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   585563篇
  免费   4173篇
  国内免费   1300篇
化学   285617篇
晶体学   8294篇
力学   30812篇
综合类   17篇
数学   85040篇
物理学   181256篇
  2021年   5040篇
  2020年   5479篇
  2019年   6223篇
  2018年   13031篇
  2017年   13426篇
  2016年   13902篇
  2015年   6581篇
  2014年   10508篇
  2013年   23573篇
  2012年   20907篇
  2011年   29163篇
  2010年   20580篇
  2009年   20561篇
  2008年   26791篇
  2007年   28908篇
  2006年   18747篇
  2005年   20057篇
  2004年   17212篇
  2003年   16109篇
  2002年   14826篇
  2001年   14834篇
  2000年   11593篇
  1999年   8786篇
  1998年   7629篇
  1997年   7487篇
  1996年   7088篇
  1995年   6362篇
  1994年   6348篇
  1993年   6103篇
  1992年   6456篇
  1991年   6940篇
  1990年   6652篇
  1989年   6562篇
  1988年   6411篇
  1987年   6209篇
  1986年   5955篇
  1985年   7504篇
  1984年   7872篇
  1983年   6621篇
  1982年   6915篇
  1981年   6414篇
  1980年   6097篇
  1979年   6613篇
  1978年   6845篇
  1977年   6659篇
  1976年   6647篇
  1975年   6359篇
  1974年   6182篇
  1973年   6519篇
  1972年   4746篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
112.
An existence theorem is proved for a strictly majorizing test of composite hypotheses. Statistical corollaries of the theorem are explored.Translated from Statisticheskie Metody Otsenivaniya i Proverki Gipotez, pp. 73–78, 1986.  相似文献   
113.
A convenient method of synthesis of 2-(methoxycarbonylmethylene)-substituted imidazolidines and imidazolidinium bromides, and also of bicyclic diazo compounds has been developed starting from methyl bromopropiolate and ethylenediamine and its derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1205–1208, September, 1991.  相似文献   
114.
We develop a method of computing the nonsteady-state and free oscillations of a framed elastic structure situated on an elastic base and containing an ideal compressible fluid. The solution uses the method of integral transforms in conjunction with the method of orthogonal polynomials. In the transform space the problem reduces to systems of linear algebraic equations. The Fourier transform is applied to return to the original space. Examples of the computation are given.Translated fromDinamicheskie Sistemy, No. 6, 1987, pp. 69–72.  相似文献   
115.
We consider the solution of integral equations in problems of three-dimensional electromagnetic fields in piecewise-homogeneous media. An algorithm is proposed for analytical isolation of singularities in the kernel and the density of the integral equation of potential theory for the case of complex boundary surfaces.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 56, pp. 14–17, 1985  相似文献   
116.
Translated from Chislennye Metody Resheniya Obratnykh Zadach Matematicheskoi Fiziki, pp. 119–127.  相似文献   
117.
The proof of the existence of classical solutions is given for the Painlevé type nonlinear ordinary differential equations. The solutions have asymptotic formulas, which can be obtained by the isomonodromic deformation method.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova, Vol. 179, pp. 101–109, 1989.  相似文献   
118.
The finite-size corrections, central chargesc, and scaling dimensionsx of tricritical hard squares and critical hard hexagons are calculated analytically. This is achieved by solving the special functional equation or inversion identity satisfied by the commuting row transfer matrices of these lattice models at criticality. The results are expressed in terms of Rogers dilogarithms. For tricritical hard squares we obtainc=7/10,x=3/40, 1/5, 7/8, 6/5 and for hard hexagons we obtainc=4/5,x=2/15, 4/5, 17/15, 4/3, 9/5, in accord with the predictions of conformal and modular invariance.  相似文献   
119.
Exact closed-form solutions are exhibited for the Hopf equation for stationary incompressible 3D Navier-Stokes flow, for the cases of homogeneous forced flow (including a solution with depleted nonlinearity) and inhomogeneous flow with arbitrary boundary conditions. This provides an exact method for computing two- and higher-point moments, given the mean flow.  相似文献   
120.
A firm's logistics cost, including shipping and inventory-carrying, is a substantial percentage of its sales. Nevertheless, typical inventory-control methods ignore or insufficiently represent the shipping cost. This paper describes a recursive algorithm that determines the reorder cycle-time that minimizes total logistics cost. It allows for a realistic accounting of shipping cost, which is modelled here as a function of shipping distance and weight. The algorithm uses a relaxation procedure to identify a suitable initial approximation to the optimal order cycle-time and then, through a series of recursive steps, moves to the optimal result. We demonstrate the algorithm with a single item, with a group of items that share a common order cycle, and with multi-items when item demands are random variables. Experience with this algorithm indicates that it converges to the optimal result in a very few steps.  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