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Stereoselective Mannich-Type Reaction ofan Acyclic Ketimine with a SubstitutedChlorotitanium Enolate: EfficientApproach to D-erythro-alfa-Trifluoromethyl-beta-hydroxyaspartic Units
No full textA mild, efficient synthesis of gem-difluorodihydrouracils
No full textAn efficient multicomponent sequential process, which occurs in mild condition has been exploited for the synthesis of systematically modified amphiphilic molecules where the cationic head is tethered to a lipophilic tail through a dihydroorotic acid linker. The process is operatively simple, high yielding, and flexible. Such a strategy could impact combinatorial synthesis of wide libraries of amphiphilic molecules to be tested as transfection agents and/or as antimicrobials
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Two Practical and Efficient Approaches to Fluorinated andNonfluorinated Chiral alfa-Imino Sulfoxides
No full textThe role of fluorine in stereoselective tandem aza-Michael addition to acrylamide acceptors: an experimental and theoretical mechanistic study
No full textStereocontrolled solid-phase synthesis of partially-modified retropeptides incorporating a trifluoroalanine surrogate via tandem aza-Michael/enolate-protonation
No full textVariations on the Author
Get PDF“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
Get PDFWe 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
Two Practical and Efficient Approaches to Fluorinated and Nonfluorinated Chiral â-Imino Sulfoxides
No full textReaction of fluorinated and nonfluorinated N-substituted imidoyl chlorides 1 with lithium derivatives
of enantiopure methyl p-tolyl sulfoxide 2a (or racemic methyl phenyl sulfoxide 2b) gave a wide
variety of chiral N-substituted â-imino sulfoxides 4 in good to excellent yields. The title compounds
(R)-4 were also prepared by aza-Wittig reaction of ç-fluoro-â-keto sulfoxides (R)-5 and N-aryl
iminophosphoranes 6. The imino-enamino equilibrium was studied, showing, in all instances,
the imino form as the predominant tautomer independent of the nature of the N-substituent. The
configuration of the CdN double bond was found to be Z for both N-alkyl and N-aryl derivatives
on the basis of 1H NMR NOE difference experiments performed over several compounds. Ab initio
calculations (HF/6-31G*) carried out on several representative examples of 1 and 4 are, in general,
consistent with the experimental results
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