全文获取类型
收费全文 | 1219篇 |
免费 | 18篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 157篇 |
金属工艺 | 3篇 |
机械仪表 | 28篇 |
建筑科学 | 38篇 |
矿业工程 | 3篇 |
能源动力 | 17篇 |
轻工业 | 112篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 138篇 |
一般工业技术 | 202篇 |
冶金工业 | 372篇 |
原子能技术 | 8篇 |
自动化技术 | 140篇 |
出版年
2023年 | 6篇 |
2022年 | 5篇 |
2021年 | 13篇 |
2019年 | 9篇 |
2018年 | 10篇 |
2017年 | 10篇 |
2016年 | 12篇 |
2015年 | 6篇 |
2014年 | 11篇 |
2013年 | 57篇 |
2012年 | 25篇 |
2011年 | 38篇 |
2010年 | 27篇 |
2009年 | 23篇 |
2008年 | 34篇 |
2007年 | 39篇 |
2006年 | 36篇 |
2005年 | 31篇 |
2004年 | 41篇 |
2003年 | 39篇 |
2002年 | 22篇 |
2001年 | 34篇 |
2000年 | 37篇 |
1999年 | 41篇 |
1998年 | 97篇 |
1997年 | 71篇 |
1996年 | 46篇 |
1995年 | 36篇 |
1994年 | 24篇 |
1993年 | 42篇 |
1992年 | 29篇 |
1991年 | 13篇 |
1990年 | 21篇 |
1989年 | 22篇 |
1988年 | 22篇 |
1987年 | 12篇 |
1986年 | 22篇 |
1985年 | 7篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 14篇 |
1978年 | 18篇 |
1977年 | 17篇 |
1976年 | 19篇 |
1975年 | 6篇 |
1974年 | 9篇 |
1973年 | 5篇 |
排序方式: 共有1238条查询结果,搜索用时 15 毫秒
31.
32.
The distracting effects of texting while driving activity of young adults are receiving increasing attention. The findings indicate that individuals involved in texting while driving also engage in other risky behaviors. Furthermore, frequency of texting while driving appears to be related to several factors, including self-control, attitudes toward texting and responsible driving, and opinions of peers, but interestingly not with social responsibility. In conclusion, the frequency of texting while driving of young adults appears to be related to several factors, suggesting possible ways the frequency of texting while driving may be affected. 相似文献
33.
Michael J. Walker Kirstin Gray Christopher Hopley David Bell Peter Colwell Peter Maynard Duncan Thorburn Burns 《Food Analytical Methods》2012,5(4):874-880
Morpholine is a precursor of carcinogenic nitrosamines and although the possibility of their formation in the human stomach
after ingestion of morpholine-treated apples is reported as highly unlikely morpholine has not been authorised as a food additive
in the EU. Methods for its detection are required since it is permitted in other jurisdictions and may be present on food
through direct treatment of fruit with waxes containing the compound, through steam treatment during processing or from packaging.
Methods using derivatising agents with the inclusion of UV chromophores such as dansyl chloride yield good separation and
high sensitivity but with mass spectrometric fragment ions predominantly originated from the derivatising group rather than
the morpholine moiety. An amine acetylation derivatisation method is proposed from which fragment ions originating from the
morpholine group are detected using widely available GC–MS. With full validation, a forensically robust confirmation of the
presence of morpholine via its N-acetyl derivative is possible in support of regulatory analysis. 相似文献
34.
The significance of guard-cam impact with respect to needle damage is briefly discussed, and a simplified theoretical analysis of guard-cam impact is derived. 相似文献
35.
Ha-Kyung Kwon Vanessa E. Lopez Raleigh L. Davis So Youn KimAdam B. Burns Richard A. Register 《Polymer》2014
Anionic polymerization was employed to synthesize well-defined diblock copolymers of polystyrene and poly(2-ethylhexylmethacrylate), PS-PEHMA. Diblock morphologies in bulk and in substrate-supported thin films were characterized by small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM), respectively. PS-PEHMA diblocks exhibited thermotropic order-disorder transitions; one diblock showed a thermoreversible transition between lamellae and a higher-temperature morphology assigned as perforated lamellae. Unlike PS-poly(alkylmethacrylate) diblocks where the alkyl group is n-butyl or n-pentyl, PS-PEHMA diblocks showed a typical decreasing Flory interaction parameter with increasing temperature. Thin films of PS-cylinder-forming PS-PEHMA diblocks showed a strong preference for the cylinders to lie in the plane of the film; films of incommensurate thickness readily formed terraces. Films of commensurate thickness were easily aligned over macroscopic areas through the application of mechanical shear. 相似文献
36.
Estrogen content of dairy and swine wastes 总被引:3,自引:0,他引:3
Raman DR Williams EL Layton AC Burns RT Easter JP Daugherty AS Mullen MD Sayler GS 《Environmental science & technology》2004,38(13):3567-3573
Naturally occurring estrogens in animal wastes may cause negative environmental impacts, yet their abundance in animal waste treatment and storage structures is poorly documented. To better quantify estrogen concentrations in animal wastes, multiple waste samples were collected from treatment and storage structures at dairy and swine facilities and analyzed for concentrations of 17beta-estradiol (E2), estrone (E1), and 17alpha-estradiol by gas chromatography-mass spectroscopy and by enzyme linked immunosorbent assay (E2 only). Mass ratios of each estrogen to the macronutrients nitrogen, phosphorus, and potassium were also determined. Because manure application rates are typically macronutrient-based, estrogen to macronutrient ratios are proportional to areal mass application rates of estrogen to fields. Swine farrowing waste (from farrowing sows and piglets) had the highest ratios of E2 to macronutrients. Mean ratios in swine farrowing waste were roughly twice those in swine finishing waste (from growing male and nonpregnant female animals) and more than four times higher than those in dairy waste (from lactating cows in various stages of their reproductive cycles); these differences were statistically significant (alpha = 0.05). Estrone followed a similar trend. In contrast, ratios of 17alpha-estradiol to macronutrients were highest in dairy operations. These results can be used to better predict estrogen loading rates on fields receiving swine and dairy wastes. 相似文献
37.
A simplified mathematical analysis is made of the motion of the latch as the needle passes down the stitch cam. Two practical cases are considered: (i) when the latch retains contact with the previously formed loop of yarn as it rises towards the needle head; and (ii) when the yarn moves with a stick–slip motion such that the latch loses contact with the yarn. It is shown that among possible methods for reducing latch impact are a reduction in latch mass, a reduction in the stitch-cam angle during the period when the latch is closed, and a reduction in the latch length; an improved latch design is also suggested. 相似文献
38.
39.
B. Elhweg I.W. Burns Y.M.J. Chew P.J. Martin A.B. Russell D.I. Wilson 《Food and Bioproducts Processing》2009,87(4):266-272
We have analysed sets of capillary rheometry data (0.3 s?1 ≤ γapp ≤ 360 s?1) for a commercial ice cream as it flowed from a freezer on an industrial flow line. Pressure drop measurements were used and particular attention was paid to viscous dissipation effects. A semi-analytical model presented by Bird in 1955 indicated that over one third of the data points were subject to local wall heating, which was consistent with available temperature measurements. The filtered data were used to construct a viscosity function which, when implemented in a detailed CFD simulation of the flow, predicted the observed flow curve behaviour. The results demonstrate that viscous dissipation can be significant in ice cream and that interpretation of this behaviour in terms of wall slip is erroneous. 相似文献
40.
S. E. Burns K. Reynolds W. Reeves M. Banach T. Brown K. Chalmers N. Cousins M. Etchells C. Hayton K. Jacobs A. Menon S. Siddique P. Too C. Ramsdale J. Watts P. Cain T. Von Werne J. Mills C. Curling H. Sirringhaus K. Amundson M. D. McCreary 《Journal of the Society for Information Display》2005,13(7):583-586
Abstract— A scalable manufacturing process for fabricating active‐matrix backplanes on low‐cost flexible substrates, a key enabler for electronic‐paper displays, is presented. This process is based on solution processing, ink‐jet printing, and laser patterning. A multilayer architecture is employed to enable high aperture ratio and array performance. These backplanes were combined with E Ink electrophoretic media to create high‐performance displays that have high contrast, are bistable, and can be flexed repeatedly to a radius of curvature of 5 mm. 相似文献