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   151823篇
  免费   6143篇
  国内免费   3182篇
电工技术   4205篇
技术理论   10篇
综合类   6253篇
化学工业   23333篇
金属工艺   8454篇
机械仪表   7245篇
建筑科学   8087篇
矿业工程   2553篇
能源动力   3124篇
轻工业   7730篇
水利工程   2360篇
石油天然气   4694篇
武器工业   534篇
无线电   17252篇
一般工业技术   24843篇
冶金工业   6158篇
原子能技术   1031篇
自动化技术   33282篇
  2024年   250篇
  2023年   1122篇
  2022年   1852篇
  2021年   2520篇
  2020年   2001篇
  2019年   1761篇
  2018年   16030篇
  2017年   15264篇
  2016年   11721篇
  2015年   3219篇
  2014年   3468篇
  2013年   4073篇
  2012年   7343篇
  2011年   13743篇
  2010年   12044篇
  2009年   9156篇
  2008年   10330篇
  2007年   11316篇
  2006年   3947篇
  2005年   4519篇
  2004年   3391篇
  2003年   3140篇
  2002年   2454篇
  2001年   1844篇
  2000年   1925篇
  1999年   2080篇
  1998年   1859篇
  1997年   1511篇
  1996年   1461篇
  1995年   1089篇
  1994年   1045篇
  1993年   722篇
  1992年   560篇
  1991年   462篇
  1990年   329篇
  1989年   262篇
  1988年   247篇
  1987年   149篇
  1986年   105篇
  1985年   80篇
  1984年   38篇
  1982年   40篇
  1968年   43篇
  1966年   42篇
  1965年   44篇
  1959年   37篇
  1958年   37篇
  1957年   36篇
  1955年   63篇
  1954年   68篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
Presuppositions of utterances are the pieces of information you convey with an utterance no matter whether your utterance is true or not. We first study presupposition in a very simple framework of updating propositional information, with examples of how presuppositions of complex propositional updates can be calculated. Next we move on to presuppositions and quantification, in the context of a dynamic version of predicate logic, suitably modified to allow for presupposition failure. In both the propositional and the quantificational case, presupposition failure can be viewed as error abortion of procedures. Thus, a dynamic assertion logic which describes the preconditions for error abortion is the suitable tool for analysing presupposition.  相似文献   
22.
23.
A multilayer theory has been developed for unidirectional/cross-ply unbalanced laminates subjected to surface shear tractions, using the assumption of plane strain. The analytical solution for the stress field in the laminate is obtained and it is shown that the stresses in each layer are in good agreement with the results of a three-dimensional finite element analysis. Approximate formulae for the analytical stresses are also derived for a laminate subjected to an offset distributed force at one end. The accuracy of this solution is shown by comparison with a three-dimensional finite element analysis.  相似文献   
24.
25.
26.
介绍了质量流量计的工作原理有应用效果。这种新型质量流量计精度高,稳定性好,示值计量简便,可直接显示质量、流量、介质温度、密度等,维护量低,但必须正确安装、使用,才能发挥其应有的作用。  相似文献   
27.
28.
Development of the Chinese Scientometric Indicators (CSI)   总被引:1,自引:0,他引:1  
Jin  Bihui  Zhang  Jiangong  Chen  Dingquan  Zhu  Xianyou 《Scientometrics》2002,54(1):145-154
We describe the Chinese Scientometric Indicators (CSI), an indicator database derived from the Chinese Science Citation Database (CSCD). Its design is supported by the Natural Sciences Foundation of China (NSFC). In this indicator database data of a statistical nature are organized and categorized leading to ranked lists and providing bases for comparisons among Chinese institutions and regions.  相似文献   
29.
Three interesterified vegetable oils (IVOs) prepared from palm, cottonseed, and olive oil, respectively, have been studied for application to Frankfurters. Beef fat (10%) was replaced by one of the IVOs at 20, 60 or 100%. Fatty acid composition of the lipid fraction in the Frankfurters and saturated/unsaturated ratios were established for all batches. We found that total or partial replacement of beef fat by IVOs did not lead to significant changes in appearance, colour, texture, flavour or sensory score. We conclude that IVOs may be successfully applied as beef fat substitutes in Frankfurters.  相似文献   
30.
This study empirically examined the organisational learning effects of the nonfinancial performance information provided by management accounting information systems (MAISs) under advanced manufacturing technology (AMT). In this study, a target costing system and the frequent and quick reporting of information were considered the facilitators of learning. First, we examined the relationships between AMT level and the amount of nonfinancial performance information produced by MAISs. The empirical results showed that there are significant positive relationships between the level of AMT and nonfinancial performance information. With a systems approach, we also proved the impact of the relationships among AMT levels, nonfinancial performance information and learning facilitators on the organisational performance of a firm. The results of our research suggest that under a high level of AMT, for the provision of information to result in an increase of performance through organisational learning, a target costing system must be introduced and a large amount of information should be provided frequently and quickly. The results of this study also showed that although AMT level may be low, fairly well-arranged facilitators and a moderately large amount of information may be necessary for the improvement of performance. In conclusion, effective organisational learning depends on the provision of relevant information as well as efficient learning support mechanisms.  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