1,720,966 research outputs found
Ligandendesign für die asymmetrische Transferhydrierung in Wasser
Get PDFThe present thesis focuses on the synthesis of new chiral ionic ligands designed to fulfill the requirements for the application in asymmetric transfer hydrogenations. Based on a chiral amino alcohol and a chiral diamine structural motive, highly coordinating chiral ionic ligands with bidentate structural motive were obtained. By introducing an ionic head group, the solubility of the designed ligands could be adapted via the choice of anion. Moreover, different substitution patterns for diamine based chiral ionic ligands were exploited. The newly designed ligands were successfully applied in transition metal catalyzed asymmetric transfer hydrogenation in aqueous medium. By taking advantage of the tunable properties of the designed ligands, their positive effect on asymmetric transfer hydrogenation could be demonstrated
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Enantioselective palladium and isothiourea dual catalysis
Get PDFThis thesis details the development of dual catalytic processes involving achiral palladium and enantiopure isothiourea catalysts for the synthesis of enantioenriched and highly functionalised products. Taking inspiration from related literature examples demonstrating the compatibility of palladium and isothiourea catalysis, the extension of existing methodologies as well as the development of novel processes were investigated.
Based on the relay catalytic allylic amination/[2,3]-rearrangement protocol, previously developed in our group for the synthesis of enantioenriched α-amino ester derivatives, the scope and limitations of this process were probed. Initial studies aimed at identifying functional groups that could be tolerated in the relay catalysis. Electron-withdrawing amide substituents proved most promising and were explored in more depth to furnish enantioenriched α-amino ester derivatives featuring a 1,4-dicarbonyl motif.
As processes reported so far had focused on ammonium enolates as reaction partners, the range of reactivity modes accessible by isothiourea catalysis had not been fully exploited in dual catalytic methodologies. As such, the development of a cooperative palladium and isothiourea catalysis process employing α,β-unsaturated acyl ammonium intermediates was explored. This process furnishes enantioenriched cyclopentane products with up to four contiguous stereogenic centres with high stereoselectivity (up to 99:1 dr, up to 97:3 er). The scope and limitations of this process were probed, with subsequent derivatisation reactions demonstrating the synthetic utility of the products. In addition, a range of control experiments provided insight into the mechanism of this cooperative palladium and isothiourea catalysis
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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