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   7154篇
  免费   1660篇
  国内免费   5221篇
化学   8174篇
晶体学   111篇
力学   526篇
综合类   292篇
数学   273篇
物理学   4659篇
  2024年   68篇
  2023年   267篇
  2022年   318篇
  2021年   399篇
  2020年   333篇
  2019年   363篇
  2018年   228篇
  2017年   359篇
  2016年   383篇
  2015年   444篇
  2014年   929篇
  2013年   731篇
  2012年   632篇
  2011年   734篇
  2010年   734篇
  2009年   691篇
  2008年   638篇
  2007年   557篇
  2006年   598篇
  2005年   564篇
  2004年   496篇
  2003年   529篇
  2002年   403篇
  2001年   394篇
  2000年   269篇
  1999年   252篇
  1998年   231篇
  1997年   229篇
  1996年   224篇
  1995年   169篇
  1994年   158篇
  1993年   138篇
  1992年   147篇
  1991年   133篇
  1990年   104篇
  1989年   121篇
  1988年   17篇
  1987年   7篇
  1986年   17篇
  1985年   6篇
  1984年   2篇
  1983年   6篇
  1982年   12篇
  1959年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The structures of (ΩΩ)0 and ([1]Ω)1 are studied in the extended chiral SU(3) quark model in which vector meson exchanges are included. The effect from the vector meson fields is very similar to that from the one-gluon exchange (OGE) interaction. Both in the chiral SU(3) quark model and in the extended chiral SU(3) quark model,di-omega (ΩΩ)0 is always deeply bound, with over one hundred MeV binding energy, and ([1]Ω)1 ‘s binding energy is around 20 MeV. An analysis shows that the quark exchange effect plays a very important role for making di-omega (ΩΩ)0 deeply bound.  相似文献   
102.
We investigate the spin correlations in top quark pair production near the threshold at the e^ e^- linear collider. Comparing with the results above the threshold region, we find that near the threshold region the off-diagonal basis, the optimized decomposition of the top quark spins above the threshold region, does not exist, and the beamline basis is the optimal basis, in which there are the dominant spin components: the up-down (UD) component for e^-le^ scattering and the down-up (DU) component for eR^-e^ scattering can make up more than 50% of the total cross section,respectively.  相似文献   
103.
Based on the solution to Bargmann-wigner equation for an arbitrary half-integral spin,a direct derivation of the projction operator and propagator for an arbitrary half-intergral spin is presented.The projection operator constructed by Behrends and Fronsdal is confirmed and simplified.The commutation rules and a general expression for the Feynman propagator for a free particle with arbitrary half-integral spin are deduced.Explicit expressions for the propagators for spins 3/2,5/2and 7/2 are provided.  相似文献   
104.
The independent yield distribution of the Hg isotopes,measured for the reaction of 600MeV ^18O projectile with a ^nat.Pb target,is converted to 18O 208Phb system and is compared with an Hg-isotope distribution from the spallation reaction of 1A GeV^208Pb on proton.The comparison shows the differences between the two distributions on the production cross sections,isotope-distribution widths as well as their shapes.A great increase of the neutron-deficient Hg isotope yield with increase of bombarding energies of protons from 600MeV to 1GeV is derived.This fact results in an experimental evidence for rapid increasing neutron yields with rising proton bombarding energy from 0.6GeV to 1 GeV.  相似文献   
105.
Carbon micro-clusters are accelerated by an HI-13 tandem accelerator. The plastic nuclear track detectors CR-39are irradiated by C1-C4 beams from the HI-13 tandem accelerator and the tracks in CR-39 are studied using anatomic force microscope (AFM). The depths and diameters of C1-C4 tracks are measured for the first time in ananometre scale. An enhancement of the energy loss is obtained for carbon clusters related to single carbon ionswith the same velocity. The results show that the AFM observation is very useful in the quantitative analysis ofclusters in the track detector CR-39.  相似文献   
106.
A simplification scheme of probabilistic teleportation of two-particle state in a general form is given.By means of the primitive operations consisting of single-qubit gates,two-qubit controlled-not gates,Von Neumann measure-ment and classically controlled operations,we construct and efficient quantum logical network for implementing the new scheme of probabilistic teleportation of a two-particle state in a general form.  相似文献   
107.
罗振雄  李泽仁  郑贤旭  李作友  叶雁 《光子学报》2005,34(11):1710-1713
介绍了用同轴Fraunhofer全息测量强动载下材料表面微喷射粒子场的数据处理方法.在全息像重建过程中,将再现的三维粒子场由计算机控制分成许多小薄层采集.在数据处理过程中根据图像中粒子边缘,决定在整幅图或局部采用边缘检测的方法提取大粒子,根据图像的灰度分布将图像分成很多小区域,在每个小区域采用不同的阈值分割图像.在处理结果的校正中根据粒子场的特点,去除过大、过小和重复统计粒子.采用该方法得到了粒子的空间分布图像及粒子大小的统计结果.  相似文献   
108.
在扩展的同位旋相关的Brueckner-Hartree-Fock理论框架内,在整个同位旋自由度范围内研究了质量算子的空穴线展开中不同等级近似下非对称核物质中Hugenholtz-Van Hove定理的满足程度,并计算了中子和质子的费米能量.结果表明为了使Hugenholtz-Van Hove定理达到令人满意的满足程度,需要同时考虑质量算子中的重排贡献和重正修正,从而指出了基态关联对于非对称核物质中单粒子性质的重要性.  相似文献   
109.
The three-dimensional Klein-Gordon equation is solved for the case of equal vector and scalar second Poschl-Teller potential by proper approximation of the centrifugal term within the framework of the asymptotic iteration method. Energy eigenvalues and the corresponding wave function are obtained analytically. Eigenvalues are computed numerically for some values of n and It is found that the results are in good agreement with the findings of other methods for short-range potential.  相似文献   
110.
吴丰 《广西物理》2013,(2):39-41
运用MATLAB软件平台模拟T--维布朗运动的动态画面。并定义了粒子群分布离散度尺,研究迭代步数后,噪声强度系数。与粒子群分布离散度R的关系,通过曲线拟合得到关系式R∝√k与R∝Cs。  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