Distributed Asymmetric Key Decryption with threshold
I assume you say on the threshold encryption scheme, in which a dealer generates $(PK,SK_1,\dots,SK_n)$ and distributes the secret keys to users indexed by $1,\dots,n$, and if a combiner obtains $t$ partially-decrypted ciphertexts, it can retrieve a plaintext.


Dodis and Katz showed a generic construction of CCA-secure threshold encryption scheme from a secret sharing scheme and a CCA-secure labeled PKE scheme.
See the paper, Dodis and Katz: Chosen-Ciphertext Security of Multiple Encryption (TCC 2005).
DDH-based constructions (in ROM) are proposed by Gennaro and Shoup: Securing threshold cryptosystems against chosen ciphertext attack (EUROCRYPT 1998, JoC 2002).
You can also find a pairing-based construction in Boneh, Boyen and Halevi: Chosen Ciphertext Secure Public Key Threshold Encryption Without Random Oracles (CT-RSA 2006).