filtermask过滤式防毒面具filtern.过滤器；滤色镜；滤光器v.过滤；渗透filtering pot without valve无阀滤池filtering based on database数据库过滤filter difference technique滤光器差值法filtering back-projection滤波反投影filterable hemolytic anemia滤过性溶血性贫血filtering in Doppler domain多普勒域滤波filter discrimination ratio滤波器分辨率filtering means dehydration过滤脱水filtering conjunctival bleb结膜滤过性水泡filter commutated converter滤波换相换流器