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   2185篇
  免费   38篇
  国内免费   6篇
化学   1412篇
晶体学   25篇
力学   26篇
数学   118篇
物理学   648篇
  2022年   13篇
  2021年   21篇
  2020年   24篇
  2019年   28篇
  2018年   18篇
  2017年   16篇
  2016年   34篇
  2015年   31篇
  2014年   49篇
  2013年   108篇
  2012年   84篇
  2011年   87篇
  2010年   57篇
  2009年   60篇
  2008年   88篇
  2007年   105篇
  2006年   101篇
  2005年   117篇
  2004年   110篇
  2003年   80篇
  2002年   90篇
  2001年   55篇
  2000年   52篇
  1999年   20篇
  1998年   33篇
  1997年   30篇
  1996年   42篇
  1995年   52篇
  1994年   46篇
  1993年   40篇
  1992年   43篇
  1991年   32篇
  1990年   38篇
  1989年   36篇
  1988年   24篇
  1987年   23篇
  1986年   16篇
  1985年   23篇
  1984年   27篇
  1982年   17篇
  1981年   25篇
  1980年   23篇
  1979年   21篇
  1978年   24篇
  1977年   17篇
  1976年   13篇
  1975年   13篇
  1974年   16篇
  1973年   27篇
  1972年   14篇
排序方式: 共有2229条查询结果,搜索用时 31 毫秒
311.
    
Ohne Zusammenfassung  相似文献   
312.
Permeabilities and diffusion coefficients of various gases, Ar, N2, O2, CO2, CH4, C2H4, C3H8 and C4H10, were measured for Water-swollen gel cellophane membranes. No dependence of permeabilities on gas pressure below 1 atm was found. It was observed that the permeability coefficients were not related linearly to the coefficients in bulk water. For the two states of water in the membrane, an analytical method is presented to estimate the diffusion coefficients and the solubilities in free water and non-freezing water. It was found that the diffusion coefficients in non-freezing water were lower than those in free water, and the solubilities in non-freezing water were higher than in free water for all gases studied except CO2 and C2H4, which gave reverse results.  相似文献   
313.
A new type of 5-deazaflavin derivative with axial and planar chirality was synthesized as a flavoenzyme model. A novel optical resolution gave an enantiomeric pair of the 5-deazaflavins 1a,b. Compounds1a,b were optically stable and effectively discriminated PNPH enantiomers in a model reaction of intercoenzyme hydrogen transfer.  相似文献   
314.
We present a gluon jet model for the heavy quarkonium decay incorporating the color neutralization mechanism. Postulating that final hadrons are produced from the color singlet quark-antiquark pair originated each from different gluons, we formulate the production mechanism of hadrons from gluons explicitly. The fragmentation function thus obtained can describe the hadron production not only in the fragmentation region but also in the central one owing to the usage of the Sudakov variables. The result of the average charged multiplicity from Υ(9.46) is in reasonable agreement with the data, in contrast to the naive estimates. Furthermore, the inclusive momentum and multiplicity distributions are discussed.  相似文献   
315.
Under the assumption that a scalar diquark coexists in part of the time with a single quark within a nucleon, which is favored to describe the higher twist effects of both γ and ν induced nucleon structure functions consistently, we consider how its presence affects nucleon properties. It is shown that the sum rule and the magnetic moment constrain its contribution strongly and the asymmetry is quite sensitive to it. In particular, theR L T ratio can be explained in terms of the large transverse momentum of the diquark which arises from the consideration on the neutron charge radius value.  相似文献   
316.
317.
A self-excitation of subharmonics and their higher harmonics of a low frequency oscillation which seems to be ascribed to the current-convective instability is observed.  相似文献   
318.
319.
The second-order Raman spectra of CsCl single crystals have been measured at room temperature for different Raman polarizations and crystal orientations. With the help of the calculated selection rules for a CsCl-type lattice, observed nineteen peaks and shoulders were assigned by the critical point analysis based on the neutron scattering data. By comparing the observed Raman intensities with the thermally weighted two-phonon density-of-states calculated by using a simple shell model, it has turned out that though the measured spectra are dominantly determined by the two-phonon density-of-states, the effect of the q-dependence of the polarizability cannot entirely be neglected.  相似文献   
320.
A series of solvable lattice models with face interaction are introduced on the basis of the affine Lie algebraX n (1) =A n (1) ,B n (1) ,C n (1) ,D n (1) . The local states taken on by the fluctuation variables are the dominant integral weights ofX n (1) of a fixed level. Adjacent local states are subject to a condition related to the vector representation ofX n . The Boltzmann weights are parametrized by elliptic theta functions and solve the star-triangle relation.  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