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   242篇
  免费   7篇
  国内免费   2篇
电工技术   8篇
化学工业   41篇
金属工艺   2篇
机械仪表   9篇
建筑科学   7篇
矿业工程   1篇
能源动力   5篇
轻工业   12篇
水利工程   3篇
无线电   40篇
一般工业技术   40篇
冶金工业   63篇
原子能技术   1篇
自动化技术   19篇
  2022年   1篇
  2021年   1篇
  2020年   2篇
  2019年   2篇
  2018年   3篇
  2016年   2篇
  2015年   4篇
  2014年   3篇
  2013年   13篇
  2012年   12篇
  2011年   12篇
  2010年   11篇
  2009年   4篇
  2008年   4篇
  2007年   10篇
  2006年   11篇
  2005年   9篇
  2004年   4篇
  2003年   8篇
  2002年   7篇
  2001年   7篇
  2000年   8篇
  1999年   12篇
  1998年   25篇
  1997年   10篇
  1996年   6篇
  1995年   5篇
  1994年   6篇
  1993年   13篇
  1992年   3篇
  1991年   3篇
  1990年   2篇
  1989年   3篇
  1987年   3篇
  1986年   2篇
  1985年   4篇
  1984年   2篇
  1983年   2篇
  1980年   2篇
  1976年   3篇
  1975年   2篇
  1970年   1篇
  1968年   1篇
  1967年   1篇
  1964年   1篇
  1956年   1篇
排序方式: 共有251条查询结果,搜索用时 15 毫秒
1.
The biochemical maturation of the lung in late gestation and in the young animal is regulated by glucocorticoids. The present study was aimed at dissociating the different glucocorticoid receptor sites involved in these regulatory functions. The obese Zucker rat was selected as a model for this study as it exhibits hypersensitivity to glucocorticoid hormone action by virtue of its elevated receptor numbers and activity. Two synthetic steroid analogues were administered to obese animals; RU28362, a specific type II receptor agonist, and the type II antagonist RU486. RU28362 promoted a strong catabolic effect, which was associated with reduced food intake and the abolition of growth in the rats. The agonist, RU28362, attenuated developmental increases in antioxidant enzyme activities, and altered the growth of the tissue. At the age studied, development of the lung phosphatidylcholine (PC) system was almost complete, but RU28362 increased disaturated PC 16:0/16:0 concentrations by almost 2-fold, and altered the molecular composition of total pulmonary PC. RU486 attenuated the growth of the rats and reduced their food intake. Treatment with the type II antagonist attenuated lung growth and increased the activities of pulmonary copper zinc (Cu/Zn) and manganese (Mn) superoxide dismutases. RU486 had no effect on lung PC concentrations and molecular composition. The data suggest a role for type I glucocorticoid receptors in the regulation of the antioxidant enzyme system in the lung, as type II antagonism will channel endogenous glucocorticoid binding to the type I site. Type II receptor binding would appear to play a role in regulating the lung PC content.  相似文献   
2.
A method has been developed for the frictional assessment of powder lubricants using a shear-box tester similar to that employed by Jenike. One commercial magnesium stearate, three high-purity magnesium stearates and three high-purity magnesium palmitates were assessed using this method. Powders with a well-ordered crystal structure and particle shape have a lower initial maximum coefficient of friction μa. The difference between μa and μb, the equilibrium dynamic friction coefficient, gives an indication of lubricant film-forming propensity. The basic friction equation is obeyed by the powders for most of the load range studied but deviates slightly approaching zero normal load.  相似文献   
3.
While scan-based compression is widely utilized in order to alleviate the test time and data volume problems,the overall compression level is dictated not only by the chain to channel ratio but also the ratio of encodable patterns.Aggressively increasing the number of scan chains in an effort to raise the compression levels may reduce the ratio of encodable patterns,degrading the overall compression level.In this paper,we present various methods to improve the ratio of encodable patterns.These methods are b...  相似文献   
4.
Der Einsatz von Informationstechnologie (IT) in Organisationen bietet viele M?glichkeiten des Missbrauchs. Besch?ftigte k?nnen sich die besonderen Eigenschaften der IT zunutze machen, um sich etwa in gesch?ftssch?digender Weise Vorteile zu verschaffen. Gleichzeitig erm?glicht IT aber auch, verbotene Handlungen aufzuspüren und zu belegen (IT-Forensik). Der Beitrag beschreibt die technische Praxis von IT-forensischen Analysen und geht auf damit verbundene rechtliche Fragestellungen ein.  相似文献   
5.
Two-stage quasi-class-E power amplifier in GaN HEMT technology   总被引:2,自引:0,他引:2  
This letter presents a two-stage quasi-class-E monolithic microwave integrated circuit power amplifier at 2.0GHz, which is based on field-plated GaN high electron mobility transistor technology. It consists of a driver stage and a power stage. The circuit schematic is described. The amplifier achieves an output power of 37.5dBm into a 50-/spl Omega/ load, a power added efficiency (PAE) of 50%, and a gain of 18.2dB. A power density of 5.6W/mm is achieved.  相似文献   
6.
7.
Concerning global warming and resource depletion, the impact of buildings in subtropical regions is becoming even greater due to a high growth rate of urbanized areas. From the viewpoint of building physics, the main problem concerning subtropical climate is the high level of humidity in combination with high temperature. In this study, a flexible building envelope consisting of wood and clay components was developed so that the materials and the assemblies can be easily tailored to comply with local climatic conditions. The movement and accumulation of moisture in the wall was of prime concern. This has been investigated by means of testing full scale walls in a climate chamber and the corresponding one dimensional transient heat and transfer simulation. In order to achieve a consistency between calculation and measurement, the individual materials were tested for their hygric and thermal properties. Based on these findings attempts were made to calculate the behavior of an optimized wall assembly under real climatic conditions of central Japan. As a result, it was shown that the hygrothermal behavior of the envelope is predictable by means of the models and the simulation program used, and that no risk of interstitial condensation and mold growth was predicted under the real climatic conditions of Kyoto.  相似文献   
8.
9.
10.
相信很多人都为摇滚现场演出的效果所震撼,何不拿起你的相机,把这激动人心的时刻定格下来,作为永久的纪念呢?我们英国的编辑Ed Godden前往摇滚圣地——普利茅斯展馆剧场,拍下了"休克摇滚"之父AliceCooper的狂野演出。  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