以艾比湖流域荒漠生态系统为研究对象,选取1 hm~2荒漠植物群落样地,基于6个取样尺度(5 m×5 m,10m×10 m,20 m×20 m,25 m×25 m,50 m×50 m,100 m×100 m),利用不同的生态学模型拟合植物群落的分布格局,从而判定主导荒漠生态系统植物群落构建的主要生态学过程以及尺度效应对群落构建的影响。结果表明:(1)随着空间尺度的增加,群落中稀有种逐渐降低;常见种比
The interpretation of patterns of biodiversity requires the disentanglement of geographical and environmental variables.Disjunct alpine communities are geograph
本文介绍了用共振法测定混凝土材料动弹性模量的方法。测定混凝土梁的各阶固有频率。通过计算,求得材料的动弹性模量。考虑到混凝土梁试件长宽比一般比较小,所以着重讨论了转
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Hydrogen sulfide (H2S) plays a critical role in regulation of brain function.However, its impact on neurodegenerative disease is still unknown.The present s
Attention Deficit Disorder (ADD) is a neuro-behavioral developmental syndrome which affects 3-7 percent of school children aged 6-12 years and as many as 10
本文介绍了几种频率均衡器,讨论了各参数之间的关系,并简要地给出了设计思路,可供设计者参考。
This article describes several frequency equalizers, discusses the rela
DEAR EDITOR,rnUnderstanding dietary selection and feeding strategies is important for the conservation and management of endangered primate species.Here,we cond
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Mutations of the FMR1 gene are responsible for the FraX, FXTAS and POI syndromes.The pathogenic effects are caused by expansions of the CGG repeats located