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   213篇
  免费   3篇
  国内免费   1篇
化学   93篇
晶体学   5篇
力学   3篇
综合类   1篇
数学   6篇
物理学   20篇
无线电   89篇
  2021年   1篇
  2020年   2篇
  2019年   15篇
  2018年   2篇
  2017年   2篇
  2016年   3篇
  2015年   2篇
  2014年   8篇
  2013年   8篇
  2012年   7篇
  2011年   4篇
  2010年   2篇
  2009年   6篇
  2008年   5篇
  2007年   4篇
  2006年   10篇
  2005年   7篇
  2004年   6篇
  2003年   9篇
  2002年   8篇
  2000年   3篇
  1999年   3篇
  1998年   2篇
  1997年   6篇
  1996年   3篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1985年   13篇
  1984年   2篇
  1983年   5篇
  1982年   6篇
  1981年   18篇
  1980年   8篇
  1979年   2篇
  1978年   10篇
  1977年   6篇
  1976年   6篇
  1975年   4篇
  1974年   3篇
  1968年   1篇
  1955年   1篇
排序方式: 共有217条查询结果,搜索用时 29 毫秒
191.
(R)( — )-Mevalonolactone (hiochic acid lactone)of 91–93%e.e. was synthesized from an achiral starting material employing the Sharpless asymmetric epoxidation as the key-step.  相似文献   
192.
The IR spectra of cyclobutanecarbonyl chloride and bromide and their α-deuterated compounds have been recorded in the vapor, liquid and crystal states. The Raman spectra have also been measured in the liquid state. Comparison of the spectra in the liquid phase with those in the crystal phase reveals that these acyl halides exist in a conformational equilibrium in the liquid state. Tentative vibrational assignments are proposed on the basis of the isotope effect and previous published results for other simple cyclobutane compounds.  相似文献   
193.
A general formalism is given for treating vibrational mode mixing, frequency shifts, and atomic equilibrium position shifts under electronic excitation in resonance Raman scattering. The theory is exact for first-order scattering at T = 0 K for all linear and quadratic electron-phonon coupling strengths. Numerical results illustrating mode mixing are presented.  相似文献   
194.
The infrared and Raman spectra of solid state samples of pyromellitic dianhydride have been measured. The infrared—Raman mutual exclusion rule has been observed and the frequencies have been tentatively assigned on the basis of D2h symmetry. The values of the CO and skeletal ring stretching frequencies have been interpreted in terms of a conjugated π-system.  相似文献   
195.
Multiconfigurational many-body perturbation theory is applied to the problem of calculating ionization potentials, electron affinities, and excitation energies. H2O, C2H4, and H2 are studied, with correlation corrections through third order and inclusive of certain higher-order terms. Results are compared with those by other many-body theoretical methods.  相似文献   
196.
The Ne1(3P2) Penning electron spectra and the Ne I photoelectron spectra were measured in the gas phase. The observed systematic differences in their relative intensities were interpreted in terms of the electron distributions of the relevant molecular orbitals and used for assignment of the deep π bands, π1 (12.4 eV) for naphthalene, and π2 (11.9 eV) and π1 (12.8 eV) for anthracene.  相似文献   
197.
A photolysis of di-t-butyl peroxide (BOOB) was studied by using a thermal lensing technique. This technique is found to be applicable to the determination Of the rate Constants of the decay of t-butoxy radical (BO ) and the hydrogen abstraction reaction.  相似文献   
198.
目前在亚太地区,特别重视RFID应用的国家和地区有美国、日本、中国、新加坡、中国台湾和中国香港等。本文在研究、分析美国、日本和中国在应用RFID的不同特点的基础上,得出中国在RFID的应用上应该侧重于哪些方面的结论。  相似文献   
199.
In Japan, sol-gel research activities are very prosperous and there are many successful commercial products. It appears that this trend will continue into the future. In this article, basic sol-gel research carried out in Japanese universities and applications of the sol-gel method to industrial production will be described. It should be noted that many unique studies, including photocatalysts and products involving coatings applied to automobiles and display panels, are found in Japan.  相似文献   
200.
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