1,721,242 research outputs found
Paramagnetic metal species on highly dispersed Rhodium/Polyphosphine catalysts
No full textESR active paramagnetic species were used as a probe for the description of the metal centers in highly dispersed rhodium/polyphosphine catalysts. Magnetically dilute Rh(0) centers were observed at high P Rhs] (s = surface) ratios. Two different Rh(d0) diluted species were detected (g1 = 2.085, g2 = 2.000; g′1 = 2.045, g′2 = 2.008, g′3 = 1.975) whose relative amounts vary with the P Rhs value. At lower P Rhs values, metal crystallites play a dominant role in giving broad unresolved signals. The metal particle size and the absolute Rh% are also related to the resonance shape. It is suggested that phosphine coordinates Rh centers, where a rhombic species corresponds to a higher number of coordinated phosphines. The results of the ESR investigation are in good agreement with previous studies on the same catalysts (G. Cocco, S. Enzo, F. Pina, and G. Strukul, J. Catal. 82, 160, 1983) performed by SAXS, WAXS, TGA, TPR, and infrared study of CO adsorption
Reaction of trans-{PtH2[P(C6H11)3]2} with carbon disulphide. Kinetic study of the insertion reaction and X-ray structure of trans-{PtH(S2CH)[P(C6H11)3]2}
No full textCarbon disulphide inserts into the PtH bond of trans-{PtH2[P(C6H11)3]2} to give trans-{PtH(S2CH) [P(C6H11)3]2}. The X-ray structure shows that the -S2CH group is bonded to the metal through a sulfur atom as a monodentate thioformate anion. The kinetics of the carbon disulfide insertion have been investigated. The results account for a mechanism involving CS2 addition to trans-{PtH2[P(C6H113]2} to give a five-coordinate intermediate, which collapses to trans-{PtH(S2CH)[P(C6H11)3]2}
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
Catalytic epoxidation of 1-octene with diluted hydrogen peroxide: on the basic role of hydroxo complexes of Platinum(II) and related species
No full textStudy of the role of hydroxo complexes of platinum(II) and related species in the catalytic epoxidation of 1-octene with diluted hydrogen-peroxide
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
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
Baeyer-Villiger Lewis Acid Oxidation Catalysts Based on Cationic Platinum(II) Complexes with Fluorinated 1,2-Bis(diphenylphosphino)ethane Ligands
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