1,720,959 research outputs found
Composizione molecolare della frazione polare di Ligusticum lucidum (Mill.)
No full textIl Ligusticum lucidum (Mill.) (sinonimo di Coristospermum lucidum (Mill.) Reduron, Charpin & Pimenov) noto anche col nome comune di Motellina lucida, è una pianta erbacea perenne indigena appartenente alla famiglia delle Apiaceae.
E’ caratterizzata da un fusto eretto e robusto, con foglie triangolari voluminose e lucide, ed infiorescenze strutturate in ombrelle composte da piccoli fiori bilobati di colore bianco. Il suo areale di distribuzione è individuato prevalentemente nel panorama montano dell’Italia settentrionale ed orientale ad altitudini comprese tra i 200 ed i 1500 m s.l.m., su pietraie e terreni aridi ad elevato coefficiente calcareo.
Non sono note proprietà specifiche inerenti la specie, mentre le piante appartenenti al genere Ligusticum sono note per le loro forti proprietà anti-infiammatorie ed analgesiche. Per questo, alcune varietà del genere, hanno avuto largo impiego nella medicina tradizionale cinese, in particolare nel trattamento del dolore e per la terapia di diversi tipi di disordini ematologici, quali ischemie e trombosi, in quanto tali specie sono in grado di incrementare il flusso sanguigno soprattutto a livello cerebrale.
In letteratura sono presenti diversi studi riguardanti la composizione della frazione polare e dell’olio essenziale di specie appartenenti al genere Ligusticum mentre risultano limitati gli studi fitochimici eseguiti sulla specie lucidum, riguardanti unicamente lo studio della composizione degli acidi grassi e la caratterizzazione delle cumarine e delle loro proprietà mediche.
Ciò rappresenta la ragione per cui abbiamo iniziato tale studio allo scopo di fornire una prima analisi esaustiva della composizione molecolare della frazione polare della specie.
L’analisi è stata condotta utilizzando tecniche estrattive, cromatografiche e spettroscopiche classiche quali estrazione con etanolo, cromatografia su colonna per la separazione dei composti, spettroscopia NMR e spettrometria di Massa per l’identificazione.
Lo studio dell’estratto della frazione polare del L. lucidum, ha evidenziato la presenza di sei composti quali 3'-acetil-4'-tigloil-khellattone (1), 3'-acetil-4'-diidro-tigloil-khellattone (2), luteolina (3), 7-{[2-O-β-D-glucopiranosil)-β-D-glucopiranosil]ossi}-5-idrossi-2-(3,4-diidrossi)-4H-1-benzopiran-4-one (4), acido clorogenico (5) e acido chinico (6) più altre sostanze naturali la cui struttura è ancora oggetto di studio.
I composti (1) e (2) che sono cumarine, rappresentano composti nuovi per il genere mentre sono già stati evidenziati nella famiglia e lo stesso vale per i composti (3) e (4) che sono flavonoidi ed anzi ne rappresentano i marker chemotassonomici. Infine, il composto (5) che è un acido caffeoil-chinico e l’acido chinico libero sono stati precedentemente identificati solo nel genere
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
Phytochemical study on the leaves of Wollemia nobilis
No full textIn this work, a phytochemical study performed on the leaves of the rare species, Wollemia nobilis W.G. Jones, K.D. Hill & J.M. Allen, is reported. By means of classical column chromatography and NMR Spectroscopy and Mass Spectrometry, nine compounds were evidenced. These were: pheophorbide a (1), isocupressic acid (2), acetyl-isocupressic acid (3), sandaracopimaric acid (4), agathic acid (5), 7-4'-4'''-tri-O-methyl-agathisflavone (6), 7-4'-7''-4'''-tetra-O-methyl-agathisflavone (7), caffeic acid (8) and shikimic acid (9). Compared to our previous phytochemical analysis on the male cones, some further compounds were identified i.e. compounds 1, 5, 6, 7 and 8. This confirmed the previous chemotaxonomic considerations of the species but also added new ones which were discussed within the text. In addition, a possible different accumulation of secondary metabolites in the tissues and organs of this plant was even noticed
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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