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AGNs的铁6.4 Kev K_α线观测及对盘-线模型质疑
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作者 尤峻汉 《紫金山天文台台刊》 北大核心 1999年第3期254-256,共3页
本文简要介绍了AGNs 的铁Kα线的ASCA 观测结果,主要观测特征。这一研究课题的重要意义。以及目前解释观测的主导模型――盘- 线模型的要点。特别指出了盘- 线遇到的基本困难。从而由该模型得到的推断:即AGNs 存在中... 本文简要介绍了AGNs 的铁Kα线的ASCA 观测结果,主要观测特征。这一研究课题的重要意义。以及目前解释观测的主导模型――盘- 线模型的要点。特别指出了盘- 线遇到的基本困难。从而由该模型得到的推断:即AGNs 存在中央大质量黑洞的结论不再可靠。本文的分析也为今后进一步探讨这一重大课题找到一个方向。 展开更多
关键词 活动星系数 铁Kα线 盘-线模型 荧光机制 原子谱线
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Experimental Study on Stress Relaxation and Creep Properties of Human Thoracolumbar Vertebral Bodies and Intervertebral Discs
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作者 HUANG Jian-song HUA Hong-xing +1 位作者 WANG Yi-jin CHEN Yong 《Chinese Journal of Biomedical Engineering(English Edition)》 2009年第4期154-161,共8页
Objective:Underwater shock can produce extremely high accelerations, resulting in severe human injuries on shipboard, and human thoraco lumbar spines are prone to suffer from injuries by ship shock motion. To observe ... Objective:Underwater shock can produce extremely high accelerations, resulting in severe human injuries on shipboard, and human thoraco lumbar spines are prone to suffer from injuries by ship shock motion. To observe the viscoelasticity of thoracolumbar of young fresh cadavers, and to provide biomechanical parameters for both research and clinical practice. Materials and Methods:5 fresh young male cadavers (aged 22 to 31 years) were provided, and 15 thoracolumbar spinal anatomies of 5 samples were harvested within 1 hour of death. WE-10A universal testing machine was used for creep and relaxation tests.Results:Stress relaxation and creep deformation equations are derived from the biomechanics model and the measured and simulated curves are compared. The creep in vertebral bodies and intervertebral discs exhibited significantly changes in the first 5 min and 10 min, respectively. The stress rapidly decreased in the first 2 min, and then gradually went balance during the relaxation process. Conclusion:The change in creep rate is significant at early stage,and gradually slows down.This indicates that the differences between internal pressure and local pressure are decreased until balance. The simulated curve derived from equation coincides with the experimental data to a large degree, which states that the equation is rational and reliable. 展开更多
关键词 spine biomechanics functional spinal unit (FSU) vertebral body intervertebral disc stress relaxation creep deformation spring-dashpot
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