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Transient local anoxia of the cochlea was induced by pressing the labyrinthine artery, and compound action potential (CAP) or endocochlear potential (EP) was measured before and after transient local anoxia ranging from 5 to 60 min using 106 albino guinea pigs. The complete interruption of the cochlear blood flow by this procedure and its full restoration after releasing the pressure on the artery was confirmed by a laser-Doppler flowmeter. The anoxia of less than 10 min induced no post-anoxic cochlear dysfunction, whereas the anoxia of a longer duration induced an irreversible dysfunction of the cochlea. It was evident that the post-anoxic recovery of the CAP threshold was worse as the anoxia period was prolonged, and CAP was almost completely abolished after 60-min anoxia. In animals which were administered mannitol intravenously just after the restoration of the cochlear blood circulation, the recovery of the CAP threshold was significantly better than that in the control animals, when the animals were subjected to local anoxia of 15- to 30-min duration. No beneficial effect, however, was observed in the 60-min anoxia group. In conclusion, local anoxia of 10 min or longer caused cochlear dysfunction, which was partially but significantly alleviated by mannitol. 相似文献
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胡侃蔚 《上海冶金高等专科学校学报》1999,(2)
基于误差理论在实验曲线上进行误差计算的方法,并对通过合理操作提高精度的措施进行论述。实验表明:该方法和措施的有效性在实验测试中得到证实。 相似文献
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Interface- and diffusion-limited capillary rise of reactive melts with a transient contact angle 总被引:1,自引:0,他引:1
Rajiv Asthana 《Metallurgical and Materials Transactions A》2002,33(7):2119-2128
The kinetics of unidirectional capillary penetration by a reactive fluid under the limiting cases of diffusion control and
interface control has been derived for the reactive infiltration phenomenon characterized by a shrinking capillary radius
due to interphase formation and an exponentially decaying contact angle. The computational outcomes for the reactive penetration
of Si3N4 capillaries by AgCuTi brazes and of carbon capillaries by Si show that greater lengths are attained at lower values of the
parabolic rate constant (under diffusion control), and the limiting length is reached earlier at larger values of the linear
rate constant (under interface control). A capillary-driven flow analysis (Washburn equation) overestimates the infiltration
kinetics, whereas an analysis that considers pore shrinkage but assumes the contact angle and the capillary pressure to be
constant during flow underestimates the kinetics. The penetration lengths predicted by the analysis at pore closure due to
reaction choking exhibit a slightly better agreement with the recent measurements in the Si/C system than the models of reactive
flows currently in vogue. 相似文献
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