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831.
Schramm H Kaspereit M Kienle A Seidel-Morgenstern A 《Journal of chromatography. A》2003,1006(1-2):77-86
The improvement of the simulated moving bed (SMB) process based on the introduction of a cyclic modulation of the feed concentration is described. It is demonstrated that such a feed concentration gradient during the shifting cycle can improve the performance significantly. The productivity and the product concentrations can be increased while simultaneously the solvent consumption can be decreased compared to the conventional SMB process with constant feed parameters. 相似文献
832.
833.
Stable isotope dilution assays were developed for the quantification of the folate vitamers 5-methyltetrahydrofolate, 5-formyltetrahydrofolate, tetrahydrofolate, 10-formylfolate and pteroylglutamic acid in food samples by using deuterated isotopomers as internal standards. Vitamers and their labeled analogues were analyzed simultaneously by HPLC/MS/MS using selected reaction monitoring, which allowed a higher specificity than other methods published previously. Sample preparation involved treatment by protease in sequence with alpha-amylase and rat serum deconjugase, followed by anion exchange chromatography. The detection limits for 5-methyltetrahydrofolate, 5-formyltetrahydrofolate, tetrahydrofolate, 10-formylfolate and pteroylglutamic acid were found to be 0.5, 1.2, 1.5, 0.6 and 2.6 microg/100 g fresh weight, respectively. Using the new method, folate contents were determined in meat, cereals, and vegetables. Data were in good agreement with literature data, except results for broccoli, which were much lower than reported in previous studies. 相似文献
834.
H.?FritzscheEmail author S.?Bonn J.?Hauschild K.?Prokes J.?Klenke 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,36(2):175-181
We observed a complete suppression of the incommensurate spin-density wave in thin Cr layers of a V/Cr multilayer in a temperature range from 550 K down to 2 K. The (110)-oriented V/Cr multilayer consisting of 30 nm thick Cr layers and 5 nm thick V layers was investigated by neutron and X-ray diffraction (XRD). From the XRD experiments we were able to determine that the epitaxial strain of the Cr layers in the V/Cr multilayer is about 90% larger than in earlier studied Fe/Cr(110) multilayers. That leads to a completely different magnetic phase diagram as revealed by neutron diffraction experiments. The existence of the commensurate antiferromagnetic structure in the Cr layers can be observed in the whole temperature range without a phase transition to an incommensurate spin-density wave at lower temperatures. In order to elucidate the proximity effects further we also performed experiments in an external magnetic field. Up to a field of 4 T we found no change in the magnetic structure of the Cr films whereas in earlier experiments on Fe/Cr(110) multilayers we could observe a strong perpendicular pinning of the Cr polarization to the Fe magnetization.Received: 28 August 2003, Published online: 8 December 2003PACS:
75.30.Fv spin-density waves - 75.70.-i magnetic properties of thin films, surfaces, and interfaces - 61.12.-q Neutron diffraction and scattering 相似文献
835.
Authors Index
Author Index for Volume 12 相似文献836.
837.
838.
839.
G. Nagarajan James R. Durig Achim Müller 《Monatshefte für Chemie / Chemical Monthly》1967,98(4):1545-1553
Zusammenfassung Es werden verschiedene molekulare Konstanten der Phosphorverbindungen PF2Cl, PCl2F, PF2Br, PBr2F, PCl2Br und PBr2Cl berechnet. Mit Hilfe der Methode vonCyvin werden mittlere Schwingungsamplituden für Zimmertemperatur ermittelt. Die mittleren Amplituden des P–F-, P–Cl- und P–Br-Abstandes nehmen mit zunehmender Gruppenelektronegativität der Halogenatome 1/3X
i
ab. Weiterhin werden thermodynamische Funktionen sowie molekulare Polarisierbarkeiten nach der Methode vonLippincott undStutman berechnet. 相似文献
840.