问题 单项选择题

适用于具有挥发性的、能随水蒸气蒸馏而不被破坏,且难溶或不溶于水的成分的提取方法是()。

A.浸渍法

B.渗漉法

C.煎煮法

D.回流提取法

E.水蒸气蒸馏法

答案

参考答案:E

解析:本题考查要点是"溶剂提取法的适用范围及特点"。①煎煮法是中药材加入水浸泡后加热煮沸,将有效成分提取出来的方法。此法简便,但含挥发性成分或有效成分遇热易分解的中药材不宜用此法。②水蒸气蒸馏法适用于具有挥发性的、能随水蒸气蒸馏而不被破坏,且难溶或不溶于水的化学成分的提取。此类化合物的沸点多在100℃以上,并在100℃左右有一定的蒸气压。③浸渍法是在常温或温热(60℃~80℃)条件下用适当的溶剂浸渍药材以溶出其中成分的方法。本法适用于有效成分遇热不稳定或含大量淀粉、树胶、果胶、黏液质的中药的提取。但本法出膏率低,需要特别注意的是,当水为溶剂时,其提取液易于发霉变质,需注意加入适当的防腐剂。

单项选择题 B型题
单项选择题

Young girls at high risk for depression appear to have a malfunctioning reward system in their brains, a new study suggests. The finding comes from research that (1) a high-risk group of 13 girls, aged 10 to 14, who were not depressed but had mothers who (2) recurrent depression and a low-risk group of 13 girls with no (3) or family history of depression. Both groups were given MRI brain (4) while completing a task that could (5) either reward or punishment.

(6) with girls in the low-risk group, those in the high-risk group had (7) neural responses during both anticipation and receipt of the reward. (8) , the high-risk girls showed no (9) in an area of the brain called the dorsal anterior cingulated cortex (背侧前扣带皮质), believed to play a role in (10) past experiences to assist learning.

The high-risk girls did have greater activation of this brain area (11) receiving punishment, compared with the other girls. The researchers said that this suggests that high-risk girls have easier time (12) information about loss and punishment than information about reward and pleasure.

"Considered together with reduced activation in the striatal (纹状体的) areas commonly observed (13) reward, it seems that the reward-processing system is critically (14) in daughters who are at elevated risk for depression, (15) they have not yet experienced a depressive (16) ," wrote Ian H. Gotlib, of Stanford University, and his colleagues. " (17) , longitudinal studies are needed to determine whether the anomalous activations (18) in this study during the processing of (19) and losses are associated with the (20) onset of depression," they concluded. The study was published in the April of the Archives of General Psychiatry.

1()

A.embodied

B.included

C.concluded

D.consisted