5 resultados para Free access

em Universidad de Alicante


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Este artículo analiza diversas manifestaciones publicitarias aparecidas en la prensa española de los siglos XVIII y XIX. Considerando que la publicidad moderna nace en los países primero industrializados en torno a esas fechas, esta investigación se ha planteado la hipótesis de que en España, aun con retraso, se inició un proceso similar. Para la recopilación y selección de hechos, hemos utilizado las colecciones digitalizadas de portales que recientemente ofrecen el acceso libre a sus fondos; en particular, los de la Biblioteca Nacional de España, el Archivo de Revistas Catalanas Antiguas y la Hemeroteca Municipal de Madrid.

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The development of transversal competencies provides an integral education. However, its practical implementation among different subjects is not a trivial task. There are several issues that should be previously solved in an optimal way to take advantage of the synergy among subjects. Main issues are: i) the need for a common space for the documents management, ii) the availability of the document everywhere and anytime, and iii) the possibility to collaborate in the documents edition tasks. It was implemented a virtual portfolio for the students which allows the assessment of all the subjects in a global way. To this goal we used the Google apps due to its free access, availability and suitability for the collaborative editing tasks.

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El artículo proporciona una metodología sencilla para la identificación de minerales mediante la técnica de difracción de rayos X de polvo utilizando bases de datos mineralógicos de libre acceso y online. Las bases de datos utilizadas son la base de datos mineralógicas webmineral y la base de datos de estructuras cristalinas de la American Mineralogist Crystal Structure Database, AMS. En el presente trabajo se han elaborado 3 actividades resueltas de estudios reales y en orden creciente de dificultad. Se ha pretendido hacer hincapié en puntos donde el profesor puede interactuar con el alumno y promover la capacidad de análisis, síntesis y razonamiento crítico del alumno ante un problema de investigación en geología. Finalmente se ha elaborado un Anexo donde se recogen recomendaciones para que el profesor desarrolle sus propias actividades.

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(Sa)-Binam-D-prolinamide (20 mol%), instead of (Sa)-binam-L-prolinamide, in combination with chloroacetic acid (100 mol%) is an efficient organocatalyst for the direct aldol reaction between α-keto esters as electrophiles and alkyl and α-functionalised ketones, under quasi solvent-free conditions, providing access to highly functionalised chiral quaternary γ-keto α-hydroxyesters with up to 92% ee.

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BINAM-prolinamides are very efficient catalyst for the synthesis of non-protected and N-benzyl isatin derivatives by using an aldol reaction between ketones and isatins under solvent-free conditions. The results in terms of diastereo- and enantioselectivities are good, up to 99% de and 97% ee, and higher to those previously reported in the literature under similar reaction conditions. A high variation of the results is observed depending on the structure of the isatin and the ketone used in the process. While 90% of ee and 97% ee, respectively, is obtained by using (Ra)-BINAM-l-(bis)prolinamide as catalyst in the addition of cyclohexanone and α-methoxyacetone to free isatin, 90% ee is achieved for the reaction between N-benzyl isatin and acetone using N-tosyl BINAM-l-prolinamide as catalyst. This reaction is also carried out using a silica BINAM-l-prolinamide supported catalyst under solvent-free conditions, which can be reused up to five times giving similar results.