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   770篇
  免费   13篇
  国内免费   2篇
化学   579篇
晶体学   4篇
力学   7篇
数学   37篇
物理学   158篇
  2022年   6篇
  2021年   7篇
  2020年   8篇
  2019年   8篇
  2018年   9篇
  2017年   3篇
  2016年   12篇
  2015年   9篇
  2014年   17篇
  2013年   31篇
  2012年   30篇
  2011年   34篇
  2010年   18篇
  2009年   19篇
  2008年   47篇
  2007年   31篇
  2006年   29篇
  2005年   49篇
  2004年   45篇
  2003年   37篇
  2002年   40篇
  2001年   23篇
  2000年   26篇
  1999年   16篇
  1997年   7篇
  1996年   9篇
  1995年   11篇
  1994年   7篇
  1993年   8篇
  1992年   11篇
  1991年   10篇
  1990年   18篇
  1989年   11篇
  1988年   6篇
  1987年   8篇
  1986年   14篇
  1985年   20篇
  1984年   15篇
  1983年   11篇
  1982年   9篇
  1981年   5篇
  1980年   9篇
  1979年   9篇
  1978年   4篇
  1977年   3篇
  1973年   4篇
  1970年   3篇
  1968年   4篇
  1967年   2篇
  1966年   2篇
排序方式: 共有785条查询结果,搜索用时 15 毫秒
731.
We show that the percolation transition for the two-dimensional Ising model is sharp. Namely, we show that for every reciprocal temperature >0, there exists a critical valueh c () of external magnetic fieldh such that the following two statements hold.
(i)  Ifh>h c (), then the percolation probability (i.e., the probability that the origin is in the infinite cluster of + spins) with respect to the Gibbs state ,h for the parameter (,h) is positive.
(ii)  Ifhh c (), then the connectivity function ,h + (0,x) (the probability that the origin is connected by + spins tox with respect to ,h ) decays exponentially as |x|.
We also shows that the percolation probability is continuous in (,h) except on the half line {(, 0); c }.  相似文献   
732.
A galactocerebroside molecular species, CNC-2, has been isolated from the less polar lipid fraction of a chloroform/methanol extract of the starfish Culcita novaeguineae. The structure of this galactocerebroside molecular species was determined on the basis of chemical and spectroscopic evidence. CNC-2 is a phytosphingosine-type galactocerebroside molecular species with nonhydroxylated and hydroxylated fatty acyl moieties. The isolation of a galactocerebroside from echinoderms is rare.  相似文献   
733.
A search for the appearance of tau neutrinos from nu(mu) <--> nu(tau) oscillations in the atmospheric neutrinos has been performed using 1489.2 days of atmospheric neutrino data from the Super-Kamiokande-I experiment. A best fit tau neutrino appearance signal of 138+/-48(stat)-32(+15)(syst) events is obtained with an expectation of 78+/-26(syst). The hypothesis of no tau neutrino appearance is disfavored by 2.4 sigma.  相似文献   
734.
We report observations of radiative B meson decays into the K+pi(-)gamma and K+pi(-)pi(+)gamma final states. In the B0-->K+pi(-)gamma channel, we present evidence for decays via an intermediate tensor meson state with a branching fraction of B(B0-->K(*)(2)(1430)(0)gamma)=[1.3+/-0.5(stat)+/-0.1(syst)]x10(-5). We measure the branching fraction B(B+-->K+pi(-)pi(+)gamma)=[2.4+/-0.5(stat) +0.4-0.2(syst)]x10(-5), in which the B+-->K(*0)pi(+)gamma and B+-->K+rho(0)gamma channels dominate. The analysis is based on a data set of 29.4 fb(-1) recorded by the Belle experiment at the KEKB collider.  相似文献   
735.
We report the observation of the decay mode B(+/-) --> p(-)pK(+/-)based on an analysis of 29.4 fb(-1) of data collected by the Belle detector at KEKB. This is the first example of a b-->s transition with baryons in the final state. The p(-)p mass spectrum in this decay is inconsistent with phase space and is peaked at low mass. The branching fraction for this decay is measured to be B(B+/--->p(-)pK+/-) = [4.3(+1.1)(-0.9)(stat)+/-0.5(syst)]x 10(-6). We also report upper limits for the decays B(0)-->p(-)pK(S) and B(+/-)-->p(-)p pi(+/-).  相似文献   
736.
Summary We consider the Kadanoff transformation T (depending on a positive parameter p) acting on probability measures on the space {+1, –}d. A measure is called a non-trivial fixed point of T, if it is extremal in the set of T-invariant measures but is not a product measure. We describe the set of trivial fixed points and show that non-trivial fixed points exist provided that d2 and p large enough. A strong mixing condition on implies convergence of T n towards a trivial fixed point. In particular this applies to the two-dimensional Ising model except at the critical point. What happens at the critical point still remains unknown.Research supported by the Deutsche Forschungsgemeinschaft (Sonderforschungsbereich 123)  相似文献   
737.
Three-particle correlations have been measured for identified pi(-) from central 158A GeV Pb+Pb collisions by the WA98 experiment at CERN. A substantial contribution of the genuine three-body correlation has been found as expected for a mainly chaotic and symmetric source.  相似文献   
738.
We have unambiguously identified interatomic Coulombic decay in NeAr from the inner-valence double-vacancy state Ne-Ar(2+)(3s(-2)) to outer-valence triple-vacancy states Ne(+)(2p(-1))-Ar(2+)(3p(-2)) by momentum-resolved electron-ion multicoincidence. This is the first observation of interatomic Coulombic decay where three electrons (3e) participate. The results suggest that this 3e interatomic Coulombic decay is significantly faster than other competing processes like fluorescence decay and charge transfer via curve crossing.  相似文献   
739.
We report measurements of time dependent decay rates for B0(B(0))-->D((*)-/+)pi(+/-) decays and extraction of CP violation parameters containing phi(3). Using fully reconstructed D((*))pi events from a 140 fb(-1) data sample collected at the Upsilon(4S) resonance, we obtain the CP violation parameters for D(*)pi and Dpi decays, 2R(D((*))pi)sin((2phi(1)+phi(3)+/-delta(D((*))pi)), where R(D((*))pi) is the ratio of the magnitudes of the doubly Cabibbo-suppressed and Cabibbo-favored amplitudes, and delta(D((*))pi) is the strong phase difference between them. Under the assumption of delta(D((*))pi) being close to either 0 degrees or 180 degrees, we obtain |2R(D(*)pi)sin((2phi(1)+phi(3))|=0.060+/-0.040(stat)+/-0.019(syst) and |2R(Dpi)sin((2phi(1)+phi(3))|=0.061+/-0.037(stat)+/-0.018(syst).  相似文献   
740.
We present a measurement of CP-violating asymmetries in B0-->pi(+)pi(-) decays based on a 41.8 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We fully reconstruct one neutral B meson as a B0-->pi(+)pi(-) CP eigenstate and identify the flavor of the accompanying B meson from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we obtain the CP-violating asymmetry parameters S(pipi)=-1.21(+0.38)(-0.27)(stat)+0.16-0.13(syst) and A(pipi)=+0.94(+0.25)(-0.31)(stat)+/-0.09(syst).  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