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