The outbreak of Yantze vole ( Microtus fortis) population in Dongting Lake region is closely related to the evolvement of lake beaches,because the deposition of lake sediments results in the expansion of lake beaches,...The outbreak of Yantze vole ( Microtus fortis) population in Dongting Lake region is closely related to the evolvement of lake beaches,because the deposition of lake sediments results in the expansion of lake beaches,which provides the possibility of the increase of the vole's population. Reclaiming farmland from lake via building cofferdams,eliminating snails by building cofferdams for eradicating schistosomiasis,and over-hunting predators in the region cause the voles becoming a pest after the 1970s. In recent years,the Three Gorges Project and the conversion from farmland into lake have had deep impacts on the environment in the lake region. The dispatching of the down flow rate by the project has induced the expansion of the low and medium level beaches in the lake region,while converting farmland into lake directly has induced the expansion of the lake beaches,both of which have expanded the potential habitats of the vole's population. Therefore,more attention should be paid to the quantitative variation trend of the vole's population in the future.展开更多
In the paper, Ding projective modules and Ding projective complexes are considered. In particular, it is proven that Ding projective complexes are precisely the complexes X for which each Xm is a Ding projective R-mod...In the paper, Ding projective modules and Ding projective complexes are considered. In particular, it is proven that Ding projective complexes are precisely the complexes X for which each Xm is a Ding projective R-module for all m ∈ Z.展开更多
基金Supported by the National Natural Science Foundation(30870402,31170396)Key Knowledge Innovation Project of Chinese Academy of Sciences(KSCX-EW-N-05)
文摘The outbreak of Yantze vole ( Microtus fortis) population in Dongting Lake region is closely related to the evolvement of lake beaches,because the deposition of lake sediments results in the expansion of lake beaches,which provides the possibility of the increase of the vole's population. Reclaiming farmland from lake via building cofferdams,eliminating snails by building cofferdams for eradicating schistosomiasis,and over-hunting predators in the region cause the voles becoming a pest after the 1970s. In recent years,the Three Gorges Project and the conversion from farmland into lake have had deep impacts on the environment in the lake region. The dispatching of the down flow rate by the project has induced the expansion of the low and medium level beaches in the lake region,while converting farmland into lake directly has induced the expansion of the lake beaches,both of which have expanded the potential habitats of the vole's population. Therefore,more attention should be paid to the quantitative variation trend of the vole's population in the future.
基金Supported by National Natural Science Foundation of China(Grant Nos.11561039 and 11761045)Natural Science Foundation of Gansu Province of China(Grant No.17JR5RA091)
文摘In the paper, Ding projective modules and Ding projective complexes are considered. In particular, it is proven that Ding projective complexes are precisely the complexes X for which each Xm is a Ding projective R-module for all m ∈ Z.
