骨关节植入物 脊柱损伤基础实验 骨与关节三维有限元分析 腰椎 有限元 生物力学 应力 脊柱 CT 网格 椎间盘 省级基金 bone and joint implants basic experiment of spinal cord injury three-dimensional finite element analysis of bone and joint lumbar spine finite element biomechanics stress spine computed tomography meshing disc provincial grants-supported paper