全文获取类型
收费全文 | 789篇 |
免费 | 30篇 |
专业分类
电工技术 | 13篇 |
综合类 | 3篇 |
化学工业 | 124篇 |
金属工艺 | 20篇 |
机械仪表 | 10篇 |
建筑科学 | 36篇 |
矿业工程 | 1篇 |
能源动力 | 18篇 |
轻工业 | 120篇 |
水利工程 | 3篇 |
石油天然气 | 37篇 |
无线电 | 53篇 |
一般工业技术 | 86篇 |
冶金工业 | 201篇 |
原子能技术 | 6篇 |
自动化技术 | 88篇 |
出版年
2022年 | 7篇 |
2021年 | 15篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 14篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 6篇 |
2014年 | 19篇 |
2013年 | 48篇 |
2012年 | 24篇 |
2011年 | 25篇 |
2010年 | 25篇 |
2009年 | 29篇 |
2008年 | 24篇 |
2007年 | 34篇 |
2006年 | 21篇 |
2005年 | 24篇 |
2004年 | 25篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 20篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 35篇 |
1997年 | 31篇 |
1996年 | 21篇 |
1995年 | 16篇 |
1994年 | 14篇 |
1993年 | 15篇 |
1992年 | 14篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 15篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 14篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1977年 | 6篇 |
1976年 | 15篇 |
1975年 | 12篇 |
1973年 | 9篇 |
1972年 | 7篇 |
1971年 | 8篇 |
排序方式: 共有819条查询结果,搜索用时 15 毫秒
41.
C. Paal und Conrad Amberger 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1909,17(1):1-22
Ohne ZusammenfassungMitteilung aus dem Pharmaceutisch-chemischen Institut der Universität Erlangen. 相似文献
42.
Conrad DonovanAlim Dewan Huan PengDeukhyoun Heo Haluk Beyenal 《Journal of power sources》2011,196(3):1171-1177
One of the challenges in using wireless sensors that require high power to monitor the environment is finding a renewable power source that can produce enough power. Sediment microbial fuel cells (SMFCs) are considered an alternative renewable power source for remote monitoring, but current research on SMFCs has demonstrated that they can only produce several to tens of mW of continuous power. This limits the use of SMFCs as an alternative renewable remote power source to mW-level power. Such low power is only enough to operate a low-power sensors. However, there are many remote sensors that require higher power, on the order of watts. Current technology using a SMFC to power a remote sensor requiring watts-level intermittent power is limited because of limitations of power management technology. Our goal was to develop a power management system (PMS) that enables a SMFC to operate a remote sensor consuming 2.5 W of power. We designed a custom PMS to store microbial energy in capacitors and use the stored energy in short bursts. Our results demonstrate that SMFCs can be a viable alternative renewable power source for remote sensors requiring high power. 相似文献
43.
Richard B Kreider Colin D Wilborn Lem Taylor Bill Campbell Anthony L Almada Rick Collins Mathew Cooke Conrad P Earnest Mike Greenwood Douglas S Kalman Chad M Kerksick Susan M Kleiner Brian Leutholtz Hector Lopez Lonnie M Lowery Ron Mendel Abbie Smith Marie Spano Robert Wildman Darryn S Willoughby Tim N Ziegenfuss Jose Antonio 《Journal of the International Society of Sports Nutrition》2010,7(1):1-43
Sports nutrition is a constantly evolving field with hundreds of research papers published annually. For this reason, keeping up to date with the literature is often difficult. This paper is a five year update of the sports nutrition review article published as the lead paper to launch the JISSN in 2004 and presents a well-referenced overview of the current state of the science related to how to optimize training and athletic performance through nutrition. More specifically, this paper provides an overview of: 1.) The definitional category of ergogenic aids and dietary supplements; 2.) How dietary supplements are legally regulated; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of the ergogenic value of nutrition and dietary supplementation in regards to weight gain, weight loss, and performance enhancement. Our hope is that ISSN members and individuals interested in sports nutrition find this review useful in their daily practice and consultation with their clients. 相似文献
44.
The plastic deformation kinetics of electrodeposited (EP) Cu foil (grain size d=0.6 μm) were determined at 296–448 K and compared
with those for vapor-deposited (VP) foil (d=0.5 μm) tested at 77–473 K. The apparent activation volume v=kT ∂ ln
for both materials exhibited a minimum at ∼350 K, and at this temperature, there occurred a marked increase in the temperature
dependence of the flow stress σ. The rate-controlling mechanism in both materials at T<373 K appears to be grain boundary
shear induced by dislocation pileups at the grain boundaries. The results at T=373–473 K suggest that the dislocation pileups
are relieved or prevented and that either cross slip or intersection of dislocations is rate controlling with stronger support
for the latter. The determination of the rate-controlling mechanism at the higher temperatures is complicated by possible
changes in defect structure due to thermal annealing, and therefore, the operative mechanism corresponds to a structure that
may differ from the initial, as-deposited condition. 相似文献
45.
The plastic deformation kinetics of 99.4% MgO (d
o = 5.3 m) was investigated at 1500°–1600°C in uniaxial tension. It was determined that the stress exponent n 1 and the activation energy Q = 204 kJ/mole. Neither the present results on MgO, nor data in the literature on MgO and other oxide ceramics, can be fully explained by the models usually proposed for the plastic deformation of fine-grained oxide ceramics. The present results are however in good agreement with the model for grain boundary diffusion plastic flow recently developed by Kim, Estrin and Bush. 相似文献
46.
Quality-aware images. 总被引:4,自引:0,他引:4
Zhou Wang Guixing Wu Hamid Rahim Sheikh Eero P Simoncelli En-Hui Yang Alan Conrad Bovik 《IEEE transactions on image processing》2006,15(6):1680-1689
We propose the concept of quality-aware image, in which certain extracted features of the original (high-quality) image are embedded into the image data as invisible hidden messages. When a distorted version of such an image is received, users can decode the hidden messages and use them to provide an objective measure of the quality of the distorted image. To demonstrate the idea, we build a practical quality-aware image encoding, decoding and quality analysis system, which employs: 1) a novel reduced-reference image quality assessment algorithm based on a statistical model of natural images and 2) a previously developed quantization watermarking-based data hiding technique in the wavelet transform domain. 相似文献
47.
PURPOSE: Endosonographic image and surgical therapy of a retrorectal bowel duplication are described. METHODS, RESULTS, AND CONCLUSIONS: Compared with standard investigations, the most accurate information about a retrorectal mass in a 35-year-old woman could be obtained by means of endorectal ultrasound. Guided by endorectal ultrasound, the mass was excised using a transanal-transrectal approach, and Kraske's operation could be avoided. Additionally, histopathologic analysis of this rare disease is presented. 相似文献
48.
Marijuana use was assessed in 186 people seeking treatment for cocaine dependence. Comparisons were made between clients who did and did not report using marijuana and between marijuana users who did and did not meet diagnostic criteria for marijuana dependence. The relationship between marijuana use and treatment outcome was also explored. A high rate of current marijuana use (59%) was observed at intake, and the majority of the marijuana users (74%) used marijuana at some point during treatment. Marijuana use at intake was associated with increased psychosocial impairment and substance-use severity. However, no significant adverse relations were observed between marijuana use at intake or during treatment and treatment outcome. Such functional independence may have important implications for addressing marijuana use during treatment for cocaine dependence. These findings should be interpreted with caution pending replication in prospective studies and with other treatment approaches. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
49.
Kai Grjotheim Conrad Krohn Roger Naeumann Knut Tørklep 《Metallurgical and Materials Transactions B》1970,1(11):3133-3141
The convection pattern in the bath electrolyte and the cathode metal of 150 kamp prebaked anode aluminum reduction cells has been studied by means of radioactive tracers. The initial distribution of the tracers—24Na for the bath and198Au for the metal phase-indicates a fast circulating movement with vortices at the ends in both phases. Circulation rates up to 100 cm per sec were observed, and an average value seemed to be 10 cm per sec. The implications of the convection on the mechanism of the secondary reactions, the dissolution of alumina in the bath electrolyte and the distribution of carbon particles in the cell are discussed. 相似文献
50.
S. P. Agrawal G. A. Sargent H. Conrad 《Metallurgical and Materials Transactions B》1974,5(11):2415-2422
Hexagonal dislocation networks which occurred in as-annealed commercial Ti-A 50 rod and following partial extrusion under
hydrostatic pressure at room temperature were studied using transmission electron microscopy. For the as-annealed condition
networks were observed on the prism, basal and {2•1•1x} planes, while for the extrusion networks were only observed on the
basal plane. The various stages in the development of the networks are presented and mechanisms by which they form are proposed.
The self energies of the dislocation hexagons constituting the various networks are calculated using the equations proposed
by de Wit and Ruff. They increase in the order: a) networks on the basal plane in the as-annealed condition, b) networks on
the prism plane in the asannealed condition and c) networks on the basal plane in the partially extruded condition.
This paper is based on Doctoral Thesis presented in October 1973 by S. P. AGRAWAL to the Department of Metallurgical Engineering
and Materials Science at the University of Kentucky. 相似文献