1,721,001 research outputs found
Electronic Structure of [Ni(η5-C5H5)(μ-CO)]2 by He I and He II Photoelectron Spectroscopy
No full textThe electronic structure of the title compound is discussed on the basis of the He(I) and He(II) excited photoelectron spectra and extended Hückel calculations. The compared He(I) and He(II) band intensities proved to be of crucial importance in order to assign the very complicated spectral pattern. The most interesting result of this study is the observation that four metal-based d electrons are strongly involved in two back-bonding interactions to bridging carbonyl π* molecular orbitals which are localized respectively in- and out-of-the-plane defined by the Ni2(CO)2 core
UV Photoelectron and Theoretical Studies of Organometal Carbonyl Clusters of Ruthenium and Osmium. u-Hydrido-u3-Alkynyl Triangulo Cluster Compounds
No full textT h e electronic s t r u c t u r e of p-hydrido-p,-alkynyl t r i angulo clusters of ruthenium a n d osmium is discussed on the basis of their H e I excited vapor-phase photoelectron spectra a n d on t h e basis of C N D O quantum-me chani c a l calculations. T h e theoretical results contribute to t h e discussion of the highly complex PE spectra and provide novel insights into the bonding scheme of these molecules. T h e most interesting f e a tur e t h a t emerges from this s tudy is t h e inadequa cy of the usual representation of t h e molecular s t r u c t u r e with thr e e metal-metal bonds since t h e p-H-bridged me t a l a toms show a very low bond overlap population. O n t h e othe r hand, t h e commonly accepted qua l i t a t ive description of t h e alkynyl-cluster
interactions, in t e rms of one u bond a n d two weaker a interactions, receives s t rong suppor t . S ome selected f e a tur e s of the reactivity of the s e clusters a r e discussed on the basis of t h e emerging electronic s t ruc tural pictur
Uv Photoelectron and Theoretical-studies of Organometal Carbonyl Clusters of Ruthenium and Osmium - Mu-hydrido-mu-3-allyl and Mu-hydrido-mu-3-allenyl Triangulo Cluster Compounds
No full text.The electronic structures of p-hydr idep3- a l lyl and p-hydridep,-allenyl triangulo clusters of ruthenium and osmium a r e discussed on the basis of both H e I and H e I1 gas-phase UV-PE spectra and C N D O quantum-mechanical calculations. T h e theoretical results contribute t o t h e discussion of the P E d a t a and t o a deeper understanding of the bonding scheme in these very complex organometallic clusters. T h e description of the allyl cluster interactions in terms of one K and two u bonds seems to be adequate. On the other hand, t h e formal distinction into one u and two K bonds of the allenyl ligand cluster interaction is quite a n oversimplification of the a c tua l bonding scheme. T h e differences in thermodynamical stability between the allenyl and allyl derivatives a r e in agreement with the CNDO- comput ed total energie
UV Photoelectron Spectra of some Organometallic Carbonyl Osmium Clusters
No full textThe He(I) excited PE spectra of HOs3(μ3-L)(CO)9 (L-allenyl, allyl) and of HOs3(μ2-vinyl)(CO)10 are presented. Some gross spectral features are discussed on the basis of a direct comparison with previous results for Os3(CO)12 and the alkynyl corresponding cluster derivative. Large perturbations in the OsOs bonding levels are induced by the bridging hydride and the interaction with the organic substrate
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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