1,720,995 research outputs found
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
Oxone: a Convenient Reagent for the Oxidation of Acetals
No full textSymmetrical cyclic and acyclic acetals by oxidation with Oxone(R) gave the corresponding esters in good yield. Treatment of tetrahydropyranyl derivatives of alcohols with the same reagent resulted in oxidative regeneration of the alcohols
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
Carbamate Synthesis from Amines and Dimethyl Carbonate under Ytterbium Triflate Catalysis
No full textReductive Etherification of Aldehydes and Ketones with Alcohols and Triethylsilane Catalysed by Yb(OTf)3: an Efficient One-Pot Benzylation of Alcohols
No full textThe one-pot synthesis of symmetrical and unsymmetrical ethers from aldehydes and ketones can be conveniently performed using Yb(OTf)(3) as catalyst and triethylsilane as reducing agent in presence of alcohols. This methodology leads to the synthesis of ether derivatives with good yields. Notably, this process resulted a useful tool to protect alcohols as benzyl ether derivatives using differently substituted benzaldehydes as protecting agents under mild conditions. A plausible mechanism was also proposed
The Synthesis of Solvent-Free Glycidic Esters from Diazoesters and Carbonyl Compounds Catalysed by Lanthanide Triflates
No full textThe results of the reaction between ethyl diazoacetate and carbonyl compounds catalysed by lanthanide triflates are described, Aldehydes, and alpha-unsubstituted and alpha-monosubstituted cyclohexanones react to give the selective formation of alpha,beta-epoxy esters (glycidic esters), whereas other ketones are unreactive
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