共查询到20条相似文献,搜索用时 15 毫秒
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《Spectrochimica Acta Part B: Atomic Spectroscopy》1999,54(1):223-226
Tungsten (W) MIII X-ray absorption spectra of a periodic multilayer, (Si/W)100/Si, were measured with the change of X-ray grazing angle using sample current method. Under not total reflection condition, the absorbance changed little except at W MIII absorption edge. While under the total reflection condition, the absorbance increased with the increase of the X-ray energy and the increment changed from low to high at the W MIII absorption edge. This result reflected the variation of the X-ray evanescent wavelength caused by the absorption effect of W. 相似文献
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Xu Jingran Zhu Chenguang Xie Xiao Yan Chenguang Wang Yikai 《Journal of Thermal Analysis and Calorimetry》2020,140(5):2317-2324
Journal of Thermal Analysis and Calorimetry - Presented herein is a study on the ignition reaction kinetics and mechanism of B4C/KNO3 and B4C/KClO4 pyrotechnic smoke compositions using the... 相似文献
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A comprehensive review of the chemistry of polyhedral cluster complexes in whichs,p,d, andf-block metals are incorporated into C2B4-carborane cages to form the respective metallacarboranes is presented. The main focus of the review is directed toward systematizing the chemistry of metallacarboranes in order to promote their use as possible electronic, ceramic, and/or catalytic materials in addition to providing information on which we can test and expand our knowledge about the fundamental interactions that are at work in determining the structures and properties of these cluster complexes. 相似文献
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Wanping Zhang Liaoyuan Zhang Dan Zhu Yiwei Wu Yubo Qin Wenhua Ou 《Journal of Dispersion Science and Technology》2013,34(11):1637-1644
AbstractThe aim of this work was to study the encapsulation properties of polyols-in-oil-in-water (P/O/W) multiple emulsions for Vitamin C (Vc). The influence of formulation factors, including the concentration of lipophilic emulsifier, hydrophilic emulsifier, salt and glycerol had been investigated. The results indicated that the encapsulation stability could be improved by increasing the lipophilic emulsifier concentration which could strengthen the interfacial film. In contrast, the excess of hydrophilic emulsifier destabilized the emulsion. The presence of glycerol in the outer aqueous phase accelerated the phase transfer, thus reduced the encapsulation rate. The addition of salt in inner polyols phase had little effect on encapsulation rate while markedly affected the morphology and stability of this system. P/O/W multiple emulsions showed better encapsulation stability than the W/O/W multiple emulsions as the former’s encapsulation rate could remain more than 75% after 2?weeks while the latter only remained less than 60%. Meanwhile, the P/O/W emulsions exhibited higher storage modulus (G’), bigger loss modulus (G’’) and broaden linear viscoelastic regions than W/O/W emulsions. 相似文献
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Emmett B. Moore Jr. 《Theoretical chemistry accounts》1967,7(2):144-149
Population matrices have been calculated from molecular orbital wave functions of N2O4, B2Cl4, and B2F4 in order to understand further the bonding in these molecules which are isoelectronic in valence electrons but different in structure. C2H4 and C3H4 have been included in this study as check cases.
Zusammenfassung Ausgehend von Molekülorbitalen werden Besetzungsmatrizen für N2O4, B2Cl4 und B2F4 berechnet, um die Bindung in diesen Molekülen, die in den Valenzelektronen isoelektronisch sind, aber unterschiedliche Strukturen aufweisen, besser zu verstehen. C2H4 und C3H4 sind in dieser Untersuchung als Prüffälle eingeschlossen.
Résumé Des matrices d'occupation ont été calculées à partir des orbitales moléculaires de N2O4, B2Cl4 et B2F4, afin de comprendre plus profondément la liaison dans ces molécules, qui sont isoélectroniques par leurs électrons de valence, mais qui n'ont pas la même structure. C2H4 et C3H4 sont considérés dans cette étude à titre de vérification.相似文献
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Krawietz R Wehner B Meyer D Richter K Mai H Dietsch R Hopfe S Scholz R Pompe W 《Analytical and bioanalytical chemistry》1995,353(3-4):246-250
Microstructural properties of Ni/C multilayers prepared by PLD (pulsed laser deposition) have been investigated after heat treatment in vacuum at temperatures in the range of 50 degrees C to 500 degrees C. X-ray diffractometry, X-ray reflectometry, fluorescence EXAFS (extended X-ray absorption fine structure) and HREM (high resolution transmission electron microscopy) have been applied to characterize samples in the initial state and after annealing. The multilayer reflectivity remained unchanged or increased at temperatures below 400 degrees C due to sharpening of the interfaces caused by the formation of alpha-nickel and nickel carbide. The reflectivity decreased at temperatures above 400 degrees C because of the fragmentation of the nickel layers. It can be shown, that both chemical and mechanical driving forces are responsible for the observed modifications of the initial specimen state. 相似文献
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R. Krawietz B. Wehner D. Meyer K. Richter H. Mai R. Dietsch S. Hopfe R. Scholz W. Pompe 《Fresenius' Journal of Analytical Chemistry》1995,353(3-4):246-250
Microstructural properties of Ni/C multilayers prepared by PLD (pulsed laser deposition) have been investigated after heat treatment in vacuum at temperatures in the range of 50°C to 500°C. X-ray diffractometry, X-ray reflectometry, fluorescence EXAFS (extended X-ray absorption fine structure) and HREM (high resolution transmission electron microscopy) have been applied to characterize samples in the initial state and after annealing. The multilayer reflectivity remained unchanged or increased at temperatures below 400°C due to sharpening of the interfaces caused by the formation of -nickel and nickel carbide. The reflectivity decreased at temperatures above 400°C because of the fragmentation of the nickel layers. It can be shown, that both chemical and mechanical driving forces are responsible for the observed modifications of the initial specimen state. 相似文献
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Single-step procedure for the extraction and purification of leukotrienes B4, C4 and D4 总被引:2,自引:0,他引:2
R Richmond N C Turner N Maltby D Heavey J Vial C T Dollery G W Taylor 《Journal of chromatography. A》1987,417(2):241-251
A rapid and simple method for the on-line concentration and high-performance liquid chromatographic (HPLC) purification of the leukotrienes in good yield from biological fluids is described. Readily available antisera are used in conjunction with this system to give a specific and sensitive assay for leukotrienes B4, C4 and D4 with sub-nanogram limits of detection. Tritium-labelled leukotrienes are used as internal standards, both to locate the leukotrienes post-HPLC and to accurately determine recoveries. 相似文献
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[reaction: see text] The first stereoselective synthesis of a potent DNA damaging agent, (-)-myristinin B/C, has been accomplished. This efficient synthesis allowed for unambiguous confirmation of the structure and absolute stereochemistry of the atropisomeric natural product. The antipode, (+)-myristinin B/C, was also synthesized, providing ample material for biological evaluation of both enantiomers. 相似文献
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Ninomiya Kazuhiko Kitanaka Michihiro Shinohara Atsushi Tampo Motonobu Miyake Yasuhiro Sakai Yoichi Kubo Michael K. 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(3):1107-1111
Journal of Radioanalytical and Nuclear Chemistry - Elemental analysis by measurement of muonic X-rays shows great potential for analyzing the elemental composition of a bulk material at a specific... 相似文献
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Effects of heteroatoms on doped LiFePO4/C composites 总被引:1,自引:0,他引:1
H. Liu C. Li Q. Cao Y. P. Wu R. Holze 《Journal of Solid State Electrochemistry》2008,12(7-8):1017-1020
A series of supervalent cation doped Li1–x M0.01Fe0.99PO4/C composites (M?=?Ti, Zr, V, Nb, and W) were synthesized by solid-state reaction. The effects of the heteroatoms were studied by X-ray diffraction, cyclic voltammetry, and electrochemical impedance measurement. After doping, the lattice structure of LiFePO4 is not destroyed and the reversibility of lithium ion intercalation and deintercalation is improved. The diffusion coefficient of lithium ions depends on the radius of the heteroatoms. As the radius of the heteroatom is larger, the diffusion coefficient increases. 相似文献
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Menghua Li Haixia Zhang Zongxu Wu Zhenxing Zhu Xinlei Jia 《Molecules (Basel, Switzerland)》2022,27(4)
The dissipative particle dynamics simulation method is adopted to investigate the microemulsion systems prepared with surfactant (H1T1), oil (O) and water (W), which are expressed by coarse-grained models. Two topologies of O/W and W/O microemulsions are simulated with various oil and water ratios. Inverse W/O microemulsion transform to O/W microemulsion by decreasing the ratio of oil-water from 3:1 to 1:3. The stability of O/W and W/O microemulsion is controlled by shear rate, inorganic salt and the temperature, and the corresponding results are analyzed by the translucent three-dimensional structure, the mean interfacial tension and end-to-end distance of H1T1. The results show that W/O microemulsion is more stable than O/W microemulsion to resist higher inorganic salt concentration, shear rate and temperature. This investigation provides a powerful tool to predict the structure and the stability of various microemulsion systems, which is of great importance to developing new multifunctional microemulsions for multiple applications. 相似文献
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The dideoxy core (23) of lomaiviticinone and congener 15 were derived starting from (-)-quinic acid in a stereocontrolled fashion. 相似文献