1,720,955 research outputs found
Sviluppo di un metodo rapido per la determinazione di anabolizzanti illeciti in bovini di allevamento mediante cromatografia liquida accoppiata a spettrometria di massa ad alta risoluzione
No full textNell’Unione Europea l’uso di promotori della crescita ad azione ormonale nell’allevamento dei bovini da carne è vietato al fine di tutelare la salute dei consumatori dalla presenza di residui potenzialmente pericolosi nelle carni.
Per ottenere il rispetto del divieto imposto sono previsti dei piani di monitoraggio basati sulla ricerca nel siero o in altre matrici biologiche dei residui delle sostanze che si presume siano utilizzate illecitamente.
Come conseguenza dell’attività di sorveglianza si sono sviluppate alcune strategie di trattamento per eludere i controlli che prevedono, accanto all’uso di sostanze vietate, anche l’uso di sostanze autorizzate per finalità e a condizioni diverse da quelle previste.
La sorveglianza dell’uso dei promotori di crescita richiede quindi la disponibilità di metodi analitici sempre più precisi e accurati per la ricerca dei residui delle sostanze usate in modo illegale.
Si presenta un metodo analitico rapido di screening mediante cromatografia liquida accoppiata a spettrometria di massa ad alta risoluzione a tempo di volo (HPLC-HR-TOF-MS), per la valutazione della presenza di composti estrogenici nel siero di bovini di allevamento.
La separazione cromatografica è stata eseguita su una semplice colonna di arricchimento, utilizzando un gradiente di una fase mobile acqua/metanolo tamponata con acetato d’ammonio.
Grazie all’ elevato grado di accuratezza di massa dello strumento utilizzato (<3 ppm), il metodo permette l’accurata conferma strutturale dei composti esaminati ottenendo cromatogrammi con ridottissime finestre di range di massa .
Il metodo è stato applicato a una serie di campioni di siero di bovini da carne, provenienti da macelli, oltre che a campioni di sangue umano
Valutazione della qualità dei prodotti petroliferi. Applicazione della gascromatografia bidimensionale comprensiva GCxGC accoppiata alla spettrometria di massa
No full textAnalytical pyrolysis-comprehnsive two-dimensional gas chromatography-mass spectrometry (PY/GCXGC/MS) in the cultural heritage field
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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
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