用PCVD法制备掺F低OH根多模梯度光纤的研究

本文叙述在PCVD法中首次应用CCl2F2作氟源,制备低OH-低损耗多模梯度光纤的研究结果。在连续制备的42km光纤中最低衰减系数已达到2.3dB/km（0.85μm）,0.41dB/km（1.3μm）和0.21dB/km（1.55μm）,在1.39μm处OH根附加衰减系数最低已接近1dB/km

Kinetic Study on the Thermal Denaturation of Rice Mitochondrial DNA

The thermal denaturation of the rice mitochondrial DNA in diFFerent solutions have been studied by using ultraviolet absorption spectrometry at 50 ℃, and their kinetic behaviour of the thermal denaturation has been discussed.The kinetic curves of the thermal denaturation of rice mitochondrial DNA in diFFerent solutions have been obtained, and the kinetic parameters and models have been calculated and established respectively.国家自然科学基

门静脉动脉化加门腔分流对肝硬化大鼠肝功能的影响

【目的】 探讨入肝门静脉动脉化加门腔分流术对肝硬化大鼠肝功能的影响.【方法】 125只肝硬化大鼠随机分为A组(n=50),入肝门静脉完全动脉化+门腔分流;B组(n=50),仅行门腔完全分流;C组(n=25),门静脉阻断30 min+右肾切除,分别检测各组大鼠术前、术后1、2、4及8周血清谷丙转氨酶(ALT)、谷草转氨酶(AST)、总胆红素(TB)、白蛋白(ALB)及吲哚氰氯15 min潴留率(ICGR15).【结果】 术前各组大鼠血清谷丙转氨酶(ALT)、谷草转氨酶(AST)、总胆红素(TB)、白蛋白(ALB)及ICGR15无明显差异(P>0.05);术后随着时间推移 ,A组大鼠的ALT、TB、AST及ICGR15较B、C两组均有明显降低,差异有明显统计学意义(AST:P<0.05,其他指标P<0.01),并于术后2周后,可达到稳态;而A组 ALB 术后较B、C两组明显升高,差异也有显著统计学意义(P<0.01),并于术后4周可达到稳态.【结论】 入肝门静脉动脉化重建入肝血流能明显促进肝硬化大鼠肝功能恢复,有助预防门腔分流术后肝功能衰竭

A study on accommodation mechanism with numerical simulation

目的:建立人眼晶状体的功能仿真模型,研究人眼的调节机制。方法:利用临床获得的数据,在计算机上建立晶状体调节的数字仿真模型,根据调节理论进行晶状体形变和调节仿真,并分析眼压对晶状体形变的影响。结果:仿真计算表明,随着调节的增加,前、后表面向远离晶状体中心的方向移动,晶状体厚度增大,前房深度减小;晶状体的前、后表面曲率半径增加,使得屈光力增大。晶状体形态对压力变化敏感:在晶状体表面施加压力后,前、后表面在压力的作用下向赤道部移动,晶状体厚度减小;前后表面曲率半径增大,赤道半径增大;屈光力随着压力的增大而增大。结论:仿真研究支持了 H elmholtz 的调节理论,与公认的调节事实相符合,表明了仿真研究是有效的研究方法。AIM: Accommodation is one of the most important functions of human eye, while its mechanism is still under discussion. This paper aimed to study accommodation mechanism with numerical simulation. · METHODS: A simulation model was constructed to study the mechanism of accommodation based on the experimental data derived from published resources. The displacement and pressure are applied on the model to study the deformation of lens during accommodating. · RESULTS: The simulation showed that, as the eye was accommodating, the thickness of the lens increased linearly, and the lens diameter decreased linearly. The optical power of the lens increased as the accommodation increased. This result was accord with the public facts in accommodation. Furthermore, the pressure was found to have a great influence on the shape of the lens and the optical power. The lens became thinner and flatter as the pressure increased and the pressure caused a remarkable increase of lens' optical power. · CONCLUSION: The outcome of this paper is consistent with the Helmholtz's hypothesis on accommodation to some extent. The analytical model presented in this paper can be used in the theoretical study of the accommodation mechanism of the human lens. ·中国国家自然科学基金资助项目(N o.60371012);; 中国福建省科技重点项目资助(N o.2002Y021)~