Nuclear Magnetic Ressonance
Mostrando 25-35 de 35 artigos, teses e dissertações.
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25. Caracterização espectroscópica e cromatrográfica de copoliésteres biodegradáveis
The recycling of poly(ethylene terephthalate) (PET) can be carried through by different techniques, one of them is the chemical recycling, where new aliphatic-aromatic copolymers are synthesized from melt reaction of the PET post-consumer with aliphatic homopolymers. The aliphatic polyesters, such as the poly(ethylene adipate) (PEA) are biodegradable. The sy
Publicado em: 2005
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26. SÃntese e avaliaÃÃo da atividade biolÃgica de novos derivados arilazo-imidazolidÃnicos e arilideno-tiazolidÃnicos frente a vermes adultos de Schistosoma mansoni (Cepa BH)
Several biological activities, includding anti-parasitic, are attributed to imidazolidinic and thiazolodinic nucleous due to their chemical reactivite and, consequently afinity; wich directed us to find new antischistossomal agents. We prepared new 5-arylazo-3-benzyl-4-thioxo-imidazolidin-2-one 8a-d and 5-arylidene-3-(4-bromo-benzyl)-thiazolidine-2,4-dione 1
Publicado em: 2004
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27. Efeitos biológicos da peçonha da aranha Parawixia bistriata em ratos: isolamento e caracterização química parcial de uma neurotoxina pró-convulsivante / Biological effects of the Parawixia bistriata spider venon in rats: isolation and partially chemical characterization of a convulsant neurotoxin.
Arthropod venoms are rich sources of neurotoxins, molecular tools with selective and specific actions over the mamalian central nervous system with great clinical and scientific importance. Previous work of our laboratory showed that the spider venom of Parawixia bistriata, when injected by intracerebroventricular (i.c.v.) route, induced convulsive seizures
Publicado em: 2003
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28. Estudo do processo de encapsulação do bioaroma de gorgonzola em Beta-ciclodextrina e em lipossomas
In this work, it was studied the stabilization of the blue cheese flavour compounds obtained from fermentation of Aspergillus sp, by complexation in P-cyclodextrin and encapsulation in liposomes. The complexation in P-cyclodextrin was carried out by coprecipitation method. Initially, the complexation was studied using concentrated solutions of the main synth
Publicado em: 2003
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29. Solid polymer electrolytes based on polysacharide: synthesis and characterization. / Eletrólitos sólidos poliméricos à base de polissacarídeos: síntese e caracterização.
The synthesis and characterization of new types of solid polymer electrolytes based on hydroxyethyl and hydroxypropyl cellulose grafted with different polyethers were investigated. The synthesis is based on the reaction between the cellulose derivative and mono and difunctional isocyanates prepared from amines of polyethylene oxide and polypropylene oxide. I
Publicado em: 2000
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30. Aplicações da Ressonância Quadrupolar Nuclear em Duas Dimensões / Aplications of the nuclear quadrupole ressonance in two dimensions
Neste trabalho implementamos a técnica da ressonância quadrupolar nuclear (RQN) em duas dimensões. O espectro bidimensional é obtido a partir do pseudo-FID usando o estimador autoregressivo. Como o gradiente de campo-elétrico (GCE) no sítio do núcleo é produzido pelas cargas externas ao núcleo e o tensor GCE é simétrico, bastam dois parâmetros pa
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 24/04/1998
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31. Reações interfaciais de Poli(dimetilsiloxano)s com superficies hidroxiladas
Polysiloxanes, commonly know as silicones, are polymers formed by an Si-O backbone containing organic groups attached to the silicon atoms. Their chemistry is basically determined by the polarization of the Si-O bonds, and by the structure of the pendant organic groups. The Si-O bond is highly resistant to homolytic cleavage, but is susceptible to heterolyti
Publicado em: 1997
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32. Obtainion and characterization of absorbent materials throught carboximelation of etanol/water pulp non fiber fraction sugar cane bagasse. / Obtenção e caracterização de materiais absorventes através de carboximetilação de polpa etanol/água de medula de bagaço de cana de açúcar.
This work describes the use of ethanol / water pulps of pith in a study aiming the obtention and characterization of substantially insoluble carboxymethylcellulose for application as an absorvente material. In a typical experiment the carboxymethylation reaction of bleached ethanol / water pulp occurred at 80°C for 4 hours in isopropanol/ water suspensio
Publicado em: 1996
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33. Dinamica e reatividade de superficie de poli (dimetilsiloxano)s
Crosslinked polydimethylsiloxane (PDMS) heated at temperatures between 200 and 280°C for short periods (one-half to two hours), reveals a partially thermoplastic behavior. Earlier studies on silicone describe the phenomena occurring under heating as due to chemical reactions leading to the formation of oligomers and oxidation products, which cause degradati
Publicado em: 1994
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34. Polpação acetosolv de bagaço de cana e madeira de eucalipto
Acetosolv pulping of sugar cane bagasse and Eucalyptus grandis wood was studied with the objective to make adequate the conditions of this process for national feedstocks and to promote the integral use of lignocellulosic materials. The pulping of extracted and depithed sugar cane bagasse (8.0% humidity, 1.2% ash, 22.7% lignin and 53.2% cellulose) and eucaly
Publicado em: 1992
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35. High resolution spectroscopy in solids for nuclear resonace / Espectroscopia de alta resolução em sólidos por ressonância magnétoca nuclear.
Este trabalho descreve técnicas de espectroscopia de alta resolução em sólidos por Ressonância Magnética Nuclear (RMN), o projeto de construção de um espectrômetro para este fim e sua avaliação experimental com a utilização deste equipamento na caracterização de amostras sólidas. O espectrômetro de alta resolução em sólidos por RMN desenv
Publicado em: 1991