988 resultados para 5-41
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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MCM-41 material was synthesized starting from hydrogel containing colloidal fumed silica, sodium silicate, cetyltetramethylammonium bromide (CTMABr) as surfactant, and distilled water as solvent. These reactants were mixed to obtain a gel with the following composition: 4SiO(2):1Na(2)O:1CTMABr:200H(2)O. The hydrogel with pH=14 was hydrothermally treated at 100 degreesC, for 4 days. Each day, the pH was measured, and then adjusted to 9.5-10 by using 30% acetic acid solution. Thermogravimetry was the main technique, which was used to monitor the participation of the surfactant on the MCM-41 nanophase, being possible to determine the temperature ranges relative to water desorption as well as the surfactant decomposition and silanol condensation.
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The AlMCM-41 material with Si/Al=50 was synthesized by hydrothermal method, using cethyltrimethylammonium as template. The protonic H-AlMCM-41 acid form was obtained by ion exchange with ammonium chloride solution and subsequent calcination. The characterization of the material by several techniques showed that a good-quality MCM-41 material was obtained. High-density polyethylene (HDPE) has been submitted to thermal degradation alone, and in presence of the exchanged H-AlMCM-41 catalyst at a concentration of 1: 1 in mass (H-AlMCM-41/HDPE). The reactor was connected on line to a gas chromatograph connected to a mass spectrometer. This process was evaluated by thermogravimetry (TG), from 350 to 600degreesC, under helium dynamic atmosphere, with heating rates of 5.0; 10.0 and 20.0 degreesC/min. From TG curves, the activation energy, calculated using a multiple heating rate integral kinetic method, decreased from 225.5 KJ.mol(-1), for the pure polymer (HDPE), to 184.7 KJ.mol(-1), in the presence of the catalyst (H-AlMCM-41/HDPE).
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Agronomia (Energia na Agricultura) - FCA
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Pós-graduação em Educação - FCT
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El Manual recoge la experiencia de DOCPAL/CELADE en la recuperacion de informacion a partir de los documentos ingresados a la coleccion. Previa la presentacion de las definiciones basicas, se discute la formulacion de estrategias de busqueda asi como las caracteristicas de la recuperacion de la informacion, incluyendose una descripcion de los instrumentos y pautas utilizadas en dicho proceso
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El informe de avance en la preparacion de los censos latinoamericanos de 1980 comprende las labores llevadas a cabo recientemente por Argentina, El Salvador, Nicaragua, Panama y Peru; respecto a este ultimo pais se trata especialmente del Censo Experimental; se incluye ademas el custionario aplicado en los ensayos censales de diciembre de 1979 en Panama.
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El manual contiene las instrucciones generales y especificas para la completacion de las seis secciones que conforman el cuestionario para el estudio de los componentes de la fecundidad en Paraguay.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)