清华大学：《文献检索》课程教学资源（PPT课件）2、计算机信息检索

计算机信息检索 computerized Information Retrieval 工程硕士) 2005.3

计算机信息检索 Computerized Information Retrieval （工程硕士） 2005.3

信息检索词汇( terms) Information retrieval (R) Information access(obtain) Information search (look for) Information searching (look for) Information seeking (focus on users, active) locate hit

2 信息检索词汇（terms） Information retrieval (IR) Information access (obtain) Information search (look for) Information searching (look for) Information seeking (focus on users, active) locate hit

1.信息检索发展阶段 ●手工操作( manua 计算机化( computerized) ●网络化( networked) ●智能化( intelligentized) ●认知化( cognized) What's searching like? Finding a needle in a haystack?

3 1. 信息检索发展阶段 ● 手工操作 (manual) ● 计算机化 (computerized) ● 网络化 (networked) ● 智能化 (intelligentized) ● 认知化 (cognized) What’s searching like? “Finding a needle in a haystack

2.主要检索系统类型 联机检索( online search 脱机检索( offline search) 光盘检索( CD search) 网络检索( Interne/ Web search) 全球数字图书馆系统( digital g1obal system)

4 2. 主要检索系统类型 • 联机检索(online search) 脱机检索（offline search） • 光盘检索（CD search） • 网络检索（Interne/Web search） 全球数字图书馆系统（digital global system）

2.1联机检索( online search) The process of locating specific pieces of info from one or more databases that reside/ on the computers(hosts). The search is a true interaction between you and search system 主机 据库 微机 WAN 检索终端 通信网络联机检索中心 Feature: interaction. rea time remote, Direct Internet

5 通信网络 联机检索中心 检索终端 数据库 2.1 联机检索(online search) The process of locating specific pieces of info from one or more databases that reside on the computers(hosts). The search is a true interaction between you and search system. 主机 Feature: interaction, real time remote, Direct Internet 微机 WAN

Online databases ● Features A test-bed for early IR experiments& development The showcase of iR technology(e.g, relevance retrieval) until the Internet, the Web became popular A laboratory for acquiring information retrieval skills ● IR capability Covers virtually every type of database structures Implement all different retrieval models and techniques -----Hahn

6 Online databases Features ¨ A test-bed for early IR experiments & development ¨ The showcase of IR technology (e.g, relevance retrieval) until the Internet, the Web became popular ¨ A laboratory for acquiring information retrieval skills IR capability ¨ Covers virtually every type of database structures ¨ Implement all different retrieval models and techniques -----Hahn

OPACS ● Features An extension of marc records A product of library automation A bibliographic database/ of library resources for an institution at various levels, e. g, local, regional national IR capability Easy to browse(resemble shelf structure) Based on well-established hierarchical database structure May provide sophisticated searching capabilities but users may not benefit from them

7 OPACs Features ¨ An extension of MARC records ¨ A product of library automation ¨ A bibliographic database of library resources for an institution at various levels, e.g, local, regional, national IR capability ¨ Easy to browse (resemble shelf structure) ¨ Based on well-established hierarchical database structure ¨ May provide sophisticated searching capabilities but users may not benefit from them

2.2光盘检索( CD search) 光盘单机检索 微机光驱 检索终端

8 光驱 检索终端 微机 2.2 光盘检索(CD search) 光盘单机检索

光盘联机检索( CD online) 微机(局域网)服务器光驱 AN 检索终端 tower jukebox

9 检索终端 局域网 服务器 光驱 微机 LAN tower jukebox 光盘联机检索(CD online)

GD-ROMS ● Features Online databases in CD-ROM medium Portability Cheaper more convenient access until the Web becomes the gateway for cd-rom access Noticeable problem in updating the database Hypertext or hypermedia is heavily used in CD-ROM Becoming an obsolete technology? g IR capabilities Introduce the browsing feature other iR techniques similar to those of online databases Slower in speed 10

10 CD-ROMs Features ¨ Online databases in CD-ROM medium ¨ Portability ¨ Cheaper & more convenient access until the Web becomes the gateway for CD-ROM access ¨ Noticeable problem in updating the database ¨ Hypertext or hypermedia is heavily used in CD-ROM ¨ Becoming an obsolete technology? IR capabilities ¨ Introduce the browsing feature ¨ Other IR techniques similar to those of online databases ¨ Slower in speed