全文获取类型
收费全文 | 151823篇 |
免费 | 6143篇 |
国内免费 | 3182篇 |
专业分类
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 |
出版年
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.
Jan van Eijck 《Formal Aspects of Computing》1994,6(1):766-787
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
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.
J-M Choe 《欧洲信息系统杂志》2002,11(2):142-158
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