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   706760篇
  免费   5357篇
  国内免费   1866篇
化学   352446篇
晶体学   9800篇
力学   36043篇
综合类   32篇
数学   102406篇
物理学   213256篇
  2021年   5841篇
  2020年   6438篇
  2019年   7237篇
  2018年   13682篇
  2017年   13989篇
  2016年   15764篇
  2015年   7978篇
  2014年   12597篇
  2013年   29223篇
  2012年   24526篇
  2011年   32844篇
  2010年   23314篇
  2009年   23250篇
  2008年   30546篇
  2007年   32307篇
  2006年   23289篇
  2005年   23497篇
  2004年   20399篇
  2003年   18966篇
  2002年   17852篇
  2001年   18026篇
  2000年   14363篇
  1999年   10886篇
  1998年   9480篇
  1997年   9384篇
  1996年   8824篇
  1995年   7813篇
  1994年   7781篇
  1993年   7598篇
  1992年   8063篇
  1991年   8545篇
  1990年   8191篇
  1989年   8089篇
  1988年   7928篇
  1987年   7688篇
  1986年   7416篇
  1985年   9520篇
  1984年   9966篇
  1983年   8274篇
  1982年   8761篇
  1981年   8181篇
  1980年   7783篇
  1979年   8352篇
  1978年   8774篇
  1977年   8571篇
  1976年   8538篇
  1975年   8118篇
  1974年   7999篇
  1973年   8384篇
  1972年   5990篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
132.
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   
133.
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   
134.
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   
135.
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   
136.
Translated from Chislennye Metody Resheniya Obratnykh Zadach Matematicheskoi Fiziki, pp. 119–127.  相似文献   
137.
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   
138.
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   
139.
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   
140.
Although coupled liquid chromatographygas chromatography (LC-GC) was first demonstrated ten years ago, only in the last few years has there been a sudden surge of interest in the technique. Approximately 70% of the total number of LC-GC applications have been published in the last two years (1987–88) alone. This review categorizes LC-GC publications into four main application areas: fossil fuels, foods, environmental samples, biologiical/pharmaceutical samples, and miscellaneous samples. Multidimensional separations carried out using other coupled-column chromatographic techniques (such as supercritical fluid chromatography (SFC) with GC, and on-line trace enrichment-GC) have also been included in this review.  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