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891.
892.
Taming the Carboxyl Group for Directed Carbometalation: Observations on the Use of Anions,Dianions and Ester Enolates
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Dr. Sandy Desrat Dr. Philip J. Gray Dr. Matthew R. Penny Prof. Dr. William B. Motherwell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(29):8918-8922
Carboxylate anions, dianions and ester enolates provide simultaneous protection and activation for directed carbometalation reactions. Advantage can be taken of the bis‐carbanionic character of the intermediate for further controlled C?C bond forming reactions. 相似文献
893.
894.
An experimental and theoretical study on the optically stimulated spin transport in zinc-blende semiconductors is presented. The first part of the paper describes an experiment which investigates the effect of a longitudinal electric field on the spin-polarized carriers induced by a circularly polarized light. Since the photo-generated hole spins relaxation is extremely fast, the experiment observes only the effect resulting from spin-polarized electrons accumulating at the transverse edges of the sample, as a result of left-right asymmetries in scattering for spin-up and spin-down electrons in the presence of spin–orbit (SO) interaction. It is found that the effect depends on the longitudinal electric field and doping density as well as on temperature. The results are discussed. The second part of the paper deals with a theoretical investigation using norm-conserving pseudopotential and Green function formalism to analyse the SO mechanism responsible for the light-induced Hall voltage. The findings resulting from the investigation are discussed and are compared with experimental data. 相似文献
895.
Ohne Zusammenfassung 相似文献
896.
A. Kühn C. W. Waidner E. F. Mueller R. Kempf A. Stock F. Henning Th. W. Richards S. Tamaru J. Timmermanns H. van der Horst H. Kamerlingh Onnes F. P. G. A. J. van Agt W. A. Noyes P. Gmelin A. W. Gray G. Dimmer W. Block Franz Neumann Fr. Knoops E. Berl A. Kullmann Y. Yamaguchi 《Analytical and bioanalytical chemistry》1928,74(3-4):114-120
897.
F. Hengl M. Harris A. Travers C. M. Smith E. H. Hamilton J. J. T. Graham A. F. Swain D. Green L. L. English L. H. Dawsey A. J. Haas H. Knight H. Martin R. S. Woglum E. R. de Ong G. P. Gray L. N. Staniland F. Tutin C. L. Walton und J. Houben 《Fresenius' Journal of Analytical Chemistry》1935,101(3-4):137-143
Ohne Zusammenfassung 相似文献
898.
Ch. Earl Gray 《Fresenius' Journal of Analytical Chemistry》1908,47(4):247-248
Ohne Zusammenfassung 相似文献
899.
900.
Alcohol ethoxylates (AEs) are nonionic surfactants. They are industrially important compounds that have historically been difficult to analyze, with the best results to date achieved through derivatization (e.g., silylation) followed by analysis by gas chromatography/mass spectrometry (GC/MS). Recently, mass spectrometric techniques such as field desorption (FD), time-of-flight secondary ion mass spectrometry (TOF-SIMS), fast atom bombardment (FAB), electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) have been employed to analyze surfynol(R) 4xx. In an effort to produce low-cost alkyl-capped AEs and anionic detergents from AEs, a fast and reliable measure of the product yields and conversions from AEs is required in research. We found that the product yields and conversions from reactions of AEs, obtained by the employment of atmospheric pressure chemical ionization (APCI), were in good agreement with those obtained from proton nuclear magnetic resonance spectroscopy ((1)H-NMR). Therefore, APCI can be used as a validated tool for studying AE reactions. Mixtures that contain either silylated or unsilylated ethoxylates and/or carboxylates yield the same APCI mass spectra. Copyright -Copyright 1999 John Wiley & Sons, Ltd. 相似文献