Abstract: A supported three-center catalyst, a preparation method and the use are provided. The catalyst comprises a porous inorganic carrier, an organic chromium active component, an inorganic chromium active component and an inorganic vanadium active component, and may further comprise a catalyst modifying component. A method involves, by means of one or more steps of dipping and drying or dipping, drying and high-temperature roasting procedures, respectively converting an organic chromium source, a chromium source, a vanadium source and a Q component into an organic chromium active component precursor, an inorganic chromium active component precursor, an inorganic vanadium active component precursor and a catalyst modifying component that are supported on the surface of the porous inorganic carrier, and then activating same with an organometallic cocatalyst or a polymerization monomer, so as to obtain the supported three-center catalyst.

Abstract: Methods are provided for in vitro maturation (IVM) of bovine oocytes that include steps of (a) pre-culturing bovine germinal vesicle (GV) oocytes in the presence of C-type natriuretic peptide (CNP) and (b) subsequently culturing the oocytes of (a) for an extended duration in medium containing follicle stimulating hormone (FSH), luteinizing hormone (LH), 17?-estradiol (E2), epidermal growth factor (EGF), and fetal bovine serum (FBS).