1,720,969 research outputs found
Copolimeri vinilici eparino-simili: funzionalizzazione chimica in massa e in superficie
No full textSono stati introdotti in un copolimero etilene vinil alcool, mediante reazione in massa e in superficie, gruppi funzionali carbossilici, solfati e solfammati al fine di preparare un materiale eparino-simile. Le misure di attività biologica hanno mostrato la buona potenzialità dei materiali preparati
Preparazione di copolimeri vinilici eparino-simili mediante loro funzionalizzazione chimica
No full textUn copolimero etilene vinil alcool è stato modificato per inserzione di gruppi solfato al fine di ottenere un materiale eparino-simile. I polimeri sono stati caratterizzati mediante analisi chimica, termica, e con tecniche spettroscopiche. L'attività biologica è stata invece valuatata con misure di APTT e di adesione piastrinica
Sulfation and preliminary biological evaluation of ethylene-vinyl alcohol copolymers
No full textIn order to obtain polymers provided with
improved haemocompatibility a commercial ethylenevinyl
alcohol copolymer (EVAL) was chemically modified
by introduction of different amounts of sulfate
groups. The sulfation reaction was carried out by the reaction
of hydroxy groups with two different sulfating
reagents (ClSO3H and PySO3). The influence of the molar
ratio of the reagents and the reaction time on the functionalization degree was evaluated also for elevated substitution degrees. No difference in the sulfation agents efficiency was noted. The new terpolymers (EVAL-SO3H)
have been characterized by chemical and physico-chemical
techniques as: titration of the acidic groups, Fourier
Transform IR reflectance spectroscopy (FTIR-ATR), differential scanning calorimetry (DSC), X-ray photoelectron
spectroscopy (XPS) and 1H-NMR. The haemocompatibility
was evaluated by in vitro plasma coagulation (APTT)
and platelet aggregation tests and is proved to be excellent
for sulfation degrees higher than 35% of the hydroxy
groups of the polymer
Preparazione e caratterizzazione di polimeri carbossilati a base vinilica
No full textIl copolimero etilene vinil alcool è stato funzionalizzato con due diversi tipi di anidride, succinica e glutarica, introducendo nel polimero gruppi polari carbossilici. I materiali ottenuti sono stati caratterizzati nelle loro proprietà fisiche
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
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