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   1034篇
  免费   25篇
  国内免费   3篇
电工技术   111篇
综合类   1篇
化学工业   393篇
金属工艺   12篇
机械仪表   16篇
建筑科学   20篇
能源动力   56篇
轻工业   84篇
水利工程   1篇
无线电   68篇
一般工业技术   163篇
冶金工业   34篇
原子能技术   33篇
自动化技术   70篇
  2022年   15篇
  2021年   21篇
  2020年   13篇
  2019年   13篇
  2018年   11篇
  2017年   8篇
  2016年   14篇
  2015年   11篇
  2014年   23篇
  2013年   39篇
  2012年   48篇
  2011年   42篇
  2010年   46篇
  2009年   34篇
  2008年   54篇
  2007年   51篇
  2006年   43篇
  2005年   42篇
  2004年   28篇
  2003年   34篇
  2002年   33篇
  2001年   20篇
  2000年   16篇
  1999年   21篇
  1998年   37篇
  1997年   24篇
  1996年   29篇
  1995年   17篇
  1994年   14篇
  1993年   20篇
  1992年   17篇
  1991年   12篇
  1990年   12篇
  1989年   23篇
  1988年   18篇
  1987年   14篇
  1986年   9篇
  1985年   14篇
  1984年   8篇
  1983年   19篇
  1982年   11篇
  1981年   11篇
  1980年   11篇
  1979年   14篇
  1978年   5篇
  1977年   8篇
  1976年   12篇
  1974年   6篇
  1973年   5篇
  1971年   3篇
排序方式: 共有1062条查询结果,搜索用时 14 毫秒
1.
2.
3.
4.
[110]-surface strained-SOI CMOS devices   总被引:1,自引:0,他引:1  
We have newly developed [110]-surface strained-silicon-on-insulator (SOI) n- and p-MOSFETs on [110]-surface relaxed-SiGe-on-insulator substrates with the Ge content of 25%, fabricated by applying the Ge condensation technique to SiGe layers grown on [110]-surface SOI wafers. We have demonstrated that the electron and the hole mobility enhancement of [110]-surface strained-SOI devices amounts to 23% and 50%, respectively, against the mobilities of [110]-surface unstrained MOSFETs. As a result, the electron and the hole mobility ratios of [110]-surface strained-SOI MOSFETs to the universal mobility of (100)-surface bulk-MOSFETs increase up to 81% and 203%, respectively. Therefore, the current drive imbalance between n- and p-MOS can be reduced. Moreover, both the electron and the hole mobilities of the [110]-surface strained-SOIs strongly depend on the drain current flow direction, which is qualitatively explained by the anisotropic effective mass characteristics of the carriers on a [110]-surface Si. As a result, the [110]-surface strained-SOI technology with optimization of the current flow directions of n- and p-MOS is promising for realizing higher speed scaled CMOS.  相似文献   
5.
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   
6.
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   
7.
The N-linked oligosaccharide moieties of sycamore (Acer pseudoplatanus L.) laccase are known to be highly heterogeneous. We confirmed that this oligosaccharide heterogeneity was caused not only during the oligosaccharide biosynthesis in Golgi apparatus, but also after the excretion of laccase protein into a culture medium. The culture medium for the sycamore cells (Acer pseudoplatanus L.) contained beta-galactosidase, alpha-L-fucosidase, beta-N-acetylglucosaminidase, alpha-mannosidase and beta-xylosidase activities. We showed that the largest sugar chain in laccase, oligosaccharide F, [formula: see text] was degraded to [formula: see text] by a crude exoglycosidase mixture in the culture medium.  相似文献   
8.
9.
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   
10.
Monolithic rat-race mixers for millimeter waves   总被引:1,自引:0,他引:1  
In this paper, we report on fully monolithic millimeter-wave Schottky-barrier diode (SBD) down-converters with an IF amplifier using heterojunction bipolar transistors (HBT's). A rat-race circuit is used for the mixer, and is analyzed using a harmonic-balance simulator. The measured conversion gain and the isolation are 7.1 and 29 dB in the V-band design, and 8.0 and 25 dB in the W-band design, respectively. The conversion gains are matched well with the circuit simulation  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