全文获取类型
收费全文 | 3016篇 |
免费 | 55篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 20篇 |
综合类 | 11篇 |
化学工业 | 235篇 |
金属工艺 | 46篇 |
机械仪表 | 24篇 |
建筑科学 | 59篇 |
矿业工程 | 2篇 |
能源动力 | 35篇 |
轻工业 | 119篇 |
水利工程 | 12篇 |
石油天然气 | 4篇 |
武器工业 | 1篇 |
无线电 | 126篇 |
一般工业技术 | 224篇 |
冶金工业 | 1954篇 |
原子能技术 | 16篇 |
自动化技术 | 191篇 |
出版年
2023年 | 9篇 |
2022年 | 12篇 |
2021年 | 14篇 |
2020年 | 10篇 |
2019年 | 20篇 |
2018年 | 16篇 |
2017年 | 19篇 |
2016年 | 26篇 |
2015年 | 29篇 |
2014年 | 32篇 |
2013年 | 55篇 |
2012年 | 49篇 |
2011年 | 63篇 |
2010年 | 48篇 |
2009年 | 44篇 |
2008年 | 49篇 |
2007年 | 57篇 |
2006年 | 38篇 |
2005年 | 80篇 |
2004年 | 40篇 |
2003年 | 39篇 |
2002年 | 41篇 |
2001年 | 40篇 |
2000年 | 27篇 |
1999年 | 72篇 |
1998年 | 512篇 |
1997年 | 326篇 |
1996年 | 211篇 |
1995年 | 132篇 |
1994年 | 126篇 |
1993年 | 134篇 |
1992年 | 29篇 |
1991年 | 31篇 |
1990年 | 36篇 |
1989年 | 44篇 |
1988年 | 44篇 |
1987年 | 40篇 |
1986年 | 34篇 |
1985年 | 36篇 |
1984年 | 14篇 |
1983年 | 13篇 |
1982年 | 20篇 |
1981年 | 21篇 |
1980年 | 27篇 |
1979年 | 13篇 |
1978年 | 9篇 |
1977年 | 49篇 |
1976年 | 129篇 |
1975年 | 23篇 |
1974年 | 11篇 |
排序方式: 共有3079条查询结果,搜索用时 15 毫秒
81.
Gilliom Miles; Shaw Daniel S.; Beck Joy E.; Schonberg Michael A.; Lukon JoElla L. 《Canadian Metallurgical Quarterly》2002,38(2):222
Emotion regulation strategies observed during an age 3 1/2 frustration task were examined in relation to (a) angry affect during the frustration task, (b) child and maternal characteristics at age 1 1/2, and (c) indices of self-control at age 6 in a sample of low-income boys (Ns varied between 189 and 310, depending on the assessment). Shifting attention away from sources of frustration and seeking information about situational constraints were associated with decreased anger. Secure attachment and positive maternal control correlated positively with effective regulatory strategy use. Individual differences in strategy use predicted self-control at school entry, but in specific rather than general ways: Reliance on attention-shifting strategies corresponded with low externalizing problems and high cooperation; reliance on information gathering corresponded with high assertiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
82.
Determination of mechanical properties of slip cast, micro powder injection moulded and microcast high aspect ratio microspecimens 总被引:3,自引:0,他引:3
In a project of the German Research Council (DFG) Collaborative Research Centre (SFB) 499 Development, production and quality assurance of moulded micro-components made of metallic and ceramic materials [SFB03] three-point bending-specimens (dimension: 1.2 × 0.2 × 0.2 mm) made of slip cast [BAU02] or micro powder injection moulded ZrO2 [RUP03] as well as tensile specimens (dimension of the gauge length: 0.78 × 0.26 × 0.13 mm) made of the micro-cast AuAgCu-alloy Stabilor G [BAU03] were investigated with respect to their behaviour under quasi-static loading.The support of the Deutsche Forschungsgemeinschaft is gratefully acknowledged. The authors appreciate the co-operation of all the project partners within the SFB 499. 相似文献
83.
84.
Organic vapor analysis with microsensor arrays relies principally on two output parameters: the response pattern, which provides qualitative information, and the response sensitivity, which determines the limit of detection (LOD). The latter is used to define the operating limit in the low-concentration range, under the implicit assumption that, if a vapor can be detected, it can be identified and differentiated from other vapors on the basis of its response pattern. In this study, the performance of an array of four polymer-coated surface acoustic wave vapor sensors was explored using calibrated response data from 16 solvent vapors in Monte Carlo simulations coupled with pattern recognition analysis. The statistical modeling revealed that the ability to recognize a vapor from its response pattern decreases with decreasing vapor concentration, as expected, but also that the concentration at which errors in vapor recognition become excessive is well above the calculated LOD in most cases, despite the LOD being based on the least sensitive sensor in the array. These results suggest the adoption of a limit of recognition (LOR), defined as the concentration below which a vapor can no longer be reliably recognized from its response pattern, as an additional criterion for evaluating the performance of multisensor arrays. A generalized method for estimating the LOR is presented, as well as a means for improving the LOR via residual error analysis. 相似文献
85.
H. W. Hahnemann A. Naumann J. C. Rotta O. Scholze J. W. Beck G. Pfotzer W. Jellinghaus H. Schuh J. Wiedemann M. Hempel H. Schwieger H. Wittmeyer G. Vogelpohl H. Roos Ch. Tönnies E. G. Niemann W. Zimmermann W. Jost P. Stottmann M. Paul D. Stockburger 《Forschung im Ingenieurwesen》1966,32(6):196-200
Ohne Zusammenfassung
VDI 相似文献
86.
87.
Christoph Beck J?rg Nagel Peter Hevesi Georg Bretthauer 《International Journal of Wireless Information Networks》2012,19(3):163-172
Emerging applications in the medical field require body sensor networks to communicate in real-time in a very energy-efficient way. An example is the Artificial Accommodation System??a set of two small active medical implants aiming at restoring accommodation of the human eye??in which sensor data have to be exchanged continuously between both eyes. To achieve energy efficiency, it is essential to operate the radios with a very low duty cycle. Therefore, idle listening and general protocol overhead must be reduced as much as possible. In this paper, we present a relative time synchronization medium access control protocol (RTS-MAC), which keeps relative time synchronization between two or more sensor nodes in a very energy-efficient manner: RTS-MAC makes use of the periodic broadcast of regular data messages and exploits the inter-arrival times to predict future arrivals within tight boundaries. Thereby, no overhead is generated for synchronization purposes, and still, idle listening is reduced to a minimum, which solely depends on the short-term accuracy of the underlying clock systems. We implemented the proposed protocol using off-the-shelf components and employed the internal low-accuracy oscillators of the microcontrollers as clock sources. Thereby, we achieved very low duty cycles close to an ideal minimum. Further, our results indicate that through omitting external crystals in favor of a minimally larger battery, the battery life of a sensor node can be prolonged. 相似文献
88.
89.
90.
Diana Nanova Sebastian Beck Andreas Fuchs Tobias Glaser Christian Lennartz Wolfgang Kowalsky Annemarie Pucci Michael Kroeger 《Organic Electronics》2012,13(7):1237-1244
The degree of charge transfer in thin films of organic charge transfer (CT)-complexes, which are deposited via thermal evaporation, is examined via infrared-spectroscopy. We demonstrate a linear relationship between the shift in the excitation energy of the CN-stretching mode of CT-complexes with the acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ) and the charge transfer. The measured correlation corresponds very well with DFT calculations. For Na-TCNQ we observe a splitting in the peak of the CN-stretching mode, which can be explained by the coupling of two modes and was confirmed by the calculations. In CT-complexes with partial charge transfer the appearance of an electronic excitation is demonstrated. 相似文献