1,720,985 research outputs found
Studio mediante spettroscopia RMN P31, H1, C13 del metabolismo del cristallino di coniglio nella cataratta da trattamento topico con desametasone
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The entry of [1-<sup>13</sup>C]glucose into biochemical pathways reveals a complex compartmentation and metabolite trafficking between glia and neurons: a study by <sup>13</sup>C-NMR spectroscopy
No full textTransient cerebral ischemia in the rat: a study by nuclear magnetic resonance spectroscopy
No full textThe energy state and the levels of metabolites involved in the phospholipid turnover during and following a transient cerebral ischemia have been evaluated with the aids of 31P and 1H nuclear magnetic resonance spectroscopy. Ischemia was induced by electrocoagulation of vertebral arteries in combination with transient occlusion of both common carotid arteries. After 10-min ischemia, the brain energy charge and the levels of high-energy phosphates were reduced, whereas lactic acid levels had undergone an 8-fold increase. Sixty minutes after cerebral blood flow recovery, brain energy charge and levels of high-energy phosphates returned to basal values, whereas lactic acid levels remained persistingly elevated; an increase in phosphocreatine was also observed. At this same time, glycerolphosphorylcholine levels were found to be significantly reduced
Preliminary study on the dehydratation of hydrogel contact lenses by NMR at low resolution
No full textLa tecnica della Risonanza magnetica nucleare (RMN) è in grado di valutare le proprietà e le caratteristiche delle lenti a contatto utilizzate per la correzione dei vizi refrattivi. In particolare essa può fornire un metodo di valutazione della quantità, dei tipi e degli stati di moto dell'acqua presenti in una lente nonchè seguirne le cinetiche di idratazione e disidratazione ed è contemporaneamente in grado di chiarire i meccanismi di tali processi. Nelle lenti è rilevata l'interazione dell'acqua con la matrice polimerica e conseguentemente i campi di esistenza, le cinetiche e i meccanismi di scambio tra gli stati dell'acqua ottenendo così informazioni riguardo le proprietà tecnologiche del materiale.
Nel nostro studio sono state prese in considerazione a temperature controllate lenti a differenti contenuti di acqua e valutazioni quantitative tramite RMN sono state confrontate con dati ottenuti con la tecnica gravimetrica. E' stato possibile delineare un meccanismo di disidratazione ed i risultati ci inducono ad ipotizzare la necessità di utilizzare tempi differenti di asciugamento in base alle caratteristiche del polimero
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
Water dynamic states in hydrogel contact lenses. Study by NMR at low resolution
No full textQuattro tipi di lenti in idrogel a diverso grado di idratazione: 38,6% (Allergan Optical, Polymacon, HEMA), 45% (Bausch & Lomb, Hetafilcon B, HEMA-NVP), 58% (Vistakon, Etafilcon A, HEMA-MA) e 78% (Toray, Incanto, MMA-VP), sono state studiate mediante NMR a bassa risoluzione riscontrando che esse sono caratterizzate dalla presenza di acqua con elevato grado di immobilizzazione mentre le lenti Toray, con un 78% di acqua nel polimero, anche da un'acqua con le caratteristiche di mobilità tipiche dei fluidi.
Si è ancora ottenuto, durante il processo di disidratazione di queste lenti, un graduale aumento in percentuale del legame dell'acqua che va dal 5% nello stato di massima idratazione al 23% dopo 27 ore
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