model obtained in this way describes a universe filled with matter, the equation of state of which changes in time from the asymptotically ultrarelativistic to the asymptotically dust state.Dnepropetrovsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 8–12, May, 1993.  相似文献   
964.
The component representation of superfields over non-Archimedean (and, in particular, p-adic) superalgebras with an infinite number of anticommuting generators is investigated. It is shown that supersmooth fields, nonpolynomial in anticommuting variables, exist in the non-Archimedean case (as opposed to the real or complex case). The superfield representation for the algebra of non-Archimedean supersymmetries is analyzed in the p-adic case (p 3 mod 4). New solutions of equations on a chiral superfield and other superfield equations are discovered in non-Archimedean theory.This work has been supported by the CNR Fund (Italy) and an Advanced Study of p-Adic Mathematical Physics Grant.Institute of Electronic Engineering, Moscow. Genova University, Italy. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 35–38, November, 1993.  相似文献   
965.
Salts of condensed 2-(N,N-dialkyl)iminio-1,3-dithiolan and 1,1-dioxothiolan rings are converted in alkaline media to 1,1-dioxothiolen esters of N,N-dialkyldithiocarbamic acids and into unsaturated bicyclic compounds. The latter are formed when the initial salts contain a bromine atom to the sulfonyl group.For Communication 2, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 40–47, January, 1993.  相似文献   
966.
For the classical ruin problem (a special case of a cyclic group), we use an explicit expression for the characteristic function of the time of first hitting an arbitrary subset of a finite solvable group by a random walk, from a fixed subset, to obtain a new proof of the well-known formula which allows one to estimate the characteristic function of the ruin probability (hitting the identity of a group) at theth- trial.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 45, No. 3, pp. 361–366, March, 1993.  相似文献   
967.
In this paper we consider , in one case that fx 0 (t) is a ΛBMV function on [0, ∞], and in another case thatfεL 1 m-1(Rn) and when |k|=m−1 and f(x)=0 when |x−x0|<δ for some δ>0. Our theormes improve the results of Pan Wenjie ([1]).  相似文献   
968.
Summary With the help of an extension of Hoeffding's equality, we develop a way for estimating the covariance structures for empirical functions of associated sequences in terms of covariances of the original random variables. Based on these estimations, a Glivenko-Cantelli lemma for associated sequences and weak convergence for empirical processes of stationary associated sequences are obtained, all under the conditions on covariances of the original random variables.This research has been supported partially by a scholarship from the Faculty of Graduate Studies and Research of Carleton University, Ottawa, and by an NSERC Canada grant of M. Csörg  相似文献   
969.
By applying the improved theory of plates, which makes it possible to determine all components of the stress tensor, we study the stressed state of glass disks under axisymmetric bending. We obtain a closed-form solution of the corresponding boundary-value problem for systems of singularly perturbed equations. It is shown that the size of the zone of pure bending-the domain with uniformly stretched surface-differs from those known in the literature. The results obtained make it possible to determine the optimal geometric parameters of the punch-glass disk-support system in strength testing of the glass by the method of axisymmetric bending.Translated fromMatematicheskie Metody i Fiziko-Mekhanicheskie Polya, Issue 34, 1991, pp. 73–79.  相似文献   
970.
Two forms of a priori information about unknown parameters in observing linear regression with noise in a Hilbert space are considered. In each section one gets best restricted linear unbiased estimates of the unknown parameters generalizing known results about the finite-dimensional case. Problems of choice of optimal designs are solved for bounded closed sets which are natural from the point of view of applications. The results are compared with those which hold without a priori information.Translated from Teoriya Sluchainykh Protsessov, No. 16, pp. 23–28, 1988.  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