目的：通过弱化筛选基因二氢叶酸还原酶基因（dhfr），构建双顺反子全抗体表达载体，实现全抗体在CHO细胞中的高效表达。方法：将dhfr基因分为......

“逆经痛”是《古方汇精》中记载的中医病名。特点为婚后患痛经，并发不孕，其病因病机为经前及经期同房，震动血海，损伤冲任，导致瘀滞凝结......

Older adults often find it difficult to perceive speech,especially in noisy conditions.Though hearing aid is one of the ......