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排序方式: 共有150条查询结果,搜索用时 8 毫秒
41.
L. Moreno R.M. Aguilar C.A. Martin J.D. Piñeiro J.I. Estévez J.L. Sánchez J.F. Sigut V.I. Jiménez 《Journal of Network and Computer Applications》1998,21(4):287-310
The study of a particular complex system by means of computer simulation is described in this paper. Hospitals are chosen as target systems where the proposed methodology is applied.In order to choose the right decisions, hospital managers need all the information about the functioning of the organization. This research project presents a simulation tool that allows virtual societies such as hospitals to be implemented. In this way, the study of emergent behaviours in these systems can be carried out.Petri nets were initially tested as a methodology to model the hospital. However, the complexity of the resulting model led us to follow a process oriented approach. 相似文献
42.
The methods of spectrometric analysis belong to a group of measurement methods that are used for their simplicity, speed of analysis, and large selectivity to solve various problems of analytes. Accuracy and reliability of any chemical analysis largely depend on the way the analyzed sample is prepared. 相似文献
43.
The owner of a mobile telephone is exposed to radiation from both the mobile telephone and base stations. They are often installed on the roofs of residential buildings. The article deals with electromagnetic fields generated by mobile communication antennas in the residential area. Measurements of electrical strength, magnetic strength and the electromagnetic field energy flux density were performed and compared to the established hygiene norms. Tests were conducted in the near and far zones of the antenna, in residential premises located directly in front of antenna, within the main radiation lobe of the antenna. 相似文献
44.
Giedrė Bubniene Tadas Malinauskas Vytautas Getautis Albina Stanisauskaite Vygintas Jankauskas Jonas Sidaravicius 《Synthetic Metals》2008
The synthesis and properties of amorphous hole-transporting 4,4′-bis[11-carbazol-9-yl)-6,8,10-tri(carbazol-9-methyl)-3-hydroxy-5,7,9-trioxa-1-thia]thiobisbenzene with two end and six pendant carbazolyl moieties, separated from the main chain by CH2 spacers, is reported. It was prepared by a multistep synthesis route from 1,6-di(carbazol-9-yl)-5-(carbazol-9-methyl)-4-oxa-2-hexanol glycidyl ether. Glass transition temperatures of intermediate and final products established by differential scanning calorimetry are reported. The hole drift mobility, measured by the time of flight technique, in this well defined molecular glass depends little on the strength of the electric field and exceeds 10−5 cm2 V−1 s−1. The ionization potentials measured by electron photoemission method, light absorption and fluorescence spectra are closed to those reported for the other organic photoconductors containing electronically isolated carbazole moieties. 相似文献
45.
N. Žurauskienė S. Balevičius P. Cimmperman V. Stankevič S. Keršulis J. Novickij A. Abrutis V. Plaušinaitienė 《Journal of Low Temperature Physics》2010,159(1-2):64-67
The magnetoresistance (MR) of polycrystalline La0.83Sr0.17MnO3 thin films have been studied in high pulsed magnetic fields up to 38 T in the temperature range 100–300 K. The lucalox substrates were used to obtain polycrystalline structures with naturally formed grain boundaries (GBs) and crystallites whose dimensions were determined by film deposition temperature. It was found that the MR value is highest in the films having smallest crystallites. The main behaviour of high-field MR was analysed using modified Mott’s hopping model assuming that the GBs might be ferromagnetic with a Curie temperature T C being reduced in comparison with that of the crystallites interior. 相似文献
46.
Erika Adomavičiūtė Julija Baltušnikaitė-Guzaitienė Vaida Juškaitė Modestas Žilius Vitalis Briedis Sigitas Stanys 《纺织学会志》2018,109(2):278-284
The search of possibilities to improve the functional properties of textile materials has been continuing for years with the aim to provide higher hygiene characteristics offer advanced therapeutic functionality. One of available approaches to provide new properties for textiles is the inclusion of natural ingredients. Propolis extracts are successfully used in practical therapeutics for accelerated wound healing and cell proliferation processes. In this study, pure multi-filament yarns and yarns saturated with propolis were developed and characterized. The effect of preparation and formulation parameters on the characteristics of yarns was evaluated; the release of propolis extract components from yarns and their possible cytotoxicity on cell formation was also determined. 相似文献
47.
As the heat-induced formation of antioxidants throughout the Maillard reaction is known, this study was undertaken to evaluate the impact of lipid oxidation-derived aldehydes and ascorbic acid in Maillard model systems on the resulting antioxidant activity. For this purpose, various fractions of melanoidin-like polycondensation products were obtained from mixtures of amino acids (glycine, lysine, arginine) and lipid oxidation-derived aldehydes (hexanal, (E)-2-hexenal), in the presence or absence of glucose or ascorbic acid. All fractions showed a significant radical scavenging capacity (DPPH assay) and ferric reducing power (FRAP assay). The activity varied according to the composition of the model system tested, although some similar trends were discovered in both assays applied. The presence of lipid oxidation products in the browning products augmented the antioxidant activity in specific cases. For instance, the combined presence of arginine, hexanal and glucose in heated model systems resulted in a significantly higher antioxidant capacity. With an exception of ascorbic acid-containing model systems, melanoidin-like polycondensation products possessed significantly stronger antioxidant activities than the corresponding unheated initial reactant mixtures. Water-soluble high molecular weight (>12kDa) and nonsoluble fractions comprised the major part of the antioxidants derived from amino acid/lipid oxidation product model systems, with or without glucose or ascorbic acid. 相似文献
48.
J. Požela K. Požela V. Jucienė A. Sužiedėlis A. S. Shkolnik S. S. Mikhrin V. S. Mikhrin 《Semiconductors》2009,43(12):1590-1596
The scattering rate of electrons in a quantum well by localized polar optical and interface phonons is considered. The dependence of the force of the electron-phonon interaction on the frequency of optical phonons in materials of the heterostructure forming the electron and phonon quantum wells is determined. It is shown that, by varying the composition of semiconductors forming the quantum well and its barriers, it is possible to vary the scattering rates of electrons by a factor of several times. The scattering rates of electrons by polar optical phonons are calculated depending on the fractions In x and In y in the composition of semiconductors forming the In x Al1 ? x As/In y Ga1 ? y As quantum wells. Dependences of the mobility and saturated drift velocity of electrons in high electric fields and quantum wells In y Ga1 ? y As on the composition of the In x Al1 ? x As barriers introduced into quantum wells are determined experimentally. The electron mobility increases, while the saturated drift velocity decreases as the fraction of In x in the composition of barriers is increased. 相似文献
49.
V. Ambrazevičienė R. Brazis A. Kunigėlis 《Journal of Infrared, Millimeter and Terahertz Waves》1987,8(4):373-380
The second harmonic radiation in millimeter wave region is found in semiconductors in the absence of the dc electric field. The observed resonant maximum of radiation intensity is shown to be related to the excitation of the free-electron plasma oscillations in the dc magnetic field. 相似文献
50.