问题 问答题 简答题

短暂性脑缺血发作(TIA)概述

答案

参考答案:

1.概念

TIA是指一过性脑缺血所致的神经系统局限性功能障碍,为一种常见的急性脑血管病。临床表现与缺血发作部位有关,可区分为颈动脉系统和椎-基底动脉系统TIA。每次发作持续数分钟至数小时,通常不超过24小时即完全恢复,但常有反复发作。

2.病因

包括微栓塞、脑血管痉挛、高凝状态、颈椎病所致的颈部血管受压、低血压及心律失常所致的血流动力学改变等。约1/3的TIA患者以后发生脑梗死,因此积极预防和治疗TIA在临床上具有重要意义。

3.临床表现

好发于50~70岁,男多于女。发作突然,历时短暂,每次发作持续数秒至24小时,通常为5~20分钟。症状完全消失,一般不留神经功能缺损。常反复发作,每次发作出现的局灶症状符合一定血管供应区的脑功能障碍。

单项选择题
填空题

Part 3


Questions 19-25


·Read the following passage and choose the correct answer from A, B, C and D.
More and more, the operation of our businesses, government, and financial institutions are controlled by information that exists only inside computer memories. Anyone clever enough to modify this information for his own purpose can reap substantial rewards. Even worse, a number of people who have done this and been caught by it have managed to get away without punishment.
It is easy for computers crime to go undetected if no one checks up what the computer is doing. But even if the crime is detected, the criminal may walk away not only unpunished but with a growing recommendation from his former employers.
Of course, we have no statistics on crimes that go undetected. But it is disturbing to note how many of the crimes we do know about were detected by accident, not by systematic inspections or other security procedures. The computer criminals who have been caught may have been the victims of uncommon bad luck.
For example, a certain keypunch operator complained of having to stay overtime to punch extra cards. Investigating revealed that the extra cards she was being asked were for dishonest transactions. In another case, dissatisfied employees of the thief tipped off the company that has been robbed.
Unlike other lawbreakers, who must leave the country, commit suicide or go to jail, computer criminals sometimes escape punishment, demanding or not only that they not be charged but that they be given good recommendations and perhaps other benefiting, their demands have been met.
Why Because company executives are afraid of the bad publicity that would result if the public found out that their computer had been misused. They hesitate at the thought of a criminal boasting in open court of how he juggled the most confidential records right under the noses of the company’s executives, accountants, and security staff. And so another staff computer criminal departs with just the recommendation he needs to continue his crime elsewhere.

In which case it’s easy for computer crimes to go undetected

A.Somebody checks up what the computer is doing.

B.No one checks up what the computer is doing.

C.No way.

D.The passage didn’t refer.