【单选题】
9在12MHz始终脉冲的8051系统里，一个机器周期有多长？___
A. 1µs
B. 12µs
C. 1ms
D. 12ms
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答案
A
解析
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相关试题
【单选题】
24在8×51的程序里，若要将某个输入/输出端口设置成输入功能，应如何处理？___
A. 先输出高电平到该输入/输出端口
B. 先输出低电平到该输入/输出端口
C. 先读取该输入/输出端口的状态
D. 先保存该输入/输出端口的状态
【单选题】
29在Keil µVision3里进行调试/仿真时，在哪里操作才能触动程序中断？___
A. 在Interrupt System
B. 在Cotorl Box对话框里
C. 直接单击魔术棒按钮即可
D. 直接按0键
【单选题】
36在12MHz的8×51系统里，哪一种方式一次可定时5ms？___
A. Mode 0及Mode 1
B. Mode 1及Mode 2
C. Mode 2及Mode 3
D. Mode3及Mode 1
【单选题】
___的一端连在电路中的一点，另一端也同时连在另一点，使每个电阻两端都承受相同的电压，这种联结方式叫电阻的并联。
A. 两个相同电阻
B. 一大一小电阻
C. 几个相同大小的电阻
D. 几个电阻
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【判断题】
(6)Toxicology deals not only with drugs used in therapy but also with many other chemicals that may be responsible for household, environmental, or industrial intoxication.
A. 对
B. 错
【判断题】
1)With the more efficient screening tests and burgeoning knowledge about how a molecules biological activities are likely to be changed, the traditional approach of discovering new drugs has been improved.
A. 对
B. 错
【判断题】
2)With the parallel synthesis used to identify which small segment of any given large protein would bind to an antibody, Mario Geysen generated a variety of short protein fragments by combining multiple amino acids in different permutations.
A. 对
B. 错
【判断题】
)A parallel synthesis and a split-and-mix synthesis are different in that in a split-and-mix synthesis, all the products are assembled separately n their respective reaction vessels.
A. 对
B. 错
【判断题】
4) In many laboratories, robots are used in the routine work of parallel synthesis to deliver small amounts of reactive molecules into appropriate wells, thus making the process more accurate and less tedious.
A. 对
B. 错
【判断题】
5) In a parallel synthesis, each compound remains in its own container; while in a split-and-min synthesis, the related ce mpounds are mixed up in the same reaction vessel.
A. 对
B. 错
【判断题】
6)In order to solve the difficulties of identifying the compounds made in a parallel synthesis scientists pull out from the mixture the beads that bear biologically active molecules and determine the molecular makeup o d attached.
A. 对
B. 错
【判断题】
1)The concentration of a drug in whole plasma is the most accurate index of the drug concentration at the site（s） of action.
A. 对
B. 错
【判断题】
(2)It is difficult to measure the total concentration of both unbound and bound drug in total plasma.
A. 对
B. 错
【判断题】
(3)The clinical effect of a drug is assumed to be directly related to the plasma drug concentration.
A. 对
B. 错
【判断题】
(4) Systemically acting drugs administered by all routes involve the absorption of drug from the place of administration into the blood.
A. 对
B. 错
【判断题】
5)Bioavailability of a drug indicates whether a therapeutically effective concentration is achieved at the site(s)of action of that drug.
A. 对
B. 错
【判断题】
(6)Prodrugs are not therapeutically effective unless they are changed into therapeutically active forms before or after reaching the systemic circulation
A. 对
B. 错
【单选题】
（3）生物圈的范围为___
A. 大气圈、水圈和岩石圈的全部
B. 大气圈和水圈的全部、岩石圈的上部
C. 大气圈的底部、水圈和岩石圈的全部
D. 大气圈的底部、水圈的全部和岩石圈的上部
【单选题】
（8）地球的表面积约为5.1亿平方千米，表面起伏不平，凸出来的地方成为陆地和山脉，而大片大片下凹的部分经过亿万年的积累，被液态海水所淹没而变成了海洋，海洋面积占地球表面积的近___。
A. 2％
B. 51%
C. 71%
D. 91%
【单选题】
（22）由于水的时空分布问题，经常造成我国不少地区的自然灾害。下列灾害的地区分布格局，属于符合我国一般规律的是 ___
A. 北涝南旱
B. 东涝西旱
C. 南涝北涝
D. 西旱东旱
【单选题】
（25）我国正在建设中的“三峡水利枢纽工程”主要是为了解决___
A. 水污染问题
B. 水资源时间分配不均的问题
C. 水资源空间分布不均的问题
D. 水资源总量不足的问题
