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31.
Markus Neuenschwander Ulrich Lienhard Hans-Peter Fahrni Beat Hurni 《Helvetica chimica acta》1978,61(7):2428-2436
Amide Synthesis by Means of ‘Push-Pull’-Acetylenes ‘Push-Pull’-acetylenes react easily with carbon acids, Addition of amines to the crude reaction mixture gives amides in an excellent yield by a simple one-pot procedure. Because of the high selectivity of the acetylenes 1 towards carboxylic functions and of the high selectivity of the enol esters 4 towards amine functions, ‘push-pull’-acetylenes could be excellent reagents for peptide synthesis. 相似文献
32.
Hans Weidmann 《Monatshefte für Chemie / Chemical Monthly》1965,96(3):766-773
Zusammenfassung Durch Acylierung. Methylierung und Benzylierung werden aus 1,2-Isopropyliden--d-glucofuranosidurono-6,3-lacton (I) selbst unter den verschiedensten Bedingungen ausschließlich die zu erwartenden 5-O-Acyl- bzw. 5-O-Alkylderivate von I erhalten. Die Dehydrierung von I ergibt 1,2-Isopropyliden--d-glucofuranosidurono-5-ulose-6,3-lacton (VI), welches keine Reduktionswirkung mehr zeigt und bei seiner Hydrierung I zurückbildet. Alle 5 möglichen Monomethyl-d-glucosen, die 3,6-Dimethyl-d-glucose, und die 5-Benzyl-d-glucofuranose, werden chromatographisch verglichen.
Frau Prof. Dr.Erika Cremer zum Geburtstag gewidmet. 相似文献
Acylation, methylation and benzylation of 1,2-isopropylidene--d-glucofuranosidurono-6,3-lactone (I) invariably give the 5-Oacyl-or the 5-O-alkylderivatives to be expected, even under the most widely differing conditions. Dehydrogenation of I yields 1,2-isopropylidene--d-glucofuranosidurono-5-ulose-6,3-lactone (VI) which no longer has reducing properties and which on hydrogenation is reconverted to I. The 5 possible monomethyl-d-glucoses, 3,6-dimethyl-d-glucose and 5-benzyl-d-glucofuranose have been compared chromatographically.
Frau Prof. Dr.Erika Cremer zum Geburtstag gewidmet. 相似文献
33.
D. Weidmann G. Wysocki C. Oppenheimer F.K. Tittel 《Applied physics. B, Lasers and optics》2005,80(2):255-260
We report the development of a field-deployable, pulsed quantum cascade laser spectrometer. The instrument is designed to measure the 13C/12C isotopic ratio in the CO2 released from volcanic vents. Specific 12CO2 and 13CO2 absorption lines were selected around 4.3 m, where the P-branch of 12CO2 overlaps the R-branch of 13CO2 of the 0001–0000 vibrational transition. This particular selection makes the instrument insensitive to temperature variations. A dual-channel cell balances the two absorption signals. We provide details of the instrument design and a preliminary demonstration of its performance based on laboratory measurements of 16O12C16O and 16O12C18O. PACS 42.55.Px; 42.62.Fi; 07.88.+y 相似文献
34.
L. Joly V. Zéninari B. Parvitte D. Weidmann D. Courtois Y. Bonetti T. Aellen M. Beck J. Faist D. Hofstetter 《Applied physics. B, Lasers and optics》2003,77(6-7):703-706
We report results of spectroscopic measurements with a continuous-wave distributed-feedback quantum-cascade laser (DFB QCL). Line intensities and self-broadening coefficients were measured in the 1 band of SO2 between 1088 and 1090 cm-1. The self-broadening coefficients in this paper confirm the typical decrease of self with increasing rotational quantum number Ka
. The line intensities determined here are smaller than those in the HITRAN 2000 database. Several lines found in this study were not present in the database. PACS 07.57.Ty; 33.20.Ea 相似文献
35.
René Csuk Alois Fürstner Heinz Sterk Hans Weidmann 《Journal of carbohydrate chemistry》2013,32(3):459-467
Hexopyranoside- and hexofuranose uloses with either ethyl 2-(branamethyl)acrylate in the presence of laminar Zn/Ag-graphite or ethyl 2-(trimethylsilylinethyl)acrylate/tetra-n-butylanrnonium fluoride undergo stereoselective branching, mainly with formation of spiro α-methylene-γ-lactones. 相似文献
36.
Schanda P Meier BH Ernst M 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,210(2):246-259
The accurate experimental determination of dipolar-coupling constants for one-bond heteronuclear dipolar couplings in solids is a key for the quantification of the amplitudes of motional processes. Averaging of the dipolar coupling reports on motions on time scales up to the inverse of the coupling constant, in our case tens of microseconds. Combining dipolar-coupling derived order parameters that characterize the amplitudes of the motion with relaxation data leads to a more precise characterization of the dynamical parameters and helps to disentangle the amplitudes and the time scales of the motional processes, which impact relaxation rates in a highly correlated way. Here. we describe and characterize an improved experimental protocol--based on REDOR--to measure these couplings in perdeuterated proteins with a reduced sensitivity to experimental missettings. Because such effects are presently the dominant source of systematic errors in experimental dipolar-coupling measurements, these compensated experiments should help to significantly improve the precision of such data. A detailed comparison with other commonly used pulse sequences (T-MREV, phase-inverted CP, R18(2)(5), and R18(1)(7)) is provided. 相似文献
37.
Walker RJ van Helden JH Kirkbride J McCormack EA Bell MT Weidmann D Ritchie GA 《Optics letters》2011,36(24):4725-4727
Two 5 μm continuous wave quantum cascade lasers are used to perform a counterpropagating pump and probe experiment on a low pressure sample of nitric oxide. The strong pump field excites a fundamental rovibrational transition and the weaker probe field is tuned to the corresponding rotationally resolved hot band transition. When both light fields are in resonance, rapid passage is observed in the hot band absorption lineshape arising from a minimally damped and velocity-selected sample of molecules in the v=1 state. The measured rapid passage signals are well described by a two-level model based on the optical Bloch equations. 相似文献
38.
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40.
The characteristics of large coherent structures in turbulent, periodically-excited, as well as naturally-developing bubbly jets are investigated, and interactions between bubbles and large-scale vortices are studied quantitatively. 相似文献