用硅胶分离和检识生物碱时常出现拖尾或形成复斑、或R值过小，影_爱下问搜题

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问题多项选择题

用硅胶分离和检识生物碱时常出现拖尾或形成复斑、或R值过小，影响检识效果，为避免这种情况，常采取措施（）

A.涂铺硅胶薄层板时加入适量的稀碱液或碱性缓冲液

B.涂铺硅胶薄层板时加入适量的稀酸液或酸性缓冲液

C.在展开槽中加一盛有氨水的小杯，用中性展开剂在氨蒸气中进行展开

D.在展开剂中加入适量的碱性试剂如二乙胺、氨水等

E.在展开剂中加入适量的酸性试剂如甲酸、乙酸等

答案

参考答案：A, C, D

解析：本题考查了生物碱薄层色谱法的吸附剂选择。用硅胶分离和检识生物碱时常出现拖尾或形成复斑、或R值过小，影响检识效果，为避免这种情况，常采取①在涂铺硅胶薄层板时用稀碱溶液（0.1-1.5N的氢氧化钠溶液）或缓冲溶液制成碱性硅胶薄板；②使色谱过程在碱性条件下进行，即在展开剂中加入少量碱性试剂，如二乙胺、氨水等；③在展开槽中放一盛有氨水的小杯，用中性展开剂在氨蒸气中进行展开。故答案选ACD。

完形填空

Long ago there was a poor farmer in Russia. He had been very 1 with everything he had. However, when he found his elder brother was 2 than him, he felt disappointed. So he 3 hard about how he could also be richer. Finally he got an idea. He started to spend less money on food and clothes to 4 some money to buy more land. Once he had enough money, he started 5 for land.
He 6 that on the neighboring land, there were some nomads (游牧民) living there. He bought some gifts and went to 7 their head. He presented the gifts to the head and told him the 8 of his visit. The head welcomed him, accepted the gifts and agreed to his 9 to get the land. The head told him that he could have the land 10 giving him anything. He can take as much land as he could 11 by walking through the land before sunset (日落). He should start in the morning and whatever distance he could travel during the 12 , he could have it.
The farmer became very 13 when he heard this offer. Now he could have lots of 14 without paying anything. He came 15 the next morning and started running, not walking, 16 he could cover the largest area. To reach his goal, he neither ate food, nor drank water, nor had any rest. He just continued 17 . Without eating, or drinking, or resting he just got very 18 . When he came back to the head in the evening, he 19 right on the spot. Sadly his son buried him in a piece of land about 6 x 4 feet.
Don’t be greedy (贪婪的) or you will 20 everything finally.

单项选择题 A1型题

不符合急性心肌梗死胸痛特点的是（）

A.在体力活动或情绪激动当时发作，休息数分钟可缓解

B.胸痛比心绞痛更严重

C.持续时间长，含硝酸甘油不缓解

D.可伴休克

E.可伴心力衰竭或心律失常