问题 问答题 简答题

什么叫梯度磁场?

答案

参考答案:

在某一方向上磁场强度随时间按一种趋势变化的磁场,在MRI中,可用这种磁场进行选择激励,从而达到选择层面之目的。同样也可用于对信号进行空间位置编码,以建立图像。

单项选择题

Since we are social beings, the quality of our lives depends in large measure on our interpersonal relationships. One strength of the human condition is our tendency to give and receive support from one another under stressful circumstances. Social support consists of the exchange of resources among people based on their interpersonal ties.

Those of us with p support systems appear better able to cope with major life changes and daily hassles (困难). People with p social ties live longer and have better health than those without such ties. Studies over a range of illnesses, from depression to heart disease, reveal that the presence of social support helps people fend off (挡开) illness, and the absence of such support makes poor health more likely.

Social support cushions stress in a number of ways. First, friends, relatives, and co-workers may let us know that they value us. Our self-respect is strengthened when we feel accepted by others despite our faults and difficulties. Second, other people often provide us with informational support. They help us to define and understand our problems and find solutions to them. Third, we typically find social companionship supportive. Engaging in leisure-time activities with others helps us to meet our social needs while at the same time distracting (转移……注意力) us from our worries and troubles. Finally, other people may give us instrumental support—financial aid, material resources, and needed services—that reduces stress by helping us resolve and cope with our problems.

Interpersonal relationships are important because ().

A. they are indispensable to people’s social well-being

B. they waken people’s desire to exchange resources

C. they help people to cope with life in the information era

D. they can cure a range of illnesses such as heart disease, etc.

单项选择题