全文获取类型
收费全文 | 1663篇 |
免费 | 44篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 17篇 |
综合类 | 1篇 |
化学工业 | 396篇 |
金属工艺 | 32篇 |
机械仪表 | 43篇 |
建筑科学 | 64篇 |
矿业工程 | 3篇 |
能源动力 | 69篇 |
轻工业 | 218篇 |
水利工程 | 15篇 |
石油天然气 | 6篇 |
武器工业 | 1篇 |
无线电 | 165篇 |
一般工业技术 | 309篇 |
冶金工业 | 70篇 |
原子能技术 | 9篇 |
自动化技术 | 292篇 |
出版年
2024年 | 23篇 |
2023年 | 31篇 |
2022年 | 55篇 |
2021年 | 74篇 |
2020年 | 72篇 |
2019年 | 73篇 |
2018年 | 57篇 |
2017年 | 56篇 |
2016年 | 55篇 |
2015年 | 53篇 |
2014年 | 66篇 |
2013年 | 129篇 |
2012年 | 97篇 |
2011年 | 138篇 |
2010年 | 92篇 |
2009年 | 73篇 |
2008年 | 100篇 |
2007年 | 68篇 |
2006年 | 61篇 |
2005年 | 43篇 |
2004年 | 44篇 |
2003年 | 47篇 |
2002年 | 32篇 |
2001年 | 15篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 19篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 13篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1985年 | 11篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有1710条查询结果,搜索用时 0 毫秒
11.
12.
It is known that a direct radial integration, used to compute the far-field from uniformly spaced plane-polar near-field measurements requires the evaluation of a large amount of Bessel functions and hence CPU time. Up to 1985 only unequally spaced fast Hankel algorithms were available. Hansen [3] developed an algorithm that was usable for equally spaced measurements points, but only for order zero. His theory is generalised in this paper and applied to a plane-polar near-field to far-field transformation. 相似文献
13.
14.
Emmanuel Kessous 《电信纪事》2007,62(11-12):1192-1206
The “Internet of things” is likely to give a second breath to the information society. However, the loss of control over personal information is both problematical and widely criticized. The “promise” of a better society offered by new services based on communication between machines carries with it frightening corollaries: it evokes a totalitarian space, where anonymous exchanges are no longer possible and the various traits of people’s digital identities are stored by agents of public and business powers. It is thus the management of digital tracking technologies that we wish to explore in this publication. Our hypothesis is that current criticism of a police state or of new forms of economic alienation is taking place at far too general a level. It obscures the real problem with the profusion of tracking methods, which for us reveals a crisis of confidence (as Giddens means it), at the individual level, in the means of production of telecommunications, which is the result of a deficit in the standardization process. From this perspective, the issue of the profusion of tracing technologies and their management transcends the issue of social control to encompass that of social responsibility and of modalities of proofs when the system fails. 相似文献
15.
Osmanski BF Pernot M Montaldo G Bel A Messas E Tanter M 《IEEE transactions on medical imaging》2012,31(8):1661-1668
Imaging intramyocardial vascular flows in real-time could strongly help to achieve better diagnostic of cardiovascular diseases. To date, no standard imaging modality allows describing accurately myocardial blood flow dynamics with good spatial and temporal resolution. We recently introduced a novel ultrasonic Doppler imaging technique based on compounded plane waves transmissions at ultrafast frame rate. The high sensitivity of this ultrafast Doppler technique permits to image the intramyocardial blood flow and its dynamics. A dedicated demodulation-filtering process is implemented to compensate for the large tissue velocity of the myocardium during the cardiac cycle. A signed power Doppler processing provides the discrimination between arterial and venous flows. Experiments were performed in vivo in a large animal open chest model ( N = 5 sheep) using a conventional ultrasonic probe placed at the surface of the heart. Results show the capability of the technique to image intramyocardial vascular flows in normal physiological conditions with good spatial (200 μm) and temporal resolution (10 ms). Flow dynamics over the cardiac cycle were investigated and the imaging method demonstrated a phase opposition of flow waveforms between arterial and venous flows. Finally, ultrafast Doppler combined with tissue motion compensation was found able to reveal vascular flow disruption in ischemic regions during occlusion of the main diagonal coronary artery. 相似文献
16.
Emmanuel Defaÿ David Wolozan Jean-Pierre Blanc Emmanuelle Serret Pierre Garrec Sophie Verrun Denis Pellissier Philippe Delpech Julie Guillan Bernard Andr Laurent Ulmer Marc Aïd Pascal Ancey 《Solid-state electronics》2007,51(11-12):1624
This paper describes realization and characterization of SrTiO3 (STO) high K MIM capacitors above BiCMOS integrated circuit (IC). These capacitances are connected to IC and are used as coupling capacitors in order to realize a high pass filter. Surface capacitance achieved is 10 nF/mm2 with capacitance value of 1.2 nF. The process for STO MIM fabrication does not exceed 400 °C, which is compatible with interconnections. Typical K and dielectric losses values obtained are, respectively 110% and 2%. Yield obtained reaches 83% for capacitors. A functional high pass filter using these STO capacitors was realized in this study. It exhibits a cut-off frequency at 6.5 kHz and a constant gain at higher frequencies of −1.3 dB. 相似文献
17.
We study an index calculus algorithm to solve the discrete logarithm problem (DLP) in degree 0 class groups of non-hyperelliptic
curves of genus 3 over finite fields. We present a heuristic analysis of the algorithm which indicates that the DLP in degree 0
class groups of non-hyperelliptic curves of genus 3 can be solved in an expected time of
. This heuristic result relies on one heuristic assumption which is studied experimentally.
We also present experimental data which show that a variant of the algorithm is faster than the Rho method even for small
group sizes, and we address practical limitations of the algorithm. 相似文献
18.
19.
Influences of matrix particle size distribution (PSD) (18, 25, 35 and 50 μm) and fat content (25%, 30% and 35%) on flavour release of dark chocolate volatiles were quantified by static headspace gas chromatography using GC–MS. Sixty-eight (68) flavour compounds were identified, comprising alcohols, aldehydes, esters, ketones, furans, pyrans, pyrazines, pyridines, pyroles, phenols, pyrones and thiozoles. From GC–olfactometry, 2-methylpropanal, 2-methylbutanal and 3-methylbutanal had chocolate notes. With cocoa/roasted/nutty notes were trimethyl-, tetramethyl-, 2,3-dimethyl-, 2,5-dimethyl-, 3(or 2),5-dimethyl-2(or 3)-ethyl- and 3,5(or 6)-diethyl-2-methylpyrazine and furfuralpyrrole. Compounds with fruity/floral notes included 3,7-dimethyl-1,6-octadien-3-ol and 5-ethenyltetrahydro-R,R,5-trimethyl-cis-2-furanmethanol. Caramel-like, sweet and honey notes were conferred by 2-phenylethanol, phenylacetaldehyde, 2-phenylethylacetate, 2,3,5-trimethyl-6-ethylpyrazine, 2-carboxaldehyde-1H-pyrrole, furancarboxaldehyde, furfuryl alcohol and 2,5-dimethyl-4-hydroxy-3(2H)furanone. There were direct relationships of fat content with 3-methylbutanal and branched pyrazines but inverse ones with 2-phenylethanol, furfuryl alcohol, methylpyrazine, phenylacetaldehyde, 2, 3, 5-trimethyl-6-ethylpyrazine and 2-carboxaldehyde-1-H-pyrrole. Particle size influenced higher alcohol, aldehyde, ester, ketone and pyrazine concentrations at all fat contents. A multivariate product space suggested flavour effects of the interacting factors. 相似文献
20.
N'Goran David Vincent Kouakou Jean-François Grongnet Nogbou Emmanuel Assidjo Eric Thys Pierre-Guy Marnet Daniel Catheline Philippe Legrand Maryline Kouba 《Meat science》2013
The aim of the present work was to study the effect of dietary supplementation of Euphorbia heterophylla on the quality of the Guinea pig meat. Forty guinea pigs were divided into two groups fed ad libitum during 46 days a Panicum maximum diet (Panicum diet) or a mixed diet (75% Panicum maximum + 25% Euphorbia heterophylla) (Paneuphorbia diet) to compare their effects on performances and on the composition of guinea pig tissues and carcass. Daily weight gain, liver weight, carcass yield, and the lipid content of both the carcass and the perirenal fat were significantly increased by the Paneuphorbia diet. Feeding Paneuphorbia diet increased (P < 0.05) the n-3 PUFA content in perirenal fat, muscle, liver and in the carcass and decreased (P < 0.05) the n-6/n-3 ratios in all these tissues and the carcass. In conclusion, this study shows that Euphorbia heterophylla is a source of n-3 fatty acids which can improve significantly the n-3 PUFA content of Guinea pig meat and carcass. 相似文献