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151.
Ohne Zusammenfassung 相似文献
152.
A 6-step synthesis of (±)-grandisol ( 1 ) is presented, which involves dichloroketene addition to 3-methyl-3-butenyl acetate ( 4 ), reductive dechlorination of the adduct 6 to the ketone 7 and saponification to 8 , aldolization of 7 or 8 with acetone and cyclization to the bicyclic ketone 9 , Wolff-kishner, reduction to 14 , and finally ring opening to 1. Since 9 is a known intermediate of the synthesis of (±)-lineatin ( 2 ), the latter can now be obtained in 6 steps. 相似文献
153.
Maik J. Geerken Max N.W. Groenendijk Rob G.H. Lammertink Matthias Wessling 《Journal of membrane science》2008,310(1-2):374-383
In this paper the fabrication and use of micro-structured metal nozzle plates as emulsification devices is investigated and discussed. These structured metal nozzle plates were fabricated via two distinct routes. Laser ablation, performed with a femtosecond laser, was used to drill micrometer-sized holes into stainless steel and aluminum foils. Also a conventional steel mesh with an average pore size of 2.4 μm fabricated by weaving and roll compaction of micrometer-sized steel wires was investigated. The perforated metal nozzle plates were used for oil-in-water and after hydrophobization with alkylchlorosilanes for water-in-oil emulsification as well. In both cases, two types of drop formation processes were observed. The first one is the shear-induced drop formation well known for cross-flow membrane emulsification. The second is the spontaneous drop formation known from microchannel emulsification. 相似文献
154.
155.
Max Gröger 《Monatshefte für Chemie / Chemical Monthly》1903,24(6):483-497
Ohne Zusammenfassung 相似文献
156.
157.
Peter Max Gehrig Bernd Roschitzki Dorothea Rutishauser Sonja Reiland Ralph Schlapbach 《Rapid communications in mass spectrometry : RCM》2009,23(10):1435-1445
In order to investigate gas‐phase fragmentation reactions of phosphorylated peptide ions, matrix‐assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) tandem mass (MS/MS) spectra were recorded from synthetic phosphopeptides and from phosphopeptides isolated from natural sources. MALDI‐TOF/TOF (TOF: time‐of‐flight) spectra of synthetic arginine‐containing phosphopeptides revealed a significant increase of y ions resulting from bond cleavages on the C‐terminal side of phosphothreonine or phosphoserine. The same effect was found in ESI‐MS/MS spectra recorded from the singly charged but not from the doubly charged ions of these phosphopeptides. ESI‐MS/MS spectra of doubly charged phosphopeptides containing two arginine residues support the following general fragmentation rule: Increased amide bond cleavage on the C‐terminal side of phosphorylated serines or threonines mainly occurs in peptide ions which do not contain mobile protons. In MALDI‐TOF/TOF spectra of phosphopeptides displaying N‐terminal fragment ions, abundant b–H3PO4 ions resulting from the enhanced dissociation of the pSer/pThr–X bond were detected (X denotes amino acids). Cleavages at phosphoamino acids were found to be particularly predominant in spectra of phosphopeptides containing pSer/pThr–Pro bonds. A quantitative evaluation of a larger set of MALDI‐TOF/TOF spectra recorded from phosphopeptides indicated that phosphoserine residues in arginine‐containing peptides increase the signal intensities of the respective y ions by almost a factor of 3. A less pronounced cleavage‐enhancing effect was observed in some lysine‐containing phosphopeptides without arginine. The proposed peptide fragmentation pathways involve a nucleophilic attack by phosphate oxygen on the carbon center of the peptide backbone amide, which eventually leads to cleavage of the amide bond. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
158.
Ohne ZusammenfassungEndlich erfülle ich gerne die angenehme Pflicht, meinem hochverehrten Lehrer, Herrn Prof. H. Weidel für die überaus grosse Liebenswürdigkeit, mit welcher er mich bei der Ausführung meiner Versuche mit Rath und That unterstützt hat, meinen ergebensten Dank auszusprechen.Ebenso sei es mir gestattet, Herrn Hofrath v. Lang für die freundliche Übernahme der krystallographischen Bestimmungen an dieser Stelle auf das Verbindlichste zu danken. 相似文献
159.
The addition–deletion theorems for hyperplane arrangements,which were originally shown by Terao [J. Fac. Sci. Univ. TokyoSect. IA Math. 27 (1980) 293–320.], provide useful waysto construct examples of free arrangements. In this article,we prove addition–deletion theorems for multiarrangements.A key to the generalization is the definition of a new multiplicity,called the Euler multiplicity, of a restricted multiarrangement.We compute the Euler multiplicities in many cases. Then we applythe addition–deletion theorems to various arrangements,including supersolvable arrangements and the Coxeter arrangementof type A3, to construct free and non-free multiarrangements. 相似文献
160.