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131.
A. Christensen 《Fresenius' Journal of Analytical Chemistry》1915,54(3):158-159
Ohne Zusammenfassung 相似文献
132.
133.
Paul Kosma Martina Strobl Andreas Hofinger Jens Ø. Duus Bent O. Petersen Klaus Bock Helmut Brade 《Monatshefte für Chemie / Chemical Monthly》2002,133(4):561-570
Summary. Methyl glycosides of Kdo and a (2→8)-linked Kdo disaccharide were prepared which contain a deuterium label at C-8 of the reducing unit. The label was introduced in fair
diastereoselectivity upon reduction of an aldehyde group using a chiral borane complex derived from N-benzyloxycarbonyl-(S)-proline which produced the 8-(S)-deuterated derivative as the major isomer. Further coupling with a Kdo bromide gave the α-(2→8)-linked disaccharide in good yield. The deprotected disaccharide serves as a model for NMR spectroscopic
studies on the side chain conformation of a carbohydrate epitope from the bacterial pathogen Chlamydia.
Received September 17, 2001. Accepted October 17, 2001 相似文献
134.
P. B. Sarkar N. R. Dhar J. M. Kalthoff J. Holluta J. Obrist G. Krüss J. Nicklès A. Skrabal J. Preiss O. T. Christensen M. Geloso P. Dubois F. P. Treadwell R. W. Coltman A. Gorgeu O. Hauser F. Wirth und O. Hackl 《Fresenius' Journal of Analytical Chemistry》1930,80(5-6):216-228
Ohne Zusammenfassung 相似文献
135.
Per Helvig Christensen Steen Mørup Henrik Topsøe Bjerne Steffen Clausen 《Hyperfine Interactions》1986,28(1-4):945-948
Bimetallic Fe-Co alloy catalysts supported on silica have been studied by use of combined Mössbauer absorption and emisson spectroscopy. Effects of carburization on samples with different particle size are discussed. 相似文献
136.
K. Köhler H. P. Geserich A. Nørlund Christensen 《Zeitschrift für Physik B Condensed Matter》1986,62(3):319-324
The reflectance spectra of TiN1–x
single crystals were measured at room temperature. The chemical composition of the crystals was varied between TiN1–0.00 and TiN1–0.43. The experimental data are analyzed on the basis of a Lorentz-Drude model in order to determine the influence of nitrogen vacancies on the electrical conductivity, on the carrier concentration, and on the collision time. 相似文献
137.
This paper presents a new algorithm for optimal parameter estimation problems with linear constraints. The algorithm developed is based on least absolute-value approximations. The problem is solved first using a least-error-square technique, where we add to the cost function the equality constraints via Lagrange multipliers, to obtain a good estimate for the residuals of the measurements, having gained this information, we choose a number of measurements with the smallest residuals. This number equals the number of parameters to be estimated minus the number of constraints. Using these measurements together with the constraints, we obtain a number of observations equal to the number of parameters to be estimated. By using this technique, we show that there is no need to either iterate or use linear programming to obtain the estimation.This work was supported by the Natural Sciences and Engineering Research Council of Canada, Grant A4146. 相似文献
138.
139.
Paulo A. Machicao Scott R. Burt Ryan K. Christensen Nathan B. Lohner J.D. Singleton Matt A. Peterson 《Tetrahedron letters》2017,58(24):2318-2321
Treatment of N-[(4-hydroxy-6-phenyl)pyrimidin-2-yl]cyanamide with 1° alkyl or arylamines in isopropyl alcohol for only 10 min at 110–120 °C under microwave conditions gave the corresponding N′-alkyl(aryl)guanidine derivatives in excellent yields (65–84%). Isolated yields were greatest when >1.0 equiv. of amines were employed, but excellent results were also obtained when aryl and alkylamines were reacted with a more atom-economical loading (1.0 equiv.; 70% and 72% ave. yields, respectively). Arylamines with either highly electron withdrawing substituents (e.g. CO2H) or pi-deficient heterocycles (e.g. variously substituted aminopyridines) did not work well under these conditions, and reaction with ureas and/or amino acids did not give detectable products. Work-up was exceedingly simple, and involved simple collection and washing of product on a sintered glass funnel. Products were obtained in analytically pure form and required approximately 1 h to prepare, start to finish. 相似文献
140.
Jan Bornholdt Dr. Jakob Felding Dr. Rasmus P. Clausen Dr. Jesper L. Kristensen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(41):12474-12480
The pyrimidine‐2‐sulfonyl (pymisyl) group is introduced as a new protecting group that can be used to activate aziridines towards ring opening. It is readily introduced and removed under mild conditions. Regioselective ring opening of pymisyl‐protected 2‐methyl‐aziridine with organocuprates gives the corresponding sulfonamides in high yields, and the pymisyl group can subsequently be removed upon treatment with a thiolate. The versatility of this new nitrogen protecting group is illustrated with a new synthesis of Selegiline, a monoamine oxidase‐B inhibitor marketed for the treatment of Parkinson’s disease. 相似文献