Browsing by Issue Date, starting with "1991"
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- The basicity of alkali metal methoxides in methanol. The effects of ion association on methoxide additions to activated anisolesPublication . Castilho, Paula C. M. F.; Crampton, Michael R.; Yarwood, JackThe formation of adducts with 1 :2 and 1:3 stoichiometry by methoxide addition to nitro-activated anisoles has been examined spectrophotometrically. For these equilibria the ‘basicity’ of sodium methoxide solutions in methanol is appreciably greater than that of corresponding potassium methoxide solutions. This is in contrast with other measures of basicity and is attributed to the association of the multi-charged adducts with cations which is stronger with sodium than with potassium ions.
- Studies of the species barrier between Drosophila subobscura and D. madeirensis I. The genetics of male hybrid sterilityPublication . Khadem, Mahnaz; Krimbas, Costas B.The genetics of hybrid male sterility between Drosophila subobscura and D. madeirensis were studied with the help of 20 markers in backcross males. A major effect resides in the sex chromo somes: backcross males with the X and Y of different origin (mad X-sub Y or sub X—mad Y) have very small and empty testes. In compatible combinations testes are of normal size but males may be sterile or fertile depending on the genetic constitution of their autosomes. Six autosomal factors affecting hybrid male fertility could be postulated. This estimation is based on the assumption of the absence of interaction between viability and fertility. The presence and the mode of such interaction may modify the number of sterility factors.