直肠肛管周围间隙不包括() ["坐骨直肠间隙","骨盆直肠间隙","直肠后间隙","肛管间隙"]
以下叙述正确的是() ["直肠瓣有阻止粪便的作用","齿线以下静脉回流至门静脉","直肠内括约肌为随意肌","肛门直肠周围间隙抗感染能力强"]
男,30岁,饱餐后劳动时,突然腹部剧烈绞痛,阵发性加重,伴呕吐。6h未排气、排便。查体:体温37℃,脉率84次/分,左腹部膨隆,压痛明显,肠鸣音高亢,移动性浊音阴性。最可能的诊断为() ["肠梗阻.","肠道蛔虫病","急性胰腺炎","溃疡病穿孔"]
下列哪项不是绞窄性肠梗阻的临床表现() ["便隐血阳性","腹痛剧烈而持续","腹部有固定压痛和腹膜刺激征","呕吐呈反射性,吐出物为食物或胃液"]
诊断绞窄性肠梗阻最可靠的依据是() ["阵发性腹部绞痛","有气过水音和金属音","X线检查小肠有多个阶梯状液平","腹肌紧张,有压痛和反跳痛"]
共价键的本质是什么?可用哪些物理量来描述?