共查询到20条相似文献,搜索用时 0 毫秒
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C Theisen N Khadiri JP Vivien I Ragnarsson CW Beausang FA Beck G Belier T Byrski D Curien de France G D Disdier G Duchêne C Finck S Flibotte B Gall B Haas H Hanine B Herskind B Kharraja JC Merdinger A Nourreddine BM Nyakó GE Perez D Prévost O Stezowski V Rauch C Rigollet H Savajols J Sharpey-Schafer PJ Twin L Wei K Zuber 《Canadian Metallurgical Quarterly》1996,54(6):2910-2915
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Energy transfer in LaOBr:Tb_(0.0075),Gd_x(x<0.30)was investigated via excitation spectra,emissionspectra,fluorescence decay function and X-ray diffraction.Effective energy transfer from Gd to Tb was found.With excitation of λ=275nm,no Gd~(3+)but only Tb~(3+)emission has been observed,and the integrated intensityof Tb~(3+)emission increases with increasing Gd content up to~5.5 times(in the sample of x=0.30)compared tothat of the sample without Gd.The existense of Gd in the sample slows down the Tb~(3+)flourescence decay,andmost likely the electric dipole-dipole interaction dominates the energy transfer process. 相似文献
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降低高纯金属铽中非稀土杂质的探索 总被引:1,自引:1,他引:0
在传统工艺的基础上,通过采取一系列辅助性措施,可将稀土金属铽(Tb)中的非稀土杂质含量,降到比国家稀土行业标准中最纯品牌金属铽的杂质含量指标更低的水平,以适应国内外市场用户的需要 相似文献
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P Fallon CW Beausang S Asztalos D Nisius RV Janssens M Bergstrom M Carpenter B Cederwall S Clarke B Crowell MA Deleplanque RM Diamond RG Henry TL Khoo T Lauritsen IY Lee AO Macchiavelli FS Stephens PJ Twin 《Canadian Metallurgical Quarterly》1995,52(1):93-98
To determine which of two treatments for reducing ischemic injury after temporal focal ischemia is more effective, the effects of mild (33 degrees C) intraischemic hypothermia were compared with those of mannitol, the most commonly used neuroprotective agent. Four groups of Sprague-Dawley rats underwent 1 hour of endovascular middle cerebral artery occlusion followed by 23 hours of normothermic reperfusion. The four experimental groups were as follows: Group A, saline control; Group B, mannitol (25%, 1 g/kg); Group C, hypothermia; and Group D, hypothermia plus man-nitol. Laser-Doppler estimates of cortical blood flow showed that hypothermia did not affect blood flow during ischemia or reperfusion. Mannitol increased cortical blood flow during ischemia and reperfusion under both normothermic and hypothermic conditions (p < 0.05). Neurological deficit was significantly less severe in treated rats (Group B, p < 0.05; Group C or D, p < 0.01) than in controls (Group A). Infarct volume, measured on semiserial Nissl-stained sections, was significantly smaller in treated rats (p < 0.01) than in controls. Infarct volume was also significantly smaller in rats treated with hypothermia than in those treated with mannitol (Group C vs. Group B, p < 0.05); there was no difference between rats treated with mannitol and those treated with mannitol and hypothermia. All three treatments reduced infarct area in the ischemic penumbra; hypothermia with or without mannitol also reduced infarct area in the ischemic core. These results demonstrate that both mild intraischemic hypothermia and mannitol reduce infarct size and neurological deficit: hypothermia reduces infarct size more effectively than mannitol, and mannitol adds no significant protection to hypothermia, whereas hypothermia adds significant protection beyond that afforded by mannitol after brief focal ischemia followed by reperfusion in rats. The results suggest that mild intraischemic hypothermia alone, or in combination with mannitol, may be useful in avoiding ischemic injury from temporary vessel occlusion during cerebrovascular surgery. 相似文献
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Human erythrocyte band 3 was purified essentially free of peripheral proteins, in particular band 4.2, using affinity chromatography. Band 3 protein was then reconstituted into liposomes of lipid type and ratio approximating that of erythrocyte membranes. Stilbenedisulfonate inhibition of band 3 mediated efflux of radiolabeled sulfate from preloaded liposomes was used to test the functionality and correct orientation of the protein. When sulfate efflux, mediated by purified band 3, was compared with partially purified band 3, which contained detectable amounts of bands 4.1 and 4.2, a clear difference in efflux was measured. Sulfate efflux was approximately 30% faster from liposomes containing purified band 3 compared with those containing partially purified protein. In order to investigate further any specific effect of band 4.2 protein on band 3 mediated anion transport, band 4.2 was purified. Increasing amounts of band 4.2 were complexed with purified band 3 and then reconstituted into liposomes. Increasing amounts of band 4.2 complexed with band 3 caused a decrease in band 3 mediated anion transport. The effect of band 4.2 on band 3 mediated anion transport appears to be specific since increasing concentrations of band 4.2 added exogenously to band 3 in reconstituted vesicles (rather than complexed with band 3 before reconstitution) produced no significant changes in sulfate efflux. Further, when increasing amounts of band 4.2 were added to the functionally active transmembrane domain of band 3 and then reconstituted into vesicles, there was also no significant change in sulfate efflux.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献