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C. A. STACE F.L.S. 《Botanical journal of the Linnean Society. Linnean Society of London》1973,66(2):97-115
The epidermal anatomy, with special reference to the glandular trichomes, is surveyed in the Asian species of the genus Combretum. Emphasis is laid on the value of such characters in reviewing the sectional classification of the genus. It is concluded that sections Quadrangulares, Squamosae, Tetragonocarpus and Flagrocarpeae should be amalgamated to form an enlarged section Tetragonocarpus. It is also likely that sections Quisqualoides, Ovalifoliae and Dasystachyeae , and sections Decandra'e and Kaloëdron , should be amalgamated. 相似文献
955.
956.
The effects produced on bacteriorhodopsin by low concentrations of several detergents have been studied by absorption and fourth-derivative spectrophotometry. Sodium dodecyl sulfate induces the appearance of the blue form of bacteriorhodopsin (λmax = 600 nm) at pH values up to 7.0 in a reversible manner. The apparent pK of the purple-to-blue transition raised with increasing concentration of SDS. Of the other detergents tested, only sodium dodecyl-N-sarcosinate showed a slight red-shift of the absorption band to 580 nm, whereas sodium taurocholate, Triton X-100 and cetyltrimethylammonium bromide did not favour the appearance of the blue form. The effect of SDS was found to be consistent with a localized conformational change that moves away the counter-ion of the protonated Schiff base. 相似文献
957.
Concentrations of soluble aluminum (Al) and manganese (Mn) frequently reach phytotoxic levels in acid soils. While dose response relationships for these metals are well documented, the effects of combined exposure have received less attention. We have examined the effect of combinations of Al and Mn on growth and metal accumulation in Vigna unguiculata (L.) Walp. grown in solution culture under conditions of low ionic strength (conductivities typically < 100 µS cm−1 ). The nature of interaction between these metals varied with the specific physiological response, the part of the plant investigated, and the relative amount of stress imposed. Analysis of growth data provided evidence for amelioration of metal toxicity (antagonistic effects), although this effect was dose dependent. Analysis of metal content data provided evidence for antagonistic and synergistic (exacerbation of toxicity) effects, again depending on dose. Analysis of foliar symptoms also provided evidence for antagonisms and synergisms, with the nature of the response dependent on the specific physiological response and specific plant part investigated. In contrast with previous reports, evidence for antagonistic, synergistic, and multiplicative effects on growth, metal uptake, and expression of foliar symptoms have been obtained under physiologically and environmentally relevant conditions. These results suggest a more detailed analysis of the potential for interactions between metals in the environment is required. 相似文献
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959.
M Nicol C Massart N Savouré 《Comptes rendus des séances de la Société de biologie et de ses filiales》1980,174(1):33-39
The stabilization by glycerol of the serum estradiol 17 beta dehydrogenase has been investigated here in terms of time and temperature. The protected enzyme is stable for a month at least at --20 degrees C. Its activity reaches a maximum at 60 degrees C. In another connection, effect of reduced glutathione, of N. acetyl-cysteine and of various mineral ions on the enzymic conversion has been studied. 相似文献
960.