Top IPC subclasses
1
|
B01D
|
1
|
Separation
|
2
|
C02F
|
1
|
Treatment of water, waste water, sewage, or sludge
|
3
|
C01G
|
1
|
Compounds containing metals not covered by subclasses C01D or C01F
|
4
|
C07F
|
1
|
acyclic, carbocyclic, or heterocyclic compounds containing elements other than carbon, hydrogen, hal
|