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   33090篇
  免费   924篇
  国内免费   66篇
电工技术   366篇
综合类   35篇
化学工业   6824篇
金属工艺   858篇
机械仪表   621篇
建筑科学   1840篇
矿业工程   247篇
能源动力   1016篇
轻工业   2763篇
水利工程   336篇
石油天然气   207篇
武器工业   2篇
无线电   2150篇
一般工业技术   5215篇
冶金工业   6650篇
原子能技术   322篇
自动化技术   4628篇
  2022年   198篇
  2021年   386篇
  2020年   332篇
  2019年   399篇
  2018年   488篇
  2017年   507篇
  2016年   520篇
  2015年   463篇
  2014年   737篇
  2013年   2133篇
  2012年   1242篇
  2011年   1592篇
  2010年   1172篇
  2009年   1263篇
  2008年   1439篇
  2007年   1469篇
  2006年   1258篇
  2005年   1174篇
  2004年   1053篇
  2003年   1028篇
  2002年   1032篇
  2001年   636篇
  2000年   617篇
  1999年   576篇
  1998年   603篇
  1997年   505篇
  1996年   606篇
  1995年   549篇
  1994年   535篇
  1993年   536篇
  1992年   491篇
  1991年   323篇
  1990年   438篇
  1989年   427篇
  1988年   380篇
  1987年   428篇
  1986年   383篇
  1985年   517篇
  1984年   491篇
  1983年   444篇
  1982年   464篇
  1981年   445篇
  1980年   353篇
  1979年   365篇
  1978年   329篇
  1977年   307篇
  1976年   269篇
  1975年   318篇
  1974年   243篇
  1973年   279篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
<正>悉尼理工大学工程和计算机系系馆位于市区的显赫地段,旨在重新给大学城市校区注入活力,成为悉尼商务中心南端的门户。建筑本体如同一件雕塑作品,迥然和周围的传统建筑风格相异。建筑地上14层,地下4层,设有先进的演讲厅、学术办公室、会议室、学习和研究实验室、营业咖啡厅、娱乐区、停车场,并在隔壁建筑旁设计自行车停靠处。  相似文献   
4.
5.
Machine Learning - We propose a set of highly scalable algorithms for the combinatorial data analysis problem of seriating similarity matrices. Seriation consists of finding a permutation of data...  相似文献   
6.
7.
Two main formation routes for thaumasite exist below 15 °C. One is the direct route from C–S–H reacting with appropriate carbonate, sulfate, Ca2+ ions and excess water. The other route is the woodfordite route from ettringite reacting with C–S–H, carbonate, Ca2+ ions and excess water, in which thaumasite arises through the intermediate formation of the solid solution woodfordite. The woodfordite route for thaumasite formation appears to be relatively quicker (although still slow) than the direct route, presumably because with the former the ettringite already has the octahedral [M(OH)6] units that can facilitate the critical change from [Al(OH)6]3− to [Si(OH)6]2− groupings. Both routes are mutually dependent on each other. The presence of magnesium salts can modify the path to thaumasite formation. High pressure might be able to stabilise [Si(OH)6]2− groupings and allow thaumasite to become formed above 15 °C. This possibility is discussed.  相似文献   
8.
At some point in their careers, clinicians who work or consult in forensic and correctional settings will almost certainly encounter individuals who exhibit psychopathic personality features. Because of the widespread use of this disorder to inform legal and clinical decision making, psychologists should be exceedingly familiar with the relevant research literature on this topic before venturing into these settings. This article reviews the empirical bases of several clinically relevant claims and assertions regarding psychopathy and concludes that many areas of research are decidedly more equivocal in their findings than is commonly perceived. Although there is much to be gained by assessing psychopathy in various contexts, clinicians need to be cautious about drawing overzealous and empirically questionable conclusions about an important disorder that also has great potential for abuse. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
9.
Using an integrated process of data and modeling in HRA   总被引:1,自引:0,他引:1  
The paper describes an approach taken to estimate the probabilities of failure associated with various railroad tasks to prevent accidents (principally collisions and derailments). These probabilities were estimated using an expert elicitation process that used partially relevant data available from a variety of databases and that were filtered and scaled to make them more directly relevant to the analyses being performed. Extensive qualitative studies were performed prior to the elicitation process to identify relevant contexts under which the tasks can be performed.  相似文献   
10.
The primary objective of this project is to identify gaps, whether real or perceived, that hinder effective groundwater management in New Zealand. These gaps show as gaps in information, gaps in implementation, gaps in technological and management tools, and gaps in understanding of fundamental processes. The secondary objective is to propose a management strategy to close the identified gaps. Several methods are used to meet these objectives: surveys distributed to selected staff in each regional council; the review of various written reports; the analysis of land-use databases; and private consultation within each regional council. Results show that groundwater management in New Zealand is generally reactionary with the main gaps being in strategic planning and national guidelines. Most gaps appear to be predominantly information and implementation issues. In some cases there are gaps in the understanding of fundamental processes within an aquifer system, including the long-term effects of land-use on groundwater quality. An adaptive management approach is suggested as a means of closing these gaps.  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