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   1373篇
  免费   29篇
电工技术   125篇
综合类   1篇
化学工业   432篇
金属工艺   30篇
机械仪表   36篇
建筑科学   29篇
能源动力   56篇
轻工业   138篇
水利工程   2篇
石油天然气   1篇
无线电   83篇
一般工业技术   209篇
冶金工业   119篇
原子能技术   37篇
自动化技术   104篇
  2022年   20篇
  2021年   30篇
  2020年   14篇
  2019年   11篇
  2018年   16篇
  2017年   15篇
  2016年   25篇
  2015年   12篇
  2014年   25篇
  2013年   59篇
  2012年   59篇
  2011年   57篇
  2010年   52篇
  2009年   45篇
  2008年   62篇
  2007年   67篇
  2006年   52篇
  2005年   34篇
  2004年   39篇
  2003年   41篇
  2002年   42篇
  2001年   38篇
  2000年   27篇
  1999年   39篇
  1998年   72篇
  1997年   43篇
  1996年   42篇
  1995年   25篇
  1994年   22篇
  1993年   22篇
  1992年   15篇
  1991年   15篇
  1990年   19篇
  1989年   26篇
  1988年   19篇
  1987年   15篇
  1986年   11篇
  1985年   17篇
  1984年   16篇
  1983年   20篇
  1982年   14篇
  1981年   14篇
  1980年   13篇
  1979年   16篇
  1978年   8篇
  1977年   13篇
  1976年   17篇
  1975年   5篇
  1974年   7篇
  1973年   6篇
排序方式: 共有1402条查询结果,搜索用时 15 毫秒
1.
Journal of Infrared, Millimeter, and Terahertz Waves - Various regimes of hybrid, bulk-surface, modes being excited in the clinotron oscillator with a sheet electron beam and nonuniform grating...  相似文献   
2.
3.
4.
A dental student developed swelling of the lips and peri-oral urticaria, immediately after placement of a dental rubber dam during a chairside demonstration of clinical dentistry. A provisional diagnosis of a Type I hypersensitivity reaction to natural rubber latex was made and an appointment organised for specialist investigations. The student reported an atopic history and allergy to peanuts. A Radioallergosorbent Test (RAST), to measure Ig-E antibodies to latex, was positive. The dental student was given advice concerning the avoidance of natural rubber latex. Dental staff must be aware of potentially serious reactions to natural rubber latex in the dental surgery.  相似文献   
5.
We have developed an innovative semianalytical technique for various substrate material characterization. The developed technique is a measurement procedure and data-reduction formulation that takes into consideration the radiation loss in a resonant structure, allowing for a more effective means of dielectric- and conductor-loss determination for a microstrip ring resonator and its substrate material. We separate dielectric and conductor loss precisely, evaluate the contribution of each term in the overall loss performance, and analytically predict the error in their respective predicted value.  相似文献   
6.
7.
Tani  M. Yamashita  S. 《Electronics letters》2003,39(19):1375-1377
204 km, 10 Gbit/s standard optical fibre transmission is successfully demonstrated using the mid-span spectral inversion technique with a stimulated Brillouin scattering suppressed fibre phase conjugator, proposed recently by Tani and Yamashita. Transmission performance has been improved compared with a conventional phase conjugator.  相似文献   
8.
Summary The effect of side chain length on intramolecular triplet energy migration of naphthalene containing polymers was investigated by a delayed fluorescence (DF) spectroscopy for the solid solution of the polymers. The degree of triplet energy migration depends strongly on whether the chromophores are directly attached to the main chain or not.  相似文献   
9.
Tomato seed oil was extracted with supercritical carbon dioxide in a semibatch-flow extractor within the temperature range 313–343 K and the pressure range 10.8–24.5MPa. The extraction rates increased with pressure, but decreased with temperature increase because of the variation in solvent density and resultant differences in oil solubility. The fatty acid composition of the extracted oil was similar to that of soybean oil.  相似文献   
10.
High-performance polymer alloys of polybenzoxazine and bismaleimide   总被引:3,自引:0,他引:3  
Two series of high-performance polymer alloys were prepared by mixing typical benzoxine monomers, 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (P-a) or 6,6-(1-methylethyliden)-bis-(3,4-dihydro-3-phenyl-2H-1,3-benzoxazine) (B-a), with a typical bismaleimide, 4,4-bismaleimidodiphenyl methane by various ratios followed by thermal treatment up to 240 °C. DSC and IR of the alloys were examined to follow the curing reaction. These analyses showed that the obtained polymer alloys are AB co-cross-linked polymer networks through the formation of ether linkage between the hydroxyl group of polybenoxazine and the double bond of bismaleimide. Viscoelastic analysis and softening temperature measurement revealed that the polymer alloys have much higher glass transition temperatures than those of each homopolymer. The thermal stability also increased with the increase of bismaleimide content as evidenced by TGA.  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