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Search Results: 1 - 10 of 156290 matches for " Chaves Mariana H. "
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Análise de extratos de plantas por CCD: uma metodologia aplicada à disciplina "química organica"
Chaves, Mariana H.;
Química Nova , 1997, DOI: 10.1590/S0100-40421997000500019
Abstract: extracts of the regional plants annona squamosa and annona muricata were analysed by silica gel thin-layer chromatography using adequate systems of solvents and spray reagents. carbohydrates, amino acids, alkaloids, flavonoids and terpenoids were detected in both species. these data agree with those on the literature about phytochemistry of the annonaceae.
Steroids and flavonoids of Porcelia macrocarpa
Chaves, Mariana H.;Roque, Nidia F.;Ayres, Mariane C. Costa;
Journal of the Brazilian Chemical Society , 2004, DOI: 10.1590/S0103-50532004000400026
Abstract: three mixtures of steroids (1a+1b, 2a+2b and 3a+3b) and two flavonoid glycosides (4 and 5) were isolated from the ethanol extract of branches of porcelia macrocarpa (warm.) r. e. fries (annonaceae). the steroids stigmasta-4,25-dien-3-one (2a) and (22e)-stigmasta-4,22,25-trien-3-one (2b) are news. the structures were elucidated by nmr and ms data and comparison with literature data of model compounds.
Triterpenóides pentacíclicos das folhas de Terminalia brasiliensis
Araújo, Delton Sérvulo;Chaves, Mariana H.;
Química Nova , 2005, DOI: 10.1590/S0100-40422005000600012
Abstract: eleven oleanane, ursane and lupane-type triterpenes were isolated from the leaves of terminalia brasiliensis camb, daturadiol (3b,6b-dihydroxy-olean-12-ene), 3b-hydroxy-30-norlupan-20-one, lupenone, b-amyrenone, a-amyrenone, lupeol, b-amyrin, a-amyrin, betulin, erythrodiol and uvaol, in addition to squalene, sitosterol and a-tocopherol. the structures of these compounds were identified by 1h and 13c nmr spectral analysis and comparison with literature data.
Extra??o de pigmentos das sementes de Bixa orellana L.: uma alternativa para disciplinas experimentais de química organica
Costa, Charllyton Luis S. da;Chaves, Mariana H.;
Química Nova , 2005, DOI: 10.1590/S0100-40422005000100026
Abstract: this paper describes methodologies for the extraction and characterization by tlc, uv-vis, ir and nmr of bixin from bixa orellana l. (urucum) seeds. based on the results, the extraction with naoh 5% is the fastest, uses low-cost materials, requires two to four laboratory hours and is a useful alternative for an experimental organic chemistry discipline.
Triterpenóides pentacíclicos das folhas de Terminalia brasiliensis
Araújo Delton Sérvulo,Chaves Mariana H.
Química Nova , 2005,
Abstract: Eleven oleanane, ursane and lupane-type triterpenes were isolated from the leaves of Terminalia brasiliensis Camb, daturadiol (3b,6beta-dihydroxy-olean-12-ene), 3beta-hydroxy-30-norlupan-20-one, lupenone, beta-amyrenone, alpha-amyrenone, lupeol, beta-amyrin, alpha-amyrin, betulin, erythrodiol and uvaol, in addition to squalene, sitosterol and alpha-tocopherol. The structures of these compounds were identified by 1H and 13C NMR spectral analysis and comparison with literature data.
Juventud negada y negativizada: Representaciones y formaciones discursivas vigentes en la Argentina contemporánea
Chaves,Mariana;
Ultima década , 2005, DOI: 10.4067/S0718-22362005000200002
Abstract: this article delivers an analysis and description of the current representations and speeches regarding the contemporary young people of argentina. this representation was built based on the field job carried out with several actors (young people, old people, communications media) during years 1998 and 2004 in the city of la plata (province of buenos aires) as a part of the doctoral investigation of the authoress (chaves, 2005). the analysis of the speeches allowed the identification of several representations over the young as well as the acknowledgement of discursive formations in which such representations were included. the note includes as well a systematization of characterizations for the young people of argentina and/or latin america, carried out by other authors. as well, equivalencies are established with the offered proposal. finally, it is interpreted that the hegemonic visions towards the young people of latin america are due to the legislature juridic and restrictive model. it is said that the young people is known by the ?great no?, it is unfit (according to the juridic model) or negative (according to the restrictive model); the young are not allowed to exist as a total entity (in transition, uncomplete, nor infant nor grown up) or their practices are condemned (they are problematic youths, uncommitted, rebels or delinquents and offenders).
Juventud negada y negativizada: Representaciones y formaciones discursivas vigentes en la Argentina contemporánea
Mariana Chaves
Ultima Década , 2005,
Abstract: En este artículo se brinda una descripción y análisis de las representaciones y discursos vigentes acerca de las y los jóvenes en la Argentina urbana contemporánea. Esta caracterización fue construida con base al trabajo de campo con diversos actores (jóvenes, no-jóvenes, medios de comunicación) realizado entre los a os 1998 y 2004 en la ciudad de La Plata (Provincia de Buenos Aires, Argentina) como parte de la investigación doctoral de esta autora (Chaves, 2005). El análisis de los discursos permitió identificar diversas representaciones sobre la juventud y reconocer formaciones discursivas en las que dichas representaciones entraban en juego. El escrito ofrece también una sistematización de caracterizaciones realizadas por otros autores para la juventud argentina y/o la juventud latinoamericana y se establecen equivalencias con la propuesta realizada. Finalmente se interpreta que las miradas hegemónicas sobre la juventud latinoamericana responden a los modelos jurídico y represivo del poder. Se sostiene que la juventud está signada por el gran NO , es negada (modelo jurídico) o negativizada (modelo represivo), se le niega existencia como sujeto total (en transición, incompleto, ni ni o ni adulto) o se negativizan sus prácticas (juventud problema, juventud gris, joven desviado, tribu juvenil, ser rebelde, delincuente).
Los espacios urbanos de jóvenes en la ciudad de La Plata
Mariana Chaves
Avá : Revista de Antropología , 2007,
Abstract:
Terpenos e ácidos graxos de Dipteryx lacunifera Ducke
Vieira Júnior, Gerardo Magela;Silva, Hilris Rocha e;Bittencourt, Thaís Chaves;Chaves, Mariana H.;Simone, Carlos Alberto de;
Química Nova , 2007, DOI: 10.1590/S0100-40422007000700030
Abstract: this paper describes the isolation of the furanocassane-type diterpene, named vinhaticoic acid, along with b-farnesene and spatulenol from fruit shells of d. lacunifera. structural determinations were accomplished by chemical derivatization and spectral analysis, including 1d and 2d nmr and x-ray crystallography. the fatty portion was extracted from the fruit kernels, transesterfied and analysed by hrgc/ms. oleic acid (75.8 ± 4.3%) was the major component. essential oil extracted from the fruit shells of d. lacunifera was analysed by hrgc/ms and nine sesquiterpenes were identified; b-farnesene (48.6%) and spatulenol (21.61%) were the major constituents.
Macrocarpane, a new sesquiterpene skeleton from the leaves of Porcelia macrocarpa
Chaves, Mariana H.;Lago, Jo?o Henrique G.;Roque, Nídia F.;
Journal of the Brazilian Chemical Society , 2003, DOI: 10.1590/S0103-50532003000100004
Abstract: the volatile oil and the hexane extract from the leaves of porcelia macrocarpa (warm.) r.e. fries, annonaceae, were submitted to chromatographic separations. nine sesquiterpenes (a-cubebene, a-copaene, germacrene-d, bicyclogermacrene, g-cadinene, d-cadinene, spathulenol, globulol and cis-cubenol) and one diterpene (phytol) were identified in the volatile oil (83.1 % in weight). two sesquiterpenes (spathulenol and macrocarp-11(15)-en-8-ol), the latter with a novel skeleton, one diterpene (phytol) and two steroids (sistosta-5,25-dien-3b-ol and sitosta-5,22,25-trien-3b-ol) were isolated from the hexane extract. these compounds were characterized by 1h and 13c nmr spectroscopy, including bidimensional analysis and mass spectrometry.
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