To get Standard ECG from PhysioNet?
I don't think that all leads are available.

I looked at the Signals combobox for different databases. This combobox seems to be the list of all available leads.

For example, take a look at iafdb (Intracardiac Atrial Fibrillation Database). It will plot you an ECG containing leads II, V1 and aVF and some other leads.

Another example is the EEG database eegmmidb (EEG Motor Movement/Image Dataset) which contains many leads.

Look also at the mimic2wdb/39 (MIMIC II waveform database, version 3 part 9) which contains 4 ECG leads and some other parameters like breath rate.