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261.
262.
Lipoperoxidation and drug-metabolizing enzymes were measured in livers and placentas of different mammal species during the perinatal perios. In placentas and fetal livers of rat, rabbit and guinea-pig, cofactor-supported lipoperoxidation was negligible, as were the activities of drug-oxidizing enzymes. Human fetal liver contained an intact drug-oxidizing electron transport chain, and lipoperoxidation activity was accordingly abserved. It is suggested that lesions mediated by lipoperoxidation may be possible in human fetus, but they are less probable in animal fetuses. 相似文献
263.
Coexistence of A- and B-form DNA in a single crystal lattice 总被引:5,自引:0,他引:5
It is well known that DNA can exist in a variety of conformations which can be interconverted by relatively mild changes in conditions. The in vivo conformation of DNA is usually thought to be the B form, but there is recent evidence that other conformations may be important in DNA-protein recognition. Different fragments of DNA crystallized under virtually identical conditions can form A, B or Z helices. A fragment that adopted an A conformation in a crystal was found in the B conformation in solution, whereas NMR spectroscopy of A-DNA films revealed the presence of a substantial amount of disordered B-DNA. Until now, however, a DNA fragment of a given sequence has not been crystallized in more than one global conformation. We report here an X-ray diffraction study of crystals of the DNA octamer dGGBrUABrUACC. In addition to a 'framework' of A-DNA, which gives discrete X-ray reflections, there are partially disordered B-DNA helices, recognized by their diffuse scattering features. 相似文献
264.
265.
Immunocytochemical localization of GnRH (gonadotropin releasing hormone) systems in the brain of a marine teleost fish,the sole 总被引:2,自引:0,他引:2
J. Nunez Rodriguez O. Kah B. Breton F. Le Menn 《Cellular and molecular life sciences : CMLS》1985,41(12):1574-1576
Summary The GnRH system was studied in the brain of the sole by immunocytochemistry (peroxidase-antiperoxidase method) (PAP) using antibodies to synthetic salmon GnRH (s-GnRH). Two centers containing immunoreactive cell bodies were observed in the forebrain, one located at the junction between the olfactory bulbs and the telencephalon and the other in the preoptic area. Numerous immunoreactive fibers were found, especially in the telencephalon, hypothalamus, pituitary, optic tectum and retina. 相似文献
266.
Zinc-indium-tin oxide (ZITO) films were grown by pulsed-laser deposition.Three different material compositions were investigated:ZITO-30,ZITO-50 and ZITO-70 in which 30%,50% and 70%,respectively,of the... 相似文献
267.
268.
A central problem in human vision is to explain how the visual world remains stable despite the continual displacements of the retinal image produced by rapid saccadic movements of the eyes. Perceived stability has been attributed to 'efferent-copy' signals, representing the saccadic motor commands, that cancel the effects of saccade-related retinal displacements. Here we show, by means of a perceptual illusion, that traditional cancellation theories cannot explain stability. The perceptual illusion was produced by first inducing adaptive changes in saccadic gain (ratio of saccade size to target eccentricity). Following adaptation, subjects experienced an illusory mislocalization in which widely separated targets flashed before and after saccades appeared to be in the same place. The illusion shows that the perceptual system did not take the adaptive changes into account. Perceptual localization is based on signals representing the size of the initially-intended saccade, not the size of the saccade that is ultimately executed. Signals representing intended saccades initiate a visual comparison process used to maintain perceptual stability across saccades and to generate the oculomotor error signals that ensure saccadic accuracy. 相似文献
269.
Summary Preliminary report on the synthesis of vitamin A methyl ether starting from 4-trimethylcyclohexenyl-2-methyl-butenal and 1-methoxy-3-methyl-pentenin. 相似文献
270.
Summary Proteins immunologically related toRhynchosciara americana larval protein 10 occur in the hemolymph and ovaries of five different fly species of the genusRhynchosciara. Electrophoretic analyses showed these proteins to have a mol.wt similar to that of theR. americana protein 10 (43,000), e.g. theR. hollanderi protein 44,300, theR. milleri protein 45,500. 相似文献