关于精原细胞的描述,哪项错误?() ["是精子发生的干细胞","部分精原细胞分化成初级精母细胞","能不断分裂产生精子","是以减数分裂进行增殖的,故染色体为单倍体","位于生精小管的基膜上"]
分封制是西周政权的基本体制形式。
下列哪些为肝炎病毒的中和抗体。() ["A、抗-HBs","B、抗-HAV","C、抗-HDV","D、抗-HCV","E、抗-HEV"]
睾丸的主要功能是?() ["产生精子","产生精子和分泌雄性激素","分泌雄激素结合蛋白","分泌雌激素","形成精液"]
抽放管路安装应平直,转弯时角度不应大于()。 ["A、65","B、60","C、55","D、50","E、45"]
如何减少培养基灵敏度下降引起的误差?