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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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David H. Naghski Joseph T. Boyd Howard E. Jackson Andrew J. Steckl 《Optics Communications》1998,150(1-6):97-100
Optical channel waveguides formed by focused ion beam (FIB) implantation-induced mixing of AlGaAs multiple quantum well structures and subsequent oxidation of the mixed regions have the potential of significantly reducing the size of integrated photonic waveguide structures. Since FIB implantation is a direct write process characterized by nanoscale precision, we suggest its use for forming channel waveguides having nanoscale (submicrometer) widths. Calculations presented for such channel waveguides show reductions in size by at least an order of magnitude are possible for directional couplers and other structures involving curved channel waveguide sections. Such size reductions would allow the realization of significantly higher levels of device integration than are now currently possible. 相似文献
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Z. Fleischman C. Munasinghe A. J. Steckl A. Wakahara J. Zavada V. Dierolf 《Applied physics. B, Lasers and optics》2009,97(3):607-618
Using combined excitation emission spectroscopy, we performed a comparative study of europium ions in GaN in samples that
have been in situ doped during interrupted growth epitaxy (IGE) or conventional molecular beam epitaxy (MBE) as well as samples
that were grown using organometallic vapor phase epitaxy (OMVPE) and subsequently ion implanted with Eu ions. Through site-selective
resonant excitation, we are able to unambiguously assign all major observed transitions to a combination of different incorporation
sites and electron–phonon coupled transitions. We identified at least nine different incorporation sites of Eu ions in GaN
and studied how these sites behave under different excitation conditions and how their relative number is modified by different
growth and doping conditions. The coupling to phonons has also been studied for a series of Al
x
Ga1−x
N samples with x=0…1. We find that a main site most resembling an unperturbed Eu ion on Ga site is always dominant, while the minority sites
are changing substantially in relative numbers and can occur in some samples fairly close in emission intensity to the main
site. In terms of the excitation pathway after the creation of electron-hole pairs, we found three types of centers: (1) sites
that are dominantly excited through shallow defect traps; (2) sites that are excited through a deep defect trap; (3) sites
that cannot be excited at all including the majority of the main sites. We interpret this finding to indicate that the ion
in this environment is not very efficient in trapping excitation and that the indirect excitation involving other traps depends
on the ion/trap distance. Many of the main sites are far away from these traps and cannot be excited through this channel
at all. The efficiency of excitation is highest for the deep traps, indicating that it would be desirable to enrich the respective
site, as has been done with some success in the IGE grown samples. 相似文献
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A procedure is explained to determined the amount of several pairs of diametrical loads applied to the outside boundary of
a ring when stresses at selected points of the inside or outside boundaries are known. Coefficients of influence are used,
following an approach similar to the one presented in a previous paper. Examples of application are given and the possible
increase in precision is shown when the number of points of measurements is larger than the number of loads to be determined. 相似文献
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