1,721,005 research outputs found
Solanum sisymbrifolium Lamarck esotica avventizia casuale di Sardegna:diffusione ed aspetti fitochimici
No full textL'attuale vegetazione esistente in Sardegna non è altro che uniinfinitesima parte del manto che sino a pochi secoli fa copriva la nostra regione. La Sardegna può ancora mostrare, in ogni modo, splendidi esempi di specie botaniche nei diversi ambienti del suo territorio siano esse spontanee, endemiche o avventizie. Tra queste ultime sono state individuate specie appartenenti al genere Solanum, due negli anni 70, ed una nel 1995, la c.d. Morella spinosissima o meglio Solanum sisymbrifolium Lamarck. S. sisymbrifolium è originaria del Sud-America e precisamente del Brasile, Paraguay, Uruguay ed Argentina.
Il presente lavoro rappresenta il primo approccio di analisi fitochimica allo studio di questa specie vegetante in Sardegna. Nella frazione contenente gli acidi grassi, i costituenti identificati sono rappresentati da elementi con una lunghezza di catena che va da 9, come l'acido octanoico, a 25, come l'acido tetracosanoico. Anche la frazione steroidica presenta delle peculiarità notevoli ed è da notare la presenza dei due stereoisomeri beta e tau del sitosterolo. Per quanto riguarda l'analisi LC/MS della frazione metanolica, è da notare la totale assenza di antociani e da un'alta concentrazione dei derivati della Luteolina. Tra gli acidi fenolici, l'acido clorogenico è quello più rappresentativo
Liquid chromatography-mass spectrometry assay for quantification of Gluten Exorphin B5 in cerebrospinal fluid
No full textA sensitive, precise and accurate method for the quantification of the alimentary opioid peptide Gluten Exorphin B5 (GE-B5, Tyr-Gly-Gly-Trp-Leu) in cerebrospinal fluid (CSF) was developed using liquid chromatography-mass spectrometry (LC-MS). Aliquots (10 μL) of sheep CSF were injected into a LC-MS instrument equipped with a reversed-phase C12 column at a flow rate of 250 μL/min. The mobile phase consisted of Eluent A water with 0.01% acetic acid as an ion-pairing reagent, and Eluent B acetonitrile. The LC-MS system was programmed to divert column flow to waste for 3.5 min after injection, after which time flow was directed into the mass spectrometer that operated in positive ion mode. DADLE (Tyr-D-Ala-Gly-Phe-D-Leu) was used as Internal Standard. No significant interfering peaks were detected at the retention times of GE-B5 in CSF blanks. The calibration curves were linear in the range of 0.39-78.00 ng/mL. The lower limit of detection and the lower limit of quantitation values for GE-B5 in CSF were established at 0.30 and 0.78 ng/mL, respectively. The intra-day and inter-day precision values were 55% after 600 min), which is reduced by the addition of protease inhibitors. This is the first reported method for the quantification of GE-B5 in CSF. © 2007 Elsevier B.V. All rights reserved
Solanum sisymbrifolium Lam., Esotica avventizia casuale di Sardegna: diffusione e aspetti fitochimici
No full textGoing 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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