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   424篇
  免费   18篇
  国内免费   2篇
化学   307篇
晶体学   3篇
力学   9篇
数学   50篇
物理学   75篇
  2023年   6篇
  2022年   7篇
  2021年   7篇
  2020年   9篇
  2019年   11篇
  2018年   14篇
  2017年   4篇
  2016年   22篇
  2015年   8篇
  2014年   18篇
  2013年   25篇
  2012年   28篇
  2011年   37篇
  2010年   21篇
  2009年   24篇
  2008年   41篇
  2007年   22篇
  2006年   22篇
  2005年   21篇
  2004年   25篇
  2003年   8篇
  2002年   16篇
  2001年   5篇
  2000年   4篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   3篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1985年   3篇
  1984年   3篇
  1983年   4篇
  1979年   1篇
  1978年   1篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1972年   1篇
  1970年   1篇
  1969年   1篇
  1966年   1篇
排序方式: 共有444条查询结果,搜索用时 15 毫秒
51.
In this paper we determine the composition series of the generalized principal seriesδσ assuming thatσ is strongly positive discrete series.  相似文献   
52.
Phenomenological consequences of a light neutral Higgs scalar S (mass < 3.7 GeV) are explored in various two-Higgs-doublet models where some of the couplings are strongly enhanced. In one class of models the two-gluon decay mode is predominant, and decays into two muons are quite suppressed. A detailed analysis of the decay b → s + S is given. The consequences a light scalar for supersymmetric models are discussed.  相似文献   
53.
54.
We suggest soft breaking of Peccei-Quinn symmetry as a simple solution to the strongCP problem without the presence of the axion. In the context of theSU(2) L ×U(1) model, it is shown how settingθ tree=0 keeps θ calculable and, furthermore, extremely small: θ?10?16. Unlike in the case of the axion the model is free from the cosmological domain wall problem. Possible extension of this idea to grand unification is discussed.  相似文献   
55.
In this paper, we construct combinatorial bases of Feigin–Stoyanovsky’s type subspaces of standard modules for level k affine Lie algebra \(C_\ell ^{(1)}\). We prove spanning by using annihilating field \(x_\theta (z)^{k+1}\) of standard modules. In the proof of linear independence, we use simple currents and intertwining operators whose existence is given by fusion rules.  相似文献   
56.
Classical Kloosterman sums have a prominent role in the study of automorphic forms on GL2 and further they have numerous applications in analytic number theory. In recent years, various problems in analytic theory of automorphic forms on GL3 have been considered, in which analogous GL3-Kloosterman sums (related to the corresponding Bruhat decomposition) appear. In this note we investigate the first four power-moments of the Kloosterman sums associated with the group SL3(?). We give formulas for the first three moments and a nontrivial bound for the fourth.  相似文献   
57.
A general procedure for the determination of the natural frequencies and buckling load for a set of beam system under compressive axial loading is investigated using Timoshenko and high-order shear deformation theory. It is assumed that the set beams of the system are simply supported and continuously joined by a Winkler elastic layer. The model of beam includes the effects of axial loading, shear deformation and rotary inertia. In the special case of identical beams, explicit expressions for the natural frequencies and the critical buckling load are determined using a trigonometric method. The influences of the compressive axial loading and the number of beams in the system on the natural frequencies and the critical buckling load are discussed. These results are of considerable practical interest and have wide application in engineering practice of frameworks.  相似文献   
58.
Electron impact excitation rate coefficients for singlet and triplet electronic states of the carbon monoxide molecule have been calculated under non-equilibrium conditions in the presence of radio-frequency electric field. A Monte Carlo simulation of electron transport has been performed in order to determine non-equilibrium electron energy distribution functions within one period of applied electric field. By using these distribution functions and corresponding cross sections, the excitation rate coefficients have been calculated for all electronic states of CO in the frequency range from 13.56 up to 500 MHz, at reduced root mean square electric field values ranging from 200 to 700 Td. We expect these rates to be valuable for modeling radio-frequency CO plasmas since excited neutrals exhibit greater chemical reactivity than neutrals in ground electronic state, hence altering many properties of plasma.  相似文献   
59.
60.
Phytochemical analysis by GC and GC/MS of the essential oil samples obtained from fresh shoots and flowers of Saponaria officinalis L. allowed the identification of 96 components in total, comprising 94.7% and 86.0% of the total oils compositions, respectively. Regarding the shoots essential oil, the major of 87 identified volatile compounds were phytol (14.1%), tricosane-6,8-dione (13.4%), patchouli alcohol (7.9%) and tricosane (7.2%), whereas patchouli alcohol (20.0%), heneicosane (11.5%) and tricosane (8.4%) were dominant among the 66 volatiles in the flower oil. Nonterpenoid compounds had the highest contribution in S. officinalis shoots essential oil (53.7%), while in the flower oil, constituents were almost evenly distributed between the oxygenated sesquiterpenoid (41.2%) and nonterpenoid compounds (39.5%).  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