You can access all the transaction codes by using the transaction code 'SDMO'.
This is the transaction code for the Dynamic Menu.
Based on your search string, you can get all related transaction codes for all the SAP application modules.
For e.g. the Search text for ADMIN returns the following results:
---------------------------------------------------------- |Tcode|Transaktionstext | ---------------------------------------------------------- |ADOK |AM: System Administration Guide | |BALE |Area Menu for Administration | |BDMO |ALE CCMS Group Administration | |CATSX|Time Sheet Admin.: Initial Screen | |CICY |CTI Administration | |CJV6 |Maintenance: Version administration | |CN84 |PS: Archiving project - admin. | |COA4 |PP: Archiving order - administration | |CSADM|Content Server Administration | |FC_BW|Administrator Workbench | |FDTA |TemSe/REGUT Data Administration | |FDTT |Treasury Data Medium Administration | |FO86 |Change active admin.contract fees | |FO8E |Create admin.contract event | |FO8F |Change admin.contract event | |FO8G |Display admin.contract event | |FO8H |Admin.costs acct sttlmnt simulation | |FOART|REsearch: Administration Web-User | |HRCMP|Compensation Administration | |HRCMP|Budget Administration: Display | |HRCMP|Budget Administration: Change | |IM_AR|Admin. of App. Request Archives | |KA18 |Archive admin: assess., distr., ... | |KE72 |Archive Administration: Line Items | |KE73 |Archive Administration: Totals Recs | |KPRO |KPRO Administration | |OAAD |ArchiveLink Administration Documents | |OG00 |Personnel Administration Customizing | |OG01 |Personnel Administration Customizing | |OMSM |CS MM Set Up Administrative Data | |OOCM_|Compensation Administration Settings | |OOML |Room Administration Mail Connection | |OOPC |Administration: Personnel No. Check | |OY22 |Create subadministrator Customizing | |OYEA |IDoc administration | |PA97 |Compensation administration - matrix | |PA98 |Compensation Administration | |PA99 |Compensation Admin. - Release Report | |PACA |PF administration | |PAT1 |Personnel Administration infosystem | |PC00_|CBS survey salary administrations | |PC00_|Tax Certificates - Administration 16 | |PP26 |Plan Scenario Administration | |PP2D |Administer Payroll Results | |PSO5 |PD: Administration Tools | |PUCA |PC administration for PF | |PVSEA|Administer Search Engine | |QD25 |Archiving Notifications: Admin. | |S002 |Menu Administration | |SA02 |Academic title (cent. addr. admin.) | |SA04 |Name prefixes (centr. addr. admin.) | |SA05 |Name suffix (centr. addr. admin.) | |SA07 |Address groups (centr. addr. admin.) | |SA08 |Person groups (centr. addr. admin.) | |SA09 |Internat. versions address admin. | |SA10 |Address admin. communication type | |SARA |Archive Administration | |SBPT |Administration Process Technology | |SCC4 |Client Administration | |SCON |SAPconnect - Administration | |SCOT |SAPconnect - Administration | |SCUA |Central User Administration | |SCUM |Central User Administration | |SE78 |SAPscript: Graphics administration | |SECST|Administration of Secure Memory | |SENG |Administration of External Indexes | |SENGE|Explorer Index Administration | |SIAC1|Web Object Administration | |SLICE|Administer SAP Licenses | |SLWA |Translation Environment Administratn | |SM14 |Update Program Administration | |SP12 |TemSe Administration | |SPAD |Spool Administration | |SPAT |Spool Administration (Test) | |SPHA |Telephony administration | |SPHB |SAPphone: System Administration | |SSAA |System Administration Assistant | |SSCA |Appointment Calendar: Administration | |SSCA1|Appointment calendar: Administration | |SSO2 |Workplace Single Sign-On Admin. | |SSO2_|Workplace Administration SSO2 Ticket | |STMA |Proposal Pool Administration | |SURAD|Survey Administration | |SURL_|Personalization for URL Gen. Admin. | |SUUMD|Display User Administration | |SWDC |Workflow Definition: Administration | |SWEAD|Event Queue Administration | |SWEQA|Event Queue Administration | |SWEQA|Queue Administrator Maintenance | |SWIA |Selection rep. for work items(admin) | |SWRK |Administrtation using work areas | |SWUF |Administration of Runtime System | |SWUL |Customizing: Process Administrator | |SWUX |SAPforms Administration | |SYSAD|System Administration: Task List | |S_ALR|IMG Activity: CIC_V_CCMCTIADMIN | |S_ALR|IMG Activity: SIMG_EURO_ADMINUSER | |S_BCE|IMG-Aktivität: BCDIGSI_ADMIN | |S_PH0|InfoSet Query: Administration | |S_PH0|InfoSet Query: Administration | |S_PH0|InfoSet Query: Administration | |S_PH0|InfoSet Query: Administration | |S_PH0|InfoSet Query: Administration | |TBD0 |Datafeed: Adminster Archives | |TBD3 |Datafeed: Market data administration | |TBD6 |Datafeed: Log file administration | |WE46 |IDoc administration | |WORKI|Administrtation using work areas | ----------------------------------------------------------