1,721,020 research outputs found
Callipeltosides B and C, two novel cytotoxic glycoside macrolides from a marine Lithistida sponge Callipeltasp.
No full textFollowing the characterization of callipeltoside A, the first member of a novel class of marine glycoside macrolides, two
more bioactive constituents, callipeltoside B (I) and C, were isolated from Callipelta sp. in very low amts. The structures,
assigned on the basis of spectral anal., include the same 14-membered macrolide in a callipeltoside A but differed in the
saccharide moieties
Isolation of callipeltins A-C and of two new open-chain derivatives of callipeltin A from the marine sponge Latrunculia sp. A revision of the stereostructure of callipeltins.
No full textTwo new callipeltin-related acyclic peptides have been isolated, together with callipeltins A-C from the marine sponge Latrunculia sp. collected at the Vanuatu Islands. The gross structures of new compounds were elucidated by spectroscopic data. The application of the Marfey's analysis on the new derivatives and on callipeltin A (1), allowed us to revise the configuration of two amino acid units in callipeltin A
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
Axinellins A and B: New proline-containing antiproliferative cyclopeptides from the Vanuatu Sponge Axinella carteri
No full textNeosiphoniamolide A, a novel cyclodepsipeptide, with antifungal activity from the marine spongeNeosiphonia superstes
No full textA novel cyclodepsipeptide, neosiphoniamolide A (I), has been isolated from the sponge Neosiphonia superstes. The
structure of I, which contains a 12-carbon hydroxy acid, glycine, valine, and a halogenated tyrosine residue is an 18-
membered ring, is related to jaspamide and the geodiamolides, previously isolated from sponges. The structure was
solved by spectroscopic analysis
Crellastatin A: a cytotoxic bis-steroid sulfate from the Vanuatu marine sponge Crella sp
No full textA new nonsym. dimeric steroid, crellastatin A (I), was isolated from the Vanuatu Island marine sponge Crella sp.
Structural assignment was accomplished through extensive 2D NMR spectroscopy. The stereochem. of I was
established from an anal. of ROESY expts. and from mol. mechanics and dynamics calcns. I, which possesses an
unprecedented connection through the side chains, exhibits in vitro cytotoxic activity against NSCLC-N6 cells (IC50 of
1.5 mg/mL)
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
Isolamento di nuove callipeltine, ciclodepsipeptidi con effetto inotropo positivo, dalla spugna Latrunculia sp.
No full text- …
