1,720,984 research outputs found
Synthesis and X-ray crystal structure of cationic polynuclear hydroxide acetylacetonate lanthanide(III) clusters with homodinuclear or heterodinuclear decacarbonyl hydrides: [HMo2(CO)10](-) and [HCrW(CO)(10)](-)
No full textThe synthesis and characterization of new polynuclear lanthanide(III) ionic clusters of general formula [Lng(acac)(16)(OH)(10)](+) [Mo-2(CO)(10)(mu-H)](-) (Ln=Sm,Eu, Gd, Dy, Yb) and [Sm-9(acac)(16)(OH)(10)](+) [CrW(CO)(10)(mu-H)](-) is reported. The polymuclear complexes, prepared under pure nitrogen atmosphere by interaction of the hydridic metal carbonyls with the beta-dichetonate Ln(acac)(3)(.)3H(2)O (Ln= Sm, Eu, Gd, Dy, Yb). The new clusters were characterized by elemental analysis, complexometric titration for Ln, atomic absorption for Cr, W and Mo, gas-volumetric analysis for CO, FTIR spectroscopy and single crystal X-ray structure determination of [Sm-9(acac)(16)(OH)(10)][Mo-2(CO)(10)(mu-H)]. The Eu and Yb complexes are isostructural to the Sm one for which, similarly to their homonuclear chromium and tungsten derivative analogues, a square antiprismatic arrangement of eight Sm ions with the ninth at the center of the antiprism has been foun
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
Key intermediates in the synthesis of enantiopure antagonists at NMDA receptors: a structural study
No full textThe two diastereomeric amino acid derivatives 8 (3aS,5R,6aS)-5-tert-butoxycarbonylamino-4,5,6,6a-tetrahydro-3aH-cyclopen ta[d]isoxazole-3,5-dicarboxylic acid diethyl ester, its epimer 9 (3aS,5S,6aS), and carboxylic acid 10 obtained by hydrolysis of 9, which are intermediates in the synthesis of novel NMDA receptor antagonists 6 and 7 (Fig. 1), have been characterized by X-ray studies at 293 K for 8 and 10, and at 100 K for 9. The configuration of the carbon binding the 5-tert-butoxycarbonylamino moiety (BOC) determines the different molecular complexity: the chain structure for 8, dimeric for 9, and chain dimers for 10. The pharmacophoric parameters in compound 8 (from which the active 7 is derived) are comparable with those observed for NMDA receptor antagonism, while 9 and 10 do not present the structural features, which match these pharmacophoric characteristics. (C) 2005 Elsevier Ltd. All rights reserved
The crystallized solvent could influence the lanthanide water bonding?
No full textTwo gadonilium DOTAM complexes [Gd(DOTAM)H2O](CF3SO3)(3) center dot 3H(2)O (1) and [Gd(DOTAM)H2O](CF3SO3)(3) center dot 0.5H(2)O center dot CH3CN (2) have the structure of the M isomer, with coordination geometry around the Gd ion capped square antiprismatic (SA). They differ for the Gd-O-water bond lengths of 2.396(6) and 2.474(7) angstrom in (2) where two independent molecules are present in the crystal cell. The factors influencing the Gd-O-water bond distance, important for the water exchange rate in MRI experiments, have been correlated to the different network of hydrogen bonds involving the Gd coordinated water molecule. The X-ray structure of the parent compound [Pr(DOTAM)H2O](CF3SO3)(3) center dot HO center dot CH3CN (3) reveals an unexpected twisted square antiprismatic (TSA) coordination geometry characteristic of the In isome
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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