1,720,957 research outputs found
APPLICATION OF THE LIGAND POLYHEDRAL MODEL TO THE FLUXIONALITY OF FE3(CO)10(CNCF3)(L) (L=CO,PME3,PET3,P(OME)3,P(OET)3
No full textThe fluxionality observed for the triiron carbonyl clusters Fe3(CO)10(CNCF3)(L) (L = CO, PMe3, PEt3, P(OMe)3, P(OEt)3) has been reassessed in the light of the ligand polyhedral model
FLUXIONAL BEHAVIOR OF THE CARBONYLS [M3(CO)12] (M = FE, RU OR OS)
No full textA study of the crystal structures of the carbonyls [M3(CO)12] (M = Fe, Ru or Os) and a series of their derivatives [M3(CO)12-nLn] has revealed good evidence in support of the hypothesis that the mechanism of ligand fluxionality goes via the intermediacy of an anticubeoctahedral complementary geometry. Several examples of systems with an icosahedral distribution of ligands and quasi-D3 symmetry have been identified providing additional support for our earlier suggestion that a second isomer of [Fe3(CO)12], which exists in solution, adopts a similar D3 structure
STEREOCHEMICAL CHANGES IN MONONUCLEAR COMPLEXES ML(N) (N=10-12)
No full textThe process of edge-cleavage (simple and multiple), recently applied to generate complementary geometries for complexes ML(n) (n = 4-9), has been extended to include values of n = 10-12
Solid-state studies into the possible rearrangement mechanisms for the fluxional behaviour of the tetranuclear carbonyls M4(CO)12 and their derivativesSolid-State Studies into the Possible Rearregment Mechenisms for the Fluxional Behavior of the Tetranuclear Carbonyls M4 (CO)12 and Their Derivatives
No full textThe deformation from an idealised geometry, observed in the solid state for a given cluster species, may indicate the paths taken by the cluster in ligand fluxionality processes. A number of single-crystal X-ray structures of M4(CO)12-n(L)n clusters (M = Co, Rh, Ir; n = 1-5) have been examined in order to elucidate any geometric trends in their ligand envelope deformations. It has been revealed that the complementary geometries adopted by M4(CO)12-n(L)n species may be both metal- and ligand-dependent. Iridium species adopt T(d)-cubeoctahedral structures, but the available data provide no clear picture for the complementary geometry adopted by cobalt or rhodium species. Additionally, tripodal ligands have been shown to stabilise D3h (icosahedral) ligand polyhedra
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
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