1,721,017 research outputs found
Callipeltoside A: a cytotoxic aminodeoxy sugar-containing macrolide of a new type from the marine lithistidasponge Callipelta sp
No full textA cytotoxic glycoside macrolide, callipeltoside A (I), has been isolated from the marine lithistid sponge Callipelta sp.,
collected off New Caledonia. Structural assignment was accomplished through extensive 2D NMR spectroscopy. The
complete relative stereochem. is proposed from the anal. of ROESY and NOE difference expts. Callipeltoside A
represents the first member of a new class of marine-derived macrolides, contg. unusual structural features including a 4-
amino-4,6-dideoxy-2-O,3-C-dimethyl-a-talopyranosyl-3,4-urethane unit
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)
Isolation and structural elucidation of the crellastatins I-M: cytotoxic bissteroid derivatives from the vanuatu marine sponge Crella sp
No full textContinued investigation of cytotoxic exts. of the marine sponge Crella sp. has resulted in the discovery of crellastatins I-M (e.g. I, crellastatin I). Their structures were detd. by interpretation of their NMR spectroscopic and FABMS data. These new bis-steroid derivs. exhibited cytotoxic activity against NSCLC cell lines with IC50 values in the range of 1-8 .mu.g/m
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 textVariations 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
Axinellins A and B: new proline-containing antiproliferative cyclopeptide from the Venuatu sponge Axinella carteri
No full textAppropriate 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
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