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   13225篇
  免费   657篇
  国内免费   31篇
电工技术   171篇
综合类   23篇
化学工业   3359篇
金属工艺   248篇
机械仪表   292篇
建筑科学   609篇
矿业工程   42篇
能源动力   325篇
轻工业   801篇
水利工程   94篇
石油天然气   50篇
无线电   994篇
一般工业技术   2937篇
冶金工业   1753篇
原子能技术   136篇
自动化技术   2079篇
  2023年   172篇
  2022年   419篇
  2021年   459篇
  2020年   326篇
  2019年   293篇
  2018年   352篇
  2017年   327篇
  2016年   430篇
  2015年   351篇
  2014年   533篇
  2013年   832篇
  2012年   684篇
  2011年   819篇
  2010年   601篇
  2009年   568篇
  2008年   611篇
  2007年   595篇
  2006年   495篇
  2005年   392篇
  2004年   352篇
  2003年   322篇
  2002年   292篇
  2001年   207篇
  2000年   181篇
  1999年   184篇
  1998年   282篇
  1997年   232篇
  1996年   159篇
  1995年   142篇
  1994年   142篇
  1993年   147篇
  1992年   104篇
  1991年   99篇
  1990年   106篇
  1989年   102篇
  1988年   104篇
  1987年   76篇
  1986年   91篇
  1985年   100篇
  1984年   98篇
  1983年   82篇
  1982年   79篇
  1981年   82篇
  1980年   68篇
  1979年   76篇
  1978年   86篇
  1977年   70篇
  1976年   103篇
  1975年   59篇
  1973年   51篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
1.
During large scale wildfires, suppression activities are carried out under the direction of an Incident Management Team (IMT). The aim of the research was to increase understanding of decision processes potentially related to IMT effectiveness. An IMT comprises four major functions: Command, Operations, Planning, and Logistics. Four methodologies were used to study IMT processes: computer simulation experiments; analyses of wildfire reports; interviews with IMT members; and cognitive ethnographic studies of IMTs. Three processes were important determinants of IMT effectiveness: information management and cognitive overload; matching component function goals to overall goals; and team metacognition to detect and counter task‐disruptive developments. These processes appear to be complex multi‐person analogues of individual Incident Command processes identified previously. The findings have implications for issues such as: creating IMTs; training IMTs; managing IMTs; and providing decision support to IMTs.  相似文献   
2.
3.
Roger L. Kemp 《Cities》1985,2(3):252-255
Since the early 1970s, local governments in the USA have faced limited tax income combined with double-digit inflation. As a result, every local service from fire prevention to recreation has had to be closely scrutinized. Local administrators and politicians have evolved new and innovative retrenchment management policies to respond to both the demands of citizens and the fewer dollars available. A combination of denial of new programmes and public sector pay austerity, with public education and use of community organizations is providing ways to stretch limited funds. The reality in many communities across the USA is that local government and its services will not be growing in the future.  相似文献   
4.
5.
This paper assesses the potential of natural zeolite utilization as a low-cost ion-exchange and sorbent material in pollution control and recovery of metals. The improvement of the purity of natural zeolites coupled with their chemical modification capabilities in order to provide specific properties may provide a cost-effective alternative for the treatment of heavy metal contaminated soil and water. The application of natural zeolites in industrial pollution control is becoming important and the level of technical effort is increasingly expanding. The extent of application is unlikely to be related solely to their low cost, but also to improved properties and performance characteristics, which will advance the practical implementation of natural zeolites' technology.  相似文献   
6.
The interaction of ammonium stearate (AS) and γ-aminopropyltriethoxysilane (APS) treatments with a magnesium hydroxide flame retardant filler and their effects on its use in an ethylene vinyl acetate copolymer compound have been investigated. The work has shown clear evidence of changes in the structure of the surface layers formed on the filler as the amount of additive is increased and the levels at which these occur can be correlated with theoretical monolayer quantities. Infrared (IR) spectroscopy data suggest that the stearate coating changes from a half salt to a full salt as the coating level is increased and that the APS coating on the filler initially has a significant bicarbonate content, presumably due to reaction with atmospheric carbon dioxide. The effect of coating level on the melt flow rate, insoluble matrix content, crystallisation behaviour, tensile properties, limiting oxygen index, and ageing of the filled compound has been studied. Distinct trends have been observed, many of which can be correlated with the structure of the filler surface layers. Of particular importance is the observation that, unlike APS, excess stearate appears to promote detrimental ageing effects.  相似文献   
7.
8.
9.
The effects of particle size and food on the absolute bioavailability of U-78875 in dogs after oral administration of either a suspension or tablet dosage form were investigated. A reduction of particle size caused a significant increase in bioavailability along with an increase in dissolution rate. Additionally, both suspension and tablet dosage forms administered after food caused an increase in bioavailability. Thus, to accelerate drug dissolution, a reduction of U-78875 particle size from the unmilled state is important for the optimization of formulation compositions. To increase the bioavailability of U-78875, postprandial dosing should be considered.  相似文献   
10.
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