1,720,998 research outputs found
Synthesis of 1,2,4,-Triazolo[4',3':1,6]pyridazino[4,5-b]quinoline Derivatives
No full textThis paper reports the synthesis of 10‐phenyl‐2H‐pyridazino[4,5‐b]quinoline‐1‐thione 10 and its further transformation into the hitherto unknown 12‐phenyl‐1,2,4‐triazolo[4′,3′:1,6]pyridazino[4,5‐b]quinoline 4. 3‐Carbethoxy‐2‐dichloromethyl‐4‐phenylquinoline 8 was reacted with hydrazine to give 9 which in turn was transformed by the Lawesson Reagent into the corresponding thione 10. On treating 10 with anhydrous hydrazine, 11 was obtained and subsequently cyclized in the presence of formic or acetic acids to afford the tetracyclic derivatives 4a and 4b, respectively, in satisfactory yields. When 3‐carbethoxy‐2‐chloromethyl‐4‐phenylquinoline 5 was reacted with hydrazine, compound 7 was the sole isolated product. Copyright © 1990 Journal of Heterocyclic Chemistr
Synthesis of Functionalized Derivatives of Quinazolines and 1,4-Benzodiazepines
No full textThe 2-substituted 1,4-benzodiazepines (4 and 6) were synthesized. The reaction of 2-aminobenzophenone oximes with ethyl 4-chloroacetoacetate gave the 1,4-benzodiazepines (4) and the 1,2-dihydroquinazolines (5); the latter were treated with a base to result ring expansion giving the 1,4-benzodiazepines (6)
Characterization of quinoline derivatives. I. 6,7-Dihydro-8-(4-methyl-1-piperazinyl)[1]-benzoxepino[4,5-c]quinoline 0.13-hydrate
No full textThe title compound, C22H23N3O.0.13H(2)O, is a novel potent and selective serotonin 5-HT3 receptor antagonist. Three independent molecules constitute the asymmetric unit. While two of these molecules show only small differences in their metric and conformational parameters, the third differs from the other two, mainly as a result of the conformation of the oxepine ring. The conformations of the seven-membered ring determine quite different orientations of the oxepine-fused benzene ring, whose role is important in the exploitation of biological activity
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
Mapping the peripheral benzodiazepine receptor binding site by conformationally restrained derivatives of 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxamide (PK11195)
No full textA synthetic-computational approach to the study of the binding site of peripheral benzodiazepine receptor (PER) ligands related to 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3- isoquinolinecarboxamide (PK11195, 1) within their receptor has been developed. A wide series of conformationally restrained derivatives of 1 has been designed with the aim of probing the PER binding site systematically. The synthesis of these compounds involves palladium-catalyzed coupling and amidation as the key steps. Twenty-nine rigid and semirigid derivatives of 1 were tested in binding studies using [H-3]-1, and most of these showed PER affinities in the nanomolar range. The essential role of the carbonyl moiety as a primary pharmacophoric element in the recognition by and the binding to PER has been confirmed, and the restricted range of the carbonyl orientations, which characterizes the most potent ligands, points to a specific hydrogen-bonding interaction, mainly directed by the geometrical factors, when the electronic ones are fulfilled. Moreover, the fundamental importance of the short-range dispersive interactions in the modulation of the binding affinity and, hence, in the stabilization of the ligand-receptor complex, emerged from the QSAR models reported
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