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排序方式: 共有315条查询结果,搜索用时 15 毫秒
61.
S. Girginoudi D. Girginoudi N. Georgoulas A. Thanailakis 《Materials Science in Semiconductor Processing》1998,1(3-4)
The deposition and crystallization of a-Si thin films grown by rapid thermal processing have been studied, using transmission electron microscopy. The a-Si films were deposited in a rapid thermal processor at reduced pressures in the temperature range of 530–580°C, at different deposition pressures and silane flow rates and subsequently were annealed in-situ by high temperature rapid thermal annealing (RTA) or by a two-step annealing process involving low temperature furnace annealing (FA) followed by high temperature RTA. The activation energy of a-Si deposition was found to be approximately 1.7 eV, in reasonable agreement with the conventional LPCVD technique. It has been found that the deposition temperature and deposition rate have a strong effect on the grain size, which is attributed to the nucleation processes in the bulk of the films. The combination of low deposition temperature, high deposition rate and a two-step annealing process permits the low temperature growth of poly-Si films of 100 nm thickness, with large grains of 520 nm size, containing a low density of microtwins and characterized by very low surface roughness of 2.2 nm. 相似文献
62.
This paper reviews some of the progress made on wellbore stability modeling during the last two decades. First we demonstrate the improvement made on mud-pressure predictions by moving from analytic elastic solutions to finite element elastoplastic modeling. We show this progress, presenting a finite element model based on a generalized plane strain formulation for analyzing efficiently the three-dimensional problem of stability in deviated wellbores. On a more research oriented work, we present results from two advanced theories capable of modeling localization of deformation in shear bands, which causes borehole breakouts. The first theory is based on a more established approach, the Cosserat continuum. The second theory, called gradient elastoplasticity, is being developed to resolve some of the drawbacks of gradient plasticity theories. Gradient elastoplasticity is a unified theory where both elastic and plastic parts are of gradient type. We demonstrate that both theories, in addition to localization, can also model the scale effect observed in thick-walled cylinder tests. 相似文献
63.
Tzionas P.G. Tsalides P.G. Thanailakis A. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》1994,2(3):343-353
A new, parallel, nearest-neighbor (NN) pattern classifier, based on a 2D Cellular Automaton (CA) architecture, is presented in this paper. The proposed classifier is both time and space efficient, when compared with already existing NN classifiers, since it does not require complex distance calculations and ordering of distances, and storage requirements are kept minimal since each cell stores information only about its nearest neighborhood. The proposed classifier produces piece-wise linear discriminant curves between clusters of points of complex shape (nonlinearly separable) using the computational geometry concept known as the Voronoi diagram, which is established through CA evolution. These curves are established during an “off-line” operation and, thus, the subsequent classification of unknown patterns is achieved very fast. The VLSI design and implementation of a nearest neighborhood processor of the proposed 2D CA architecture is also presented in this paper 相似文献
64.
Antonios E. Goulas Antonios Kokkinos Michael G. Kontominas 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1995,201(1):74-78
Food-grade PVC and PVDC/PVC films containing 28.3% dioctyladipate (DOA) and 5.0% acetyltributylcitrate (ATBC) plasticizers, respectively, were brought into contact with olive oil and were irradiated with -radiation [60Co] at doses equal to 4 kGy and 9 kGy corresponding to cold pasteurization. Irradiation was carried out at 8–10 °C and samples were subsequently stored at 4–5 °C. Contaminated oil samples were analysed for DOA and ATBC at intervals between 7 h and 97 h of contact, using an indirect GC method. Identical nonirradiated (control) samples were also analysed for DOA and ATBC content. Results showed no statistically significant differences in migrated amounts of DOA and ATBC between irradiated and non-irradiated samples. Neither were differences observed between samples irradiated at 4 kGy and 9 kGy. This was supported by identical IR spectra recorded for irradiated and non-irradiated samples and leads to the conclusion that at such intermediate radiation doses (9 kGy) the migration characteristics of both PVC and PVDC/PVC films are not affected. The amount of DOA that migrated into olive oil was dependent on time, reaching equilibrium after approximately 47 h of contact (302.8 mg/l). The amount of ATBC that migrated into olive oil was non-detectable (<1 mg/1) for all samples stored at 4–5 °C after 97 h. In non-irradiated samples (PVDC/PVC in contact with oil) stored at 20 °C, small amounts of migrated ATBC were determined (3.3 and 5.1 mg/l after 29 h and 94 h of contact respectively). Furthermore, in thermally treated samples heated to 80 °C for 30 min and 60 min, the respective amounts of migrated ATBC determined were 2.9 mg/l and 19.3 mg/l. 相似文献
65.
Vassilios Vonikakis Rigas Kouskouridas Antonios Gasteratos 《Multimedia Tools and Applications》2018,77(8):9211-9231
This paper presents a comparison framework for algorithms that can diminish the effects of illumination in images. Its main objective is to reveal the positive and negative characteristics of such algorithms, allowing researchers to select the most appropriate one for their target application. The proposed framework utilizes artificial illumination degradations on real images, which are then processed by the tested algorithms. The results are evaluated by an ensemble of performance metrics, highlighting the various characteristics of the algorithms across a range of different image attributes. The proposed framework represents a useful tool for the selection of illumination compensation algorithms due to a) its quantitative nature, b) its multifaceted analysis and c) its easy reproducibility. The validity of the proposed framework is tested by applying it to the enhancement results of four illumination compensation algorithms, which are used as preprocessing in two classic computer vision applications. The improvements brought about by the algorithms are in accordance with the predictions of the proposed framework. 相似文献
66.
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68.
Ra Won-Sang Whang Ick-Ho Shin Hyo-Sang Tsourdos Antonios 《International Journal of Control, Automation and Systems》2017,15(4):1969-1974
International Journal of Control, Automation and Systems - This paper proposes an efficient aimpoint tracking filter for high-range resolution FMCW radar seekers. A modified probabilistic data... 相似文献
69.
In this work, we present an overview of recently developed methods for control and optimization of complex process systems described by multiscale models. We primarily discuss methods developed in the context of our previous research work and use examples of thin film growth processes to motivate the development of these methods and illustrate their application. 相似文献
70.
George Tsilomelekis Antonios Christodoulakis Soghomon Boghosian 《Catalysis Today》2007,127(1-4):139-147
The structural and catalytic properties of MoO3 catalysts supported on ZrO2, Al2O3, TiO2 and SiO2 with Mo surface densities, ns, in the range of 0.5–18.5 Mo/nm2 were studied for the oxidative dehydrogenation (ODH) of ethane by in situ Raman spectroscopy and catalytic activity measurements at temperatures of 400–540 °C. The molecular structure of the dispersed surface species evolves from isolated monomolybdates (MoO4 and MoO5, depending on the support) at low loadings to associated MoOx units in polymolybdate chains at high loadings and ultimately to bulk crystalline phases for loadings exceeding the monolayer coverage of the supports used. The nature of the oxide support material and of the Mo–O–support bond has a significant influence on the catalytic behaviour of the molybdena catalysts with monolayer coverage. The dependence of reactivity on the support follows the order ZrO2 > Al2O3 > TiO2 > SiO2. The oxygen site involved in the anchoring Mo–O–support is of relevance for the catalytic activity. 相似文献