全文获取类型
收费全文 | 3645篇 |
免费 | 17篇 |
专业分类
电工技术 | 29篇 |
化学工业 | 78篇 |
金属工艺 | 12篇 |
机械仪表 | 17篇 |
建筑科学 | 46篇 |
矿业工程 | 1篇 |
能源动力 | 20篇 |
轻工业 | 76篇 |
石油天然气 | 3篇 |
无线电 | 132篇 |
一般工业技术 | 91篇 |
冶金工业 | 3059篇 |
原子能技术 | 4篇 |
自动化技术 | 94篇 |
出版年
2023年 | 5篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 10篇 |
2017年 | 5篇 |
2016年 | 10篇 |
2015年 | 14篇 |
2014年 | 12篇 |
2013年 | 27篇 |
2012年 | 18篇 |
2011年 | 27篇 |
2010年 | 22篇 |
2009年 | 19篇 |
2008年 | 20篇 |
2007年 | 24篇 |
2006年 | 25篇 |
2005年 | 21篇 |
2004年 | 16篇 |
2003年 | 20篇 |
2002年 | 15篇 |
2001年 | 23篇 |
2000年 | 21篇 |
1999年 | 111篇 |
1998年 | 887篇 |
1997年 | 501篇 |
1996年 | 348篇 |
1995年 | 195篇 |
1994年 | 179篇 |
1993年 | 195篇 |
1992年 | 27篇 |
1991年 | 41篇 |
1990年 | 49篇 |
1989年 | 55篇 |
1988年 | 55篇 |
1987年 | 50篇 |
1986年 | 39篇 |
1985年 | 45篇 |
1984年 | 10篇 |
1983年 | 17篇 |
1982年 | 21篇 |
1981年 | 23篇 |
1980年 | 41篇 |
1979年 | 14篇 |
1978年 | 17篇 |
1977年 | 106篇 |
1976年 | 232篇 |
1975年 | 9篇 |
1973年 | 4篇 |
1972年 | 6篇 |
1955年 | 4篇 |
排序方式: 共有3662条查询结果,搜索用时 15 毫秒
81.
Capillary flow studies on bulk molding compound (BMC) using an instrumented injection-molding machine are reported. The significance of extensional flow effects with fiber-reinforced materials is emphasized. The extensional flow behavior in converging dies is modeled, and a means of evaluating both extensional and shear viscosity from capillary flow data is proposed. Methods of correcting results for the effect of deformation heating are discussed. The shear and extensional flow behavior of BMC in the temperature region 18 to 58°C can be fitted to a simplified Arrhenius Law. 相似文献
82.
Christopher H. Braithwaite Jiri Pachman Jiri Majzlik David M. Williamson 《Propellants, Explosives, Pyrotechnics》2012,37(5):614-620
A series of gap‐test experiments were conducted in accordance with the EMTAP Test 22a guidelines to characterize the stress output from a donor charge of ROWANEX 3601. Forty eight successful gap‐tests were conducted at the University of Pardubice in addition to two supporting plate impact experiments performed at the Cavendish Laboratory, University of Cambridge. The experiments indicated that there are two principal release mechanisms, which produce the observed reduction in stress with increasing gap distance. The first is attenuation of the input wave, something which is expected during explosive loading due to the triangular nature of the loading pulse. The second is an interaction between the input wave and lateral release waves from the edges of the test sample at the measurement station. Attenuation of the input wave due to visco‐elastic loss in the PMMA “gap” used is likely to be less significant than these other two release mechanisms. The data generated by this investigation forms a robust dataset that gives an accurate calibration for ROWANEX 3601 for users of the EMTAP 22a test procedure. In addition the data represent an excellent “set problem” for those developing and wishing to validate, computational models of similar physical phenomena. 相似文献
83.
Julie Hatfield Ann Williamson Shauna Sherker Rob Brander Andrew Hayen 《Accident; analysis and prevention》2012
The objective of this research was to evaluate a campaign to improve beachgoer recognition of calm-looking rip currents, known to contribute to surf drowning. Posters, postcards, and brochures conveying the message “Don’t get sucked in by the rip” were distributed in an intervention area. Beachgoers were interviewed in this and a similar control area one year before and immediately after the intervention (respective response rates: 69.9% and 82.3%), Consenting respondents were sent follow-up questionnaires after approximately 6 months and 55% responded. In the intervention area, 28.8% of post-intervention, and 57.2% of follow-up respondents, had seen our campaign. At post-intervention, intervention respondents demonstrated improvement (relative to baseline) in intentions to swim away from a calm-looking rip, ability and confidence in identifying a rip, intention never to swim at unpatrolled beaches, and responses to being caught in a rip, compared to the control respondents. Similar improvements were observed post-intervention for respondents in the intervention area who had seen our campaign (relative to those who had not), and at 6 month follow-up for intervention respondents (relative to control respondents). The relatively brief print-based campaign was effective in warning beachgoers about calm-looking rips. 相似文献
84.
85.
86.
87.
Message passing notations (language, package, etc.) typically include some form of asynchronous or synchronous invocation. In a synchronous invocation, the invoker waits for the invocation's servicer to pass back results. Some message passing notations also include early reply or deferred reply (including forwarding), which alters how and when the servicer passes back its results; this additional flexibility is useful in realistic applications. It is well known how to transform a synchronous invocation into only asynchronous invocations. This paper extends such transformations to early reply and forward. This paper also describes the use of these transformations within the implementations of programming notations. Using the transformation simplifies the implementation without significantly affecting run‐time costs. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
88.
Zhuyun Li Cory M. Dungan Bradley Carrier Todd C. Rideout David L. Williamson 《Lipids》2014,49(12):1193-1201
The mammalian target of rapamycin (mTOR) signaling pathway is hyperactive in liver, adipose and skeletal muscle tissues of obese rodents. Alpha‐lipoic acid (αLA) has been well accepted as a weight‐loss treatment, though there are limited studies on its effect on mTOR signaling in high‐fat fed, obese rodents. Therefore, the goal of this study was to determine mTOR signaling and oxidative protein alterations in skeletal muscle of high‐fat fed, obese rats after αLA supplementation. Phosphorylation of the mTOR substrate, eukaryotic initiation factor (eIF) 4E‐binding protein 1 (4E‐BP1) and eIF4B were significantly reduced (p < 0.05) in muscle from αLA supplemented rats. Activation of AMP‐activated protein kinase (AMPK), an mTOR inhibitory kinase, was higher (p < 0.05) in the αLA group. Protein expression of markers of oxidative metabolism, acetyl CoA carboxylase (ACC), cytochrome c oxidase IV (COX IV), peroxisome proliferator‐activated receptor (PPAR), and PPAR gamma coactivator 1‐alpha (PGC‐1α) were significantly higher (p < 0.05) after αLA supplementation compared to non‐supplemented group. Our findings show that αLA supplementation limits the negative ramifications of consuming a high fat diet on skeletal muscle markers of oxidative metabolism and mTORC1 signaling. 相似文献
89.
90.
The paper shows how the techniques of generalized harmonic analysis may be used to simulate the steady-state behavior of a multiphase cage induction motor with any form of open-circuit or short-circuit fault in the stator winding. The analytical model is verified using a four-pole machine with a 48-slot stator. Each coil of the stator winding of this machine is brought out to a patchboard that enables the stator to be configured for single-phase, two-phase, three-phase, four-phase, six-phase, or 12-phase excitation. Experimental results are compared with computer predictions for a six-phase machine with both open-circuit and short-circuit faults. 相似文献