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   123815篇
  免费   11142篇
  国内免费   7665篇
电工技术   10313篇
技术理论   27篇
综合类   13810篇
化学工业   3636篇
金属工艺   1442篇
机械仪表   6170篇
建筑科学   15125篇
矿业工程   4411篇
能源动力   2565篇
轻工业   2494篇
水利工程   5471篇
石油天然气   4534篇
武器工业   1061篇
无线电   14212篇
一般工业技术   6106篇
冶金工业   5805篇
原子能技术   1177篇
自动化技术   44263篇
  2024年   180篇
  2023年   1183篇
  2022年   2475篇
  2021年   3272篇
  2020年   3505篇
  2019年   2593篇
  2018年   2384篇
  2017年   3062篇
  2016年   3659篇
  2015年   4204篇
  2014年   9493篇
  2013年   7911篇
  2012年   9090篇
  2011年   9809篇
  2010年   7604篇
  2009年   7839篇
  2008年   8307篇
  2007年   9785篇
  2006年   8320篇
  2005年   7281篇
  2004年   6271篇
  2003年   5455篇
  2002年   4236篇
  2001年   3143篇
  2000年   2527篇
  1999年   1861篇
  1998年   1338篇
  1997年   1052篇
  1996年   858篇
  1995年   770篇
  1994年   582篇
  1993年   429篇
  1992年   292篇
  1991年   266篇
  1990年   195篇
  1989年   194篇
  1988年   150篇
  1987年   97篇
  1986年   124篇
  1985年   156篇
  1984年   127篇
  1983年   146篇
  1982年   80篇
  1981年   52篇
  1980年   30篇
  1979年   44篇
  1978年   15篇
  1977年   32篇
  1976年   16篇
  1959年   16篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
在线学习已逐渐成为高职院校一种重要学习形式,该领域也成为当前研究热点之一。对在线学习进行介绍,同时对大数据技术在在线学习平台中的应用进行分析,重点对五年制高职护生在线学习行为要素进行研究分析,为更好地开展在线学习评价提供参考,促进高职院校更好地开展在线学习,提高在线学习质量。  相似文献   
32.
With the development of 5G, big data, cloud computing, IOT, mobile Internet and other information technologies of new generation, the design of forestry information system establishes a new mode of forestry development integrating three-dimensional perception, collaborative management and internal and external services by means of perception, IOT and intelligence. Intelligent forestry system is a comprehensive information management system integrating forest management, intelligent forestry business management, green maintenance management and emergency command and dispatching management. Based on the specific project practice, this paper puts forward the overall framework design scheme and management platform design scheme of intelligent forest- ry.  相似文献   
33.
This paper analyzes the problems existing in the teaching of data structure course, and puts forward the reform from the as- pects of strengthening basic programming, visualized explanation of abstract theory, combination of C++, Java programming, ratio- nal use of online platform, and stratification of exercises, aiming at improving students' practical ability, learning interest and self- confidence.  相似文献   
34.
The importance of data processing and storage to colleges and universities is increasing day by day. However, many colleg- es and universities are still at a low level in the process of data recovery and application reduction, and its RPO and RTO indicators need to be improved by adopting the dual active technology architecture. Taking the Guizhou Vocational Technology Institute as an example, this paper focuses on the analysis of the architecture of the double active data center, aiming at the actual situation of the college, and gradually realizes multiple disaster recovery level of data level, application level and business level.  相似文献   
35.
随着高校扩招,应届毕业生人数逐年增长,就业压力不容小觑。针对就业难的问题,进行招聘网站数据分析,挖 掘出岗位所需技能,再结合学生在校时所学课程,二者对比,就能很好地给学生推荐合适的工作,并且给学校专业人才培养方 案中的岗位职业定位  相似文献   
36.
伴随着互联网+的风生水起,信息量暴增的大数据时代应运而来,"网络原住民"大学生不可避免、理所当然地处于大数据洪流之中,但也为其个人隐私保护带来了极大挑战。文章针对大数据带来的安全隐私问题,指出大学生个人隐私泄露的可能原因,提出可以采取的个人隐私保护措施,给出大数据时代隐私保护几种技术,期望能给相关人士提供有效参考。  相似文献   
37.
Lack of constraint-free crane path planning is one of the critical concerns in the dynamic on-site assembly process of prefabrication housing production (PHP). For decades, researchers and practitioners have endeavored to improve both the efficiency and safety of crane path planning from either static environment or re-planning the path when colliding with constraints or periodically updating the path in the dynamic environment. However, there is a lack of approach related to the in-depth exploration of the nature of dynamic constraints so as to assist the crane operators in making adaptive path re-planning decisions by categorizing and prioritizing constraints. To address this issue, this study develops the smart work packaging (SWP)-enabled constraints optimization service. This service embraces the core characteristics of SWP, including adaptivity, sociability, and autonomy to achieve autonomous initial path planning, networked constraints classification, and adaptive decisions on path re-planning. This service is simulated and verified in the BIM environment, and it is found that SWP-enabled constraints optimization service can generate the constraint-free path when it is necessary.  相似文献   
38.
39.
In the water distribution network (WDN), although the water demand of the node is changing constantly, the water quantity and water pressure of the node need to be met at each moment. To realize energy saving and consumption reduction, it is proposed to control the nodal water head of WDN in an appropriate narrow range. The frequent large fluctuation of the water demand, which may lead the water pressure exceed the expected range, increases the difficulty of the zone control. To realize optimized WND control, a novel zone predictive control is proposed, where two switching cases are considered. The switching condition is whether there are feasible solutions to keep the pressure within the expected region over the prediction horizon. When the condition is satisfied, the controller minimizes the variation of inputs with constraints of pressure range for ensuring the tank level staying within the expected zone and obtaining optimal economic cost. When the current pressure is out of the expected region or the condition is not satisfied due to the large variation of water demand, a reference trajectory of outputs is introduced, which is combined with the inputs as an optimization variable, and the constraints of expected zone are moved from the output to the introduced reference trajectory. Through minimizing the distance between reference trajectory and output, the controller will keep the tank level from deviating too far from the expected zone and will drive the tank level rapidly into the expected zone once the tank level exceeds the expected range. An application of the proposed zone MPC to WDN in Shinan District of Shanghai is given to illustrate its effectiveness.  相似文献   
40.
Improvements in information and communications technologies (ICTs) have facilitated the inclusion of the sharing economy (SE) in societies more than ever. In the aftermath of recent disasters, the SE played significant roles to help the affected people and support official responders. However, the literature has not effectively explored these roles, and thus, no framework can support the systematic inclusion of the SE in disasters management. This paper aims to address the gap through a two-stage exploratory research approach. First, we conduct a systematic literature review to identify the extent to which the SE is taken into consideration in disasters. After that, we investigate the role of three Iranian SE-based companies that were involved in the 2019 Iran floods response. We collect empirical data by conducting semi-structured interviews and reviewing official reports.Our findings indicate that very few studies discuss the different roles of the SE in disasters, although SE companies have often provided effective solutions to address critical post-disaster logistics challenges. Four research propositions are presented to describe emerging roles for SE companies. The contribution of our study is twofold. First, our research identifies the different roles that the SE could play in disasters and therefore, brings a new perspective to the literature. Second, the study suggests opportunities for collaboration and partnership models from the point of origin to delivery that can support coordination and logistics in disasters.  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