全文获取类型
收费全文 | 30123篇 |
免费 | 3283篇 |
国内免费 | 605篇 |
专业分类
电工技术 | 2163篇 |
技术理论 | 1篇 |
综合类 | 1213篇 |
化学工业 | 10548篇 |
金属工艺 | 1098篇 |
机械仪表 | 1178篇 |
建筑科学 | 1565篇 |
矿业工程 | 523篇 |
能源动力 | 501篇 |
轻工业 | 2544篇 |
水利工程 | 358篇 |
石油天然气 | 835篇 |
武器工业 | 93篇 |
无线电 | 2018篇 |
一般工业技术 | 4459篇 |
冶金工业 | 956篇 |
原子能技术 | 188篇 |
自动化技术 | 3770篇 |
出版年
2023年 | 824篇 |
2022年 | 653篇 |
2021年 | 1172篇 |
2020年 | 1048篇 |
2019年 | 906篇 |
2018年 | 953篇 |
2017年 | 807篇 |
2016年 | 988篇 |
2015年 | 1265篇 |
2014年 | 1440篇 |
2013年 | 2069篇 |
2012年 | 1314篇 |
2011年 | 1210篇 |
2010年 | 1471篇 |
2009年 | 1611篇 |
2008年 | 1109篇 |
2007年 | 1098篇 |
2006年 | 970篇 |
2005年 | 862篇 |
2004年 | 611篇 |
2003年 | 662篇 |
2002年 | 556篇 |
2001年 | 499篇 |
2000年 | 425篇 |
1999年 | 450篇 |
1998年 | 520篇 |
1997年 | 452篇 |
1996年 | 498篇 |
1995年 | 395篇 |
1994年 | 333篇 |
1993年 | 349篇 |
1992年 | 248篇 |
1991年 | 206篇 |
1990年 | 218篇 |
1989年 | 220篇 |
1988年 | 170篇 |
1987年 | 187篇 |
1986年 | 202篇 |
1985年 | 176篇 |
1984年 | 178篇 |
1983年 | 184篇 |
1982年 | 163篇 |
1981年 | 206篇 |
1980年 | 170篇 |
1979年 | 172篇 |
1975年 | 202篇 |
1974年 | 189篇 |
1973年 | 367篇 |
1972年 | 213篇 |
1968年 | 153篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Our emphasis in this paper has been on the knowledge-based and cognitive issues pertinent for improved interactions between workers and manufacturing computer systems. We believe that these techniques are as necessary and applicable to manufacturing as to any other vocation, especially as the difference in collar color of shop people becomes less noticeable in their increasing role as knowledge workers. 相似文献
32.
The transition from basic automation to flexible manufacturing is an expensive and tedious procedure. It requires meticulous planning and almost clairvoyant forecasting to insure that the initial flexibility obtained is sufficient to allow growth and expansion in the future. This paper will suggest a systematic and methodological approach to achieve optimal flexibility and describe the present results of its application to an ongoing system transformation.
Conclusions based on existing levels of completion are presented along with identification of critical and non critical flexibility requirements. The considerations and steps taken are summarized in a procedural format which may then be applied to a wide variety of system transformations. 相似文献
33.
M. Schedl Dipl.-Ing. E. Pampalk Dipl.-Ind. G. Widmer Univ.-Prof. Dr. 《e & i Elektrotechnik und Informationstechnik》2005,122(7-8):232-237
In this paper we present a general approach to the automatic content-based organization and visualization of large digital music collections. The general methodology consists in extracting musically and perceptually relevant patterns (‘features’) from the given audio recordings (e.g., mp3 files), using topology-preserving data projection methods to map the entire music collection onto two-dimensional visualization planes (possibly in a hierarchical fashion), and using a new display metaphor (the ‘Islands of Music’) to display the inherent structure of the music collection to the user. It is shown how arbitrary meta-data can be integrated into the visualization process, and how similarity according to different viewpoints can be defined and exploited. The basic methodology is briefly described, three prototype systems are presented, and a general discussion of the practical application possibilities of such technologies is offered. 相似文献
34.
Many organisations suspect that their internal security threat is more pressing than their external security threat. The internal threat is predominantly the result of poor user security behaviour. Yet, despite that, security awareness programmes often seem more likely to put users to sleep than to improve their behaviour. This article discusses the influences that affect a user's security behaviour and outlines how a well structured approach focused on improving behaviour could be an excellent way to take security slack out of an organisation and to achieve a high return for a modest, low-risk investment. 相似文献
35.
Jens‐Peter Heinß Dr. 《真空研究与实践》2007,19(5):20-23
Hydrogen free amorphous carbon coatings ‐ deposited with plasma‐activated high‐rate evaporation By using the technology of the plasmaactivated electron beam evaporation we deposited hydrogen free amorphous carbon coatings with deposition rates of up to 100 μm/h. The results of the mechanical and tribological investigations show the potential of these layers for the use in case of wear resistance. Hardnesses of up to 16GPa were proved. The actual state of the characterisation of the coatings is described and the outlook onto possibilities of further optimisation is given. 相似文献
36.
D. Surek Prof. Dr.‐Ing. habil. 《真空研究与实践》2007,19(3):32-36
Helium leak test devices for the quality inspection of housings for vacuum compressors The well‐known and wide‐spread helium leak test method is a safe and fast quality testing method for construction units of any kind. Due to its safe examination and the short time of examination it is predominantly inserted into automated production lines as e.g. in the automobile supporting industry up to the examination by Airbags and rims of wheel. Likewise in addition, for the construction units, machines and devices of the vacuum engineering. From this the demand results simple and in particular economical devices for the helium leak test of construction units with small numbers of items of under 200 pieces per day. For these manufacturing profiles economical ways for the helium leak test are pointed out. 相似文献
37.
38.
39.
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
40.