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   11575篇
  免费   2388篇
  国内免费   1850篇
化学   5649篇
晶体学   120篇
力学   1009篇
综合类   132篇
数学   1730篇
物理学   7173篇
  2024年   22篇
  2023年   106篇
  2022年   218篇
  2021年   253篇
  2020年   325篇
  2019年   285篇
  2018年   269篇
  2017年   355篇
  2016年   422篇
  2015年   501篇
  2014年   618篇
  2013年   922篇
  2012年   666篇
  2011年   824篇
  2010年   729篇
  2009年   823篇
  2008年   875篇
  2007年   902篇
  2006年   816篇
  2005年   764篇
  2004年   582篇
  2003年   640篇
  2002年   555篇
  2001年   479篇
  2000年   452篇
  1999年   443篇
  1998年   322篇
  1997年   272篇
  1996年   232篇
  1995年   169篇
  1994年   170篇
  1993年   116篇
  1992年   112篇
  1991年   99篇
  1990年   56篇
  1989年   74篇
  1988年   51篇
  1987年   44篇
  1986年   24篇
  1985年   51篇
  1984年   27篇
  1983年   15篇
  1982年   34篇
  1981年   19篇
  1980年   11篇
  1979年   17篇
  1977年   7篇
  1976年   10篇
  1974年   5篇
  1973年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
刘炳灿  潘学琴  田强  吴正龙 《中国物理》2006,15(5):1067-1070
The semiconductor CdSeS quantum dots (QDs) embedded in glass are analysed by means of absorption spectra, photoluminescence (PL) spectra and photoluminescence excitation (PLE) spectra. The peaks of absorption spectra shift to lower energies with the size of QD increasing, which obviously shows a quantum-size effect. Using the PLE spectra, the physical origin of the lowest absorption peak is analysed. In PLE spectra, the lowest absorption peak can be deconvoluted into two peaks that stem from the transitions of 1S3/2--1Se and 2S3/2--1Se respectively. The measured energy difference between the two peaks is found to decrease with the size of QD increasing, which agrees well with the theoretical calculation for the two transitions. The luminescence peak of defect states is also analysed by PLE spectra. Two transitions are present in the PLE, which indicates that the transitions of 1S3/2--1Se and 2S3/2--1Se are responsible for the defect states luminescence.  相似文献   
62.
Probabilistic teleportation of a non-symmetric three-particle state   总被引:1,自引:0,他引:1       下载免费PDF全文
陈秀波  温巧燕  朱甫臣 《中国物理》2006,15(10):2240-2245
This paper proposes a scheme for teleporting a kind of essential three-particle non-symmetric entangled state, which is much more valuable than a GHZ and W state for some applications in quantum information processing. In comparison with previous proposal of teleportation, the resources of entangled states as quantum channel and the number of classical messages required by our scheme can be cut down. Moreover, it is shown that there exists a class of transformations which ensure the success of this scheme, because the two-particle transformation performed by the receiver in the course of teleportation may be a generic two-particle operation instead of a control-NOT (CNOT) operation. In addition, all kinds of transformations performed by sender and receiver are given in detail.  相似文献   
63.
Based on the technique of integral within an ordered product of nonlinear bosonic operators we construct a kind of tripartite nonlinear entangled states, which can make up a complete set. As its application, we also derive nonlinear 3-mode charge-related entangled state. The essential point for constructing these states lies in choosing the appropriate charge operator.  相似文献   
64.
The total attenuation cross-section of Rg (3P2) (Rg = Ar, Kr) by the collision with CF3Br is measured as a function of the magnetic sub level MJ of Rg (3P2) and the collision energy. For Ar (3P2), the attenuation process indicates a MJ dependence, in particular, the cross-section of the MJ = 0 state is lower compared with that for other states. On the other hand, Kr (3P2) shows no MJ dependent attenuation.  相似文献   
65.
We propose a scheme for generating a hyperentangled four-photon cluster state that is simultaneously entangled in polarization modes and spatial modes. This scheme is based on linear optical elements, weak cross-Kerr nonlinearity, and homodyne detection. Therefore, it is feasible with current experimental technology.  相似文献   
66.
The microstructure and morphology of metal oxide films have a large influence on the sensitivity, selectivity and stability of the gas sensors and catalysts. Considering that the sensing properties of thin film sensors are strongly related to their microstructures and to the exact stoichiometry of their surfaces, an accurate control of these parameters is extremely important for the production of sensors with reproducible behavior. In this paper, an influence of preparation and annealing conditions on the physical and chemical properties of tungsten oxide thin film is investigated. Two types of samples having polycrystalline structure were prepared by different methods (deposition under UHV conditions, oxidation of metallic tungsten layer in air). The samples were reduced by heating in UHV at different temperatures and/or by Ar ion bombardment. It was found that the stability of tungsten oxide layer with respect to the treatment procedures depends strongly on the preparation conditions of the sample. The reduction process is discussed in terms of different oxidation states resolved in the W4f photoelectron spectrum. Easy reducibility of the tungsten oxide layer prepared by vacuum deposition was found to be a consequence of its nano-crystalline structure.  相似文献   
67.
68.
《Physics letters. A》2014,378(16-17):1085-1090
The formations of n-order two-soliton bound states (TSBSs) in the Bose–Einstein condensates with spatiotemporally modulated nonlinearities are studied. Exact analytical expressions of the n-order TSBSs are derived by means of the similarity transformations. Further, the numerical simulations are carried out, consistent with the analytical results very well. The stability analysis shows that the solutions can be stable. Our results indicate that the attractive spatiotemporal inhomogeneous nonlinearities can support n-order TSBSs, which has the potential applications to the generation of matter-wave bright solitons in harmonic traps.  相似文献   
69.
We present a model for a one-dimensional anisotropic exclusion process describing particles moving deterministically on a ring of lengthL with a single defect, across which they move with probability 0 p 1. This model is equivalent to a two-dimensional, six-vertex model in an extreme anisotropic limit with a defect line interpolating between open and periodic boundary conditions. We solve this model with a Bethe ansatz generalized to this kind of boundary condition. We discuss in detail the steady state and derive exact expressions for the currentj, the density profilen(x), and the two-point density correlation function. In the thermodynamic limitL the phase diagram shows three phases, a low-density phase, a coexistence phase, and a high-density phase related to the low-density phase by a particle-hole symmetry. In the low-density phase the density profile decays exponentially with the distance from the boundary to its bulk value on a length scale . On the phase transition line diverges and the currentj approaches its critical valuej c = p as a power law,j c – j –1/2. In the coexistence phase the width of the interface between the high-density region and the low-density region is proportional toL 1/2 if the density f 1/2 and=0 independent ofL if = 1/2. The (connected) two-point correlation function turns out to be of a scaling form with a space-dependent amplitude n(x1, x2) =A(x2)A Ke–r/ withr = x 2x 1 and a critical exponent = 0.  相似文献   
70.
本文应用群论原理及不可约张量性质,详细推导了Oh型分子三重简并态Amat-Nielsen方案中精确到四级的Hamiltonian算符,为Oh型分子精细结构理论和光谱的进一步研究做了数学上的准备。  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