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   305567篇
  免费   1803篇
  国内免费   649篇
化学   146753篇
晶体学   4478篇
力学   15113篇
综合类   6篇
数学   46552篇
物理学   95117篇
  2020年   1985篇
  2019年   2276篇
  2018年   10963篇
  2017年   11681篇
  2016年   8012篇
  2015年   3120篇
  2014年   3954篇
  2013年   9454篇
  2012年   10900篇
  2011年   19897篇
  2010年   12533篇
  2009年   12584篇
  2008年   17852篇
  2007年   21231篇
  2006年   7835篇
  2005年   12996篇
  2004年   9285篇
  2003年   8904篇
  2002年   6870篇
  2001年   6111篇
  2000年   5009篇
  1999年   3519篇
  1998年   3072篇
  1997年   3064篇
  1996年   3009篇
  1995年   2439篇
  1994年   2514篇
  1993年   2548篇
  1992年   2679篇
  1991年   2744篇
  1990年   2648篇
  1989年   2636篇
  1988年   2572篇
  1987年   2536篇
  1986年   2449篇
  1985年   3133篇
  1984年   3309篇
  1983年   2669篇
  1982年   2931篇
  1981年   2806篇
  1980年   2603篇
  1979年   2846篇
  1978年   2967篇
  1977年   2903篇
  1976年   2915篇
  1975年   2751篇
  1974年   2721篇
  1973年   2908篇
  1972年   1923篇
  1967年   1878篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
    
Ohne Zusammenfassung  相似文献   
993.
Zur Harnanalyse     
Ohne Zusammenfassung  相似文献   
994.
995.
996.
997.
Data on the spatial distribution of radionuclides (241Am, 239Pu, 137Cs and 152Eu) formed during nuclear explosions of different types near P2 SNTS test site are presented. Radionuclide contamination induced by the explosions varies in the concentrations of individual radionuclides, their proportions and species. Examination of the variations is a crucial task to plan remediation activities as well as those aimed at decrease of radiation risk for population and prevention of repeated contamination. Concentrations of 241Am and 239+240Pu that are the most toxic radionuclides in the area lie in hundred thousands of Bqkg?1. The most contaminated areas are classified by the radionuclide concentration, ratio and form present in soil.  相似文献   
998.
We present a few estimates of energy densities reached in heavy-ion collisions at the CERN SPS. The estimates are based on data and models of proton-nucleus and nucleus-nucleus interactions. In all of these estimates the maximum energy density in central Pb+Pb interactions is larger than the critical energy density GeV/fm3 following from lattice gauge theory computations. In estimates which we consider as realistic the maximum energy density is about . In this way our analysis gives some support to claims that deconfined matter has been produced at the CERN SPS. Any definite statement requires a deeper understanding of formation times of partons and hadrons in nuclear collisions. We also compare our results with implicit energy estimates contained in earlier models of anomalous suppression in nuclear collisions. Received: 3 February 2003 / Revised version: 5 March 2003 / Published online: 5 May 2003  相似文献   
999.
A search for sleptons, neutralinos, charginos, sgoldstinos and heavy stable charged sleptons in the context of scenarios where the lightest supersymmetric particle is the gravitino, is presented. Data collected during 2000 with the DELPHI detector at centre-of-mass energies from 204 to 208 GeV were analysed and combined with all the data collected from 1995 to 1999 at lower energies. No evidence for the production of sleptons, neutralinos and charginos has been found, therefore new limits on the mass of these supersymmetric particles and on the model parameter space are set. The search for heavy stable charged sleptons also updates the stable sleptons mass limit. The absence of evidence for sgoldstino production allows limits to be set on its mass and on the scale of supersymmetry breaking. Received: 6 November 2002 / Published online: 14 February 2003  相似文献   
1000.
Deformed squeezed states are introduced as the q-analogues of the conventional undeformed harmonic oscillator algebra squeezed states. It is shown that the boundary vectors in the matrix-product states approach to multiparticle diffusion processes are deformed coherent or squeezed states of a deformed harmonic oscillator algebra. A deformed squeezed and coherent-states solution to the n-species stochastic diffusion boundary problem is proposed and studied.Received: 31 January 2003, Published online: 10 October 2003  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