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Search Results: 1 - 10 of 13363 matches for " Laura Nadxieli Palacios-Grijalva "
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Sulphated Zirconia as an Eco-Friendly Catalyst in Acylal Preparation under Solvent-Free Conditions, Acylal Deprotection Assisted by Microwaves, and the Synthesis of Anhydro-Dimers of o-Hydroxybenzaldehydes
Laura Nadxieli Palacios-Grijalva,Deysi Y. Cruz-González,Leticia Lomas-Romero,Eduardo González-Zamora,Gerardo Ulibarri,Guillermo E. Negrón-Silva
Molecules , 2009, DOI: 10.3390/molecules14104065
Abstract: A solvent-free approach is described for the regioselective synthesis of acylals (1,1-diacetates) in shorter reaction times and higher yields, compared to conventional methodology using solvents. In the protection reaction of the o-hydroxybenzaldehyde the formation of acetyl compounds and anhydro-dimers was observed. The deprotection reaction involves microwave (MW) exposure of diluted reactants in the presence of solid sulphated zirconia (SZ) catalyst that can be easily recovered and reused. The sulphated zirconia was recycled several times without any loss of activity.
Synthesis of New Pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione (PCU) Cyanosilylated Derivatives Using Sulphated Zirconia and Hydrotalcite as Catalysts in Microwave-Assisted Reactions under Solvent Free Conditions
Nahí Adriana Guerra-Navarro,Laura Nadxieli Palacios-Grijalva,Deyanira Angeles-Beltrán,Guillermo E. Negrón-Silva,Leticia Lomas-Romero,Eduardo González-Zamora,Rubén Gavi?o-Ramírez,Juan Navarrete-Bola?os
Molecules , 2011, DOI: 10.3390/molecules16086561
Abstract: A comparison was made of the effectiveness of the functionalization reactions of pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione (PCU) using sulphated zirconia in protection-deprotection reactions and Mg/Al hydrotalcite in a cyanosilylation reaction, under classical thermal conditions and imposing microwave radiation; improved yields and reaction times were considered.
Life cycle, feeding and defecation patterns of Rhodnius ecuadoriensis (Lent & León 1958) (Hemiptera: Reduviidae: Triatominae) under laboratory conditions
Villacís, Anita G;Arcos-Terán, Laura;Grijalva, Mario J;
Memórias do Instituto Oswaldo Cruz , 2008, DOI: 10.1590/S0074-02762008000700011
Abstract: rhodnius ecuadoriensis is the second most important vector of chagas disease (cd) in ecuador. the objective of this study was to describe (and compare) the life cycle, the feeding and defecation patterns under laboratory conditions of two populations of this specie [from the provinces of manabí (coastal region) and loja (andean region)]. egg-to-adult (n = 57) development took an average of 189.9 ± 20 (manabí) and 181.3 ± 6.4 days (loja). mortality rates were high among lojan nymphs. pre-feeding time (from contact with host to feeding initiation) ranged from 4 min 42 s [nymph i (ni)] to 8 min 30 s (male); feeding time ranged from 14 min 45 s (ni)-28 min 25 s (male) (manabí) and from 15 min 25 s (ni)-28 min 57 s (nymph v) (loja). the amount of blood ingested increased significantly with instar and was larger for manabí specimens (p < 0.001). defecation while feeding was observed in manabí specimens from stage nymph iii and in lojan bugs from stage nymph iv. there was a gradual, age-related increase in the frequency of this behaviour in both populations. our results suggest that r. ecuadoriensis has the bionomic traits of an efficient vector of trypanosoma cruzi. together with previous data on the capacity of this species to infest rural households, these results indicate that control of synanthropic r. ecuadoriensis populations in the coastal and andean regions may have a significant impact for cd control in ecuador and northern peru.
Edad, producción académica y jubilación en la Universidad de Sonora: una primera exploración
Rodríguez Jiménez, José Raúl;Urquidi Trevi?o, Laura Elena;Mendoza Grijalva, Guadalupe;
Revista mexicana de investigación educativa , 2009,
Abstract: this article offers initial exploration of the aging of faculty at universidad de sonora, especially of fulltime professors, by approaching the relationship among age, academic production, and the retirement system at the institution. the analyzed information shows that at present, the aging of the faculty does not represent a serious problem since a balance between younger and older professors exists. however, within ten years, a considerable number of these professors will reach their sixth decade of life and can be expected to decrease noticeably their academic production; they may also postpone their retirement since the current system of pensions and retirement implies significant economic losses.
Absence of domestic triatomine colonies in an area of the coastal region of Ecuador where Chagas disease is endemic
Grijalva, Mario J;Palomeque, Francisco S;Villacís, Anita G;Black, Carla L;Arcos-Terán, Laura;
Memórias do Instituto Oswaldo Cruz , 2010, DOI: 10.1590/S0074-02762010000500013
Abstract: rhodnius ecuadoriensis is considered the second most important vector of chagas disease in ecuador. it is distributed across six of the 24 provinces and occupies intradomiciliary, peridomiciliary and sylvatic habitats. this study was conducted in six communities within the coastal province of guayas. triatomine searches were conducted in domestic and peridomestic habitats and bird nests using manual searches, live-bait traps and sensor boxes. synantrhopic mammals were captured in the domestic and peridomestic habitats. household searches (n = 429) and randomly placed sensor boxes (n = 360) produced no live triatomine adults or nymphs. in contrast, eight nymphs were found in two out of six searched campylorhynchus fasciatus (troglodytidae) nests. finally, trypanosoma cruzi dna was amplified from the blood of 10% of the 115 examined mammals. environmental changes in land use (intensive rice farming), mosquito control interventions and lack of intradomestic adaptation are suggested among the possible reasons for the lack of domestic triatomine colonies.
A Simple Method to Obtain Single Conidium Isolates Directly from Banana (Musa sp.) Leaves Infected with Mycosphaerella fijiensis Morelet
Conde-Ferráez, Laura;Grijalva-Arango, Rosa;Raigoza-Flores, Néstor Eduardo;James-Kay, Andrew C.;
Revista mexicana de fitopatología , 2008,
Abstract: a simple methodology to isolate conidia of mycosphaerella fijiensis from infected banana leaves was implemented. a method reported previously was laborious and required skilled trained personnel. here we describe a sampling method that consumes short periods of time and low costs and that can be carried out and reproduced by personnel with limited lab experience or expertise. it is practical and useful for extensive studies of foliar pathogen population and distribution.
Acción bioquímica y tóxica de compuestos organofosforados
Ruth Román Palacios,Laura García Chávez
Revista de la Sociedad Química de México , 1997,
Abstract:
Análisis de la salida del mercado. Fracaso vs. abandono en la franquicia
M. Victoria Bordonaba Juste,Laura Lucia Palacios,Yolanda Polo Redondo
Cuadernos de Economía y Dirección de la Empresa , 2009,
Abstract: El estudio de la supervivencia empresarial ha sido un tema relevante tanto en el ámbito académico como empresarial. Actualmente los trabajos se centran en examinar por separado las distintas formas que tiene una empresa de salir del mercado. Esta investigación pretende comparar y examinar las diferencias entre los factores que determinan dos tipos de salida del mercado: el fracaso empresarial y el cese de actividad. El estudio se lleva a cabo para el sistema de franquicia, donde la decisión de abandonar la actividad franquiciadora ha sido escasamente estudiada. En concreto se examina el efecto del momento de entrada, la estructura organizativa y la política de incentivos sobre ambas salidas del mercado, a partir de una muestra de 387 empresas franquiciadoras operativas entre 1986 y 2004. Los resultados permiten observar que las empresas que fracasan como organización son seguidoras, conexperiencia media y una elevada centralización y control de la cadena; mientras que las que optan por abandonar el mercado pertenecen al grupo de empresas seguidoras o primera mayoría, con escasa experiencia, baja expansión y un elevado nivel de centralización.
GENERACIóN DE EMPLEOS EN LA FRONTERA NORTE DE MéXICO: QUIéNES HAN APROVECHADO EL TLC?
Gabriela Grijalva Monteverde
Frontera norte , 2004,
Abstract: El objetivo de este trabajo es mostrar que los estados que conforman la frontera norte de México se han beneficiado en forma diferencial de los avances de su integración económica con Estados Unidos y Canadá, con lo que se ha producido después de los primeros a os de operación del Tratado de Libre Comercio de América del Norte (TLCAN) un verdadero reordenamiento de las capacidades productivas reconstruidas en las entidades fronterizas durante el proceso de integración con Norteamérica. Se muestra que en este proceso de reestructuración productiva, los estados que han resultado ganadores no han sido necesariamente los que habían mantenido anteriormente mayores niveles de desarrollo. En particular, Baja California y Sonora aparecen como los estados ganador y perdedor, respectivamente, en términos de los empleos generados.
Regime constitucional da biodiversidade: patrim nio natural, ecossistemas frágeis e recursos naturais
Agustín Grijalva
Meritum : Revista de Direito da Universidade FUMEC , 2012,
Abstract: Pela Constitui o equatoriana de 2008, a soberania é relativa, o que implica que esse poder-dever do Estado se encontra limitado externamente pelo Direito Internacional e internamente pela própria Constitui o – em especial pelos direitos ela estabeleceu. Além disso, vale salientar que o titular da soberania n o é o governo, mas, sim, o povo, que a exerce, mediante um complexo de órg o públicos com competências constitucionais e formas específicas de participa o cidad direta. Essa perspectiva adotada na Constitui o equatoriana tem consequências relevantes em matéria ambiental, pois implica que nenhum governo pode violar os direitos internacionais e constitucionais no ambito ambiental sob o argumento de exercício da sua soberania sobre os recursos naturais. As limita es constitucionais à soberania s o claramente exemplificadas no caso da proibi o quanto à explora o de recursos naturais n o renováveis em áreas de preserva o e em áreas de prote o integral. Embora a Constitui o autorize, em caráter excepcional, o desenvolvimento de atividades extrativistas nessas áreas, a Carta Fundamental estabelece padr es e procedimentos rigorosos para assegurar a validade constitucional formal e material de qualquer decis o das autoridades públicas nesse sentido. Portanto, esses atos de autoridades públicas, assim como toda norma, est o sujeitos a um controle constitucional anterior e posterior à sua ado o. No caso das áreas de prote o integral em que habitam povos em isolamento voluntário, a Constitui o já estabelece diretamente uma pondera o de direitos que proíbe definitivamente qualquer atividade econ mica nessas áreas, priorizando, assim, a sobrevivência física e cultural desses povos. Outra pondera o de direitos diretamente estabelecida pela Constitui o diz respeito ao direito à água, uma vez que, expressamente, prioriza a sustentabilidade dos ecossistemas e o consumo humano. Também no caso da propriedade privada e comunitária, em áreas caracterizadas por elevada biodiversidade, a Constitui o imp e uma fun o ambiental à propriedade, a qual fica sujeita a um sistema institucional sob seu controle. Em outras situa es em que os direitos constitucionais ambientais podem entrar em conflito com outros direitos constitucionais, é necessário realizar um processo de pondera o, seja mediante lei ou mediante a jurisprudência constitucional. Para tal, deve-se considerar que a Constitui o equatoriana outorga igual hierarquia aos direitos e considera-os como complementares uns aos outros, de modo que qualquer regulamenta o de um direito deve ser realizada em
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