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   5875篇
  免费   208篇
  国内免费   33篇
化学   3667篇
晶体学   23篇
力学   194篇
数学   1196篇
物理学   1036篇
  2023年   59篇
  2022年   137篇
  2021年   180篇
  2020年   156篇
  2019年   153篇
  2018年   129篇
  2017年   116篇
  2016年   242篇
  2015年   230篇
  2014年   240篇
  2013年   335篇
  2012年   411篇
  2011年   463篇
  2010年   268篇
  2009年   246篇
  2008年   374篇
  2007年   339篇
  2006年   308篇
  2005年   297篇
  2004年   233篇
  2003年   176篇
  2002年   189篇
  2001年   70篇
  2000年   46篇
  1999年   63篇
  1998年   51篇
  1997年   64篇
  1996年   48篇
  1995年   48篇
  1994年   45篇
  1993年   33篇
  1992年   25篇
  1991年   29篇
  1990年   21篇
  1989年   19篇
  1988年   23篇
  1987年   25篇
  1986年   19篇
  1985年   27篇
  1984年   22篇
  1983年   13篇
  1982年   22篇
  1981年   12篇
  1980年   15篇
  1979年   14篇
  1978年   15篇
  1977年   9篇
  1976年   6篇
  1973年   7篇
  1972年   5篇
排序方式: 共有6116条查询结果,搜索用时 15 毫秒
21.
We exhibit a general class of interactive decision situations in which all the agents benefit from more information. This class includes as a special case the classical comparison of statistical experiments à la Blackwell. AMS 2000 Subject Classification:Primary 91A35.The work of Bruno Bassan and Marco Scarsini was partially supported by MIUR-COFIN. The authors express their thanks to Sylvain Sorin for enlightening comments.  相似文献   
22.
We implement a second-order exponential integrator for semidiscretized advection–diffusion–reaction equations, obtained by coupling exponential-like Euler and Midpoint integrators, and computing the relevant matrix exponentials by polynomial interpolation at Leja points. Numerical tests on 2D models discretized in space by finite differences or finite elements, show that the Leja–Euler–Midpoint (LEM) exponential integrator can be up to 5 times faster than a classical second-order implicit solver.  相似文献   
23.
New fluorinated, polyfunctional propenyl ether functionalized resins were synthesized, and their behavior in cationic photopolymerization was investigated. The photopolymerization proceeded efficiently with a high double‐bond conversion (>90%), giving rise to UV‐cured coatings characterized by low glass‐transition temperatures (?33 °C ≤ glass‐transition temperature ≤ ?15 °C) and hydrophobic surface properties. A fluorinated additive was also employed as a reactive additive in the cationic photopolymerization of trimethylolpropane tripropenyl ether, increasing the double‐bond conversion, polymer network flexibility, thermal stability, and surface hydrophobicity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6943–6951, 2006  相似文献   
24.
We study Willmore immersed submanifoldsf: M m S n into then-Möbius space, withm≥2, as critical points of a conformally invariant functionalW. We compute the Euler-Lagrange equation and relate this functional with another one applied to the conformal Gauss map of immersions intoS n . We solve a Bernestein-type problem for compact Willmore hypersurfaces ofS n , namely, if ?a? n+2 such that <γf, a > ≠ 0 onM, whereγ f is the hyperbolic conformal Gauss map and <, > is the Lorentz inner product of? n+2, and iff satisfies an additional condition, thenf(M) is an (n?1)-sphere.  相似文献   
25.
Proton-proton small angle correlations have been measured in neon-nucleus collisions, using the 4 pi detector Diogene, at 400 and 800 MeV per nucleon incident energies. Values of the size of the emitting region are obtained by comparison with the Koonin formula, taking into account the biases of the apparatus. The dependence of the density on target mass and incident energy is also analysed.  相似文献   
26.
The solubility parameter of poly(hexamethylene oxide) has been estimated by measuring solution viscosities and by turbidimetric titrations in a series of solvents. From both experimental methods, a value of δp = 33.9 J12cm?32 (8.1 cal12cm?32) was obtained, whence the cohesive energy density is 274.5 J cm?3 (65.6 cal cm?3). These experimental values are compared with those calculated by empirical methods.  相似文献   
27.
Journal of Algebraic Combinatorics - We define a new type of Golomb ruler, which we term a resolvable Golomb ruler. These are Golomb rulers that satisfy an additional “resolvability”...  相似文献   
28.
We consider the statistical properties of solutions of Burgers' equation in the limit of vanishing viscosity, , with Gaussian whitenoise initial data. This system was originally proposed by Burgers[1] as a crude model of hydrodynamic turbulence, and more recently by Zel'dovichet al..[12] to describe the evolution of gravitational matter at large spatio-temporal scales, with shocks playing the role of mass clusters. We present here a rigorous proof of the scaling relationP(s)s 1/2,s1 whereP(s) is the cumulative probability distribution of shock strengths. We also show that the set of spatial locations of shocks is discrete, i.e. has no accumulation points; and establish an upper bound on the tails of the shock-strength distribution, namely 1–P(s)exp{–Cs 3} fors1. Our method draws on a remarkable connection existing between the structure of Burgers turbulence and classical probabilistic work on the convex envelope of Brownian motion and related diffusion processes.Inadvertently the sequel to this article, Statistical Properties of Shocks in Burgers Turbulence, II. Tail Probabilities for Velocities, Shock-Strengths and Rarefaction Intervals has already appeared in an earlier issue of Commun. Math. Phys. (Commun. Math. Phys.169, 45–59 (1995).  相似文献   
29.
The setting up and updating of a Mössbauer laboratory imply the acquisition and assembling of different units. Guidelines concerning either the construction or the acquisition of the various parts which compose a Mössbauer spectrometer are given in this paper.  相似文献   
30.
Rigorous asymptotic approximations of the WKB (or Liouville-Green) type are obtained for a basis of solutions to in the framework of -algebras. Both cases and are included, thus generalizing the classical theory for scalar equations developed by F.W.J. Olver to matrix as well as to infinite-dimensional equations.

  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