1,720,963 research outputs found
Higly Selective Extraction of Uranyl Ion by Acyclic Ligands Containing L-Phenylalanine Moieties
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Synthesis of naphtho[2,3-b]indolizine-6,11-dione derivatives by iodine oxidation of 2-alkyl-1,4-naphthoquinones in the presence of substituted pyridines
No full textIodine oxidation of 2-alkyl-1,4-naphthoquinones (1) in the presence of substituted pyridines (2) afforded naphtho[2,3-b]indolizine-6,11-dione derivatives (3). Other oxidant systems (MnO2/I- or Fe(ClO4)3/I2) can be used and 2-alkylbenzoquinones reacted in lower yield. Iodination of 3 by I2 and dibenzoyl peroxide occurred seelctively at position 1
The Crystal Structure of the Inclusion Complex of the Sodium Salt of Piroxicam with beta-Cyclodextrin
No full textThe structural characterization by X-ray diffraction analysis of the title compound is reported. Crystallographic details are: C42H70O35°C15H12N3O4 SNa·8D2O, triclinic, space group P1, a = 14.767(3), b = 12.237(2), c = 11.537(2)Å, α = 79.49(1), β = 110.91-(1), c = 104.61(1)°, d calc = 1.460 g/cm3, Z = 1, R = 0.045 for 6635 observed reflections. The crystal structure consists of head-to-tail β-cyclodextrin molecules (β-CD) linked together by piroxicam anions in infinite polymeric chains running along the c axis. In a chain each β-CD molecule takes up simultaneously two guest molecules including on the secondary hydroxyl end the benzene ring and on the primary hydroxyl end the pyridine ring of two adjacent piroxicam anions. The piroxicam anion is located with its central hydrophilic moiety at the interface between two adjacent β-CD molecules, forming with them hydrogen bonds through the enolate and amide oxygen atoms. Conformation of piroxicam is different from those observed for its neutral and zwitterionic forms. It assumes the ZZE conformation expected for the enolate. The six-coordinated sodium cation acts as a bridge between adjacent polymeric chains linking them along the b axis. This results in the formation of hydrophilic channels filled by deuterium oxide molecules
Variations on the Author
Get PDF“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
Solution- and solid-state structures of the (-)-n-heptylcarbamate of geneseroline and its hydrochloride salt
No full textAppropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Get PDFWe 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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