1,721,105 research outputs found
STRUCTURAL ELUCIDATION OF ISOMERIC METHYL (E)-3-[5AMINOBENZOTRIAZOL-1(2)(3)-YL]PROPENOATES BY NMR SPECTROSCOPY
No full textRevised attribution of methyl (E)-3-[5aminobenzotriazol-l(2)(3)-yl]propenoate ((E)-2, 3 and 4), using combined experiments of mono- and two-dimensional NMR spectroscopy, is reporte
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
Heterogeneous Phase-Transfer Catalysts: High Efficacy of Catalysts Bonded by a Long Chain to a Polymeric Matrix
No full textHeterogeneous phase-transfer catalysts, such as phosphonium salts and crown-ethers, immobilized on a polystyrene matrix, show an increase in activity approaching that of the corresponding non-immobilized catalysts, when they are bonded with a long spacer chain to the polymeric support
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
Polymer-supported phase-transfer catalysts. High catalytic activity of ammonium and phosphonium quaternary salts bonded to a polystyrene matrix
No full textPhase-transfer (PT) catalysts, namely, phosphonium salts, have been immobilized on silica gel; good organofunctionalization
has been obtained ranging from 1 .O to 0.7 mequiv [PRd]+/g. The synthesis of phosphonium salt functionalized
silica gels 1-4, with different spacer chain lengths between the polymeric matrix and the catalytic center (from 3 to 27 atoms),
is reported. Ketone adsorption constants (K&) on nonfunctionalized and functionalized silica gel, and their comparison with
pseudo-first-order rate constants (kobsd) in the aqueous sodium borohydride reduction of ketones under PTC conditions, show
that adsorplion phenomena are the main factors determining the reaction rate; moreover, C,O-alkylation experiments show
that the catalyzed reaction takes place in a very polar environment formed by the functionalized silica gel and the water adsorbed
on it. These immobilized catalysts can be reused several times with a little loss of activity, but they are hydrolyzed at
high pH values
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
