A NOR gate can be improvised using one NAND gate of a 4011 as shown here. The diodes are general-purpose types, such as the 1N914 or 1N4148. Inverters or even Schmitt triggers, such as the 4093 or 40108, can be used in this configuration. If more inputs are needed, simply add more diodes to the input.
NOR Gate Using NAND
