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71.
Alessandro Sorrenti Marco Diociaiuti Valentina Corvaglia Pietro Chistolini Giovanna Mancini 《Tetrahedron: Asymmetry》2009,20(23):2737-2741
The recognition of the enantiomeric couples of ditryptophan in Langmuir films of N-hexadecanoyl-l-proline was investigated by surface pressure–area (π–A) isotherm measurements and Brewster angle microscopy experiments. The π–A isotherms relative to the films including the enantiomeric dipeptides show small differences whereas an evident enantiodiscrimination is observed by Brewster angle microscopy images. 相似文献
72.
Pietro Bollinger Philip Cooper Hans U. Gubler Albert Leutwiler Trevor Payne 《Helvetica chimica acta》1990,73(5):1197-1204
Compound (Z)- 8a has been found to display interesting antiinflammatory activity. In order to prepare derivatives with a wide variety of substituents in the aromatic part of the molecule, a new synthesis of the key intermediates 9a-g was developed starting from thiophene-3-carboxylic acid ( 11 ) and substituted benzyl bromides. The conversion of 9a-g to 10a-g follows a known procedure. Ketones 10a-g , on reaction with alkyl (dialkoxy-phosphoryl)acetate, followed by isomer separation and alkaline ester hydrolysis, yielded the desired derivatives (Z)- 8a-g and (E)- 8a-g . The biologically most interesting compound (Z)- 8a is currently undergoing clinical trials. 相似文献
73.
Pietro Pellogio 《Fresenius' Journal of Analytical Chemistry》1867,6(1):396-398
Ohne ZusammenfassungVon dem Verf. in französischer Sprache mitgetheilt. 相似文献
74.
Characterization of a Marshall-Olkin type class of distributions 总被引:1,自引:0,他引:1
Pietro Muliere Marco Scarsini 《Annals of the Institute of Statistical Mathematics》1987,39(1):429-441
Summary A class of bivariate distributions that generalize Marshall-Olkin's one is characterized through a functional equation which
involves two associative operations. The obtained distributions concentrate positive mass on the linex=y when the two associative operations coincide; otherwise a positive mass is concentrated on a continuous monotone function.
Work performed while the authors were members of CNR-GNAFA. 相似文献
75.
Pietro Burgatti 《Annali di Matematica Pura ed Applicata》1931,9(1):121-142
Sunto Si studiano le varietà a due dimensioni immerse in unS
4
euclideo. Definite certe due normali principali, si esaminano le proprietà delle superficie nell'intorno di un punto, le
curvature, e le sue linee più caratteristiche. Infine si dà sotto forma esplicita ed espressiva un gruppo di formule fondamentali
relative all'impiego delle tre forme differenziali quadratiche atte a definire la varietà considerata. 相似文献
76.
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78.
Rendiconti del Circolo Matematico di Palermo Series 1 - 相似文献
79.
80.
Loris Tonidandel Eugenio Ragazzi Pietro Traldi 《Rapid communications in mass spectrometry : RCM》2009,23(3):403-408
Baltic amber contains high levels of succinic acid, most of which is part of the polymer framework, and only recently has the presence of microcrystals of free succinic acid been documented by scanning electron microscopy and X‐ray diffraction analysis. The determination of succinic acid can be used for an easy identification of Baltic amber among other fossil resins and to distinguish it from imitations, widely diffused on the market, produced with natural or modified recent or sub‐fossil resins, such as copals. We report here a simple method, based on negative ion electrospray ionization mass spectrometry, for evaluating the free succinic acid content in water/methanol extracts of ambers from different origin, using a sample of about 20 mg. The limit of quantification is better than 1 ppm and, when applied to a set of amber samples of different origin, it was able to distinguish those of Baltic origin (showing free succinic acid levels in the range 50–400 ppm) from the others (for which succinic acid was undetectable, i.e. at levels lower than 1 ppm). Copyright © 2009 John Wiley & Sons, Ltd. 相似文献