Universal Product Code
What are the zebra stripes (See the figure) on the Instant Mashed Patato Flakes package? They are special black and white vertical lines. These black and white stripes can be read by an optical scanner, or computer. The "scanner", which reads the lines of code, is a small laser beam of light. When the light rays is broken by the black stripes, the computer "reads" the information about the product.
This code is called the Universal Product Code (UPC). It is designed to add speed and efficiency to stores by using computers. It can do this in several ways. First, it is not necessary for workers to put individual prices on items. By using UPC, the computer can print out the accurate price of the item. Errors in prices are eliminated, or done away with. Also, the time spent checking out is reduced UPC gives an itemized receipt to the customer with all the items, prices, and totals. The store clerk does not need to spend time checking the price on the item and punching it into the cash register. This UPC computerized system will probably save as much as 45 percent of the checkout clerk's time.
What do the stripes mean? How does the computer interpret the stripes? The number printed below the vertical bars identifies the manufacturer and the manufacturer's item. As many as 10 trillion individual machine-readable numbers can be used with this system. In the example, the 0 on the left side means that it is a grocery item. The numbers 36800 indicate the manufacturer, in this case it is the Food Club Company. The last five digits, 51512, mean it is a pack of mashed patato flakes. The light rays from the light beam read these lines, and the message is sent directly to the computer. The computer then finds the information about this product (price, inventory data) and sends it instantly back to the terminal at the checkout counter. At the same time, it keeps an inventory for the store manager. Many products have labels with these stripes.
The figures printed below the stripes are codes of the producer and the product.
A.right
B.wrong
C.Doesn't say
第2题
“脑血管的自身调节”是指有动脉血压下降到低于正常值的多少时,脑血流才出现较明显减少
A、10%
B、20%
C、50%
D、70%
E、80%
第3题
“脑血管的自身调节”是指只有动脉血压下降到低于正常值的多少时,脑血流才出现较明显减少
A、10%
B、20%
C、50%
D、70%
E、80%
第4题
A.慢性高血压
B. 正常患者平均动脉压在60~140mmHg的范围内变化
C. PaCO2升高
D. PaO2降低
E. 脑组织酸中毒
第5题
麻醉期间高二氧化碳血症对脑血流和颅内压的影响,错误的是
A、脑血管显著扩张
B、脑血管的自身调节作用增强
C、脑血流量相应增加
D、颅内压增加
E、易产生脑水肿
第9题
脑血流自身调节功能是指下列哪一指标在一定范围内波动,脑血流保持相对恒定
A、心率
B、呼吸频率
C、颅内压
D、颅脑灌注压
E、动脉二氧化碳分压
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