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排序方式: 共有143条查询结果,搜索用时 31 毫秒
21.
CM Silva MF Duarte ML Mira MH Florêncio K Versluis AJ Heck 《Rapid communications in mass spectrometry : RCM》1999,13(12):1098-1103
Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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Linda Feketeová Jan Žabka Fabio Zappa Verena Grill Paul Scheier Tilmann D. Märk Zdenek Herman 《Journal of the American Society for Mass Spectrometry》2009,20(6):927-938
Surface-induced interactions of the projectile ion C2D4+ with room-temperature (hydrocarbon covered) stainless steel, carbon highly oriented pyrolytic graphite (HOPG), and two different
types of diamond surfaces (O-terminated and H-terminated) were investigated over the range of incident energies from a few
eV up to 50 eV. The relative abundance of the product ions in dependence on the incident energy of the projectile ion [collision-energy
resolved mass spectra, (CERMS) curves] was determined. The product ion mass spectra contained ions resulting from direct dissociation
of the projectile ions, from chemical reactions with the hydrocarbons on the surface, and (to a small extent) from sputtering
of the surface material. Sputtering of the surface layer by low-energy Ar+ ions (5–400 eV) indicated the presence of hydrocarbons on all studied surfaces. The CERMS curves of the product ions were
analyzed to obtain both CERMS curves for the products of direct surface-induced dissociation of the projectile ion and CERMS
curves of products of surface reactions. From the former, the fraction of energy converted in the surface collision into the
internal excitation of the projectile ion was estimated as 10% of the incident energy. The internal energy of the surface-excited
projectile ions was very similar for all studied surfaces. The H-terminated room-temperature diamond surface differed from
the other surfaces only in the fraction of product ions formed in H-atom transfer surface reactions (45% of all product ions
formed versus 70% on the other surfaces). 相似文献
24.
Alemani M Peters MV Hecht S Rieder KH Moresco F Grill L 《Journal of the American Chemical Society》2006,128(45):14446-14447
The electric field applied between the tip of a scanning tunneling microscope and a metallic surface is shown to induce the reversible trans-cis isomerization of single azobenzene derivatives adsorbed on a Au(111) surface. The investigated molecule is symmetrically equipped with four tert-butyl groups, which decouple the azobenzene core from the metallic surface, facilitating the formation of highly ordered islands. Due to the spatial extension of the electric field, it is possible to switch many molecules within the same island simultaneously. 相似文献
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Upon exposure to commercial bleach (approximately 5% aqueous sodium hypochlorite), nickel(II) chloride or nickel(II) acetate is transformed quantitatively into an insoluble nickel species, nickel oxide hydroxide. This material consists of high surface area nanoparticles (ca. 4 nm) and is a useful heterogeneous catalyst for the oxidation of many organic compounds. The oxidation of primary alcohols to carboxylic acids, secondary alcohols to ketones, aldehydes to carboxylic acids, and alpha, beta-unsaturated carboxylic acids to epoxy acids is demonstrated using 2.5 mol % of nickel catalyst and commercial bleach as the terminal oxidant. We demonstrate the controlled and selective oxidation of several organic substrates using this system affording 70-95% isolated yields and 90-100% purity. In most cases, the oxidations can be performed without an organic solvent, making this approach attractive as a "greener" alternative to conventional oxidations. 相似文献
26.
Two non-confocally adjusted spherical transducers are employed to implement an acoustic microscope operating in transmission with an approximately line-shaped point spread function (PSF). Such a PSF is of advantage in acoustic transmission line tomography and spatially resolved velocity measurements in solids. The foci of the transducers are viewed as diffraction-limited point transducers and appropriate time-selective signal acquisition is designed to restrict the ultrasound wave paths to the line connecting them. It is found that for typical commercially available transducers the largest contribution to the detected signal is not due to the direct ultrasound wave but due to the edge waves emanating from the rim of the focusing transducer. This poses constraints on achieving a line-shaped PSF in defocused acoustic transmission microscopy. It is shown that, due to the strong contribution from edge waves, it is impossible to achieve a line-shaped PSF in the case of application of a long exciting toneburst. The influence of the exciting pulse length, as well as the position of the time gate on the obtainable PSF is investigated. 相似文献
27.
P. Hschl E. Belas L. Turjanska R. Grill J. Franc R. Fesh P. Moravec 《Journal of Crystal Growth》2000,220(4):444-448
Conductivity of CdTe single crystals fabricated in our laboratory by vertical gradient freeze method was studied at temperatures 400–1200°C. Two clear slopes are seen — 0.7 eV in the solid and 4.6 eV in the liquid. Experimental value of electrical conductivity at the melting point 10 Ω−1 cm−1 was observed. A model explaining the experimental data is suggested. 相似文献
28.
K. Grill 《Probability Theory and Related Fields》1995,102(4):567-573
Summary We prove an almost sure lower limit law for the square integral of the large increments of the Wiener process, extending results obtained by Li (1992).Work supported by an NSERC Foreign Researcher Award at Carleton University 相似文献
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