全文获取类型
收费全文 | 4500篇 |
免费 | 139篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 72篇 |
综合类 | 29篇 |
化学工业 | 1347篇 |
金属工艺 | 112篇 |
机械仪表 | 87篇 |
建筑科学 | 274篇 |
矿业工程 | 8篇 |
能源动力 | 80篇 |
轻工业 | 354篇 |
水利工程 | 25篇 |
石油天然气 | 1篇 |
无线电 | 264篇 |
一般工业技术 | 826篇 |
冶金工业 | 609篇 |
原子能技术 | 39篇 |
自动化技术 | 522篇 |
出版年
2022年 | 49篇 |
2021年 | 56篇 |
2020年 | 48篇 |
2019年 | 57篇 |
2018年 | 66篇 |
2017年 | 57篇 |
2016年 | 96篇 |
2015年 | 82篇 |
2014年 | 114篇 |
2013年 | 208篇 |
2012年 | 171篇 |
2011年 | 257篇 |
2010年 | 187篇 |
2009年 | 169篇 |
2008年 | 198篇 |
2007年 | 189篇 |
2006年 | 132篇 |
2005年 | 160篇 |
2004年 | 135篇 |
2003年 | 106篇 |
2002年 | 88篇 |
2001年 | 87篇 |
2000年 | 85篇 |
1999年 | 91篇 |
1998年 | 109篇 |
1997年 | 93篇 |
1996年 | 81篇 |
1995年 | 79篇 |
1994年 | 72篇 |
1993年 | 79篇 |
1992年 | 70篇 |
1991年 | 53篇 |
1990年 | 76篇 |
1989年 | 47篇 |
1988年 | 47篇 |
1987年 | 53篇 |
1986年 | 43篇 |
1985年 | 67篇 |
1984年 | 60篇 |
1983年 | 49篇 |
1982年 | 57篇 |
1981年 | 45篇 |
1979年 | 43篇 |
1978年 | 45篇 |
1977年 | 67篇 |
1976年 | 45篇 |
1975年 | 42篇 |
1974年 | 56篇 |
1972年 | 43篇 |
1970年 | 40篇 |
排序方式: 共有4649条查询结果,搜索用时 15 毫秒
11.
Prof. Dr.-Ing. Klaus Gersten 《Forschung im Ingenieurwesen》1992,58(5):113-118
Zusammenfassung Es wird ein allgemeines Widerstandsgesetz für Stufendiffusoren hergeleitet, bei dem die Widerstandszahl den Zusatzverlust
gegenüber den Verlusten der bis zum Kontursprung reichenden fiktiven Kanal- bzw. Rohrstr?mungen in der Zu- und Abstr?mung
beschreibt. Unter vereinfachenden Annahmen reduziert sich dieses Gesetz auf die bekannte Carnot-Formel. Insbesondere wird
dabei der Anteil des Zusatzverlustes, der vom Unterdruck an der Stufe und von der Wandschubspannungs?nderung unmittelbar hinter
der Stufe herrührt, vernachl?ssigt. Die Berücksichtigung dieses Anteils führt zu einem gegenüber der Carnot-Formel verbesserten
Widerstandsgesetz.
Herrn Prof. Dr.-Ing. Martin Fiebig zum 60. Geburtstag 相似文献
12.
Klaus Lorenz 《化学,工程师,技术》1992,64(4):341-348
13.
Joern Ploennigs Mario Neugebauer Klaus Kabitzsch 《International Journal on Software Tools for Technology Transfer (STTT)》2006,8(6):607-620
Large technical systems need to be designed both reliable and efficient. Specialized design tools offer therefore a simplified,
abstract design and extend details autonomously in the background. Analytic and simulation based models could improve the
quality by testing and dimensioning the design before implementation, but setting up the necessary models is time-consuming
and expensive. Therefore many developers ask for analysis tools which are able to create their models from the available information
in the design tools. This paper presents such an automated modeling approach basing on an existing design database at the
example of a network analysis for building automation fieldbuses. The process of automated modeling is unfolded, and the potentials
and limitations are discussed. 相似文献
14.
Klaus G. Johannsen 《International Journal of Satellite Communications and Networking》1987,5(3):233-247
Several domestic satellite systems have been more than 10 years in operation. During this time, the world has experienced a dramatic growth in communication. While the demand for more telephony and data circuits and television channels is still on the rise, new methods of signal transmission and circuit compression have been developed which may balance or reduce the need for more satellite trunk capacity. And while whole national networks are converting to digital transmission, new transmission media like optical fibre, are finding application, and may take over some of the heavy traffic routes previously carried by satellite. On the other side, business data communication between roof-top terminals, thin route traffic to remote users, television distribution by direct satellite broadcasting are becoming more popular and satellite land mobile communication may soon be a reality. Thus the domestic satellite's role appears to be slowly changing towards thin route and mobile traffic and DBS-type distribution and perhaps even radio position determination. System planners are adapting to the new trends in satellite communication and are trying to accommodate the various service payloads on a single satellite. This article discusses some aspects of the emerging multi-purpose domestic satellite, which carries fixed and mobile services, TV direct broadcasting and radio position determination, in view of network digitalization, network expansion, circuit compression, synchronization. The discussion centres on transponder supply and demand, satellite replenishment, Ku-band vs. C-band for TV direct satellite broadcasting, choice of modulation/multiple access for mobile communication, and expected accuracy in radio position determination. 相似文献
15.
16.
Thomas Stieglitz Martin Schuettler Klaus Peter Koch 《IEEE engineering in medicine and biology magazine》2005,24(5):58-65
In the following article, the technologies to fabricate polyimide-based thin and flexible substrates with monolithically integrated electrode arrays and printed circuit boards (PCB) for hybrid electronic assemblies as well as an assembling technique that connects bare electronic dice with flexible PCBs are presented. The concept of modular, flexible biomedical microsystems as neural prostheses is introduced in general and described in detail in three examples. A cuff electrode with integrated multiplexer circuitry and standard implantable cables represents the combination of microtechnology with precision mechanics; a sieve electrode used as an implant in peripheral nerve regeneration studies demonstrates the next level of integration density but still uses a cable connection; and last, joint effort to fabricate the demonstrator of a vision prosthesis that is completely implantable in the eye with a wireless link for energy supply and data transmission is presented. System design, hybrid assembling technology, and flexible multilayer encapsulation using parylene and silicone rubber are the key components for creating a new generation of neural prostheses for complex and challenging new applications. 相似文献
17.
Liisa Lhteenmki Klaus Grunert
ydis Ueland Annika strm Anne Arvola Tino Bech-Larsen 《Food quality and preference》2002,13(7-8):523-533
European consumers, in general, have negative attitudes towards the use of gene technology in food production. The objective of this study was to examine whether taste and health benefits influence the acceptability of genetically modified (gm) products when they are presented as real product alternatives. Consumers in Denmark, Finland, Norway and Sweden (n=738) assessed two cheeses: one was labelled as genetically modified (preferred in an earlier product test) and the other as conventional (neutral in an earlier product test). A smaller control group received two cheeses with blind codes. Labelling decreased consumers' intentions to buy the originally preferred gm-labelled cheese, but still the intentions were at the same level with the conventionally labelled option. Participants chose two gm cheeses out of five possible when given the option to take cheese home after tasting. Intentions to buy gm cheese could best be explained by respondents' attitudes towards gene technology and perceived taste benefits. General health interest was also a reinforcer of intentions for gm cheese with reduced fat content. 相似文献
18.
19.
Works of adhesion at the carbon fiber-liquid interface determined using a modified wetting technique
Works of adhesion WSL between aqueous solutions with pH values in the range from 1 to 14 and carbon fibers from different sources, which were additionally treated in an inert atmosphere or in oxygen, were measured by use of a microbalance. These works of adhesion WSL were found to show distinct stepwise dependencies on the pH value. The works of adhesion WSL are attributed to dispersion interactions WSL1 and various acid-base interactions wslab—in the latter case between the acidic and basic surface groups of carbon and the various basic and acidic aqueous solutions. 相似文献
20.