下列哪一个不是电喷雾离子化方式的优点?()
A.可以产生[M+nH]n+或[M-nH]n-
B.可以分析非极性化合物
C.化学噪音低
D.容易获得碎片离子信息
参考答案:B
The little girl has been in a poor _____ of health since she was born, which has made her parents very worried.
A.position
B.situation
C.state
D.condition
日光性角化病的主要临床特点是()。
A.好发于皱褶部位
B.皮疹表现为不规则皮色肥厚性斑块
C.皮疹表面易破溃
D.多伴有明显的疼痛和瘙痒
E.若不治疗约20%的患者皮损可发展为鳞癌