nichen.壁龛；适当的位置；（特定产品或服务的）用户群；[生]生态龛；生态位；小生态环境vt.放在适当的位置niche overlapping生态位重叠niche-buttressed带凹龛条槽支墩的niche width theory资源分割观niche construction生态位构建niche of population种群生态位niche fitness model生态位适宜度模型niche with projectio壁龛式芽枝niche specialization生态位特化niche of round window蜗窗小窝niche global operator占一席地位的全球运营公司