排序方式: 共有47条查询结果,搜索用时 203 毫秒
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S. V. Bobashev R. V. Vasil’eva A. V. Erofeev T. A. Lapushkina S. A. Poniaev D. M. Van Wie 《Technical Physics》2003,48(2):177-184
Effective ways for controlling shock wave configurations by means of external actions are sought. One such way is a local effect of electric and magnetic fields. In this paper, the local effect of external fields is implemented by current localization in a limited region of a diffuser. The experiment is carried out in a diffuser providing the complete internal compression of the gas with a Mach number at the inlet M=4.3. As a working medium, a xenon plasma is used. The plasma flow is formed in a shock tube equipped with an accelerating nozzle. Two ways of current localization are tested. In the first one, the diffuser inlet is a short channel of Faraday generator type. In this case, the ponderomotive force basically decelerates or accelerates the flow depending on the direction of the electric field. In the second way, the current flows through a narrow near-wall region between adjacent electrodes. In this case, the ponderomotive force compresses or expands the gas. In both cases, it is shown that the angle of an attached shock due to MHD interaction can be both decreased and increased. The central problem with the MHD control of shock waves is near-electrode and near-wall phenomena. 相似文献
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Kwak WJ Han CK Chang HW Kim HP Kang SS Son KH 《Chemical & pharmaceutical bulletin》2003,51(3):333-335
A new triterpenoid saponin, loniceroside C was isolated from the aerial parts of Lonicera japonica. Its structure was established to be 3-O-beta-D-glucopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl (1-->2)-[beta-D-xylopyranosyl(1-->6)]-beta-D-glucopyranosyl ester by spectroscopic techniques and chemical transformations. Loniceroside C showed in vivo antiinflammatory activity against mouse ear edema provoked by croton oil. 相似文献
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J. P. R?nspies S. Wie?ell H. Pfnür 《Applied Physics A: Materials Science & Processing》2010,100(4):1007-1012
We studied the local electronic transport properties of a monolayer thick Pb wire by local potentiometry with the tip of a
tunneling microscope. 50-nm-wide wires on bare Si(557) were generated by direct writing with an electron beam in an ultrathin
film of SiO2 using the process of electron-beam-induced selective stimulated thermal desorption of oxygen (EBSTD) in combination with
a shadow-mask technique and macroscopic TiSi2 contacts. The resistivity of this wire agrees well with expectations derived from anisotropic monolayer thick Pb films on
Si(557). Although small Pb clusters nucleated during annealing and desorption of excess Pb, they had a negligible effect on
the local resistive properties of the wire. Steps in the substrate of atomic height apparently do not interrupt the conducting
path, but due to local scattering at step edge states increase the local resistivity by more than one order of magnitude. 相似文献
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G. Velardi Angeli Angelico und Wie Rimini 《Fresenius' Journal of Analytical Chemistry》1907,46(2-3):185
Ohne Zusammenfassung 相似文献
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Muhammad Ali Inam Rizwan Khan Kang Hoon Lee Muhammad Akram Zameer Ahmed Ki Gang Lee Young Min Wie 《Molecules (Basel, Switzerland)》2021,26(22)
Arsenic (As)-laden wastewater may pose a threat to biodiversity when released into soil and water bodies without treatment. The current study investigated the sorption properties of both As(III, V) oxyanions onto iron hydroxide (FHO) by chemical coagulation. The potential mechanisms were identified using the adsorption models, ζ-potential, X-ray diffraction (XRD) and Fourier Transform Infrared Spectrometry (FT-IR) analysis. The results indicate that the sorption kinetics of pentavalent and trivalent As species closely followed the pseudo-second-order model, and the adsorption rates of both toxicants were remarkably governed by pH as well as the quantity of FHO in suspension. Notably, the FHO formation was directly related to the amount of ferric chloride (FC) coagulant added in the solution. The sorption isotherm results show a better maximum sorption capacity for pentavalent As ions than trivalent species, with the same amount of FHO in the suspensions. The thermodynamic study suggests that the sorption process was spontaneously exothermic with increased randomness. The ζ-potential, FT-IR and XRD analyses confirm that a strong Fe-O bond with As(V) and the closeness of the surface potential of the bonded complex to the point of zero charge (pHzpc) resulted in the higher adsorption affinity of pentavalent As species than trivalent ions in most aquatic conditions. Moreover, the presence of sulfates, phosphates, and humic and salicylic acid significantly affected the As(III, V) sorption performance by altering the surface properties of Fe precipitates. The combined effect of charge neutralization, complexation, oxidation and multilayer chemisorption was identified as a major removal mechanism. These findings may provide some understanding regarding the fate, transport and adsorption properties onto FHO of As oxyanions in a complex water environment. 相似文献
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The structure elucidation of the title compounds isolated from a toxic mushroom is reported. Orellanine was found to be the bis N-oxide of orelline for which 3,3′,4,4′-tetrahydroxy-2,2′-bipirydyl structure was ascribed. 相似文献