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   256篇
  免费   8篇
  国内免费   22篇
电工技术   5篇
综合类   2篇
化学工业   12篇
金属工艺   11篇
机械仪表   3篇
建筑科学   2篇
矿业工程   2篇
能源动力   1篇
轻工业   10篇
石油天然气   4篇
武器工业   4篇
无线电   9篇
一般工业技术   3篇
冶金工业   167篇
原子能技术   11篇
自动化技术   40篇
  2014年   1篇
  2013年   1篇
  2012年   2篇
  2011年   8篇
  2010年   5篇
  2009年   1篇
  2007年   1篇
  2006年   1篇
  2004年   16篇
  2003年   6篇
  2002年   13篇
  2000年   2篇
  1999年   20篇
  1998年   31篇
  1997年   26篇
  1996年   24篇
  1995年   19篇
  1994年   44篇
  1993年   5篇
  1992年   1篇
  1991年   4篇
  1990年   4篇
  1989年   6篇
  1988年   3篇
  1987年   2篇
  1986年   5篇
  1985年   1篇
  1981年   2篇
  1980年   3篇
  1977年   7篇
  1976年   11篇
  1972年   1篇
  1968年   1篇
  1960年   2篇
  1959年   2篇
  1958年   1篇
  1943年   1篇
  1882年   3篇
排序方式: 共有286条查询结果,搜索用时 15 毫秒
241.
铅锌烧结电除尘器设计与应用   总被引:1,自引:0,他引:1  
针对铅锌精矿烧结机作业特点、产生烟气条件及烟尘性质,分析、论述了电除尘器的设计,并介绍设备的调试与生产运行情况。  相似文献   
242.
243.
In mammalian cells, DNA topoisomerase II is the product of two distinct genes encoding the alpha and beta isoforms of the enzyme. Besides homodimeric topoisomerase IIalpha and IIbeta, we have recently shown that alpha/beta heterodimers constitute a third population of topoisomerase II in HeLa cells. We found that topoisomerase II heterodimers are not restricted to HeLa cells but exist in different mammalian cell types, and up to 25% of the total topoisomerase IIbeta population is involved in heterodimer formation. Studies of topoisomerase II phosphorylation in HeLa cells show that heterodimers are phosphorylated in vivo to a significantly lower level compared to homodimeric alpha enzymes, but in contrast to the latter neither heterodimers nor topoisomerase IIbeta homodimers coprecipitate together with a kinase activity that is able to mediate their phosphorylation. However, both enzymes can still be phosphorylated by exogenously added casein kinase II. The differential phosphorylation of topoisomerase II heterodimers suggests an alternative regulation of this topoisomerase II subclass compared to the homodimeric topoisomerase IIalpha counterparts.  相似文献   
244.
根据挤压机压型嘴在挤压过程中的工作特点及受力状况,分析了压型嘴断裂破坏的原因及预防改进措施。  相似文献   
245.
246.
David 《变频器世界》2012,(6):131-132
1引言过去十年是世界光伏快速成长的十年,中国光伏产业也快速崛起。国家非常重视这一新兴战略性产业的发展,出台的"十二五"能源规划中提到要大力发展光伏应用。作为亚洲规模最大的电源生产王国,  相似文献   
247.
Diabetes mellitus is associated with an increased risk of premature vascular disease. Vascular research is focusing on a potential role of adhesion molecules in diabetes mellitus, since classical risk factors including hyperlipidemia and hypertension do not completely account for the increased incidence of atherosclerosis in diabetes. After the expression of adhesion molecules on the cell surface, they are shed into plasma. Thus plasma concentrations of circulating adhesion molecules may be representative for endothelial activation, damage or turnover. Recently, evidence has been accumulating that increased plasma levels of adhesion molecules may predict cardiovascular disease, may be pathognomonic for diabetic microangiopathy or may even play a functional pathophysiologic role. The purpose of this article is to briefly summarise the role of (circulating) adhesion molecules in diabetes mellitus.  相似文献   
248.
249.
250.
The compaction properties of a 1:1 acetaminophen and microcrystalline cellulose (MCC) mixture have been studied using a compaction simulator to make tablets by single compression and by a combination of precompression and main compression. The tensile strengths of the tablets and the energies involved in the compressions were determined. The tensile strengths of the tablets increased with increases in single compression pressure from 80 to 400 MPa and as the total applied pressure increased from 80 MPa up to around 400 MPa when combinations of precompression and main compression pressures were used. The tablet porosity decreased with increase in main compression pressure while the tablet tensile strengths increased. At minimum tablet porosity, further increase in main compression pressure could no longer result in increase in tablet strengths. Tablets compressed with combinations of precompression and main compression were stronger (2.15 +/- 0.02 to 3.99 +/- 0.1 MPa) than those produced with single compression (0.73 +/- 0.01 to 3.09 +/- 0.05 MPa). The total gross energies of compression increased with an increase in pressure of both the precompression and main compression. The elastic energies during main compression increased with an increase in precompression pressure as the tablet exhibited greater elastic deformation and reduced plasticity on second compression. The increase in elastic energies during main compression may also be because elastic energy is recoverable and is independent of precompression. As the precompression pressure increased, the minimum tablet porosity was attained; hence, the plastic energy during main compression became smaller while the elastic energy increased. Thus, a combination of low precompression and main compression pressures of 160/80 MPa or 80/160 MPa are more advantageous in the tableting of the 1:1 acetaminophen:MCC than a high single compression pressure of 320 or 400 MPa.  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