主成分分析法在香菇化学成分评价中的应用

为了研究主成分分析法在香菇(Lentinula edodes)化学成分评价中的应用,利用SPSS软件对8种常用香菇栽培材料的多糖、蛋白、糖醇和核苷类共9种化学成分进行分析。提取的前3个主成分的累计方差贡献率为91.73%。决定第1主成分大小的主要是蛋白、尿嘧啶、尿苷、腺苷和香菇嘌呤;决定第2主成分大小的主要是阿糖醇和甘露醇;决定第3主成分大小的主要是多糖和海藻糖。综合试验材料的主成分得分和综合得分,S604、S605和S606化学成分组成优于其他品种。利用SPSS软件和主成分分析法可以有效地比较香菇品种材料间化学成分品质差异,适用于香菇化学成分评价。     

新疆伊犁河岸小叶白蜡复叶构件的表型可塑性1）

小叶白蜡为奇数羽状复叶,常由5～13片小叶组成。通过大样本取样测量,分析了不同小叶数复叶的表型可塑性及其各构件大小之间的关系。结果表明：小叶白蜡叶轴长和复叶长在不同复叶之间的可塑性较大,其差异大多数均达到了显著水平（ p＜0．05）,而在各复叶内的可塑性较小,其变异系数均小于10％;小叶长和小叶宽在不同复叶之间的可塑性较小,其差异大多数均不显著,而在各复叶内的可塑性较大,其变异系数均大于20％。复叶长与叶轴长、复叶长与复叶宽均为对数函数或指数函数的异速生长型,小叶长与小叶宽既有幂函数关系的异速生长型,又有直线关系的同速生长型,各构件在复叶生长过程中的相对生长快慢可通过各函数的性质反映。     

Making valid causal inferences from observational data

The ability to make strong causal inferences, based on data derived from outside of the laboratory, is largely restricted to data arising from well-designed randomized control trials. Nonetheless, a number of methods have been developed to improve our ability to make valid causal inferences from data arising from observational studies.     

Deciduous and deciduous—evergreen forests in Northeast China

Two types of forests in Northeast China is divided in this paper, that is, the deciduous forests in the northern part and the deciduous—evergreen forests in the eastern part. Both distributions of the two types of forests have also been presented. Meanwhile, the development and succession as well as components of forests have been studied in detail. In the end, the vertical distribution of the deciduous forests have been shown, in which, the near—temperate cold temperate deciduous coniferous forests are distributing in the low elevation area between 450m—600m from the north to the south, the typical Siberian cold temperate deciduous coniferous forests are widely distributing from 450m–820m in the north to 600m-1050m in the south, the humid cold temperate deciduous coniferous forests can only be found in high elevation area from 820m–1100m in the north to 1050m–1380m in the south, the cold temperate deciduous coniferous open forests can seldom appear at the top of a few peaks.     

DECIDUOUS AND DECIDUOUS-EVERGREEN FORESTS IN NORTHEAST CHINA

Two types of forests in Northeast China is divided in this paper,that is,the decidu-ous forests in the northern part and the deciduous-evergreen forests in the eastern part.Both distri-butions of the two types of forests have also been pre sented.Meanwhile,the development and suc-cession as well as components of forests have been studied in detail.in the end,the vertical distribu-tion of the deciduous forests have been shown,in which,the near-temperate cold temperate decidu-ous coniferous forests are distributing in the low elevation area between 450m—600m from the northto the south,the typical siberian cold temperate deciduous coniferous forests are widely distributingfrom 450m—820m in the north to 600m—1050m in the south, the humid cold temperate deciduousconiferous forests can only be found in high elevation area from 820m—1100m in the north to1050m—1380m in the south,the cold temperate deciduous coniferous open forests can seldom ap-pear at the top of a few peaks.     

不同林木类型昆虫群落结构及变化规律研究

应用多项群落特征参数和主分量分析方法，研究了毛白杨、国槐、枣树3种林木类型内昆虫群落的结构及变化规律。研究表明：不同林木类型内昆虫群落的组成结构、时间结构等有明显的不同，其中，枣树林昆虫群落复杂程度最高，寄生性昆虫数量最大；毛白杨昆虫群落中害虫数量和捕食性天敌昆虫数量最多；国槐昆虫群落在时间过程中多样性指数波动最大。     

呼和浩特市城市基准地价变化的驱动因子分析

本文利用主成分分析法对呼和浩特市城市基准地价变化的影响因素进行了分析, 认为城市的经济、城市规模、基础设施、产业结构是城市基准地价变化的主要驱动因子。     

陕西吴起县植被盖度变化及其影响因素研究

植被是生态系统中的重要组成部分,植被盖度的高低与全球气候和国家长远的经济效益密切相关。文中采用主成分分析法对吴起县的植被盖度变化与影响因子关系进行分析,分别提取了四个主成分,并用Pearson相关系数法将植被盖度和四个主成分进行相关性分析。结果表明:影响因子与植被盖度之间的相关性与吴起县的半干旱大陆性气候特点和人为种植抚育林草的积极作用有关。在今后的发展中,吴起县应继续提高林草建设质量,强化林草管护,在巩固扩大退耕还林成果的同时,促使生态优势向经济优势转化。     

新疆几种旱生植物的耐旱性评估

本文以束缚水/自由水比值、保水能力、相对含水量、水势、蒸腾速率和chl a/b为指标,应用主分量分析法,进行耐旱性综合评价。结果表明,其耐旱性由强到弱的顺序为:梭梭——白梭梭——多枝柽柳——头状沙拐枣——红果沙拐枣——箭杆杨。