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   426篇
  免费   25篇
化学   402篇
晶体学   10篇
数学   5篇
物理学   34篇
  2023年   2篇
  2022年   3篇
  2021年   11篇
  2020年   11篇
  2019年   5篇
  2018年   4篇
  2017年   4篇
  2016年   6篇
  2015年   16篇
  2014年   10篇
  2013年   21篇
  2012年   31篇
  2011年   27篇
  2010年   18篇
  2009年   12篇
  2008年   26篇
  2007年   30篇
  2006年   21篇
  2005年   24篇
  2004年   26篇
  2003年   13篇
  2002年   11篇
  2001年   5篇
  2000年   12篇
  1999年   5篇
  1998年   6篇
  1997年   2篇
  1996年   6篇
  1995年   3篇
  1994年   1篇
  1993年   6篇
  1992年   6篇
  1991年   8篇
  1990年   13篇
  1989年   10篇
  1988年   14篇
  1987年   10篇
  1986年   3篇
  1985年   6篇
  1984年   2篇
  1969年   1篇
排序方式: 共有451条查询结果,搜索用时 15 毫秒
41.
42.
We show that the structure of a polymer electrolyte may be solved by growing single crystals of an oligomeric (short chain) complex which provided an adequate starting model for refinement of the equivalent polymeric structure using powder diffraction: the efficacy of this method has been demonstrated by determining for the first time the structure of an 8 : 1 complex, poly(ethylene oxide)(8) : NaBPh(4).  相似文献   
43.
44.
We propose a picture of Wigner function scars as a sequence of concentric rings along a two-dimensional surface inside a periodic orbit. This is verified for a two-dimensional plane that contains a classical hyperbolic orbit of a Hamiltonian system with 2 degrees of freedom. The stationary wave functions are the familiar mixture of scarred and random waves, but the spectral average of the Wigner functions in part of the plane is nearly that of a harmonic oscillator and individual states are also remarkably regular. These results are interpreted in terms of the semiclassical picture of chords and centers.  相似文献   
45.
For central collisions of (17-115)A MeV 40Ar+Cu, Ag, Au, an overall balance is determined for the average mass, energy, and longitudinal momentum. Light charged particles and fragments are separated into forward-focused and isotropic components in the frame of the heaviest fragment. Energy removal by the isotropic component reaches 1-2 GeV. For such high deposition energies, statistical multifragmentation models predict much more extensive nuclear disassembly than is observed.  相似文献   
46.
Discrete Gamow-Teller (GT) transitions 176Yb-->176Lu at low excitation energies have been measured via the ( 3He,t) reaction at 450 MeV and at 0 degrees. For 176Yb, two low-lying states are observed, setting low thresholds Q(nu) = 301 and 445 keV for neutrino ( nu) capture. Capture rates estimated from the measured GT strengths, the simple two-state excitation structure, and the low Q(nu) in Yb-Lu indicate that Yb-based nu detectors are well suited for a direct measurement of the sub-MeV solar electron-neutrino ( nu(e)) spectrum including pp neutrinos.  相似文献   
47.
48.
49.
Water plays an important role in ionothermal synthesis and it has been suggested that it can influence phase selection. We have carried out an extensive study to determine the phases produced at various ratios of water to ionic liquid in the microwave assisted ionothermal synthesis of fluorinated aluminium phosphate frameworks using 1-ethyl-3-methylimidazolium bromide and 1-ethylpyridinium bromide. Aluminophosphate chabazite is the main product under ionothermal conditions while at increased levels of water the ionic liquids appear to be poor templates with dense phases predominating. The low synthesis pressure in ionothermal reactions is demonstrated and the role of template breakdown in phase selection is also discussed.  相似文献   
50.
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