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   4705篇
  免费   61篇
  国内免费   8篇
化学   3266篇
晶体学   14篇
力学   61篇
综合类   1篇
数学   644篇
物理学   788篇
  2016年   58篇
  2015年   47篇
  2014年   56篇
  2013年   138篇
  2012年   128篇
  2011年   119篇
  2010年   86篇
  2009年   74篇
  2008年   112篇
  2007年   139篇
  2006年   115篇
  2005年   117篇
  2004年   105篇
  2003年   89篇
  2002年   80篇
  2001年   71篇
  2000年   63篇
  1999年   56篇
  1998年   55篇
  1997年   52篇
  1996年   48篇
  1995年   64篇
  1994年   72篇
  1993年   65篇
  1992年   51篇
  1991年   64篇
  1990年   57篇
  1989年   59篇
  1988年   64篇
  1987年   58篇
  1986年   54篇
  1985年   74篇
  1984年   77篇
  1982年   71篇
  1981年   63篇
  1980年   70篇
  1979年   71篇
  1978年   93篇
  1977年   109篇
  1976年   82篇
  1975年   74篇
  1974年   73篇
  1973年   85篇
  1972年   69篇
  1971年   75篇
  1970年   51篇
  1969年   47篇
  1968年   50篇
  1967年   55篇
  1966年   53篇
排序方式: 共有4774条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
The 351 nm laser-damage thresholds (at 0.7 nm pulse length) of monomeric liquid crystals are reported and results from aromatic-core samples are compared with those from fully saturated systems. The role of π-electron conjugation is examined and identified as the key cause for laser damage. For UV laser compatibility of devices, the damage behaviour of an alignment-layer polymer (nylon 6/6) was also investigated.  相似文献   
25.
The three-body Coulomb problem for nuclear clusters is solved numerically for a model below three-body breakup threshold. An orthogonalized multi-channels method is employed. The method allows to check for convergence by considering the norm square of the closed-channels part of the wave function. The numerical results show that convergence can well be achieved on present-day computers.  相似文献   
26.
27.
28.
29.
The ferroelastic domains of the orthorhombic phase of YBa2Cu3O7- have been observed in polarized light on ceramics and single crystals. By combining polarized light microscopy with the X-ray precession technique, the correlation of the orientation of the orthorhombica- andb-axes with that of thea-b-plane bireflectance, reflection dichroism, transmission dichroism (at a thickness of about 1m), reflection tints generated with compensators and upon uncrossing of polars, as well as the orientation of etch pits has been realized on ferroelastic single domains, bi-domains and more complicated domain patterns. Four ferroelastic orthorhombic domain states have been identified, at variance with former group theoretical considerations, predicting only two states. Ensembles of lamellar domains beyond optical resolution generate strong bireflectance with principal axes rotated by 45° relative to the truea, b-directions.  相似文献   
30.
Two different 6-quark resonating group models of the deuteron are investigated to study the off-shell property of theN-N interaction. In the first model the quarks interact by a central one-gluon-exchange potential plus confinement potential. The meson-exchange contribution to then-p potential is simulated by a central GaussianN-N potential. In the second model the quarks interact by one-gluon-and one-pion-exchange potentials (central and noncentral) plus confinement potential. A small additional -exchange potential between neutron and proton binds the deuteron at the correct energy.Several off-shell variants of the two resonating group models are compared with each other by analyzing their elastic electron scattering cross sections. It is found that the standard renormalized version of the resonating group model yields potentials and wave functions that may be considered physical within the limitations of the model. Unitary off-shell transformations, which modify potentials and wave functions in any sizeable way, lead to a disagreement between the charge distribution predicted by the model via analysis of electron scattering and the charge distribution following from the microscopic quark distribution.Both of the 6-quark models support a soft repulsive core of the tripletn-p potential with a core height of around 900 MeV.  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