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91.
Giannetti L Barchi D Fiorucci F Gennuso E Sanna P Pallagrosi M Neri B 《Journal of chromatographic science》2005,43(7):333-336
Different extraction and purification methods are described here to determine medroxyprogesterone acetate (MPA) in pork meat and serum. Spiked samples are investigated over the concentration range of MPA 0.5-20 ng/g. Pork meat tissues are subjected to extraction using organic solvent, and pork serum is simply diluted with acetate buffer. Clean-up is performed using solid-phase extraction on a C18 cartridge, and MPA is eluted with ethanol. Aliquots are injected into a high-performance liquid chromatography-mass spectrometry system. MPA content is determined on the basis of m/z 387-327 and 387-123 transitions. 相似文献
92.
We present a novel approach to explore the conformational space of globular proteins near their native state. It combines the advantages of coarse-grained models with those of all-atoms simulations, required to treat molecular recognition processes. The comparison between calculated structural properties with those obtained with all-atoms molecular dynamics simulations establishes the accuracy of the model. Our method has the potential to be extended to molecular recognition processes in systems whose characteristic size and time scale prevent an analysis based on all-atoms molecular dynamics. 相似文献
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Odo Klais Philip C. Anderson Allan H. Laufer Michael J. Kurylo 《Chemical physics letters》1979,66(3):598-601
An upper limit for the rate constant of the bimolecular reaction CH3 + O2 – OH + H2CO at 368 K has been measured by monitoring OH using the flash photolysis-resonance fluorescence technique. Careful modeling of the system in conjunction with statistical analysis indicates upper limit of k ? 3 x 10?16cm3 molec?1 s?1. The rate constant of the reaction of OH with azomethane has also been measured. 相似文献
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Analytical investigation of the SAFE diagram for bladed wheels,numerical and experimental validation
Compressor and turbine bladed wheels interact with the fluid distributed by the stator vanes. They are subject to vibration and fatigue loading, especially when resonance conditions are excited. Avoiding resonance is fundamental when designing bladed wheels. The Campbell diagram approach is too conservative since bladed wheels show many close frequency natural modes, thus it is almost impossible to avoid frequency matching. Singh?s Advanced Frequency Evaluation (SAFE) diagram, or interference diagram, also introduces shape matching in addition to the frequency, for resonance prediction, therefore many frequency matching cases can be identified as non-critical and thus tolerated. The present paper explains and demonstrates the SAFE diagram by introducing an analytical expression to identify bladed wheel resonance conditions. The mode shape matching with a harmonic component is investigated by means of specific examples. Symmetry properties of the matching distribution of harmonic indices and mode shapes are also introduced and demonstrated. Finally, a bladed wheel analysis is used for validation, both in FE simulations and experiments. 相似文献
100.
Prof. Dr. Raffaele Saladino Dr. Veronica Neri Dr. Paola Checconi Dr. Ignacio Celestino Dr. Lucia Nencioni Prof. Dr. Anna Teresa Palamara Dr. Marcello Crucianelli 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(7):2392-2404
This paper describes a new route for the synthesis of 1′‐homo‐N‐nucleoside derivatives by means of either methyltrioxorhenium (MTO) or supported MTO catalysts, with H2O2 as the primary oxidant. Under these selective conditions, the oxyfunctionalization of the heterocyclic ring and the N heteroatom oxidation were operative processes, regardless of the type of substrate used, that is, purine or pyrimidine derivatives. In addition, the oxidation of 1′‐homo‐N‐thionucleosides, showed the occurrence of site‐specific oxidative nucleophilic substitutions of the heterocyclic ring. The MTO/H2O2 system showed, in general, high reactivity under both homogeneous and heterogeneous conditions, affording the final products with high conversion values of substrates and from medium to high yields. Many of the novel 1′‐homo‐N‐nucleoside analogues were active against the influenza A virus, without any cytotoxic effects, retaining their activity in both protected and unprotected forms. 相似文献