1,721,068 research outputs found
Vinyl Cations in Organic Synthesis. Part 2. A Novel Synthesis of Methylene-1H-indenes (Benzofulvenes) by Cyclisation of Phenyl-Substituted But-1-en-3-ynes
No full textA series of phenyl-substituted but-1 -en-3-ynes has been prepared and their reactivity toward a acid-catalysed cycloisomerisation investigated. In boiling dichloromethane or 1,2-dibromoethane, in the presence of a catalytic amount of methanesulfonic acid, 1,1,2,4-tetraphenylbutenyne, 1,1,4-triphenylbutenyne, and (Z)-1,2,4-triphenylbutenyne afforded 1-benzylidene-2,3-diphenyl-1H-indene, (E)- and (Z)-l-benzylidene-3-phenyl-1H-indene and (E)- and (Z)-l-benzylidene-2-phenyl-1H-indene, respectively, in fair to good yields. Under the same conditions, (E)-1,2,4-triphenylbutenyne and (E)- and (Z)-1,4-diphenylbutenyne did not afford cyclisation products and were recovered unchanged. The cycloisomerisation reaction is rationalised in terms of formation of vinyl cation intermediates by exclusive protonation at the 4-position of the butenyne chain followed by intramolecular electrophilic attack on a suitably located and orientated phenyl nucleus in the 1-positio
Reductive Electrophilic Substitution of Pyrogallol Derivatives: Synthesis of 2,3-Disubstituted Phenols
No full text1,2-Dimethoxy-3-methoxymethoxybenzene, 1, was used as the starting material for the transformation of a 1,2,3-trioxybenzene into various 1-oxy-2,3-dicarbobenzenes, via regioselective reductive electrophilic substitution of the 2-methoxy group followed by Pd-catalyzed cross-coupling reactio
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
Emergency psychiatry: Crisis and organization of interventions
No full textThe approach to Psychiatric Emergencies and crisis situations has now become an essential element in the context of the definition of a coherent psychiatric care policy. This paper seek to provide a more comprehensive review of the literature about Emergency Psychiatry. In this context it's possible to Identify some areas of interest: definitions, factors influencing recovery's decision, type of patients, aggressiveness and violence, ethical problems, therapeutic approaches. In the definition of emergency authors underline the importance of concepts of crisis, seriousness and necessity for Immediate intervention. Different studies demonstrated the influence of factors such as psychiatrist's experience, psychosocial elements, symptoms seriousness in determining decision for hospitalization. The patients of the Psychiatric Emergency Services (PES) are represented mostly by patients which repeatedly use the Psychiatric Services (heavy users, revolving door patients). The international literature develops the theme of aggressiveness of psychiatric patients around problems connected with the patient himself (existence of a relation between illness ad violence; risk factors) and with the risk for the medical staff, with references to the most exposed categories and to aspects of prevention. In therapeutic approaches, particular attention is paid to psycotherapeutic interventions that are usually indicated with the generic term of Crisis Intervention (CI) which has been used by several therapists with different aims and models of intervention. In conclusion it is essential to recognize the importance of the Psychiatric Emergency Services, that, according to Mendoza, acts as a barometer it measures the integrity of the entire health care system
An Improved Synthesis of 7,8-Bis(methylene)-bicyclo(2.2.2)octa-2,5-diene
No full texta cheaper and more expeditious synthesis of 7,8-dimethyl-bis(methylene)-bicyclo[2.2.2]octa-2,5-diene is reporte
Dichotomy in the Double Bond Reactivity of 2,3-Bis(phenylsulphonyl)bicyclo-(2.2.1)hepta-2,5-diene and Related Compounds
No full textSelectivity between the two double bonds of the title compound was observed for a number of reagents. For example, cycloaddition with cyclopentadiene and anthracene, as well as reduction with molecular hydrogen (uder Pd catalysis), took place at the unsubstitued double bond, while cyclohexadiene and alfa terpinene gave (uncatalyzed) reduction at the more substituted double bond
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