Differential diagnosis of gallbladder bulging lesions by gray - scale sonography and color dopper flow imaging 二维超声与彩色多普勒血流显像对胆囊隆起性病变的鉴别诊断
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In chapter 3 , we studied the effect of gaussian transverse profile for the driving and laser fields on lasing without population inversion ( lwi ) in a closed v - type system and an open v - type system . moreover , we discussed also the effect of the unsaturated gain coefficient , the cavity - damping rate , the ratio of the atomic injection rates and atomic exit rate on the corresponding systems . in chapter 4 , we mainly discussed the effect of doppler broadening on the gain , dispersion and the frequency up - conversion of the open v - type lwi system and compared the differences and the same between the open system and the corresponding closed system 发现： ( 1 )在考虑doppler展宽的情况下，通过选取合适的实验室条件(比如合适的原子环境温度等)可得到合适doppler展宽值，从而使系统获得最佳增益； ( 2 )要想实现系统的频率上转换，同时又要获得足够强的无反转激光增益，则系统频率转换比不能选取的太大； ( 3 )对于开放系统，比较小的粒子注入速率比与退出速率对产生无反转激光是有利硕士学位论文摘要的： （ 4 ）由于dopp1oy展宽的存在，当探测场与驱动场的传播方向相反时，增益在探测场失谐的某一段区域产生振荡，且振荡的振幅、频率失谐范围的大小与dopper展宽的取值有关。
