Zur Bestimmung von Cer in einer methanolischen Aluminiumoxidsuspension

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The median procedure in cluster analysis and social choice theory

Classical approachs for fitting and aggregation problems, specially in cluster analysis, social choice theory and paired comparisons methods, consist in the minimization of a remoteness function between relational data and a relational model. The notion of median, with its algebraic, metric, geometrical and statistical aspects, allow a unified treatment of many of base problems. Properties of median procedures are organized according to four directions: stabilities and axiomatic characterizations; Arrow-like properties; combinatorial properties; effective computational possibilities. Finally, interesting mathematical problems, related to the notion of median are surveyed.     

1. Elementaranalyse

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Alcoyl-gluco-alcaloides: nouveaux composes isoles de pauridiantha lyalii brem (rubiacees)

La structure destrans fe´ruloyl-6′ ettrans sinapoyl-6′ lyaloside, isole´s des feuilles dePauridiantha Lyalii, ae´te´de´termine´e par de´gradation chimique et par spectroscopie (Masse, RMN¹H et¹³C). Ces compose´s font partie d'un groupe structural caracte´rise´par un enchai?nement alcaloide-monoterpe`ne-ose-acide (C<sub>6</sub>-C<sub>3</sub>), groupe dont un seul repre´sentant semble avoire´te´isole´jusqu'a`pre´sent. Leur fonction dans le ve´ge´tal est discute´e.     

Gaschromatographie

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Mono et Diglycosylbutadiynes

Mono and Diglycosylbutadiynes Cadiot's dissymmetric coupling of bromoethynylsugar derivatives with therminal acetylenes led in good to excellent yields to the expected mono or diglycosylbutadiynes. In the same way, terminal acetylenic sugar derivatives could be coupled with bromoacetylenic compounds. Symmetric coupling of sugars bearing a bromoethynyl group has also been achieved. (UV., CD., IR., ¹H-NMR.) of these compounds are reported and discussed.