全文获取类型
收费全文 | 158篇 |
免费 | 8篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 18篇 |
金属工艺 | 2篇 |
机械仪表 | 1篇 |
建筑科学 | 8篇 |
能源动力 | 8篇 |
轻工业 | 15篇 |
水利工程 | 2篇 |
无线电 | 7篇 |
一般工业技术 | 29篇 |
冶金工业 | 39篇 |
原子能技术 | 2篇 |
自动化技术 | 28篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 2篇 |
2017年 | 6篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 9篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 12篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1980年 | 2篇 |
排序方式: 共有166条查询结果,搜索用时 62 毫秒
11.
Several biclustering algorithms have been proposed in different fields of microarray data analysis. We present a new approach that improves their performance in using the ensemble methods. An ensemble biclustering is considered and formalized by a problem of binary triclustering. We propose a simple and efficient algorithm to solve it. To illustrate the interest of our ensemble approach, numerical experiments are performed on both artificial and real datasets with two biclustering algorithms commonly used in bioinformatics. 相似文献
12.
Instruments and Experimental Techniques - Charging phenomena of insulating materials were studied thanks to a scanning electron microscope SEM LEO 440 which allows the injection of electrons doses... 相似文献
13.
14.
Janes Amy C.; Frederick Blaise deB.; Richardt Sarah; Burbridge Caitlin; Merlo-Pich Emilio; Renshaw Perry F.; Evins A. Eden; Fava Maurizio; Kaufman Marc J. 《Canadian Metallurgical Quarterly》2009,17(6):365
[Correction Notice: An erratum for this article was reported in Vol 18(3) of Experimental and Clinical Psychopharmacology (see record 2010-11933-011). In the article the authors find it necessary to redefine the thresholding procedure used for data analyses, due to problems in the Brain Voyager software. This does not affect the main findings of the paper.] Reactivity to smoking-related cues may play a role in the maintenance of smoking behavior and may change depending on smoking status. Whether smoking cue-related functional MRI (fMRI) reactivity differs between active smoking and extended smoking abstinence states currently is unknown. We used fMRI to measure brain reactivity in response to smoking-related versus neutral images in 13 tobacco-dependent subjects before a smoking cessation attempt and again during extended smoking abstinence (52 ± 11 days) aided by nicotine replacement therapy. Prequit smoking cue induced fMRI activity patterns paralleled those reported in prior smoking cue reactivity fMRI studies. Greater fMRI activity was detected during extended smoking abstinence than during the prequit assessment subcortically in the caudate nucleus and cortically in prefrontal (BA 6, 9, 44, 46), primary somatosensory (BA 1, 2, 3), temporal (BA 22, 41, 42), parietal (BA 7, 40) anterior cingulate (BA 24, 32), and posterior cingulate (BA 31) cortex. These data suggest that during extended smoking abstinence, fMRI reactivity to smoking versus neutral stimuli persists in brain areas involved in attention, somatosensory processing, motor planning, and conditioned cue responding. In some brain regions, fMRI smoking cue reactivity is increased during extended smoking abstinence in comparison to the prequit state, which may contribute to persisting relapse vulnerability. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
15.
The partial hydrogenation of propyne was studied over copper-based catalysts derived from Cu–Al hydrotalcite and malachite precursors and compared with supported systems (Cu/Al2O3 and Cu/SiO2). The as-synthesized samples and the materials derived from calcination and reduction were characterized by XRF, XRD, TGA, TEM, N2 adsorption, H2-TPR, XPS, and N2O pulse chemisorption. Catalytic tests were carried out in a continuous flow-reactor at ambient pressure and 423–523 K using H2:C3H4 ratios of 1–12 and were complemented by operando DRIFTS experiments. The propyne conversion and propene selectivity correlated with the copper dispersion, which varied with the type of precursor or support and the calcination and reduction temperatures. The highest exposed copper surface was attained on hydrotalcite-derived catalysts, which displayed C3H6 selectivity up to 80% at full C3H4 conversion and stable performance in long-run tests at T ? 473 K. Both activated Cu–Al hydrotalcites (this work) and Ni–Al hydrotalcites [S. Abelló, D. Verboekend, B. Bridier, J. Pérez-Ramírez, J. Catal. 259 (2008) 85] exhibited a relatively high alkene selectivity under optimal operation conditions, but they present a markedly distinctive catalytic behavior with respect to temperature and hydrogen-to-alkyne ratio. The product distribution was assigned through Density Functional Theory (DFT) simulations to the different stability of subsurface phases (carbides, hydrides) and the energies and barriers for the competing reaction mechanisms. The behavior of Cu in partial alkyne hydrogenation resembles that of Au nanoparticles, while Ni is closer to Pd. 相似文献
16.
A.C. de la Casa G.G. Ovando A.C. Ravelo E.G. Abril H. Bergamaschi 《International journal of remote sensing》2013,34(4):1295-1308
Ground cover by foliage is a biophysical property of vegetation linked both to the interception of photosynthetically active radiation and to the crop transpiration rate. The spectral information provided by the Moderate Resolution Imaging Spectroradiometer on board the Aqua (Aqua-MODIS) satellite, which has a spatial resolution of 250 m, is an observation and monitoring resource that may be appropriate for estimating the ground cover of maize when plots exceed 40 ha. In this research, 10 maize plots were monitored in the central region of the province of Córdoba, Argentina, during the 2005–2006 growing season, obtaining photographic records of ground cover and soil moisture data. The normalized difference vegetation index (NDVI) of the Aqua-MODIS images showed a significant linear relationship with maize ground cover which, when the complete cycle is taken into account, is sufficient to explain 87% of the variability of ground cover, with an RMSE of 9%, a level of accuracy that increases when the crop is in the vegetative stage and the moisture conditions of the soil are less limiting. Other vegetation indices and linear mixed models were assessed. In addition to using data from the red and near-infrared channels, they incorporate information about soil conditions, but they showed no predictive advantages compared to the NDVI, resulting in simple models that explained between 77% and 87% of the variability of ground cover, with RMSE values of between 9% and 14%. 相似文献
17.
Several formalisms and tools for software development use hierarchy in system design, for instance statecharts and diagrams
in UML. Message sequence charts (MSCs) are a standardized notation for asynchronously communicating processes. The norm Z.120
also includes hierarchical HMSCs. Algorithms on MSCs rarely take into account all possibilities covered by the norm. In particular,
hierarchy is not taken into account since the models that are usually considered are (flat) MSC-graphs, that correspond to
the unfolding of hierarchical HMSCs. However, complexity can increase exponentially by unfolding. The aim of this paper is
to show that basic algorithms can be designed such that they avoid the costly unfolding of hierarchical MSCs and HMSCs. We
show this for the membership and the pattern matching problem. We prove that the membership problem for hierarchical HMSCs
is PSPACE-complete. Then we describe a polynomial time algorithm for the pattern matching problem on hierarchical MSCs.
The results were obtained while B. Genest was affiliated with LIAFA, Université Paris 7. 相似文献
18.
Blaise Nsom 《Canadian Metallurgical Quarterly》2002,128(5):543-546
This paper considers dam-break flow occurring in a horizontal smooth channel. Experiments were carried out with highly viscous Newtonian fluids, e.g., glucose syrup–water solutions. The frontal shape of dam-break flow and its evolution, as well as the free-surface profile, were measured using video-photographic and ultrasonic equipment, respectively. New features of viscous dam-break flow are pointed out. Notably indicated are flow regimes and the effect of reservoir length as well as the effect of fluid viscosity on flow development. Equations describing dam-break flow are derived in nondimensional form, then compared with the results from experiments. 相似文献
19.
Pierre Blaise Veronique Tropini Marie Farines Robert L. Wolff 《Journal of the American Oil Chemists' Society》1997,74(2):165-168
The positional distribution of various Δ5-acids in the seed triacylglycerols from several conifer species has been established
after partial chemical degradation with Grignard reagent. The species studied were representative of four conifer families
and were specially selected for their particularly high Δ5-acid contents. These species were Taxus baccata (Taxaceae; 5,9-18:2 acid, 11.9%), Larix decidua (Pinaceae; 5,9,12-18:3 acid, 28.5%), Sciadopytis verticillata (Taxodiaceae; 5,11,14-20:3 acid, 16.7%), and Juniperus communis (Cupressaceae; 5,11,14,17-20:4 acid, 19.8%). Calculations from the fatty acid compositions of triacylglycerols and of the
mixture of 1,2- and 2,3-diacylglycerols generated by the Grignard reagent indicated that, for the four species, there was
a considerable enrichment of Δ5-acids (generally more than ten times) in the 1,3-positions as compared to the 2-position,
where Δ5-acids represented always less than 2% of total fatty acids esterified to triacylglycerols. This distribution was
practically independent from the species (four families studied), the chainlength (18 or 20 carbon atoms), and the number
of ethylenic bonds (two to four) in the Δ5-acids. Similar distributions were established for triacylglycerols from the seeds
of three pine species that are available on a ton-scale: Pinus pinea, P. koraiensis, and P. pinaster. These observations confirm and extend previous studies conducted with other conifer species by similar techniques or by
13C-nuclear magnetic resonance spectroscopy. Consequently, the almost exclusive location of Δ5-acids in the external positions
of triacylglycerols is now well established and appears to be a general feature of conifer seed oils. 相似文献
20.