肾盂及肾盏的上皮为()。? ["单层扁平上皮","单层立方上皮","单层柱状上皮","变移上皮","复层扁平上皮"]
振动给煤机的()调的太大,可能会发生停机时自流煤的现象。 ["料槽的倾斜角","振幅","电压","晶闸管导通角"]
日负荷曲线上的某点表示此时刻的()大小。 ["功率","电量","有功","无功"]
工作场所中总尘容许浓度是()mg/m. ["4","6","8"]
在肾皮质内,肾小管周围毛细血管的血液来自()。? ["弓形动脉","出球微动脉","小叶间动脉?","直小动脉","被膜下动脉?"]
生产中常采用哪四种方法形成过饱和溶液而使目标产物结晶?