1,721,429 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
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
Synthesis and characterization of Nb(OR)4[OC(O)OR] (R= Me, Et, allyl) and their reaction with the parent alcohol to afford organic carbonates
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Direct carboxylation of alcohols to organic carbonates: comparison of the Group 5 element alkoxides catalytic activity. An insight into the reaction mechanism and its key steps
No full textThe reaction of carboxylation of alcohols is a sustainable technology for the synthesis of dialkylcarbonates that avoids the use of phosgene. In this paper we describe the behaviour of metal alkoxides of Group 5 elements as homogeneous catalysts in the above reaction, and the isolation and characterization of the active species, i.e. the hemicarbonates formed upon insertion of carbon dioxide into the M-OR bond. Ta and V alkoxo complexes are comparatively discussed with respect to the Nb-analogues, whose synthesis and catalytic properties have been published [M. Aresta, A. Dibenedetto, C. Pastore, Inorg. Chem. 42 (10) (2003) 3256, and references therein].
In this paper, we report for the first time the evidence of insertion of carbon dioxide in tantalum alkoxides [Ta(OR)(5)](2) [R = methyl (Me), ethyl (Et)]. The relevant hemicarbonates Ta(OR)(4)[OC(O)OR] have been characterized using spectroscopic techniques (IR and NMR). Tantalum alkoxides and the vanadium compound VO(OR)(3) are shown to be able to catalyze the carboxylation of alcohols at 413 K and 5.5 MPa of CO2.
The trend of reactivity for the Group 5 alkoxides as catalysts for the carboxylation of alcohols is Nb >> Ta >
La biodiversità Viticola in Emilia Romagna
No full textL’Emilia-Romagna, che rappresenta la terza regione italiana per la produzione di vino, è caratterizzata da una piattaforma ampelografica che, pur dominata da Lambruschi, Sangiovese e Trebbiano romagnolo, vanta una notevole ricchezza in termini di “biodiversità” viticola, testimoniata dalle 99 varietà di vite appartenenti al Registro Nazionale delle varietà di Vite e autorizzate alla coltivazione in regione. Tale notevole variabilità, autoctona e alloctona, è ancora oggi molto esposta a rischio di erosione genetica e di estinzione dei genotipi ‘minori’ o estremamente rari. Partendo da queste considerazioni, la Regione Emilia-Romagna ha finanziato nel corso degli ultimi 20 anni numerosi progetti volti alla ricognizione, salvaguardia e valorizzazione del patrimonio viticolo.
I risultati del progetto PSR 2014-2020 - Sal.Va.Re.Bio.Vit.E.R. (2017-2020), Recupero, salvaguardia e valorizzazione della biodiversità viticola in Emilia-Romagna, conclusosi nel dicembre 2020, hanno consentito di implementare le conoscenze sulla biodiversità viticola presente in Emilia-Romagna. Nel complesso, le attività di ricognizione condotte sul territorio hanno permesso di individuare 46 accessioni delle quali è stato analizzato il profilo molecolare basato sui 10 marcatori microsatellite. Tra queste, 24 sono risultate accessioni locali, 14 delle quali non conosciute e 10 delle quali, pur non iscritte al Registro Nazionale delle Varietà e neppure al Repositorio, erano già state caratterizzate geneticamente ma solo parzialmente dal punto di vista morfologico e spesso con denominazioni differenti. I vitigni individuati verranno sottoposti a ulteriori indagini di fenotipizzazione per arrivare in primo luogo alla iscrizione al Repositorio regionale e per valutare, con ulteriori approfondimenti di natura agronomica ed enologica, le possibilità di una loro valorizzazione e di una eventuale iscrizione al Registro Nazionale delle Varietà di Vite, condizione indispensabile per rendere possibile la loro coltivazion
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