1,721,009 research outputs found
Advances in chemoselective intermolecular cross-benzoin-type condensation reactions
No full textThe intermolecular cross-benzoin and acyloin condensation reactions are powerful approaches to α-hydroxy carbonyls in a single step. However, their potentiality suffers from the occurrence of side reactions including self-condensation and the formation of the undesired cross-acyloin. The broad range of azolium salt precatalysts available confers high tunability to NHC mediated benzoin condensation, assuring a good level of selectivity to the direct coupling between two non-equivalent aldehydes. Many efforts have also been devoted to the design of strategies that expand the range of suitable reaction partners beyond the traditional aldehydes and to the discovery of novel umpolung catalytic systems. The synthesis of both racemic and enantiomerically enriched acyloins is reviewed
Esercizi di identificazione e caratterizzazione strutturale di composti organici
No full textQuesto eserciziario nasce dalla sentita esigenza degli autori di organizzare in modo razionale e rendere disponibile agli studenti il materiale didattico raccolto e utilizzato nei tanti anni dedicati a vario titolo all'insegnamento nei corsi istituzionali di metodi fisici in chimica organica per le lauree magistrali in Chimica e Tecnologia Farmaceutica e Biotecnologie del Farmaco. L'eserciziario è rivolto agli studenti dei corsi di laurea e laurea magistrale che nei diversi percorsi di studio affrontano per la prima volta le problematiche relative alla identificazione e caratterizzazione strutturale di composti organici
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
Structure determination of organic compounds, practical exercises
No full textThe authors have conceived and organized this workbook to provide students with the educational materials collected and used along the years for their lectures in Organic Spectroscopy courses at the University of Milan. This workbook is directed to bachelor and master students facing their first issues related to the identification and characterization of organic compounds by combination of the most common key techniques (IR, NMR and MS). To make the most of the contents of this book, students are required to be skilled in organic chemistry as well as in basic spectroscopic theory. The spectra collection is arranged in ascending order of difficulty, starting from the examination of simple compounds whose structures can be recognized through the analysis of 1H and 13C NMR, IR and MS spectra (chapters 1-3). Chapters 4 and 5 present a second set of compounds, analyzed through 1D and/or 2D NMR techniques when these are useful to solve particular structural issues. There is no specific chapter devoted to NMR spectra of nuclei other than H and C: however, in order to introduce the concepts of heteronuclei coupling, chapter 4 includes several examples of compounds containing F and P atoms
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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