5Bennett E M,Peterson C D,Levitt E A.Looking to the future of ecosystem services[J]. Ecosystems,2005,8:125-132.
6Bai Y,Han X,Wu J,et al.Ecosystem stability and compensatory effects in the Inner Mongolia grassland [J].Nature,2004,431:181-184.
7Wei L P. Grassland degradation of different factors on the extent of the impact study of Xilin Gol[D]. Hohhot: Inner Mongolia Agriculture University,2009.
8Ao Y H, Huang G A, Xing Q, et al.Grassland resource utilizati on and countermeasures in Inner Mongolia [A].Liu Y Z. Inner Mongolia grassland research [C].Huhhot : Inner Mongolia People Publishing House,2004:30-34.
9Chesbrough H W. Open innovation: The new imperativefor creating and profiting from technology[M]. Harvard Business Press, 2003.
10Foray D. Economics of knowledge[M]. MIT press, 2004.