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   4884篇
  免费   1142篇
  国内免费   1715篇
化学   3405篇
晶体学   228篇
力学   313篇
综合类   169篇
数学   762篇
物理学   2864篇
  2024年   5篇
  2023年   41篇
  2022年   181篇
  2021年   141篇
  2020年   150篇
  2019年   160篇
  2018年   160篇
  2017年   236篇
  2016年   167篇
  2015年   241篇
  2014年   297篇
  2013年   443篇
  2012年   399篇
  2011年   431篇
  2010年   468篇
  2009年   449篇
  2008年   530篇
  2007年   447篇
  2006年   463篇
  2005年   374篇
  2004年   302篇
  2003年   207篇
  2002年   214篇
  2001年   204篇
  2000年   205篇
  1999年   107篇
  1998年   56篇
  1997年   54篇
  1996年   39篇
  1995年   43篇
  1994年   53篇
  1993年   48篇
  1992年   68篇
  1991年   51篇
  1990年   42篇
  1989年   53篇
  1988年   33篇
  1987年   32篇
  1986年   23篇
  1985年   12篇
  1984年   15篇
  1983年   14篇
  1982年   14篇
  1981年   19篇
  1980年   15篇
  1979年   10篇
  1978年   9篇
  1977年   4篇
  1965年   6篇
  1963年   2篇
排序方式: 共有7741条查询结果,搜索用时 15 毫秒
881.
颗粒与顺列管束磨损的数值模拟   总被引:2,自引:0,他引:2  
采用直接数值模拟方法模拟了在管道中直径80μm的颗粒对顺列10×10管束的碰撞和磨损.圆管与流场流体之间的相互作用采用内嵌边界方法进行计算并得到流场结构.颗粒的运动采用了拉格朗日跟踪方法计算并与流场之间进行了双向耦合.计算分析了沿流向以及垂直于流向各排管束受到颗粒的碰撞产生的磨损量.计算结果表明沿流向第三排管束以后的各排管束应采取防磨措旌.  相似文献   
882.
Characteristic Numbers of Matrix Lie Algebras   总被引:1,自引:0,他引:1  
A notion of characteristic number of matrix Lie algebras is defined, which is devoted to distinguishing various Lie algebras that are used to generate integrable couplings of soliton equations. That is, the exact classification of the matrix Lie algebras by using computational formulas is given. Here the characteristic numbers also describe the relations between soliton solutions of the stationary zero curvature equations expressed by various Lie algebras.  相似文献   
883.
We introduce the quantum Hadamard operator in continuum state vector space and find that it can be decomposed into a single-mode squeezing operator and a position-momentum mutual transform operator. The two-mode Hadamard operator in bipartite entangled state representation is also introduced, which involves the two-mode squeezing operator and [η〉 ←→|ξ〉 mutual transformation operator, where [η〉 and |ξ〉 are mutual conjugate entangled states. All the discussions are proceeded by virtue of the IWOP technique.  相似文献   
884.
We present a scheme for probabilistic remote preparation of multi-qubit with three-party from a sender to either of two receivers. The quantum channel is composed of a partial entangled tripartite GHZ state. We obtain the successful totM probability of the scheme in the general case and special case, respectively. We also calculate total classical communication cost required in the RSP process with three-party in the general case and special case, respectively.  相似文献   
885.
In this work we show that tending to thermal equilibrium in one system, at least in certain cases, is associated with the coherent dynamical evolution of this system in interaction with another identical system. The temperature varying effect with time is manifestly shown in our analyses.  相似文献   
886.
By virtue of the invariant eigen-operator method we search for the invariant eigen-operators for some Hamiltonians describing nonlinear processes in particle physics. In this way the energy-gap of the Hamiltonians can be naturally obtained. The characteristic polynomial theory has been fully employed in our derivation.  相似文献   
887.
Based on our previous paper (Commun. Theor. Phys. 39 (2003) 417) we derive the convolution theorem of fractional Fourier transformation in the context of quantum mechanics, which seems a convenient and neat way. Generalization of this method to the complex fractional Fourier transformation case is also possible.  相似文献   
888.
889.
The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity. Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-access and hazardous. In addition, optical fiber dosimeters are immune to electrical and radio-frequency interference. In this paper, a novel remote optical fiber radiation dosimeter is described. The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL. The measuring range of the dosimeter is from 0.1 to 100 Gy.  相似文献   
890.
For the first time we introduce an operator Δ h (γ,ε;κ) for studying Husimi distribution function in phase space (γ,ε) for electron’s states in uniform magnetic field, where κ is the Gaussian spatial width parameter. The marginal distributions of the Husimi function are Gaussian-broadened version of the Wigner marginal distributions. Using the Wigner operator in the entangled state 〈λ | representation we find that Δ h (γ,ε;κ) is just a pure squeezed coherent state density operator | γ,ε κ κ γ,ε |, which brings much convenience for studying Husimi distribution, so we name Δ h (γ,ε;κ) the Husimi operator. We then derive Husimi operator’s normally ordered form that provides us with an operator version to examine various properties of the Husimi distribution. Work supported by the National Natural Science Foundation under the grant: 10775097.  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