在进行选择育种时,群体遗传变异越大,则所能获得的遗传进展()。 ["越大","无关","越小","无法判断"]
患者,男,48岁。因患肝硬化5年,近1年来明显腹胀,尿少,食欲下降,下肢水肿来院。查体:一般情况差,腹膨隆,可见腹壁静脉曲张,移动性浊音阳性。该患者还可能出现的体征是() ["振水音阳性","剑突下可闻静脉“营营”音","肝浊音界消失","肠鸣音亢进","肠鸣音减弱"]
最早真核生物出现的时间是() ["30亿年前","25亿年前","20亿年前","15亿年前"]
长期应用盐皮质激素常发生() ["高钾血症","高钙血症","低钾血症","低钙血症","高镁血症"]
最早原核生物出现的时间是() ["45亿年前","40亿年前","35亿年前","30亿年前"]
溶剂浸出法