DSA(digital subtraction angiography)

[单选题]关于DSA成像的基本原理，哪项描述不正确A．数字荧光成像(digital fluorography，DF)是DSA的基础B．需将影像增强电视系统(image intensify television)图像像素化C．经A/D转换器，将像素转换为数字，即数字化D．经计算机减影处理E．图像进行模拟减影

[单选题]is a device which enables digital microcomputers to communicate across analog telephone lines.A．The switchB．The modemC．The hubD．The repeater

[单选题]Modern handheld digital tachometers operated by counting light pulses returned to the unit byA．the tach generatorB．either the coupling or shaftC．a small bulb attached to the shaftD．a piece of reflective tape

[名词解释] digital signature数字签名

[单选题]DSL（DIGITAL SUBSCRIBER LINE）是指（）。A .模拟用户线路技术B .数据用户线路技术C .图像用户线路技术D .数字用户线路技术

[单选题]E．-checks require digital______and authentication services to digitally process information between the payer payee,and bank．A．signaturesB．messageC．documentD．encrypt

[单选题]A．lmost all（ ）have built-in digital cameras capable of taking images and video.A．scannersB．smart phonesC．computersD．printers

[单选题]I needed to buy a digital camera, one that was simply good at taking good snaps (快照), maybe occasionally for magazines. Being the cautious type, I fancied a reliable brand. So I went on the net, spent 15 minutes reading product reviews on good websit

[填空题] ADSL技术，即Asymmetric Digital Subscriber Line，中文名称为（），ADSL为充分利用频谱，ADSL一般采用（）调制技术。，提供宽带接入，上行速率可达到1Mbit/s，下行速率可达到（）bit/s。

[名词解释] 英译中：Integrated service digital network