1,721,259 research outputs found
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
A new and efficient route to the synthesis of pyrazole and pyrimidine C-nucleoside derivatives
No full textA new route to the synthesis of pyrazole and pyrimidine C-nucleosides, involving as the key step a metal catalysed reaction of beta-D-ribofuranosyl ketoesters with alkyl cyanoformates, is described. 2,3,5-Tri-O-benzoyl-beta-D-ribofuranosyl cyanide (1) reacts with alpha-bromoesters, in the presence of zinc dust, to give beta-D-ribofuranosyl-enaminoesters 2 which are easily hydrolised to beta-ketoesters 3. The reactions of compounds 3 with alkyl cyanoformates, in the presence of catalytic amounts of [Cu(acac)(2)], afford C-glycosyl enaminoketosters 4. These compounds react with benzylhydrazine and acetamidine to give pyrazole and pyrimidine C-nucleosides 5 and 6 respectively. (C) 1998 Elsevier Science Ltd. All rights reserved
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
Synthesis of pyrazole C-nucleosides via Tin(IV) chloride-promoted reactions of beta-D-ribofuranosyl cyanide with beta-dicarbonyl compounds
No full text2,3,5-Tri-O-benzoyl-beta-D-ribofuranosyl cyanide reacts with methyl acetoacetate and diethyl malonate in the presence of stoichiometric amounts of SnCl4 to give a beta-D-ribofuranosyl-enaminoketoester and a beta-D-ribofuranosyl-enaminodiester, respectively. The beta-D-ribofuranosyl-enaminoketoester was debenzoylated, treated with 2,2-dimethoxypropane and tert-butyl-dimethylsilyl chloride to give the methyl 3-amino-3-(5'-O-tert-butyldimethylsilyl-2',3'-O-isopropylidene-beta-D-ribofuranosyl)-2-acetyl propanoate obtained in good yield together with small amounts of its alpha-anomer. The reactions of the beta-anomer with hydrazine, methyl- and phenylhydrazine carried out under controlled experimental conditions, afforded the pyrazole C-nucleosides in good yields as beta-anomers. (C) 2002 Elsevier Science Ltd. All rights reserved
The Michael reaction of N-cinnamoylazoles with phenols. A simple synthesis of 4-arylchroman-2-ones and 1-arylbenzo[f]chroman-3-ones
No full text4-Arylchroman-2-ones 3 and 1-arylbenzo[f]chroman-3- ones 6 have been prepared in moderate to good yields by reaction of dihydric or trihydric phenols with p-substituted N-cinnamoylazoles in dichloromethane under reflux in the presence of DBU
Viscoelastic properties of the semitendinosus and gracilis tendons in reconstruction of the ACL: an in vivo evaluation.
No full textTensioning of the tendons of the semitendinosus and the gracilis used to reconstruct the anterior cruciate ligament (ACL) of the knee is one of the main factors to take into consideration during surgery that aims at obtaining good postoperative joint stability. Some authors have shown in vitro that the viscoelastic nature of the patellar tendon is responsible for its gradual release (loss of tension). It is the purpose of this study to verify in vivo the biomechanical behavior of the semitendinosus and gracilis tendons. A total of 40 consecutive patients were submitted to reconstruction of the ACL with flexor tendons of the knee using a method that allows for the gradual tensioning of the doubled semitendinosus and gracilis tendons using the Swing Bridge method. Patients were divided into 2 groups: in the first 20 patients (group I), after adequate manual pretensioning and tibial and femoral stabilization, the tendons were twisted using a dynamometer to measure torsion forces until tensioning equal to 2.5 N was achieved. The control group (group II) was made up of the successive 20 patients in whom tensioning of the tendons at 2.5 N was carried out in many phases. Five minutes after initial tensioning at 2.5 N the decrease in tension was recorded that returned to initial values. A similar procedure was carried out after 5 more minutes. The patients in both groups were evaluated using a KT-1000 arthrometer one year after surgery. The patients in group II showed a decrease in torsion equal to 37.2% after the first 5 minutes, and a further 26.8% after 5 more minutes, and measurement by means of KT-1000 revealed mean values for S/S 30 lb. and S/S MM of 1.3 mm and 1.7 mm, respectively, that proved to have a statistically significant difference (p < 0.05) as compared to the patients in group I (S/S 30 lb.: 2.0 mm; S/S MM: 2.4 mm). Although these data do not provide indications on the amount and duration of pretensioning and definitive tensioning to be applied to the transplant, they do clearly show the viscoelastic properties of the tendons. These properties require a more in-depth study to better determine the exact tensioning of the neoligament
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
- …
