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71.
Gottfried Köthe 《Mathematische Annalen》1939,116(1):719-732
Ohne Zusammenfassung 相似文献
72.
A. S. Vorokh N. S. Kozhevnikova A. A. Rempel A. Magerl 《Journal of Structural Chemistry》2010,51(6):1170-1175
Dense thin nanostructured films of cadmium sulfide CdS obtained by chemical deposition from aqueous solutions are strongly
bound to a substrate due to the formation of cadmium hydroxide Cd(OH)2 in the system. By X-ray reflectometry and grazing incidence diffraction it is found that at the beginning of the deposition
a dense Cd(OH)2/SiO2 layer is produced on the surface of a silicon or glass substrate. This layer is formed through the atomic-layer adsorption
of crystalline 1–3 nm thick Cd(OH)2 film by the oxygencontaining substrate surface. During sulfidation of this cadmium-containing substrate layer, a surface
nucleation layer of CdS/Cd(OH)2/SiO2 forms, which provides the growth, denseness, and strong adhesion to the substrate of nanostructured CdS film with a disordered
structure. According to the obtained experimental data, a “hydroxide scheme” of film deposition is confirmed and refined,
and the stages of CdS nanofilm formation are determined. 相似文献
73.
Birgit Krimmel Friederike Swoboda Sonja Solar Gottfried Reznicek 《Radiation Physics and Chemistry》2010,79(12):1247-1254
The OH-radical induced degradation of hydroxybenzoic acids (HBA), hydroxycinnamic acids (HCiA) and methoxylated derivatives, as well as of chlorogenic acid and rosmarinic acid was studied by gamma radiolysis in aerated aqueous solutions. Primary aromatic products resulting from an OH-radical attachment to the ring (hydroxylation), to the position occupied by the methoxyl group (replacement –OCH3 by ?OH) as well as to the propenoic acid side chain of the cinnamic acids (benzaldehyde formations) were analysed by HPLC–UV and LC–ESI–MS. A comparison of the extent of these processes is given for 3,4-dihydroxybenzoic acid, vanillic acid, isovanillic acid, syringic acid, cinnamic acid, 4-hydroxycinnamic acid, caffeic acid, ferulic acid, isoferulic acid, chlorogenic acid, and rosmarinic acid. For all cinnamic acids and derivatives benzaldehydes were significant oxidation products. With the release of caffeic acid from chlorogenic acid the cleavage of a phenolic glycoside could be demonstrated. Reaction mechanisms are discussed. 相似文献
74.
Radiation damping on 600 and 800 MHz cryoprobes was investigated. The phase angle β between a vector 90° phase shifted to the precessing magnetization and the rf field induced in the coil was found to depend markedly on whether an FID was being acquired or not. The magnitude of the radiation damping field was sufficiently strong to restore 95% of the equilibrium water magnetization of a 90% H2O sample in a 5 mm sample tube within about 5 ms following a 165° pulse. This can be exploited in water flip-back versions of NOESY and TOCSY experiments of proteins, but care must be taken to limit the effect of the radiation damping field from the water on the Ha protons. Long water-selective pulses can be applied only following corrections. We developed a program for correcting pulse shapes if β is non-zero. The WATERGATE scheme is shown to be insensitive to imperfections introduced by radiation damping. 相似文献
75.
Rudolf Lang und Gottfried Mück 《Fresenius' Journal of Analytical Chemistry》1933,93(3-4):100-102
Ohne Zusammenfassung 相似文献
76.
Gottfried Pohlentz Ioannis Marlis Heinz Egge 《Journal of carbohydrate chemistry》2013,32(7):1151-1165
Abstract N-Phthaloyl, N-acetyl, N-benzyl, N-acetyl-N-methyl, N,N-dimethyl, N-benzoyl, and N,N-dibenzoyl derivatives of the trisaccharide β-D-glucopyranosyl-(1-3)-O-(2-deoxy-2-amino-β-D-glucopyranosyl)-(1-4)-O-β-D-glucopyranose were synthesized and analyzed by FAB MS. The intensity ratios of the peaks resulting from cleavage of the anomeric bond of the glucosamine residue and the respective molecular ion peaks turned out to be high for the N-acyl derivatives and up to two orders of magnitude lower for the N-alkyl compounds. These results show that fragmentation at the anomeric carbon of the amino sugar may be assisted by the carbonyl group and the resulting cation is stabilized by delocalization of the positive charge. 相似文献
77.
Cadmium determination in biological samples by direct solid sampling flame atomic absorption spectrometry 总被引:1,自引:0,他引:1
rico Marlon de Moraes Flores Jos Neri Gottfried Paniz Ayrton Figueiredo Martins Valderi L. Dressler Edson Irineu Müller Adilson Ben da Costa 《Spectrochimica Acta Part B: Atomic Spectroscopy》2002,57(12):2187-2193
A direct solid sampling flame atomic absorption spectrometric procedure for trace determination of cadmium in biological samples has been developed. Test samples (0.05–2.00 mg) were ground and weighed into small polyethylene vials, which were connected to the device for solid sample introduction into a conventional air/acetylene flame. Test samples were carried as a dry aerosol to a quartz cell, placed between the burner and the optical path, which had a perpendicular entrance and a slit in the upper part. The atomic vapor generated in the flame produced a transient signal that was totally integrated within 1 s. The effect of operating conditions and the extent of grinding on the analytical signal were evaluated. Background signals were always low and a characteristic mass of 0.29 ng Cd was obtained. Calibration was performed using different masses of solid certified reference materials. Results obtained for certified and in-house reference materials were typically within the 95% confidence interval of the certified and/or reference value, and the precision, expressed as relative standard deviation, was between 3.8 and 6.7%. The proposed system is simple and it might be adapted to conventional atomic absorption spectrometers allowing the determination of Cd in more than 80 test samples per hour, excluding weighing. 相似文献
78.
79.
Patrik Andersson Arto Annila Gottfried Otting 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1998,133(2):364-367
A generalized version of the TROSY experiment allows the spin-state selective editing of the four multiplet components of15N–1H cross peaks of amide groups in proteins into four different subspectra, with no penalty in sensitivity. An improvement by
in sensitivity results, if only two of the four multiplet components are selected. Use of the experiment for the measurement of1JHNcoupling constants is discussed. A water flip-back version of the experiment is demonstrated with a 45 kDa fragment of15N/2H labeledStaphylococcus aureusgyrase B. 相似文献
80.