1,721,006 research outputs found
1,2,3-TRIAZOLO[4,5-e]-1,2,4-TRIAZOLO[3,4-c]PYRIMIDINES
No full textSome new 1,2,3-triazolo[4,5-e]-1,2,4-triazolo[3,4-c]pyrimidines were prepared starting from the corresponding 1,2,3-triazolo[4,5-d]pyrimidines via the formation of the 1,2,4-triazole ring. Thus suitable hydrazino derivatives 6 were condensed with triethyl orthoformate, triethyl orthoacetate and triethyl orthobenzoate to give the expected tricyclic derivatives 7, 8 and 9. Intramolecular cyclization of the ethoxycarbonylhydrazino derivatives 10 gave the tricyclic compounds 11 bearing an hydroxyl group in the 3 position. The v-triazolo-s-triazolopyrimidine derivatives were tested towards the A1 and A(2A) adenosine receptors in binding assays, but they did not show any receptor affinity
NEW 1,2,3-TRIAZOLO[4,5-E]1,2,3-TRIAZOLO[4,3-C]PYRIMIDINE DERIVATIVES.II
No full textThe 7-chloro-3-(2-chlorobenzyl)- and 7-chloro-3-(2-fluorobenzyl)-1,2,3-triazolo[4,5-d]pyrimidines (1 and 4), by nucleophilic replacement with some hydrazides, gave the corresponding 7-hydrazidoderivatives (2a-e and 5a-e). These, by heating in Dowtherm, underwent an intramolecular cyclization to form the new tricyclic 7-substituted-3-(2-chlorobenzyl)- and 3-(2-fluorobenzyl)-1,2,3-triazolo[4,5-e]1,2,4-triazolo[4,3-c]pyrimidines (3a-d and 6a-d). The 7-hydrazino-3-(2-chlorobenzyl)- and 7-hydrazino-3-(2-fluorobenzyl)-triazolo-pyrimidines (9a and 9b) were also prepared via the corresponding mercapto (7a and 7b) and thiomethyl (8a and 8b) derivatives
CHARACTERIZATION AND PRELIMINARY EMPLOYMENT OF 1-, 2- AND 3-METHYL-5-PHENYL-7-CHLORO-1,2,3-TRIAZOLO[4,5-D]PYRIMIDINE
No full textThis paper reports synthesis and characterization, by spectroscopic methods, of three new N-methyl-5-phenyl-7-chloro-1,2,3-triazolo[4,5-d]pyrimidine isomers 3a, 3b and 3c. For comparison purpose the 3-benzyl-5-phenyl-7-chloro-1,2,3-triazolo[4,5-d]pyrimidine (7) was also prepared. Starting from the isomer mixture 3a–c and the chloroderivative 7, by nucleophilic substitution reaction with ethyl carbazate and subsequent intramolecular cyclization, the new tricyclic derivatives 5a–c and 9 were prepared and tested towards the benzodiazepine and adenosine A1 and A2A receptors
NEW 2-(2'-PHENYL-9'-AZAPURIN-6'-YLAMINO)-CARBOXYLIC ACID METHYLESTERS AS LIGANDS FOR A1 ADENOSINE RECEPTORS
No full textSynthesis of a series of new 2-phenyl-9-benzyl-8-azaadenines bearing on N6 an alkyl or aralkyl chain having a carbonyloxymethyl group on the carbon bound to N6 were reported. The ester group could assure to the molecule a better water-solubility than the 8-azaadenines 2, 6 and 9 substituted with lipophilic groups synthesised in the past. Compounds synthesised demonstrated only little capability of binding A1 adenosine receptors
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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