The polymerization characteristics of cis-1,4-polybutadiene rubber synthesized with nickel catalyst system,active center model,polymerization mechanism,polymerization dynamics,and advances of improving nickel catalyst system were introduced.

The reaction performance of ethylene oligomerization is reviewed from the aspects of catalysts,active site,the varieties,valent state,coordination state of metal cation,the roles of co-catalysts.

The tryptophan residues, serine residues and histidine residues might be involved in the active site of the enzyme.

In this paper,three kinds of catalysts are introduced and discussed according to the acid or base active site.

Soluble expression of human carboxypeptidase A1 active center in pichia yeast;

Cloning and prokaryotic expression of the carboxypeptidase Al and the active center gene;

Cloning and prokaryotic expression of human carboxypeptidase A1 active center gene;

The distribution of active sites had been predicted by theory of X-ray diffraction and structure chemistry,they were distributed around framework oxygen on the walls of channel.

Types of the defects and hence the active sites formed are affected by composition of starting NiAl alloy and preparation methods.

The problem with the heterogeneous catalysts for propylene oligomerization was the loss of the active sites in the reaction.

Development of single site homogeneous catalyst systems is a focus in olefin polymerization fields.

This paper summarized the development of metallocene catalyst and single-site center technology, and introduced the developing trends of polyethylene producing processes including bimodal PE production technology, responser new disposition technology and condensed and super-condensed technology.