全文获取类型
收费全文 | 141篇 |
免费 | 6篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 24篇 |
机械仪表 | 1篇 |
建筑科学 | 8篇 |
能源动力 | 29篇 |
轻工业 | 6篇 |
水利工程 | 2篇 |
无线电 | 16篇 |
一般工业技术 | 17篇 |
冶金工业 | 9篇 |
原子能技术 | 1篇 |
自动化技术 | 32篇 |
出版年
2023年 | 1篇 |
2021年 | 6篇 |
2019年 | 4篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 11篇 |
2011年 | 18篇 |
2010年 | 7篇 |
2009年 | 8篇 |
2008年 | 13篇 |
2007年 | 7篇 |
2006年 | 7篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 1篇 |
排序方式: 共有147条查询结果,搜索用时 46 毫秒
1.
2.
Abstract We consider the tunnelling particle as a pre- and post-selected system and prove that the tunnelling time is the expectation value of the position of a ‘clock’ degree of freedom weakly coupled to it. Such a value, called a ‘weak value’, typically falls outside the eigenvalue spectrum of the operator. The appearance of unusual weak values has been associated with a unique interference structure called ‘superoscillations’ (band-limited functions which on a finite interval, approximate functions with spectra well outside their band). It is proposed that superoscillations play an important role in the interferences which give rise to superluminal effects. To demonstrate that, we consider a certain simple tunnelling barrier which allows a wave packet to travel in zero time and negligible distortion, a distance arbitrarily longer than the width of the wave packet. The peak is shown to result from a superoscillatory superposition at the tail. Similar reasoning applies to the dwell time. For this system, both the Wigner time (related to the group velocity) and a clock time correspond to superluminal velocities. 相似文献
3.
In this letter we propose a novel distributed technique for dynamic spectrum management of DSL lines. The proposed method generalizes several known techniques, by imposing pricing for use of spectrum. We propose a simple mechanism that allows each line to choose an appropriate pricing function independently of the other lines. Finally, by incorporating a total power constraint, the algorithm is capable of self-correcting an overly ambitious pricing function. We also provide simulated examples based on measured DSL lines. 相似文献
4.
Domestic energy use accounts for more than a quarter of CO2 emissions in the UK. Traditional approaches to energy reduction look at direct emissions savings, and recommend insulation
and efficiency as more cost-effective than microgeneration. However, microgeneration has indirect, ‘soft’ benefits and could
play a significant role in emissions reduction. Current uptake of microgeneration in the UK is low, with various barriers—economic,
technical, cultural, behavioural and institutional—both to uptake and to maximising energy and emissions savings once installed.
Subsidies and spreading information alone do not guarantee maximising uptake, and even if successful, this is not enough to
maximise savings. The industry focuses on maximising sales, with no incentives to ensure best installations and use; householders
do not have access to the best information, and user behaviour does not maximise energy and emission savings. This is related
to a broader state of socio-technical ‘lock-in’ in domestic energy use; there’s a lack of connection between personal behaviour
and energy consumption, let alone global climate change. This suggests that a major cultural–behavioural shift is needed to
reduce energy/emissions in the home. Transition theory and strategic niche management provide insights into possible systemic
change and a suitable framework for future policies, such as supporting a variety of radically innovative niches, both technological
and social. Microgeneration, properly employed, has the potential to play a part in such a transition by increasing awareness
and energy literacy and empowering people to seriously engage in energy debates as producers, as well as consumers, of energy.
This deeper understanding and heightened responsibility are crucial in a shift toward bottom-up emission-reducing behaviour
change and better acceptance of top-down energy-saving policy measures, as part of a new domestic energy paradigm. The implications
for policy are that, as well as supporting the technologies, it needs to support existing niches and to develop new niche
experiments. Policy needs to consider how to promote empowerment and responsibility and support or even develop new energy
sector models; this will involve a range of stakeholders and multiple governance levels, not just national incentive schemes. 相似文献
5.
Anton Batliner Stefan Steidl Björn Schuller Dino Seppi Thurid Vogt Johannes Wagner Laurence Devillers Laurence Vidrascu Vered Aharonson Loic Kessous Noam Amir 《Computer Speech and Language》2011,25(1):4-28
In this article, we describe and interpret a set of acoustic and linguistic features that characterise emotional/emotion-related user states – confined to the one database processed: four classes in a German corpus of children interacting with a pet robot. To this end, we collected a very large feature vector consisting of more than 4000 features extracted at different sites. We performed extensive feature selection (Sequential Forward Floating Search) for seven acoustic and four linguistic types of features, ending up in a small number of ‘most important’ features which we try to interpret by discussing the impact of different feature and extraction types. We establish different measures of impact and discuss the mutual influence of acoustics and linguistics. 相似文献
6.
Parameter Sweep Workflows for Modelling Carbohydrate Recognition 总被引:1,自引:0,他引:1
Tamas Kiss Pamela Greenwell Hans Heindl Gabor Terstyanszky Noam Weingarten 《Journal of Grid Computing》2010,8(4):587-601
Carbohydrate recognition is a phenomenon critical to a number of biological functions in humans. Understanding the dynamic
behaviour of oligosaccharides should help in the discovery of the mechanisms which lead to specific and selective recognition
of carbohydrates by proteins. Computer programs which can provide insight into such biological recognition processes have
significant potential to contribute to biomedical research if the results of the simulation can prove consistent with the
outcome of conventional wet laboratory experiments. In order to validate these simulation tools and support their wider uptake
by the bio-scientist research community, high-level easy to use integrated environments are required to run massively parallel
simulation workflows. This paper describes how the ProSim Science Gateway, based on the WS-PGRADE Grid portal, has been created
to execute and visualise the results of complex parameter sweep workflows for modelling carbohydrate recognition. 相似文献
7.
Tsviya Olender Marilyn Safran Ron Edgar Gil Stelzer Noam Nativ Naomi Rosen Ronit Shtrichman Yaron Mazor Michael D. West Ifat Keydar Noa Rappaport Frida Belinky David Warshawsky Doron Lancet 《Israel journal of chemistry》2013,53(3-4):185-198
A network of biological databases is reviewed, supplying a framework for studies of human genes and the association of their genomic variations with human phenotypes. The network is composed of GeneCards, the human gene compendium, which provides comprehensive information on all known and predicted human genes, along with its suite members GeneDecks and GeneLoc. Two databases are shown that address genes and variations focusing on olfactory reception (HORDE) and transduction (GOSdb). In the realm of disease scrutiny, we portray MalaCards, a novel comprehensive database of human diseases and their annotations. Also shown is GeneKid, a tool aimed at generating novel kidney disease biomarkers using systems biology, as well as Xome, a database for whole-exome next-generation DNA sequences for human diseases in the Israeli population. Finally, we show LifeMap Discovery, a database of embryonic development, stem cell research and regenerative medicine, which links to both GeneCards and MalaCards. 相似文献
8.
Jianfeng Jiang Wenfeng Lo Peter Müller Noam D. Fine Myrium Maruani Alexander Raytman 《Inorganic chemistry communications》2009,12(6):527-529
fac-[FeII(CO)3X3]1? (X = Br, I) are synthesized and their structures have been determined. They are the first crystallographically characterized iron tricarbonyl trihalide complexes. fac-[FeII(CO)3X3]1? (X = Br, I) are fairly thermally stable and therefore lead themselves as excellent starting materials for the preparation of various iron carbonyl complexes since both the halide and carbonyl ligands are substitutionally labile. 相似文献
9.
Small angle X-ray scattering experiments indicate that egg phosphatidylcholine dissolved in benzene at a concentration of 12–50 mM organizes into approximately isometric inverse micelles with a size that depends upon the amount of water present. These inverse micelles can serve as self-assembled hosts for monosaccharide derivatives. For a given amount of water, addition of carbohydrates causes an increase in the micelle size. In contrast, cyclohexane solutions of egg phosphatidylcholine contain highly anisotropic structures, possibly elongated rods. Monosaccharide derivatives can be extracted into these structures and are bound, at low water content, to the polar head groups. Upon addition of water the sugar is probably displaced from the polar head groups and gains some motional freedom in the water pool which is formed. This fact indicates that the polar head group of phosphatidylcholine interacts, probably by means of hydrogen bond formation, with monosaccharides and brings about their solubilization in nonpolar solvents. 相似文献
10.
Noam Bernstein Michael J. Aziz Efthimios Kaxiras 《Journal of Computer-Aided Materials Design》1998,5(1):55-60
We simulate the amorphous–crystal interface in silicon using a combination of interatomic potential molecular-dynamics and tight- binding conjugate-gradient relaxation. The samples we create have high quality crystalline and amorphous portions. We develop some localized measures of order to characterize the interface, including a missing neighbor vector and the bond angle deviation. We find that the measures of order interpolate smoothly from a bulk crystal value to a bulk amorphous value across a 7 Å thick interface region. The interface structures exhibit a number of interesting features. The crystal planes near the interface are nearly perfect, with a few dimer defects similar to the Si(100) 2×1 reconstruction. Interfaces produced with one constant temperature simulation method are rough, with several layers of atoms forming <110> chains and (111) facets. A different simulation method produces more planar interfaces with only a few <110> chains. 相似文献