The origin and classification of soil enzymes are summarized in this paper. The foregone research results discover the close relationship between soil enzyme activity and soil quality (including soil chemical, physica...The origin and classification of soil enzymes are summarized in this paper. The foregone research results discover the close relationship between soil enzyme activity and soil quality (including soil chemical, physical and biological properties), and long-or short-term response of soil enzyme activity to disturbance of soil ecosystem. Meanwhile, soil enzyme activity is sensitive to slightly change of soil quality, which suggests soil enzyme activity can act as one of key indicators for assessment and forecast of soil quality. Some problems in soil enzyme studies are discussed and further possible research of soil enzyme activity is also presented. Ref展开更多
城市休闲商务区(Recreational Business District,RBD)作为城市重要的游憩空间,为外来游客和城市居民提供休闲消费的场所,逐渐受到学界和业界重视。目前大多数研究还停留在概念层面,在分类、空间结构、分布规律、分异成因等方面上还缺...城市休闲商务区(Recreational Business District,RBD)作为城市重要的游憩空间,为外来游客和城市居民提供休闲消费的场所,逐渐受到学界和业界重视。目前大多数研究还停留在概念层面,在分类、空间结构、分布规律、分异成因等方面上还缺乏一定的实证和定量研究。结合前人研究经验,重新定义RBD,并依据城市RBD的特征和属性将其分为大型购物中心、休闲商业街、城市休闲区三类。选取1990年、2000年、2014年三个时间截面对北京各类城市RBD点进行统计,采用基尼系数、空间插值、核密度分析、地理探测器等方法,结合Arc GIS软件,对北京城市RBD的时空分布特征和成因进行分析,得出以下结论:1时序上看,北京城市RBD的数量和规模不断增加,增速变快,不同类型的RBD出现不同幅度的空间扩张;2北京城市RBD的空间集聚程度不断加强,不同类型的RBD,存在一定的增幅和增速差异;3北京城市RBD的整体空间结构呈"单核聚集—双核发展—网状扩散"的发展模式;4城市RBD多选址在交通便利、临近旅游景区、居民和游客密度较高、地价相对较高的地区。5游客密度对各类型的城市RBD规模均有较大影响;对于不同类型的城市RBD,各因素对其规模的影响也有所不同。展开更多
文摘The origin and classification of soil enzymes are summarized in this paper. The foregone research results discover the close relationship between soil enzyme activity and soil quality (including soil chemical, physical and biological properties), and long-or short-term response of soil enzyme activity to disturbance of soil ecosystem. Meanwhile, soil enzyme activity is sensitive to slightly change of soil quality, which suggests soil enzyme activity can act as one of key indicators for assessment and forecast of soil quality. Some problems in soil enzyme studies are discussed and further possible research of soil enzyme activity is also presented. Ref
文摘城市休闲商务区(Recreational Business District,RBD)作为城市重要的游憩空间,为外来游客和城市居民提供休闲消费的场所,逐渐受到学界和业界重视。目前大多数研究还停留在概念层面,在分类、空间结构、分布规律、分异成因等方面上还缺乏一定的实证和定量研究。结合前人研究经验,重新定义RBD,并依据城市RBD的特征和属性将其分为大型购物中心、休闲商业街、城市休闲区三类。选取1990年、2000年、2014年三个时间截面对北京各类城市RBD点进行统计,采用基尼系数、空间插值、核密度分析、地理探测器等方法,结合Arc GIS软件,对北京城市RBD的时空分布特征和成因进行分析,得出以下结论:1时序上看,北京城市RBD的数量和规模不断增加,增速变快,不同类型的RBD出现不同幅度的空间扩张;2北京城市RBD的空间集聚程度不断加强,不同类型的RBD,存在一定的增幅和增速差异;3北京城市RBD的整体空间结构呈"单核聚集—双核发展—网状扩散"的发展模式;4城市RBD多选址在交通便利、临近旅游景区、居民和游客密度较高、地价相对较高的地区。5游客密度对各类型的城市RBD规模均有较大影响;对于不同类型的城市RBD,各因素对其规模的影响也有所不同。
