1,720,959 research outputs found
PROCESS FOR THE PREPARATION OF FLUOROXY-HALO COMPOUND
No full textFluoroxy-halo-compounds are prepared by direct reaction between fluorine and organic compounds having a molecular structure in which at least one oxygen atom is directly bound to a carbon atom in the carbonylic form, in the presence of a fluorination catalyst, in a gaseous phase, at an absolute pressure of between 50 and 800 kPa and at a temperature higher than -50 DEG C and up to 150 DEG C, under conditions of continuous feeding of the reactants and a continuous removal of the reaction product
Process for the preparation of halobenzoic acids
No full textA new process for the preparation of halobenzoic acids and in particular fluorobenzoic acids is based on reaction between the corresponding halobenzyl chlorides and sodium hypochlorite. The new process makes it possible to obtain halobenzoic acids in a single stage reaction using cheap and/or easily obtained reagent
Electrochemical fluorination of 4-(perfluoro-n-butyl)-n-butanoyl chloride
No full textElectrochemical fluorination of 4-(perfluoro-n-butyl)-n-butanoyl chloride produces perfluoroactanoyl fluoride in higher yields tha those obtained from n-octanoyl chloride, which is the usual starting material
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
Determination of the fluorine solubility in various solvents
No full textFluorine solubility is an important parameter in fluorination reactions, both from the viewpoint of controlling reaction exothermicity and of carrying out reactions homogeneously. Several solvents have been studied in order to define their solubilization ability towards fluorine; some (such as CFCl3 or CFCl2CF2Cl) were virtually inert, whilst others (such as CF3COOH or CF3CH2OH) were capable of forming hypofluorites with fluorine. Particular additives (such as pentachlorophenol, 2,4-dinitrophenol or 3,5-dichloropyridine) were used in order to favour the formation-of hypofluorites or complexes able to increase the amount of dissolved fluorine
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