1,721,011 research outputs found
Organometallic synthesis via "surface-mediated" reactions: high-yield route to HOs3(CO)10(OH)
No full textThe silica-anchored hydrido cluster HOs3-(CO)10(OSi←) is easily prepared from physisorbed Os3(CO)12. Chemical displacement from the surface with HF leads to the isolation of pure HOs3(CO)10(OH). This approach is far simpler and gives much higher yields than the conventional syntheses in solution
SURFACE ORGANOMETALLIC CHEMISTRY - A MOLECULAR APPROACH TO HETEROGENEOUS CATALYSIS AND A NEW PERSPECTIVE FOR THE SYNTHESIS OF METAL-CARBONYL CLUSTERS
No full textThe chemical behavior of supported metal fragments obtained from metal carbonyl clusters has been shown to be dependent upon the acid-base properties of the surface of the inorganic oxide and the chemical reactivity of the metal cluster precursor. This 'molecular approach' to material science, heterogeneous catalysis in particular, via supported clusters has allowed the identification of new synthetic pathways to molecular metal carbonyl complexes as well as new heterogeneous catalysts
TEMPERATURE-PROGRAMMED OXIDATIVE DECOMPOSITION (TPOD) TECHNIQUE FOR THE CHARACTERIZATION OF SUPPORTED METAL-CLUSTERS - A COMPARISON WITH DIFFERENTIAL THERMAL GRAVIMETRY (DTG) TECHNIQUE
No full textThe surface chemistry of supported organometallic clusters as precursors of heterogeneous catalysts is investigated by means of DTG (differential thermal gravimetry) and TPOD (temperature-programmed oxidative decomposition) techniques, as unique signatures of the occurrence of chemical interactions between the organometallic cluster and the surface sites of the support
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
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
SURFACE-MEDIATED SYNTHESIS OF H4RU4(CO)12, H4OS4(CO)12 ON HYDROXYLATED SILICA
No full textThe surface reactivity with hydrogen of silica-supported M3(CO)12 (M = Ru, Os) has been investigated at atmospheric pressure and temperatures between 25 and 100°C. Pure H4M4(CO)12 complexes are selectively obtained and almost quantitatively recovered from the solid sample by solvent extraction. In the case of H4Os4(CO)12, significative advantages over the conventional synthesis in solution are obtained
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