1,720,967 research outputs found
Regio- and enantioselective properties of the lipase-catalyzed irreversible transesterification of some 2-substituted-1,4-butanediols in organic solvents
No full textThe regioselectivity of the Pseudomonas fluorescens (P. cepacia) lipase (PFL)-catalyzed irreversible transesterification of 2-substituted-1,4-butanediols 1a-3a has been studied and, in the case of 3a, it has been shown that (R)- and (S)-diols are acylated with opposite regioselectivity
Baker's yeast mediated biohydrogenation of 2-substituted allyl alcohols: Synthesis of enantiomerically pure (2S)-3-benzyloxy-2-methyl-1-propanol
No full textThe baker's yeast biohydrogenation of the 2-substituted allyl alcohol 2a, in turn prepared from dihydroxyacetone dimer (DHAD) 7a afforded the enantiomerically pure (2S)-3-benzyloxy-2-methyl-1-propanol 1a (>98% ee)
The first example of lipase-catalyzed resolution of a stereogenic center in steroid side chains by transesterification in organic solvent
No full textThe Pseudomonas cepacia lipase selectively catalyzes the acylation of the (20S)-isomer of the 22-alcohol group in the C-22 steroid compounds 1a and 4a when the transesterification is irreversibly carried out with vinyl acetate in an organic solvent. (C) 1996 Elsevier Science Lt
Total assignment of H-1 and C-13 NMR spectra of 13 alpha- and 13 beta-estrone methyl ethers
No full textThe complete H-1 and C-13 chemical shift assignments of the 13 alpha -epimer of estrone methyl ether and of estrone methyl ether itself were carried out, making use of one- and two-dimensional NMR techniques (1D HOHAHA, COSY, NOESY, TOCSY and HSQC)
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
Lipase-catalyzed resolution of stereogenic centers in steroid side chains by transesterification in organic solvents: the case of a 26-hydroxycholesterol
No full textThe Pseudomonas cepacia (PCL) lipase selectively catalyzes the acylation of the (25S)-isomer of the (25R,S)-26-hydroxycholesterol la when the transesterification is irreversibly carried out with vinyl acetate in a mixture of organic solvents (chloroform/tetrahydrofuran). (C) 1998 Elsevier Science Ltd. All rights reserved
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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