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Arthur Hughes M.A. Ph.D. Sc.D. 《Annals of science》2013,70(3):233-264
This note discusses lecture plates at the Hugo de Vries Laboratorium that may be relevant to Hugo de Vries's claim to have independently discovered Mendel's law of segregation. Dating when the plates were made is problematic. 相似文献
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The evolutionary divergence of five closely related populations of the yellow monkey flower. Mimulus guttatus was compared with the length of time the populations could have occupied the site and with the ability of the populations to intercross. Populations from the younger sites were found to be morphologically intermediate to populations from the older sites. Ability to intercross was not correlated with morphological divergence at this stage of evolution. 相似文献
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Systematic determination of genetic network architecture. 总被引:39,自引:0,他引:39
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Trace element analyses of flint show statistically valid differences between products of major British and European Neolithic flint mines. 相似文献
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Plasmids of the same Inc groups in Enterobacteria before and after the medical use of antibiotics 总被引:8,自引:0,他引:8
Conjugative plasmids were common in enterobacteria isolated before the medical use of antibiotics. Plasmid F of Escherichia coli K-12 was one example and we identified others in over 20% of a collection of strains isolated between 1917 and 1954, the Murray collection. In the past 25 years, conjugative plasmids encoding antibiotic resistances have become common in bacteria of the same genera as those of the Murray Collection--Salmonella, Shigella, Klebsiella, Proteus, Escherichia. The present study was made to show whether the 'pre-antibiotic' plasmids belonged to the same groups, as defined by incompatibility tests (Inc groups), as modern R plasmids. Of 84 such plasmids established in E. coli K-12, none with antibiotic resistance determinants, 65 belonged to the same groups as present resistance (R) plasmids. Thus the remarkable way in which medically important bacteria have acquired antibiotic resistance in the past 25 years seems to have been by the insertion of new genes into existing plasmids rather than by the spread of previously rare plasmids. 相似文献
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Summary A histochemical study has been made of the main cranial muscles which produce ventilation movements of the rainbow trout. It is shown that a greater proportion of red(aerobic) fibres is present in those muscles known to be active during shallow ventilation than those which become active at greater ventilation volumes. An ordered recruitment of red, pink and white fibres within these muscles is also likely.This work was carried out when I.A. Johnston was holding an NERC Post-Doctoral Research Fellowship (1973–75). 相似文献
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F. C. Copp G. G. Coker A. F. Green R. Hughes R. H. Nimmo-Smith 《Cellular and molecular life sciences : CMLS》1972,28(1):47-48
Résumé Le chlorure de 1,1-octaméthylène et le méthylsulfate de 5,5-octaméthylènebis ont chez le chat un effet de blocage neuro-musculaire non dépolarisant, de courte durée. Les comparaisons faites avec des analogues voisins suggèrent que l'activité de ces composés est influencée par le degré d'empêchement stérique autour des atomes d'azote quaternaire. Les composés inhibent les acétylcholinestérases et s'opposent à des degrés divers aux effects muscariniques de l'acétylcholine. 相似文献