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多根树 被引量:2
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作者 陈有祺 《南开大学学报(自然科学版)》 CAS CSCD 1989年第3期26-28,共3页
关键词 多根树 定义 图论
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基于语义的通用数据抽取方法 被引量:1
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作者 张建英 孙永洁 王秀坤 《计算机科学》 CSCD 北大核心 2010年第3期178-181,共4页
关系数据库可以看作是元组以及外键关系构成的有向图。为便于数据复制以及共享,在进行数据抽取时,往往既要使语义上相关的数据一起抽取,又要使得抽取的数据尽量逻辑上独立。将多根树作为语义上相关、逻辑独立的数据集,给出了关系数据抽... 关系数据库可以看作是元组以及外键关系构成的有向图。为便于数据复制以及共享,在进行数据抽取时,往往既要使语义上相关的数据一起抽取,又要使得抽取的数据尽量逻辑上独立。将多根树作为语义上相关、逻辑独立的数据集,给出了关系数据抽取方法并进行了实现。在Oracle中,使用TPC-C数据库结构对该方法进行了测试与分析,从而验证了算法的有效性和通用性。 展开更多
关键词 多根树 语义相关 数据抽取
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Root Structure,Distribution and Biomass in Five Multipurpose Tree Species of Western Himalayas 被引量:1
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作者 Kartar Singh VERMA Sandeep KOHLI +1 位作者 Rajesh KAUSHAL Om Parkash CHATURVEDI 《Journal of Mountain Science》 SCIE CSCD 2014年第2期519-525,共7页
【Title】【Author】【Addresses】1The tree root distribution pattern and biomass of seventeen year old trees of Grewia optiva, Morus alba, Celtis australis, Bauhinia variegata and Robinia pseudoacacia were studied by e... 【Title】【Author】【Addresses】1The tree root distribution pattern and biomass of seventeen year old trees of Grewia optiva, Morus alba, Celtis australis, Bauhinia variegata and Robinia pseudoacacia were studied by excavation method. B. variegata roots penetrated to a maximum depth of 4.78 m, whereas, M. alba roots were found down to 1.48 m depth. Lateral spread was minimum in B. variegata (1.10 m)and maximum inR. pseudoacacia (7.33 m). Maximum root biomass of 6.30 kg was found in R. pseudoacacia and minimum (2.43 kg) was found in M. alba. For four species viz.,G. optiva, M. alba, C. australis andR. pseudoacacia, 68%-87% root biomass occurred within top 0-30 cm soil depth, but forB. variegata this was only45%. The soil binding factor was maximum in G. optiva and minimum in B. variegata. Soil physico-chemical properties also showed wide variation. The study suggests thatB. variegata with a deep root system is the most suitable species for plantation under agroforestry systems. R. pseudoacacia and G. optiva with deep root systems, more lateral spread and high soil binding factor are suitable for plantation on degraded lands for soil conservation. 展开更多
关键词 Root categories Root distribution Root biomass Soil binding factor Soil conservation NUTRIENTS
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