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   304693篇
  免费   27312篇
  国内免费   14350篇
电工技术   20177篇
技术理论   73篇
综合类   43645篇
化学工业   31321篇
金属工艺   10937篇
机械仪表   16972篇
建筑科学   45042篇
矿业工程   17341篇
能源动力   8969篇
轻工业   17138篇
水利工程   16755篇
石油天然气   12979篇
武器工业   2774篇
无线电   20555篇
一般工业技术   21807篇
冶金工业   17453篇
原子能技术   2917篇
自动化技术   39500篇
  2024年   3351篇
  2023年   3891篇
  2022年   5971篇
  2021年   6965篇
  2020年   7382篇
  2019年   5922篇
  2018年   5598篇
  2017年   6916篇
  2016年   8252篇
  2015年   9340篇
  2014年   18029篇
  2013年   15576篇
  2012年   20408篇
  2011年   21405篇
  2010年   17052篇
  2009年   18002篇
  2008年   16769篇
  2007年   21829篇
  2006年   20756篇
  2005年   18004篇
  2004年   15158篇
  2003年   13689篇
  2002年   11215篇
  2001年   9485篇
  2000年   7965篇
  1999年   6416篇
  1998年   4761篇
  1997年   4134篇
  1996年   3821篇
  1995年   3216篇
  1994年   2875篇
  1993年   2157篇
  1992年   1894篇
  1991年   1415篇
  1990年   1245篇
  1989年   1097篇
  1988年   872篇
  1987年   591篇
  1986年   453篇
  1985年   370篇
  1984年   354篇
  1983年   257篇
  1982年   219篇
  1981年   181篇
  1980年   145篇
  1979年   118篇
  1978年   71篇
  1977年   75篇
  1976年   58篇
  1975年   64篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Provides the biography of Dante Cicchetti and announces that he has received the APA Award for Distinguished Senior Career Contributions to Psychology in the Public Interest (2004) for his seminal role in bridging theory, research, and practice by fostering the emergence and coalescence of the field of developmental psychopathology. A selected bibliography is also provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
52.
Costs of ASTM E399 and ASTM E1921 tests, which were developed to determine the fracture toughness (KIc) and the ductile–brittle transition temperature of ferritic steels, respectively, are considered high and the procedures are also very complicated. In this study, a method, which is more cost‐effective and easier to carry out, is proposed.  相似文献   
53.
Safe and Economic Operation of Power Plants – Research Results in the Field of Materials, Design and Maintenance Components of power plants which undergo high temperatures are subjected to complex loading situations. The requirements on the used materials result from the special operation conditions of the plants and have to be adjusted to the steadily growing requirements on higher efficiency of the complete power plant as well as to those of safe and economic operation. The expenses for control and downtimes are directly connected with economic efficiency and availability. However, in case of new procedures or components it is not possible to revert to the existing know‐how. Different failure mechanisms than known before can occur. The same goes for the load situation. Therefore the knowledge base has to be extended to in‐advance or even parallely running scientific examinations that life assessment and maintenance strategies can be applied which guarantee the operational reliability and the efficiency of the plant. The main emphasis of these F&E works has to be put on condition monitoring based on actual operational data, the standard materials’ and component’s behaviour (deformation, damage and failure behaviour) in connection with design of components and the related material laws. In the framework of applied AVIF projects, following problems are handled:. – qualification of materials by determinating parameters related to practise. – optimal design of components by making available material laws and numerical tools. – economic manufacturing of components by qualifying processing methods such as welding. – The results can be transferred to concepts for safe and economic operation of power plants, especially for newly introduced materials for which there is no operational experience available.  相似文献   
54.
In a series of experiments, participants were required to keep track of 1 or 2 working memory (WM) objects, having to update their values in 80% of the trials. Updating cost, defined as the difference between update and non-update trials, was larger when 2 objects were involved compared with when there was only 1 object was involved. This finding was interpreted as evidence that the updating process encompasses both objects in WM, even though only 1 of them is actually updated. This feature of WM updating is limited to objects defined as "updateable," throughout the trial sequence. The results are explained by the need to reprogram the phonological loop when updating or the need for desynchronization followed by resynchronization of WM contents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
55.
介绍了我院资源开发工程系的历史、现状和前景,指出了面临的问题及摆脱困境的途径。  相似文献   
56.
全文围绕树立和落实科学发展观这一主题 ,研究和探索如何在新时期、新阶段进一步做好国土资源管理工作的新思路、新途径和新方法。提出要进一步加强国土资源宏观管理 ,更好地为甘肃省经济社会的协调、可持续发展提供保障服务。  相似文献   
57.
人类聚居环境学对于居住区规划设计的启示   总被引:1,自引:0,他引:1  
高向鹏 《山西建筑》2007,33(18):24-25
以人类聚居环境学的研究方法从若干方面对目前的居住区规划设计进行了一定的探讨,分析规划设计及建设方面目前存在的主要问题,提出以人类聚居环境学为指导的居住区规划设计理念。  相似文献   
58.
Distinctive features of architectural-structural organization and use of memory networks are considered with the aim of choosing an optimal configuration in designing distributed computer systems.  相似文献   
59.
对职业教育的大众性问题进行了论述、实证分析和理论、政策、改革等思考。  相似文献   
60.
Failure analysis of hollow glasses The failure analysis is very important to clarify damages of hollow glasses. Damages of glass bottle through over pressure are very often linked with damages to persons. This is the reason why the causal research is from particular importance. Different surface characteristics of glass fragments as well as the fracture pattern give hints to the direction of the crack, the stress just before breakage and the reason of stress. A reconstruction of the bottle is a further helpful instrument for cause studies. The difference of the various characteristics of the surface will be explained. Further on there will be discussed different reasons and mechanism of fracture.  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