1,720,971 research outputs found
3-Vinyl-1,2,4-triazines comme plateformes bifonctionnelles pour la synthèse de nouvelles structures tétrahydro-[1,6]-naphthyridines
No full textThe development of new methods for the synthesis of original heterocyclic molecules represents a current concern in organic chemistry, aiming to furnish medicinal chemistry and chemical biology with new chemical tools and contribute to the exploration of chemical space.In this context, the work which was carried out during this PhD thesis focused on the elaboration of new approaches for the synthesis of tetrahydro-[1,6]-naphthyridine scaffolds. The original use of 3-vinyl-1,2,4-triazines as bifunctional synthetic platforms, able to react both as Michael acceptor and as aza-diene in inverse-electron-demand Diels-Alder cycloadditions, is the keystone our methodology is based upon. The development of domino reactions – allowing quick and efficient synthesis of targeted compounds – remaineda perpetual concern evolving along side our preoccupation to access enantioselective transformations relying on organocatalysis.The synthesis of new 3-vinyl-1,2,4-triazines platforms and the elaboration of domino conjugate addition/cycloadditions and orgonocatalyzed one-pot synthesis strategies enabled to synthetize a wide panelof new diversly substituted tetrahydro-[1,6]-naphthyridines compounds.Le développement de nouvelles méthodes de synthèse de molécules hétérocycliques originales représente un enjeu actuel majeur en chimie organique. L’objectif est de fournir de nouveaux outils chimiques pour le développement de molécules actives en chimie médicinale et/ou pour l’étude de la biologie chimique, tout en contribuant à l’exploration de l’espace chimique.Dans ce contexte, le travail effectué au cours de cette thèse de doctorat a visé à élaborer de nouvelles voies de synthèse de motifs tétrahydro-[1,6]-naphtyridines. La pierre angulaire des méthodologies développées réside dans l’utilisation des 3-vinyl-1,2,4-triazines comme des plateformes synthétiques bifonctionnelles. Ces composés ont été développés pour réagir à la fois comme accepteurs de Michael et comme aza-diènes dansdes cycloadditions de Diels-Alder à demande électronique inverse. Un intérêt tout particulier a été porté à lamise au point de stratégies synthétiques innovantes, par des réactions en cascade permettant une synthèse rapide et efficace des molécules cibles, et des approches de catalyse organique visant des transformations énantiosélectives.La synthèse de nouvelles 3-vinyl-1,2,4-triazines et le développement de stratégies de réactions d’addition conjuguée/cycloadditions en cascade et de synthèses monotopes organocatalysées ont fournis l’accès à une vaste gamme de nouvelles tétrahydro-[1,6]-naphthyridines diversement substituées
3-vinyl-1,2,4-triazines as bifunctional platforms towards new tetrahydro-[1,6]-naphthyridines scaffolds synthesis
No full textLe développement de nouvelles méthodes de synthèse de molécules hétérocycliques originales représente un enjeu actuel majeur en chimie organique. L’objectif est de fournir de nouveaux outils chimiques pour le développement de molécules actives en chimie médicinale et/ou pour l’étude de la biologie chimique, tout en contribuant à l’exploration de l’espace chimique.Dans ce contexte, le travail effectué au cours de cette thèse de doctorat a visé à élaborer de nouvelles voies de synthèse de motifs tétrahydro-[1,6]-naphtyridines. La pierre angulaire des méthodologies développées réside dans l’utilisation des 3-vinyl-1,2,4-triazines comme des plateformes synthétiques bifonctionnelles. Ces composés ont été développés pour réagir à la fois comme accepteurs de Michael et comme aza-diènes dansdes cycloadditions de Diels-Alder à demande électronique inverse. Un intérêt tout particulier a été porté à lamise au point de stratégies synthétiques innovantes, par des réactions en cascade permettant une synthèse rapide et efficace des molécules cibles, et des approches de catalyse organique visant des transformations énantiosélectives.La synthèse de nouvelles 3-vinyl-1,2,4-triazines et le développement de stratégies de réactions d’addition conjuguée/cycloadditions en cascade et de synthèses monotopes organocatalysées ont fournis l’accès à une vaste gamme de nouvelles tétrahydro-[1,6]-naphthyridines diversement substituées.The development of new methods for the synthesis of original heterocyclic molecules represents a current concern in organic chemistry, aiming to furnish medicinal chemistry and chemical biology with new chemical tools and contribute to the exploration of chemical space.In this context, the work which was carried out during this PhD thesis focused on the elaboration of new approaches for the synthesis of tetrahydro-[1,6]-naphthyridine scaffolds. The original use of 3-vinyl-1,2,4-triazines as bifunctional synthetic platforms, able to react both as Michael acceptor and as aza-diene in inverse-electron-demand Diels-Alder cycloadditions, is the keystone our methodology is based upon. The development of domino reactions – allowing quick and efficient synthesis of targeted compounds – remaineda perpetual concern evolving along side our preoccupation to access enantioselective transformations relying on organocatalysis.The synthesis of new 3-vinyl-1,2,4-triazines platforms and the elaboration of domino conjugate addition/cycloadditions and orgonocatalyzed one-pot synthesis strategies enabled to synthetize a wide panelof new diversly substituted tetrahydro-[1,6]-naphthyridines compounds
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
Full text linkIn the quest for molecular complexity, the direct and selective functionalization of C(sp3) centers is of paramount importance. As sulfur- and/or fluorine-containing molecules are particularly important, the development of methods to (regio)selectively introduce moieties containing these atoms on a C(sp3) center by direct C–H bond functionalization or decarboxylative reaction has garnered our interest in the last few years. Given the challenges that the direct functionalization of C(sp3) centers represents, this account summarizes our recent contributions thanks to strategies based on transition metal catalysis and photochemistry
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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