Search results for "divergent"
showing 10 items of 43 documents
Repetitive‐Synthesis of Bulky Dendrimers – A Reversibly Photoactive Dendrimer with Six Azobenzene Side Chains
1993
Dendrimers with bulky repeating units containing up to 43 benzene rings (in 9) have been obtained by using a repetitive divergent synthetic strategy (three generations). The new functional dendrimer 13 containing six azobenzene units at the periphery was synthesized allowing a reversible switching of the shape and size of the molecule upon irradiation. An X-ray structure analysis of the dendritic molecule 3a shows the inclusion of acetonitrile.
Idle minds are the devil's tools? Coping, depressed mood and divergent thinking in older adults.
2017
The main aim was to test a causal relations model of the problem-focused and emotion-focused coping styles, depressed mood, and divergent thinking (DT) in older adults. It was hypothesized that both forms of coping would have a significant effect on predicting depressed mood, and that problem-focused coping and depressed mood would have a significant effect on DT.Participants were 135 subjects with ages ranging between 55 and 84 years old, who took part in a personal interview and filled out several questionnaires. The statistical analysis included structural equations models (SEM).The initial model led to a final model endorsed by the goodness of fit, composite reliability, and discriminan…
A multi-country test of brief reappraisal interventions on emotions during the COVID-19 pandemic
2021
© The Author(s), under exclusive licence to Springer Nature Limited 2021, corrected publication 2022
Quelques éléments sur la vie et l'oeuvre de Robert d'Adhémar.
2010
Nous avons rassemblé dans cette note divers éléments sur la vie et les travaux scientifiques de Robert d'Adhémar. A notre connaissance, il n'existe pas de notice sur Robert d'Adhémar. Nous donnons quelques extraits de lettres écrites par Robert d'Adhémar à son ami, le mathématicien Robert de Montessus de Ballore.
Enantioselective Total Syntheses of (+)-Hippolachnin A, (+)-Gracilioether A, (-)-Gracilioether E, and (-)-Gracilioether F.
2018
The Plakortin polyketides represent a structurally and biologically fascinating class of marine natural products. Herein, we report a unified strategy that enables the divergent syntheses of various Plakortin polyketides with high step-economy and overall efficiency. As proof-of-concept cases, the enantioselective total syntheses of (+)-hippolachnin A, (+)-gracilioether A, (-)-gracilioether E, and (-)-gracilioether F have been accomplished based on a series of bio-inspired, rationally designed, or serendipitously discovered transformations, which include (1) an organocatalytic asymmetric 1,4-conjugate addition to assemble the common chiral γ-butenolide intermediate enroute to all of the afo…
Enantioselective Total Syntheses of (+)-Hippolachnin A, (+)-Gracilioether A, (-)-Gracilioether E and (-)-Gracilioether F
2018
The Plakortin polyketides represent a structurally and biologically fascinating class of marine natural products. Herein, we report a unified strategy that enables the divergent syntheses of various Plakortin polyketides with high step-economy and overall efficiency. As proof-of-concept cases, the enantioselective total syntheses of (+)-hippolachnin A, (+)-gracilioether A, (−)-gracilioether E, and (−)-gracilioether F have been accomplished based on a series of bio-inspired, rationally designed, or serendipitously discovered transformations, which include (1) an organocatalytic asymmetric 1,4-conjugate addition to assemble the common chiral γ-butenolide intermediate enroute to all of the afo…
Visible-light-accelerated amination of quinoxalin-2-ones and benzo[1,4]oxazin-2-ones with dialkyl azodicarboxylates under metal and photocatalyst-fre…
2021
A direct sp3 C-H amination of cyclic amines (dihydroquinoxalinones and dihydrobenzoxazinones) with dialkyl azo dicarboxylates accelerated by visible-light irradiation under metal and photocatalyst-free conditions is described. This protocol features very mild reaction conditions for the synthesis of aminal quinoxaline and benzoxazine derivatives with good to high yields (up to 99%). These aminal derivatives respresent versatile building blocks for the divergent synthesis of quinoxalin-2-one derivatives.
Croce e l'eversione della filosofia hegeliana
2013
Il contributo cerca di dimostrare quanto poco hegeliana sia filosofia di B. Croce, attraverso motivi sistematici e lungo l'intero sviluppo del pensiero crociano.
Stress generation at ridge axes by plate divergence and magma rise
1995
Abstract A model is explored for the rifting process particularly at the divergent plate boundary in Iceland, based on direct observations of the Krafla rifting episode 1975–1984. Magma accumulates near the axial crust-mantle transition as the plates diverge from each other and compression on the boundary decreases. Two-dimensional finite-element modelling is applied to investigate how divergence and buoyant rise of magma interact in triggering rifting. Both processes are found to be important, but long intervals between rifting episodes require the time-average deviatoric stress to be compressible normal to the axis.
Evolution in the Arctic: a phylogeographic analysis of the circumarctic plant,Saxifraga oppositifolia(Purple saxifrage)
2003
Summary • A survey of chloroplast DNA variation in the circumarctic-alpine plant, Saxifraga oppositifolia, has resolved two highly divergent cpDNA lineages with geographically widespread and mainly allopatric distributions that are largely concordant with those of two subspecies, that is, subspp. oppositifolia and glandulisepala. These subspecies differ for a single morphological trait and hence level of morphological divergence does not equate to molecular divergence within the species. • The two cpDNA lineages were estimated to have diverged from their most recent common ancestor 5.37–3.76 Ma, that is, during the early to mid-Pliocene. • A nested clade analysis was conducted in an attempt…