1,720,954 research outputs found
Amino acid-sesquiterpene lactone conjugates from the aerial parts of Centaurea pungens and evaluation of their antimicrobial activity
No full textTwo new amino acid-sesquiterpene lactone conjugates, named centaureolide A (1) and centaureolide B (2) along with a germacrane derivative (3), five flavonoids (4–8) and one quinic acid derivative (9) have been isolated from the aerial parts of Centaurea pungens (Asteraceae). Their structures were established by a combination of one- and two-dimensional NMR techniques, and mass spectrometry. The never reported sesquiterpene lactones have been determined as germacrane derivatives (1 and 2) characterized by the unusual occurrence of a proline moiety. In order to validate the use of the extract of C. pungens in folk medicine, the antimicrobial activity of the isolated compounds against the Gram-positive strains Bacillus cereus, Staphylococcus aureus and Listeria innocua and the Gram-negative strains Pseudomonas aeruginosa and Pseudomonas fragi was evaluated
Chemical constituents of the aerial parts of santolina chamaecyparissus and evaluation of their antioxidant activity
No full textSantolina chamaecyparissus is an aromatic evergreen herb growing in North Africa and near the Mediterranean coasts of Southern Europe. Literature data focused mainly on the investigation of the essential oil content of the aerial parts of S. chamaecyparissus, but few is known on the chemical composition of its polar extract. Total phenolic content was determined by the Folin-Ciocalteau method and the antioxidant activity of the n-butanol and chloroform fractions of S. chamaecyparissus was tested by Trolox equivalent antioxidant capacity (TEAC) and diphenyl-2-picrylhydrazyl radical (DPPH) assays. Difference of the phenolic content and of the antioxidant activity between the two extracts prompted us to investigate their chemical composition. Five compounds, eupatilin (1), circimaritin (2), 4'-hydroxy-5,6,7-trimethoxyflavone (3), 1,3-propanediol,2-amino 1-(4-hydroxy-3-methoxyphenyl) (4) and luteolin (5) have been isolated from the chloroform extract, while the investigation of butanolic extract led to the isolation of seven compounds, prunasin (6), luteolin 7-O-Î2-D-glucopyranoside (7), syringoside (8), junipeionoloside (9), citroside A (10), lonicerin (11) and apigenin 7-O-Î2-D-neohesperidoside (12). Their structures were elucidated by extensive spectroscopic methods including 1D- (1H, 13C and TOCSY) and 2D-NMR (DQF-COSY, HSQC, HMBC) experiments as well as ESIMS analysis
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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