1,720,976 research outputs found
Synthesis of bioactive cyclohexenyl chalcones and flavonoid derivatives / Chee Chin Fei
Full text linkFlavonoids are a class of natural products that are well known to possess a wide range of pharmacological properties. Due to their recent discovery in modulating muscarinic receptor activity and its inhibitory effect against dengue-2 virus NS3 protease, flavonoids are idea candidates for drug development. This dissertation describes the syntheses of several flavones and some Diels-Alder adducts derived from chalcones.
A modified Baker-Venkataraman method has been developed where flavones were prepared in a one-pot procedure from the corresponding 2-hydroxyacetophenones and acyl chlorides under different conditions. When 2-hydroxyacetophenone is heated with a stoichiometric amount of acyl chloride, either in a DBU/pyridine system or in an open K2CO3/acetone system, only the flavone is obtained, albeit in modest yield. However, when it is heated with an excess of acyl chloride in a DBU/pyridine system, the 3-acylflavone is the only product, while treatment in an open K2CO3/acetone system afforded the flavone as the major product and a smaller amount of 3-aroylflavone. Panduratin A and its regioisomer isopanduratin A have been synthesized in four steps from (E)-ocimene, [(E)-3,7-dimethyl-1,3,6-octatriene] via a Diels–Alder cycloaddition reaction. An overall yield of 75% was achieved from 2,6-dihydroxy,4-methoxyacetophenone. The mulberry Diels-Alder adducts pentamethyl ethers of the kuwanon V and dorsterone have been synthesised via a biomimetic intermolecular [4+2] cycloaddition reaction between a highly electron-rich dienophile and a Lewis acid sensitive diene derived from chalcone. Cycloaddition reaction under thermal condition afforded the kuwanon V and dorsterone in a 3:2 ratio. Cycloaddition catalysed by AgOTf/Bu4NBH4 gave higher yield of adducts
Anti-inflammatory trends of new benzimidazole derivatives
No full textAim: In present study, the anti-inflammatory activities of a new series of benzimidazole derivatives were studied, investigating their inhibition of secretory phospholipase A2, lipoxygenase, COXs and lipopolysaccharide-induced secretion of TNF-α and IL-6 in mouse RAW264.7 macrophages. Results: Synthesized compounds effectively inhibited proinflammatory enzymes and cytokines. Conclusion: A strong inhibition of secretory phospholipases A2 was exhibited by benzimidazole derivatives with trifluoromethyl and methoxy substitutions at position 4 of attached phenyl, whereas compound 8 containing pyridine ring substituted with amino group showed very potent 5-lipoxygenase inhibition. Molecular docking experiments were carried out to elucidate the molecular basis of the observed inhibitory activities
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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