1,720,993 research outputs found
Studies on the biosynthesis of syringomycin E and syringopeptin 22A
No full textFeeding radioactive putative precursors to the bacterial cultures of Pseudomonas syingae pv. syringae in the presence of a protein synthesis inhibitor allowed the formation of radiolabelled syringomycin and syringopeptin. The result indicates that a nonribosomal mechanism of peptide synthesis is operating in the formation of these peptide metabolites
Evidence of the non ribosomal biosynthetic mechanism in the formation of syringomycin and syringopeptin, bioative lipodepsipeptides of the phytopathogenic bacterium Pseudomonas syringae pv. syringae
No full textSyringomycin and syringopeptins are lipodepsipeptide metabolites produced by the phytopathogenic bacterium Pseudomonas syringae pv. syringae. Radioactively labelled lipopeptides were produced in whole cell cultures supplemented with radioactively labelled putative biosynthetic precursors in the presence of the protein synthesis inhibitor, chloramphenicol. The results indicate that these lipopeptides are formed by a nonribosomal mechanism of peptide synthesis
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
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
ANALYSIS OF LEMON AND BERGAMOT ESSENTIAL OILS BY HPLC WITH MICROBORE COLUMNS
No full textSome citrus essential oils were analyzed by HPLC with both microbore and standard columns in reversed and normal phase. Volatile and non-volatile fraction were investigated. In the non-volatile fraction some coumarins have been identified. Fractions are detected spectrophotometrically at 220 nm and 320 nm before and after evaporation of samples. Some components were also identified by LC/MS. © 1990 Friedr. Vieweg & Sohn Verlagsgesellschaft mbH
Biosintesi dei lipodepsipeptidi bioattivi del batterio fitopatogeno Pseudomonas syringae pv. syringae
No full textViene dimostrato che i lipopeptidi di Pseudomonas syringae sono formati mediante il meccanismo di sintesi peptidica non ribosomiale. Gli esperimenti di marcatura isotopica e degradazione dei metaboliti marcati, dimostrano che la treonina è il l precursore biosintetico dell'acido 2,3-deidroamminobutirrico. Vengono caratterizzati fenotipicamente quattro mutanti di Pseudomonas syringae pv. syringae ottenuti per inserimento di trasposone, syrA, syrB, syrC e syrD
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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