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| Registros recuperados: 2.719 | |
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| PONTES-BUARQUE,MILA; TESSIS,ANA C.; BONAPACE,JOSÉ A. P.; MONTE,MARISA B. M.; SOUZA-BARROS,FERNANDO DE; VIEYRA,ADALBERTO. |
| There exists an extensive literature on the possible roles of minerals in the prebiotic stages of the chemical evolution of life (Bernal 1951, Cairns-Smith 1982, Wächtershäuser 1992, Vieyra et al. 1995, Tessis et al. 1999, see Lahav (1994) for a review). Among the original proposals, minerals have been considered in: (a) processes that would discriminate molecular chirality; (b) condensation reactions of biomolecular precursors; (c) prebiotic catalysis; (d) biochemical templates; and (e) autocatalytic metabolism. In this communication it is emphazised the complex properties of both surface reactions and interfaces between minerals and aqueous solutions simulating Archean scenarios. The properties of pyrite surface net charge and of its interface with a... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Prebiotic reactions; Mineral interfaces; Surface reactions. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652000000300005 |
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| SCHNEIDER,HORACIO. |
| Four DNA datasets were combined in tandem (6700 bp) and Maximum parsimony and Neighbor-Joining analyses were performed. The results suggest three groups emerging almost at the same time: Atelidae, Pitheciidae and Cebidae. The total analysis strongly supports the monophyly of the Cebidae family, grouping Aotus, Cebus and Saimiri with the small callitrichines. In the callitrichines, the data link Cebuela to Callithrix, place Callimico as a sister group of Callithrix/Cebuella, and show Saguinus to be the earliest offshoot of the callitrichines. In the family Pithecidae, Callicebus is the basal genus. Finally, combined molecular data showed congruent branching in the atelid clade, setting up Alouatta as the basal lineage and Brachyteles-Lagothrix as a sister... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: New World monkeys; Platyrrhine; Taxonomy; Molecular; Evolution. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652000000200005 |
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| CONSTANTINO,VERA R. L.; BARBOSA,CÉSAR A. S.; BIZETO,MARCOS A.; DIAS,PATRÍCIA M.. |
| Two-dimensional inorganic networks can shown intracrystalline reactivity, i.e., simple ions, large species as Keggin ions, organic species, coordination compounds or organometallics can be incorporated in the interlayer region. The host-guest interaction usually causes changes in their chemical, catalytic, electronic and optical properties. The isolation of materials with interesting properties and making use of soft chemistry routes have given rise the possibility of industrial and technological applications of these compounds. We have been using several synthetic approaches to intercalate porphyrins and phthalocyanines into inorganic materials: smectite clays, layered double hydroxides and layered niobates. The isolated materials have been characterized... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Intercalation compounds; Layered double hydroxides; Smectite clays; Layered niobates. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652000000100006 |
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| AMORIM,MARÚCIA I. M.; MERGLER,DONNA; BAHIA,MARCELO O.; DUBEAU,HÉLÈNE; MIRANDA,DANIELA; LEBEL,JEAN; BURBANO,ROMMEL R.; LUCOTTE,MARC. |
| The mercury rejected in the water system, from mining operations and lixiviation of soils after deforestation, is considered to be the main contributors to the contamination of the ecosystem in the Amazon Basin. The objectives of the present study were to examine cytogenetic functions in peripheral lymphocytes within a population living on the banks of the Tapajós River with respect to methylmercury (MeHg) contamination, using hair mercury as a biological indicator of exposure. Our investigation shows a clear relation between methylmercury contamination and cytogenetic damage in lymphocytes at levels well below 50 micrograms/gram, the level at which initial clinical signs and symptoms of mercury poisoning occur. The first apparent biological effect with... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Brazilian Amazon; Mercury; Mitotic Index; Cytogenetics. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652000000400004 |
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| LÓPEZ,LUCIENE BOTTENTUIT; BRAGA,MARIANE BANDEIRA DE MELO; ORTEGA LÓPEZ,JAIME; ARROYO,ROSSANA; SILVA FILHO,FERNANDO COSTA E. |
| The interaction between each one of Trichomonas vaginalis and Tritrichomonas foetus with their hosts is a complex process in which components associated to the cell surfaces of both parasites and host epithelial cells, and also to soluble components found in vaginal/urethral secretions, are involved. Either cytoadhesion or the cytotoxicity exerted by parasites to host cells can be dictated by virulence factors such as adhesins, cysteine proteinases, laminin-binding proteins, integrins, integrin-like molecules, a cell detachment factor, a pore-forming protein, and glycosidases among others. How trichomonads manipulate informations from the extracellular medium, transduce such informations, and respond to them by stimulating the activities of some surface... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Trichomonas vaginalis; Tritrichomonas foetus; Parasitic protozoa; Host-cell parasite interaction relationships; Trichomonal virulence. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652000000200006 |
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| Registros recuperados: 2.719 | |
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