40年代诞生的电子计算机技术,50年代就开始用来进行文献检索。目前,世界各地已设有数以万计的终端,可远隔重洋,在几分、十几分钟之内检索到所需要的文献资料,效率之高是手工检索无法比拟的,查全率也比手工检索高得多。我国各情报、图书单位从国外已引进30多种磁带文档,用于定题服务(SDI);另外, The computer technology that was born in the 40s began to be used for literature retrieval in the 1950s. At present, tens of thousands of terminals have been set up all over the world to retrieve the required documents within a few minutes and ten minutes. The high efficiency is unmanned by manual retrieval, Manually retrieve much higher. All intelligence and library units in our country have imported more than 30 kinds of tape documents from abroad for use in the fixed-topic service (SDI). In addition,