已知某化合物的化学物质登记号,用CA数据库检索时应选用哪个字段。()
A、CASRN
B、CAN
C、FORMULA
D、CASECTION
参考答案:A
In the modulation style of PSK, if a kind of Modem's modulation rate is 3200baud and it's phase is 8, what is the data transfer rate of this kind of Modem
A.14.4kbps
B.28.8kbps
C.9600bps
D.3200bps
角膜上皮细胞层具有极敏感的()反映。
A.视觉
B.感觉
C.痛觉
D.色觉