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   661篇
  免费   13篇
  国内免费   1篇
电工技术   21篇
综合类   1篇
化学工业   123篇
金属工艺   28篇
机械仪表   7篇
建筑科学   21篇
能源动力   23篇
轻工业   50篇
水利工程   9篇
石油天然气   4篇
无线电   42篇
一般工业技术   146篇
冶金工业   153篇
原子能技术   12篇
自动化技术   35篇
  2022年   3篇
  2021年   12篇
  2020年   5篇
  2019年   10篇
  2018年   11篇
  2017年   7篇
  2016年   12篇
  2015年   6篇
  2014年   19篇
  2013年   47篇
  2012年   33篇
  2011年   27篇
  2010年   33篇
  2009年   40篇
  2008年   20篇
  2007年   21篇
  2006年   20篇
  2005年   20篇
  2004年   20篇
  2003年   13篇
  2002年   9篇
  2001年   8篇
  2000年   12篇
  1999年   20篇
  1998年   56篇
  1997年   25篇
  1996年   28篇
  1995年   10篇
  1994年   10篇
  1993年   14篇
  1992年   3篇
  1991年   5篇
  1990年   4篇
  1989年   4篇
  1988年   4篇
  1987年   7篇
  1986年   11篇
  1985年   10篇
  1984年   7篇
  1982年   4篇
  1981年   6篇
  1980年   3篇
  1979年   8篇
  1978年   3篇
  1977年   5篇
  1976年   4篇
  1975年   3篇
  1974年   2篇
  1971年   4篇
  1970年   3篇
排序方式: 共有675条查询结果,搜索用时 109 毫秒
91.
92.
We observed the excess specific heat (anomaly) other than nuclear origins above 10 mK in bcc solid 3 He of 24.21 cm 3/mole. We checked whether it arises from spin polarons due to vacancies out of equilibrium by applying a strong magnetic field, in which vacancies should diffuse and vanish due to high polarization. The specific heat is the same before and after applying a magnetic field of 10 T. This fact indicates that vacancies did not vanish even in a strong field or the anomaly arises from the origin different from vacancies.  相似文献   
93.
94.
A novel type of intelligent power device (IPD), which is suitable for automotive monolithic high side switch with high current capability, is presented. An integration of a vertical-power DMOSFET and planar MOS IC devices is performed by the newly developed junction-isolation technique using only one epitaxial growth. The isolation voltage of 80 V has been obtained, which is large enough for automotive IPDs if they are protected against high voltage transients on the battery line. A rugged vertical DMOSFET (VDMOS) has also been developed for this IPD. It has a cellular Zener diode between its source and drain, which prevents the secondary breakdown of parasitic bipolar transistor, and the resulting avalanche capability enhancement is more than an order of magnitude. This VDMOS is used for both output power device and protection device for low-voltage MOS circuitry, which makes the IPD free from any transients in the automobile without the need for external protection  相似文献   
95.
96.
97.
T. Asakawa  S. Matsushita 《Lipids》1980,15(11):965-967
A colorimetric microassay is described for the determination of lipid hydroperoxides. Hydroperoxides are reacted with potassium iodide in the presence of an acid catalyst and liberated iodine is measured. Aluminum chloride, an alcohol-soluble Lewis acid, is used as catalyst. Liberated iodine is measured colorimetrically at 560 nm after addition of starch in 0.01 N hydrochloric acid. The range of the measurement was 0.05–0.5 μmol of hydroperoxides.  相似文献   
98.
The authors have infected 127 B. glabrata by 2 miracidia of S. mansoni, either on the Same day, or introducing a second miracidium after 3, 7 and 16 days. 1 All the groups of planorbid snails had a low percentage of positivity (31 to 41 %). 2 The first cercarial emissions, in the 4 groups were scattered in the time, the delay being in correlation with the second infection. 3 In the snails reinfected after 3 and 7 days occured the highest emissions, those with the simultaneous double infection or second infection delayed to 16 days, had the lesser emissions. 4 An interval cycle of about 3 weeks was discovered for the highest emissions. All those phenomena are probably due to competition between the sporocysts born from both miracidia. Moreover, evident reduction of the fecundity in the positive snails were shown only after the beginning of the cercarial emissions, while a normal, or even increased fecundity was established in the prepatent period of the infected snails.  相似文献   
99.
100.
This paper shows that optimal preview control system approaches to a decoupled preview control system as the weighting factors for the control input variables in the quadratic performance index tend towards zero. Therefore, to examine the characteristics of the decoupled preview control system also means to examine the asymptotic characteristics of the optimal preview control system. By this property, relationships between the design parameters and the response of the optimal preview control system become clear and the design of the optimal preview control can be simplified by utilizing the properties that the decoupled preview control system features. Further, the decoupled preview control method is applied to the vector control system for an induction motor drive. By this application, a trade off between the conditions of the vector control and the magnitude of input variables becomes easy. To demonstrate the significance of this proposed method, simulation results of this application are carried out  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