LF351 is a OPAMP (Operational Amplifier). For a picture you can ask Google, and as far he tells it is not in production anymore.
7805 and 7905 are Voltage Regulators which take voltage IN (pin named IN), and send it OUT at a predefined voltage (7805 - 05 means it outputs 5V; 78xx outputs positive voltages; 79xx outputs negative voltages).
All voltage regulators also need ground - COM pin.