993 resultados para C ... f, B ... n.
Resumo:
A range of new alkylpyridinium and imidazolium carborane salts with [nido-C2B9H12](-), [closo-CB11H12](-), and [RC2B11H11](-) (R = methyl or butyl) anions have been prepared and characterized by physical and thermal methods, including the solid state structures of five of the salts determined by single crystal X-ray diffraction. The tendency of the salts to form low-melting ionic liquids has been assessed; all the salts studied with [nido-C2B9H12](-) anions melted below 100 degrees C and, significantly, have melting points that are 25-85 degrees C lower than those of the corresponding [closo-CB11H12](-) analogs, demonstrating that a wider range of boron-rich ionic liquid materials can be readily accessed.
Resumo:
Se analiza el Proyecto de Ciencia integrada para Bachillerato o proyecto C.I.B. Se trata de un intento de renovación didáctica en el área de Ciencias realizado por el departamento de Ciencias Naturales del IEPS. La conclusión principal a que se llegó fue que el Proyecto deberÃa incluir las pautas necesarias para realizar programaciones integradas del currÃculum para alumnos de Bachillerato, que abarcaran las materias FÃsica, QuÃmica, BiologÃa y GeologÃa. En los grupos de trabajo se analizaron datos de la realidad como cuestión previa: hacia dónde va la investigación educativa en relación a la renovación de los currÃculos a nivel internacional; y las posibilidades de renovación que ofrece y admite nuestra realidad nacional. Por otro lado se señalan los principios básicos del proyecto CIB, que son: principio de activación, principio de realismo, principio de flexibilidad y principio de creatividad. A continuación se pormenorizan los objetivos generales del proyecto CIB, y los materiales necesarios para llevarlo a cabo. Para concluir se estudia el papel de la fÃsica y la quÃmica en el proyecto CIB, y el material para el estudio integrado de la fÃsica y la quÃmica.
Resumo:
Objective.-to examine the c-erb B-2 expression and nuclear DNA content in samples of breast lesions to ascertain any relationship between c-erb B-2 expression and aneuploidy in the different types of proliferative breast lesions and in intraductal and invasive carcinomas.Design and Setting.-lmmunohistochemical analysis of c-erb B-2 expression and cytometric nuclear DNA assessment were performed in a series of 39 cases of intraductal hyperplasia without atypia, 7 cases of intraductal hyperplasia with atypia, 64 cases of intraductal carcinoma, and 85 cases of invasive breast carcinoma (30 of which had extensive intraductal component).Results.-Overexpression of c-erb B-2 was seen only in cases of carcinoma: 28 (43.7%) intraductal carcinomas and 15 (17.6%) invasive carcinomas. Aneuploidy was demonstrated in 3 (43.0%) cases of intraductal hyperplasia with atypia, in 54 (84.4%) cases of intraductal carcinoma, and in 63 (74.2%) cases of invasive carcinoma. All cases of intraductal hyperplasia without atypia were euploid and none expressed c-erb B-2. Among the carcinomas (intraductal and invasive) there was a strong relationship between aneuploidy and c-erb B-2 expression. In most instances, the intraductal and invasive components of the 30 invasive carcinomas with extensive intraductal component displayed similar DNA content and c-erb B-2 immunoreactivity; whenever there was a difference, the intraductal component tended to be aneuploid (five out of six cases) and c-erb B-2 positive (one case), in contrast to the respective invasive component.Conclusions.-The higher frequency of aneuploidy and c-erb B-2 expression in intraductal carcinomas in comparison with invasive carcinomas suggests there is not a linear relationship between DNA content abnormalities and neoplastic progression and that some invasive breast carcinomas evolve without an identifiable intraductal phase or are unrelated to disturbances at the c-erb B-2 locus.