1,720,960 research outputs found
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
Screening and confirmation analysis of anabolic agents in human urine by gas chromatography - Hybrid mass spectrometry (high resolution - Time of flight)
No full textthis work presents a novel method for the detection of anabolic agents administration by the anal. of human urine. The method here presented allows both the screening and the confirmation of five anabolic agents at concns. below 1 .mu.g l-1, i.e. whenever it is not possible to obtain a full spectrum by gas chromatog. technique with mass spectrometry detection unit (GC-MS) (single quadrupole mass detector), neither in electron impact (EI) nor in chem. ionization (CI) mode. The instrumental app. here used is constituted by a gas chromatograph (GC) coupled to a hybrid mass spectrometry detection (MS) unit, formed by a high resoln. magnetic mass spectrometer (HRMS) and by a time of flight (TOF) orthogonal mass spectrometer. The proposed approach has been revealed very useful in the long term retrospective anal. of low concn. of anabolic agents and/or their metabolites, and esp. of the five major anabolic agents (unchanged clenbuterol, and the main metabolites of methandienone, methyltestosterone, 19-nortestosterone and stanozolol), whose detection and quant. confirmation, at levels of 2 .mu.g l-1, is presently imposed by the International Olympic Committee Medical Commission for the antidoping anal. of athletes urine
Capillary GC-MS investigation of the metabolism and excretion of oxabolone in man
No full textThe metabolism of oxabolone cipionate, 17-(3-cyclopentyl-1-oxopropoxy)-4-hydroxyestr-4-en-3-one, a synthetic anabolic steroid, was investigated in man, the cumulative urinary excretion and the metabolism of the compounds being studied by GC-MS in both electron impact and chemical ionization modes. After administration by injection to volunteers, five different metabolities were detected in urine. The metabolites and the parent compound were detected in urine up to a week after administration
Excretion study of stanozolol in bovine by HPLC-tandem mass spectrometry
No full textStanozolol is an anabolic steroid illicitly used for growth promoting purposes in animal prodn. For reasons of public health the use of anabolic steroids as growth promoters is officially banned in Europe in animals intended for consumption. The aim of this work is the investigation of stanozolol metabolites, 3'-hydroxystanozolol, 4.beta.-hydroxystanozolol and 16.beta.-hydroxystanozolol in urine samples after stanozolol administration to a young calf. After solid phase extn. of urine samples, detection is carried out by HPLC-MS-MS multiple reaction monitoring. Av. recovery for the three metabolites is 80%. The method is highly specific and has been validated in terms of linearity, inter and intra day precision. In addn. the decision limit CC.alpha. and the detection capability CC.beta. have been detecte
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
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
- …
