Presently two preparations of meningococcal vaccines are registered in hong kong - the bivalent serogroups a c and the quadrivalent serogroups a , c , y w135 二价疫苗可以预防a型和c型脑膜炎双球菌，四价疫苗则可以预防a c w135和y型脑膜炎双球菌。
2.
In chapter 5 , based on the measured refractive index distribution curve , according as the theoretical model of light transmission in the grin medium , using quadrivalent runger - kutta method to carry out the light tracking , we studied retro - reflection of grin polymer micro - sphere and its application and concluded the best conditions to get good results . in chapter 6 we analyzed the two ways to improve the retro - reflection effect of grin polymer micro - sphere using the light tracking and discuss the pleasant results we got 第五章从上一章测量所得折射率分布曲线出发，根据梯度介质球内光线传输的理论模型，用光线追迹的方法分析了327 #微球透镜的反光性能，并对最佳性能条件进行了总结分析，发现效果提高并不明显，进而在第六章中提出了提高grin聚合物微球回归反射性能的两个基本途径，并用光线追迹方法进行了详细的分析，最终得到了良好的效果，并对结果进行了一定的分析解释。
3.
Locally , the incidence of meningococcal infections is low and about half of the meningococcal infections were caused by neisseria meningitidis serogroup b . the quadrivalent meningococcal vaccine does not confer protection against meningococcal infections caused by serogroup b , its duration of protection is short and it is relatively ineffective in children aged under 2 本港每年的脑膜炎双球菌感染病例中，约一半为b型的双球菌所引致。由于脑膜炎双球菌感染在本港并不常见，加上四价疫苗对b型的双球菌没有效用有效期间较短及对两岁以下儿童的效果较低，故此疫苗并不在本港免疫注射计划采用之列。
4.
Chapter 5 . based on the measured refractive index distribution curve , according as the theoretical model of light transmission in the grin medium , using quadrivalent runger - kutta method to carry out the light tracking , by this means the mainly imaging character index of the micro - lens such as foci , longitudinal and transverse spherical aberrations aberration etc is calculated . i 第五章从测量所得折射率分布曲线出发，根据梯度介质球内光线传输的理论模型，用四阶runger - kutta方法进行光线追迹，计算了此种梯度球的纵横向球差等光学特性，给出所制作梯度折射率微球透镜成像性能的评价。
