1,723,142 research outputs found
Mechanistic Investigations into the Palladium-Catalyzed Decarboxylative Allylic Alkylation of Ketone Enolates Using the PHOX Ligand Architecture
Get PDFPalladium-catalyzed asymmetric allylic alkylation has become a large and important field for chemical synthesis. Many methodologies in this field offer mild conditions under which challenging and important molecular features can be reliably synthesized, including chiral all-carbon quaternary stereocenters. As a result, palladium- catalyzed asymmetric allylic alkylation has found significant use in total synthesis, and growing use in industry. While the general process of palladium-catalyzed asymmetric allylic alkylation has been studied for decades, there have been a number of recent modifications and developments, such as asymmetric versions of decarboxylative allylic alkylation procedures that are not yet well understood. The development of future implementations and improvements to palladium-catalyzed asymmetric allylic alkylation and related methodologies is expected to be facilitated by a better understanding of these more recent developments, and thus further mechanistic investigation is warranted.
Reported herein is a set of investigations into the palladium-catalyzed decarboxylative asymmetric allylic alkylation of ketone enolates using the PHOX ligand architecture. By monitoring the reaction via 31P NMR, a series of previously unidentified key intermediates is discovered. Two representatives of these key intermediates are isolated and characterized. The solution behavior of these species under reaction-like conditions is studied along with a few novel and related complexes. The role of these intermediates and their impact on the behavior of the reaction and product formation is discussed. Previously confounding experimentally observed behavior for this methodology is rationalized via the properties elucidated for these discovered intermediates.</p
A Novel Synthetic Vitamin A-like Compound (A Polyprenoic Acid Derivative, E-5166) Inhibits the Release of Arachidonic Acid Stimulated by Epidermal Growth Factor
No full textLittle is known about the mechanisms of anti-inflammatory activity of retinoids. A new synthetic vitamin A-like compound (polyprenoic acid derivative, E-5166) has a strong in vitro binding affinity to intracellular binding proteins for acidic retinoids. In order to elucidate the anti-inflammatory activity of E-5166, we studied the effect of E-5166 on the epidermal growth factor (EGF)-stimulated arachidonic acid (AA) release of pig epidermis. E-5166 significantly inhibited the EGF-stimulated AA release and this inhibitory effect of E-5166 required a longer incubation than hydrocortisone did. Furthermore, E-5166 inhibited the EGF-stimulated phosphatidylinositol (PI) turnover of pig epidermis. These results indicate that E-5166 inhibited the EGE-stimulated AA release through the inhibition of the EGF-stimulated PI turnover
Técnica dinámica grupal en la comunicación oral en estudiantes de primaria de la I.E. 5166 Bella Aurora - 2018
Get PDFLa presente investigación titulada: Técnica: Dinámica grupal en la comunicación
oral en estudiantes de primaria de la I.E. 5166 Bella Aurora - 2018, tuvo como
objetivo general determinar el efecto de la aplicación de la técnica dinámica grupal
en la comunicación oral en estudiantes de primaria de la I.E. 5166 Bella Aurora –
2018.
El método utilizado fue hipotético deductivo, diseño cuasi experimental. La
población estuvo conformada por 60 estudiantes de educación primaria de la
Institución Educativa 5166 Bella Aurora. La técnica empleada para recolectar
información fue la observación y el instrumento de recolección de datos fue la lista
de cotejo que fueron debidamente validados a través de juicios de expertos y
determinado su confiabilidad a través del estadístico de fiabilidad Alfa de
Cronbach.
Los resultados evidencian que la técnica dinámica grupal tuvo diferencia
positiva en la comunicación oral del grupo de control y experimental en
estudiantes del 5to grado de primaria de la I.E 5166 Bella Aurora, 2018
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
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
Ihre künstlichen Zähne sitzen wieder bei Gebrauch von Apollopulver, aromat. Ges.gesch. 5166, Nur echt in geschlossenen Blechdosen a- 50 Pfg., Geo Dötzer Frankfurt a/Main., Cjr- Weoersaller, Nürnberg
No full textIHRE KÜNSTLICHEN ZÄHNE SITZEN WIEDER BEI GEBRAUCH VON APOLLOPULVER, AROMAT. GES.GESCH. 5166, NUR ECHT IN GESCHLOSSENEN BLECHDOSEN A- 50 PFG., GEO DÖTZER FRANKFURT A/MAIN., CJR- WEOERSALLER, NÜRNBERG
Ihre künstlichen Zähne sitzen wieder bei Gebrauch von Apollopulver, aromat. Ges.gesch. 5166, Nur echt in geschlossenen Blechdosen a- 50 Pfg., Geo Dötzer Frankfurt a/Main., Cjr- Weoersaller, Nürnberg ( -
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