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   1077篇
  免费   39篇
  国内免费   30篇
化学   641篇
晶体学   7篇
力学   24篇
综合类   1篇
数学   221篇
物理学   252篇
  2023年   6篇
  2022年   9篇
  2021年   14篇
  2020年   10篇
  2019年   11篇
  2018年   6篇
  2017年   6篇
  2016年   39篇
  2015年   17篇
  2014年   23篇
  2013年   48篇
  2012年   59篇
  2011年   87篇
  2010年   46篇
  2009年   33篇
  2008年   68篇
  2007年   64篇
  2006年   71篇
  2005年   47篇
  2004年   41篇
  2003年   45篇
  2002年   29篇
  2001年   24篇
  2000年   20篇
  1999年   22篇
  1998年   16篇
  1997年   8篇
  1996年   18篇
  1995年   10篇
  1994年   13篇
  1993年   14篇
  1992年   13篇
  1991年   8篇
  1990年   7篇
  1989年   12篇
  1988年   7篇
  1987年   8篇
  1986年   6篇
  1985年   18篇
  1984年   10篇
  1983年   7篇
  1982年   17篇
  1981年   11篇
  1980年   11篇
  1979年   8篇
  1978年   9篇
  1977年   12篇
  1976年   11篇
  1975年   9篇
  1974年   12篇
排序方式: 共有1146条查询结果,搜索用时 15 毫秒
81.
Low-lying vacant molecular orbitals may lead not only to a breakdown of Koopmans' theorem but also to satellite structure in photoelectron spectra. This paper reports examples of the relatively infrequent appearance of shake-up satellites in Hel photoelectron spectra, namely those of N2O4 and CH3NO. An extended version of the HAM/3 program was used to interpret these spectra.  相似文献   
82.
The excess partial molar enthalpies, the vapor pressures, and the densities of dimethylsulfoxide (DMSO)–H2O mixtures were measured and the excess partial molar Gibbs energies and the partial molar volumes were calculated for DMSO and for H2O. The values of the excess partial molar Gibbs energies for both DMSO and H2O are negative over the entire composition range. The results for the water-rich region indicated that the presence of DMSO enhances the hydrogen bond network of H2O. Unlike monohydric alcohols, however, the solute-solute interaction is repulsive in terms of the Gibbs energy. This was a result of the fact that the repulsion among solutes in terms of enthalpy surpassed the attraction in terms of entropy. The data in the DMSO-rich region suggest that DMSO molecules form clusters which protect H2O molecules from exposure to the nonpolar alkyl groups of DMSO.  相似文献   
83.
To improve the productivities of an automated container terminal, it is important to schedule different types of handling equipment in an integrated way. A mixed-integer programming model, which considers various constraints related to the integrated operations between different types of handling equipment, is formulated. A heuristic algorithm, called multi-layer genetic algorithm (MLGA) is developed with a view to overcome the computation difficulty for solving the mathematical model. A numerical experimentation is carried out in order to evaluate the performance of the algorithm.  相似文献   
84.
85.
Self-Affine Sets and Graph-Directed Systems   总被引:1,自引:0,他引:1  
He  Lau  Rao 《Constructive Approximation》2008,19(3):373-397
   Abstract. A self-affine set in R n is a compact set T with A(T)= ∪ d∈ D (T+d) where A is an expanding n× n matrix with integer entries and D ={d 1 , d 2 ,···, d N } ⊂ Z n is an N -digit set. For the case N = | det(A)| the set T has been studied in great detail in the context of self-affine tiles. Our main interest in this paper is to consider the case N > | det(A)| , but the theorems and proofs apply to all the N . The self-affine sets arise naturally in fractal geometry and, moreover, they are the support of the scaling functions in wavelet theory. The main difficulty in studying such sets is that the pieces T+d, d∈ D, overlap and it is harder to trace the iteration. For this we construct a new graph-directed system to determine whether such a set T will have a nonvoid interior, and to use the system to calculate the dimension of T or its boundary (if T o ≠  ). By using this setup we also show that the Lebesgue measure of such T is a rational number, in contrast to the case where, for a self-affine tile, it is an integer.  相似文献   
86.
87.
In this paper, we explore the properties of projections of norm one on general Banach algebras, in particular the relation with conditional expectations for algebras which arise in harmonic analysis.  相似文献   
88.
In this paper, we shall establish a fixed point property on Fréchet spaces for left reversible semitopological semigroups generalizing some classical results.  相似文献   
89.
90.
Over p-adic Nagata rings, formal p-divisible groups are classified by nilpotent displays according to T. Zink. We extend this result to arbitrary p-adic rings. The proof uses the Grothendieck–Illusie deformation theory of truncated p-divisible groups.  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