1,721,110 research outputs found
Capitolo 15 - Composti etrociclici Capitolo 17 - Lipidi Capitolo 18 - Acidi nucleici Capitolo 19 - Amminoacidi e proteine
No full textLibro di testo di Chimica organica per i corsi di laurea di Scienze Biologiche, Scienze naturali e Biotecnologie
Synthesis of the trisaccharide component of the repeating unit of the capsular polysaccharide of Streptococcus pneumoniae type 19F
No full textAcetolysis of methyl 4-O-(2-acetamido-3,4,6-tri-O-benzyl-2-deoxy-β-D-mannopyranosyl)-2,3,6-triO-benzyl-α-D-glucopyranoside (3) followed by treatment with hydrogen bromide–acetic acid afforded 4-O-(2-acetamido-6-O-acetyl-3,4-di-O-benzyl-2-deoxy-β-D-mannopyranosyl)-6-O-acetyl-2-O-benzyl-α-D-glucopyranosyl bromide (5). Compound (5) by Hg(CN)2–HgBr2 promoted condensation with benzyl 3,4-di-O-benzyl-α-L-rhamnopyranoside (6) provided the glycosylation product (22% yield) exclusively in the α-configuration.
Hydrogenolysis of the benzyl protecting groups of the obtained trisaccharide and O-deacetylation of the 6′ and 6′′ positions eventually furnished O-(2-acetamido-2-deoxy-β-D-mannopyranosyl)-(1→4)-O-α-D-glucopyranosyl-(1→2)-α,β-L-rhamnopyranose (1), the trisaccharide component of the repeating unit of Streptococcus pneumoniae type 19F
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
REGIOSELECTIVE RING-OPENING OF GLUCOSE DERIVED SPIRO EPOXIDES
No full textSpiro epoxides 2 derived from glucose can be opened either in acidic or basic conditions with opposite regioselectivity. Some examples with different nucleophiles are described. The procedure give access to intermediates which can be used in glycosidation reactions or in the synthesis of modified ketosugars
Stereoselective synthesis of the C-analogue of beta-D-glucopyranosyl serine
No full textThe [2,3]-Wittig sigmatropic rearrangement of an appropriate glucose derivative followed by further chemical modification afforded stereoselectively the C-analogue of beta-D-glucopyranosyl serine
- …
