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   298篇
  免费   4篇
  国内免费   2篇
化学   51篇
力学   8篇
数学   17篇
物理学   228篇
  2022年   1篇
  2020年   2篇
  2019年   1篇
  2018年   1篇
  2017年   4篇
  2016年   5篇
  2015年   1篇
  2014年   7篇
  2013年   9篇
  2012年   13篇
  2011年   10篇
  2010年   8篇
  2009年   5篇
  2008年   24篇
  2007年   24篇
  2006年   24篇
  2005年   26篇
  2004年   19篇
  2003年   12篇
  2002年   18篇
  2001年   11篇
  1999年   3篇
  1998年   1篇
  1997年   1篇
  1996年   14篇
  1995年   11篇
  1994年   4篇
  1993年   2篇
  1991年   1篇
  1990年   5篇
  1989年   1篇
  1988年   6篇
  1987年   2篇
  1986年   10篇
  1985年   6篇
  1984年   2篇
  1983年   3篇
  1981年   2篇
  1980年   1篇
  1979年   1篇
  1973年   1篇
  1972年   1篇
  1969年   1篇
排序方式: 共有304条查询结果,搜索用时 31 毫秒
101.
We present the first evidence of the decay B0-->rho(0)pi(0), using 140 fb(-1) of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) collider. We detect 15.1+/-4.8 signal events with a significance of 3.5 standard deviations and measure the branching fraction to be B(B0-->rho(0)pi(0))=(5.1+/-1.6(stat)+/-0.9(syst))x10(-6).  相似文献   
102.
We have searched for the lepton flavor violating decay tau(-)-->micro(-)eta using a data sample of 84.3 fb(-1) accumulated with the Belle detector at KEK. The eta meson was detected through the decay modes: eta-->gammagamma and pi(+)pi(-)pi(0). No signal candidates are found, and we obtain an upper limit for the branching fraction B(tau(-)-->micro(-)eta)<3.4 x 10(-7) at the 90% confidence level.  相似文献   
103.
We report a fully inclusive measurement of the flavor changing neutral current decay b --> sgamma in the energy range 1.8 GeV < or = E*gamma < or = 2.8 GeV, covering 95% of the total spectrum. Using 140 fb(-1), we obtain B(b --> sgamma) = (3.55+/-0.32(+0.30+0.11)(-0.31-0.07)) x 10(-4), where the errors are statistical, systematic, and from theory corrections. We also measure the first and second moments of the photon energy spectrum above 1.8 GeV and obtain (Egamma) = 2.292+/-0.026+/-0.034 GeV and (E2gamma) - (Egamma)2 = 0.0305+/-0.0074+/-0.0063 GeV2, where the errors are statistical and systematic.  相似文献   
104.
The B meson decay modes B-->Dpp; and B-->D(*)pp; have been studied using 29.4 fb(-1) of data collected with the Belle detector at KEKB. The B;(0)-->D(0)pp; and B;(0)-->D(*0)pp; decays have been observed for the first time with branching fractions B(B;(0)-->D(0)pp;)=(1.18+/-0.15+/-0.16)x10(-4) and B(B;(0)-->D(*0)pp;)=(1.20(+0.33)(-0.29)+/-0.21)x10(-4). No signal has been found for the B+-->D(+)pp; and B+-->D(*+)pp; decay modes, and the corresponding upper limits at 90% C.L. are presented.  相似文献   
105.
The lifetimes of the B(0) and B- mesons are extracted from 29.1 fb(-1) of data collected with the Belle detector at the KEK B factory. A fit to the decay length differences of neutral and charged B meson pairs, measured in events where one of the B mesons is fully reconstructed in several hadronic modes, yields tau(B(0)) = 1.554+/-0.030(stat)+/-0.019(syst) ps, tau(B-) = 1.695+/-0.026(stat)+/-0.015(syst) ps, and tau(B-)/tau(B(0)) = 1.091+/-0.023(stat)+/-0.014(syst).  相似文献   
106.
We report the first observation of chi(c2) production in B meson decays. We find an inclusive B-->chi(c2)X branching fraction of (1.80(+0.23)(-0.28)+/-0.26) x 10(-3). The data set, collected with the Belle detector at the KEKB e(+)e(-) collider, consists of 31.9 x 10(6) BB events. We also present branching fractions and momentum spectra for both chi(c1) and chi(c2) production.  相似文献   
107.
108.
109.
We report observations of the Cabibbo suppressed decays B-->D((*))K- using a 10.4 fb(-1) data sample accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) storage ring. We find that the ratios of Cabibbo suppressed to Cabibbo favored branching fractions are B(B--->D0K-)/B(B--->D0pi(-)) = 0.079+/-0.009+/-0.006, B(B(0)-->D+K-)/B(B(0)-->D+pi(-)) = 0.068+/-0.015+/-0.007, B(B--->D(*0)K-)/B(B--->D(*0)pi(-)) = 0.078+/-0.019+/-0.009, and B(B(0)-->D(*+)K-)/B(B(0)-->D(*+)pi(-)) = 0.074+/-0.015+/-0.006. These are the first observations of the B-->D+K-, D(*0)K-, and D(*+)K- decay processes.  相似文献   
110.
This paper introduces a new model for the classical Huygens? experiment on synchronization of two pendulum clocks hanging from a wooden coupling structure. The dynamics of the coupling—a beam with supporting structure—is modelled in detail using the finite element method. The pendula are considered as single dof systems with local nonlinearities—modelling the escapement. Consequently, the resulting coupled model consists of a finite set of nonlinear ordinary differential equations. Then, the existence of synchronous motion in the system is analytically investigated. Furthermore, this model is used in order to obtain numerical results illustrating the possible limit behaviour of the system. Besides in-phase and anti-phase synchronization, other kinds of limit behaviour appear, namely quenching, beating death, and modulating behaviour, phenomena, which ‘Huygens did not see’.  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