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161.
介绍了 2 0 0 1年 8月 13日山西太原尖草坪 3.8级地震前 ,太钢地震台合欢树生物电位的前兆异常变化 ,指出合欢树对于太原地区的有感地震映震性能较好 ,为进一步研究合欢树震前的异常变化 ,提出应在太原地区多增加一些合欢树地震观测点的建议 相似文献
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H.B. Akberali E.R. Trueman J.E. Black C. Hewitt 《Estuarine, Coastal and Shelf Science》1982,15(4):415-421
The effects of 1-naphthol, the first hydrolytic product of the insecticide Sevin®, have been studied on the estuarine bivalve Scrobicularia. Median lethal times for 5 and 10 mg l?1 1-naphthol were 15 and 9 days respectively. Final concentrations of 1, 5, 10 and 20 mg l?1 of 1-naphthol resulted in the immediate contraction of the isolated siphon. The contractions were more pronounced at higher concentrations. Application of the same range of concentrations of 1-naphthol to intact Scrobicularia resulted in valve closure and bradycardia. The similarity between the results of median lethal time experiments and the isolated siphonal and behavioural responses of Scrobicularia indicates the feasibility of the use of the isolated siphon preparations to make rapid assessments of environmental stress conditions. 相似文献
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Avai'o'vuna Swamp, a small coastal wetland in Vava'u, Kingdom of Tonga, produced a 4500-year pollen and sediment record. Results are: (1) a mid-Holocene sea level highstand is confirmed for Tonga between about 4500 and 2600 14C yr B.P.; marine clay contains pollen from mangroves (Rhizophora mangle), coastal forest trees (Barringtonia asiatica and Cocos nucifera), and rainforest trees (Alphitonia, Rhus, Hedycarya and Calophyllum). (2) Microscopic charcoal first appeared at 2600 14C yr B.P., coincident with the arrival of Polynesians. (3) Cocos, Pandanus, Excoecaria, Macaranga, and Elaeocarpaceae pollen reflects the establishment of a mixed coastal-lowland rainforest in the last 2500 years. (4) The loss of Hedycarya, Elaeocarpus, Calophyllum, and Guettarda and the reduction of Terminalia and taxa in the Papilionaceae family by about 1000 years ago may be due to habitat destruction and the loss of dispersal capabilities of some species through the extinction of the two largest pigeons in Tonga. 相似文献
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Effect of structure and texture on infiltration flow pattern during flood irrigation 总被引:1,自引:0,他引:1
Understanding the flow pattern of water and solute in subsurface soils is critically important in the fields of agricultural and environmental sciences. Dye tracer tests using a flood irrigation of Brilliant Blue FCF solution (5 g l-1) and excavation method was performed to investigate the effect of texture and structure on the infiltration pattern at three different field soils developed from granite (GR), gneiss (GN) and limestone (LS). The GR soil showed a homogeneous matrix flow in the surface soil with weak, medium granular structure and a macropore flow along pegmatitic vein and plant root in C horizon. The surface horizon (A1) of GN soil with moderate, medium granular structure and many fine roots had matrix flow. The fingering occurred at the interfaces of sandy loam A horizon and loamy sand C horizon in GR soil and loam A1 horizon and sandy loam A2 horizon in GN soil. The LS soil with strong, coarse prismatic structure and the finest texture showed a macropore flow along cracks and had the deepest penetration of the dye tracer. The macropore (crack and vein), layer interface and plant root induced the preferential flow in the studied soils. 相似文献
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应用遥感图像分析植物群落的分布图式 总被引:4,自引:0,他引:4
本文探讨了依据遥感图像,从整体上自动地(或半自动地)研究了植物群落的方法。针对植物群落的复杂性,本文研究了下述三个方面的内容:(1)划分植物群落,并从图像上分析群落的分异规律;(2)将植物群落序列结构化;(3)确定植物群落的分布图式。上述三个方面研究成果已应用于西藏班戈地区的植物群落分析中,事实证明,这是一种新颖且有意义的植物学研究方法 相似文献