1,721,012 research outputs found
Analysis of the transferability of similarity calculations from substructures to complex compounds
No full textUsing a canonical matching to measure the similarity between molecules: the taxol and the combretastatin A1 case
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Analysis of a Theoretical Model Based on Similarity for Studying RNA Base Pairings
No full textA theoretical model for studying RNA base pairing is presented, based on similarity measures of the bases and corresponding indexes. Similarity calculations are made by evaluating atomic importance in molecules, a method that uses an original method for the calculation of electronic energy. The application of the model to both Watson-Crick and non-Watson-Crick pairings is commented on. Some theoretical considerations concerning the capability of the genetic code to repair dangerous mutations contribute to the ongoing debate
Organic synthesis planning: Some hints from similarity
No full textDespite of the present popularity of the new usages of similarity in chemistry, and of its counterpart dissimilarity, few approaches have used it in the design of organic synthesis. In addition mast of the known applications refer to the mere comparison between structures of the synthetic tree. We would like to discuss the power of the use of similarity in organic synthesis planning and to give some examples. The possibilities of analysis of a synthesis at different levels, from the single step to the entire tree, are presented and criticised. Special attention is dedicated to the role of similarity, whilst the identification of good descriptors is postponed to future developments
Classification of organic reactions using similarity
No full textOrganic reaction classification allows for better understanding of organic reactivity, better data sharing, and better reaction storage and retrieval. The power of similarity has been often used to strengthen search methodology and to help reaction prediction systems, but seldom to optimise reaction classification. A hierarchical classification by similarity measures is proposed. It is based on electronic energy and chemical potential descriptors and on a general description of reactions. Using a main division into three reaction sets, additions, eliminations, and substitutions, followed by two successive subdivisions by number and types of reactive atoms it is possible to arrive at a hierarchy of groups containing homogeneous reaction classes. In addition, inside each set the reactions can be ordered. Some simple examples are used to demonstrate the efficiency of the classification and its overall consistency. The application of the final system to more complex examples is further proof of its efficiency. The reported classification can also be used in synthesis planning
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
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