Objective To observe the clinical effect of PCEA on expulsive pains.
目的观察pcea用于分娩镇痛的临床效果。
2
The relationship between faults activity stage and hydrocarbon expulsive stage controlled the distribution, forming and destroy of oil and gas accumulation.
断层活动时期与源岩排烃期（油气源）的匹配关系，决定油气的分布层位及油气藏的形成与破坏。
3
A comprehensive MEDLINE (1970-december 2006) search of English literature was performed to identify articles on the medical expulsive therapy of ureteral calculi.