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   282246篇
  免费   26030篇
  国内免费   13178篇
电工技术   19470篇
技术理论   66篇
综合类   38266篇
化学工业   30177篇
金属工艺   10528篇
机械仪表   15426篇
建筑科学   41492篇
矿业工程   15729篇
能源动力   10487篇
轻工业   15740篇
水利工程   14763篇
石油天然气   12041篇
武器工业   2657篇
无线电   18417篇
一般工业技术   20954篇
冶金工业   16051篇
原子能技术   3086篇
自动化技术   36104篇
  2024年   3423篇
  2023年   3771篇
  2022年   5774篇
  2021年   6869篇
  2020年   7260篇
  2019年   6223篇
  2018年   5665篇
  2017年   6705篇
  2016年   7898篇
  2015年   8568篇
  2014年   15629篇
  2013年   14354篇
  2012年   18650篇
  2011年   19706篇
  2010年   15573篇
  2009年   16225篇
  2008年   15125篇
  2007年   19783篇
  2006年   18763篇
  2005年   16364篇
  2004年   13965篇
  2003年   12564篇
  2002年   10432篇
  2001年   8761篇
  2000年   7367篇
  1999年   6059篇
  1998年   4530篇
  1997年   3998篇
  1996年   3708篇
  1995年   3120篇
  1994年   2784篇
  1993年   2074篇
  1992年   1848篇
  1991年   1380篇
  1990年   1204篇
  1989年   1060篇
  1988年   844篇
  1987年   591篇
  1986年   441篇
  1985年   364篇
  1984年   346篇
  1983年   247篇
  1982年   226篇
  1981年   168篇
  1980年   137篇
  1979年   116篇
  1978年   63篇
  1977年   72篇
  1976年   56篇
  1975年   56篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
回顾了体制、制度的改革和科学技术的发展给十局带来的巨大变化,就十局当前改革任务从理顺产权关系、进一步完善内部治理结构、继续深化三项制度改革、实施科教兴局战略等四个方面提出了看法和意见。  相似文献   
13.
14.
15.
Buffalo milk Cheddar cheese samples of different ages were analysed for compositional attributes (CA), ripening indices (RI) and Instron Textural Profile (ITP). All samples were compositionally alike, except for pH and salt-in-moisture (SM) contents. RI showed significant variations. CA and RI showed highly significant correlations within themselves and with each other, except for moisture with pH, SM with moisture, MNFS, Fat and FDM and Fat with MNFS. The ITPs of cheeses showed significant variations and had highly significant intercorrelations indicating their interdependence. CA (except moisture and MNFS) and RI showed a highly significant correlationship with ITPs. Moisture content showed a highly significant correlationship with all ITPs, except cohesiveness and springiness, where it was significant. MNFS content showed significant correlations only with hardness and brittleness. Stepwise regression analysis revealed that MI was the most predominant factor influencing cheese texture, followed by pH, SM, FDM and TVFA. Knowing Ca and RI, the textural properties of cheeses can be forecast through mathematical equations. Similarly the age of cheese can also be predicted if RI and/or textural properties are known.  相似文献   
16.
What has become known as Community Operational Research has been around in the UK for many years. The election of Jonathan Rosenhead as President of the UK OR Society in 1986–87 was the catalyst for bringing together and expanding activities which had been carried out largely by individuals working in isolation on a voluntary basis. The following five years have seen the establishment of the Community OR Unit at Northern College, the Centre for Community OR at Hull University and the Community OR Network, which supports the activities of volunteer OR workers across the UK. This paper reviews the range and types of work which have been undertaken by various practitioners. An assessment of the success of community OR is made and a number of issues which have arisen are discussed. Finally, given the diverse nature of community OR, its practice and practitioners, there is some discussion about the future of the area.  相似文献   
17.
The hydrolysis of isocyanic acid in the gaseous phase has been investigated at temperatures between 553 and 613 K by mass spectrometry and evaluated to obtain the corresponding kinetic data. The reaction order and reaction constant have been determined. Finally, the influence of water on the catalysed formation of melamine from isocyanic acid under the operating conditions employed has been investigated in order to determine whether there is a need to try the process gas.  相似文献   
18.
19.
In order to control a project, construction management requires project information. This is obtained through accounting, estimating, cost management and scheduling functions which produce project reports. These reports are best obtained by subdividing the project into small parts. The ways in which each of these functions subdivides a project in order to produce its reports is discussed, together with a means of interrelating this information with a technique known as the work breakdown structure.  相似文献   
20.
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