1,721,040 research outputs found
Opening of 2',3'-O-anhydro-ring of 2',3'-O-anhydro-lyxo-uridine by alkyl- and arylamines. Easy syntheses and preparative uses of 2'-deoxy-2'-alkylamino-xylo- and 3'-deoxy-3'-alkylamino-ara-uridines
No full textContrary to the previous report (ref. 8), under controlled conditions alkylamines, both primary and secondary and arylamines, opened the epoxide ring of 1-(5-O-trityl-2,3-O-anhydro-β-D-lyxo-furanosyl)-uracil to produce 2'-deoxy-2'-alkylamino-xylo- and 3'-deoxy-3'-alkylamino-ara-uridines without causing any significant deglycosylation. To show the utility of these products, several modified uridine derivatives were synthesised
Sugar-modified uridine bisvinyl sulfone: synthesis of a bifunctionalized nucleoside Michael acceptor and its use in stereoselective tandem cyclization
No full textA bisvinyl sulfone functionality is incorporated into the carbohydrate moiety of uridine to synthesize 6 (or 7) which is a bifunctionalized nucleoside Michael acceptor and has the potential to form covalent bond with biological nucleophiles. This compound could be used to generate a large number and a new class of bicyclic S,S-dioxidethiazine derivatives 8−12 in stereoselective fashion. Compound 6 is also useful for the synthesis of a wide variety of monosubstituted compounds 13−15. The structures of compounds 8−12 have been established unambiguously by synthesising the core structure 28 in a stereospecific fashion
3′-Deoxy-3′-(vinylsulphonyl)thymidine - a new reactive analogue of AZT; its synthesis and reactivities towards various nucleophiles
No full textA reactive triatomic analogue of AZT, 3′-deoxy-3′-(vinylsulphonyl)thymidine has been synthesised from easily accessible starting material. The vinyl-sulphone nucleoside was reacted with a variety of nucleophiles to generate new classes of modified nucleosides where the functional groups were attached to the C-3′ of a nucleoside through flexible ethyl sulphone spacer.</p
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
Vinyl sulfone-modified carbohydrates: an inconspicuous group of chiral building blocks
No full textThis article does not contain abstract
Azidonucleosides: synthesis, reactions, and biological properties
No full textThis article does not contain abstract
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
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