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51.
52.
安徽琅琊山青檀种群数量动态 总被引:1,自引:0,他引:1
以种群生命表和生存分析理论为基础,采用胸径大小分级法和分段匀滑技术,编制琅琊山青檀(Pteroceltistatarinowii)种群静态生命表,绘制了死亡率曲线、消失率曲线、存活曲线和生存函数曲线并分析种群数量特征,结合种群动态量化方法和时间序列预测模型分析种群数量动态变化。结果表明:(1)琅琊山青檀种群属稳定增长型。种群径级结构大体呈倒“J”型分布,中、幼龄阶段个体数量较为丰富,老龄阶段个体数量相对较少,种群在发育过程中存在一定波动性,但种群数量变化动态指数Kp,i。和Kp,i(考虑外部干扰时)均大于0。(2)青檀种群死亡率曲线和消失率曲线变化趋势基本一致,均出现2个高峰,一个出现在第Ⅱ龄级,另一个出现在第XI(或Ⅻ)龄级;存活曲线经统计检验趋于Deevey-Ⅱ型。(3)青檀种群的生存率曲线单调下降,累计死亡率曲线单调上升,生存率下降趋势表现为前期高于后期,累计死亡率则相反;生存函数曲线显示,青檀种群具有前期薄弱、中期稳定和后期衰退的特点。(4)在未来2、4、6、8和10a内,青檀种群幼龄级个体数量相对丰富,种群呈稳定增长趋势。 相似文献
53.
Spatial and seasonal differences in water quality of drainage water and unconfined shallow groundwater were related to irrigation in Samandağ, a Mediterranean coastal region. Eighteen wells, seven drainage points and Orontes River were monitored bimonthly for one year for analyses of electrical conductivity (EC), total dissolved solids (TDS), sodium adsorption ratio (SAR), cations (Na, K, Ca + Mg) and anions (CO3, HCO3, Cl and SO4). Agricultural irrigation using saline groundwater decreased water quality of Orontes River during the irrigation season (May to September) more than during the non-irrigation season (October to April). Seasonal fluctuations in water quality of shallow groundwater were greater during the irrigation season than the non-irrigation season in the study area. Excessive use of groundwater resulted in a decline in the water table levels in the irrigation season. Water table level rose up to the soil surface in areas where there was a lack of drainage or poor drainage, due to the impact of precipitation in the winter. SAR and pH values of drainage water increased in the irrigation season, while the other properties of drainage water decreased. Irrigation water quality of Orontes River was classified as C3S1 in both seasons. Irrigation water quality of shallow groundwater and drainage water varied from C2S1 to C4S2 in one year. Drainage and well waters were found to be different on yearly basis in terms of Na, SAR (p<0.01) and Ca + Mg concentrations (p<0.001). Ca + Mg concentrations for both sources were different for all sampling dates (p<0.001). 相似文献
54.
The investigation of object-by-attribute matrices is very common in statistics and data analysis with the aim of uncovering every possible relationship among objects and/or attributes. Formal Concept Analysis (FCA) is a method, which stems directly from partial order and lattice theory, which provides an efficient tool to symmetrically uncover linkages among objects and attributes whenever a relation stands among the two sets. It provides efficacious graphical representation and computes association rules between attributes, thus helping in the detection of possible synergism or antagonism of attributes. In this paper, FCA potentialities are discussed and described by means of a case study already investigated by other partial order techniques: the case of Lake Ontario sediment samples. Data derive from a ‘test battery’ for a simultaneous analysis of degradation of Lake Ontario samples, which are basically of two typologies: hygienic and toxicity tests. A multi-valued approach is adopted to cope with the ordinal feature of data. Results highlight interesting interaction among hygienic compounds and a synergism between the two toxicity tests. 相似文献
55.
根据电动振动台的工作原理,详细分析电动振动台磁路结构及漏磁场的来源,通过进行测量分析,并提出一种有效的漏磁场屏蔽措施。 相似文献
56.
为解决传统抑制动力学模型存在的形式不统一及参数获取困难等问题,采用表函数的方法对抑制动力学进行表述.通过引进表函数方法,对动力学测定实验方法提出了改进,采用DYNAMO软件进行数据处理.对2,4-二硝基酚抑制现象进行模拟研究.结果表明,用表函数的方法对抑制现象进行模拟是可行的.相比较传统抑制动力学,表函数的模拟曲线更加贴近实验数据,形式简单而统一,同时解决了参数获取的问题.在对复杂抑制现象进行模拟时,表函数方法具有较大优势,并可以在一定程度上简化模型的结构. 相似文献
57.
58.
本文从理论和实践两方面分析研究了水下振动台的若干关键技术问题,主要包括运动部件的设计、冷却系统的设计、密封系统的设计、压力平衡系统的设计等。解决了水下振动台设计所存在的难题。 相似文献
59.
Moti L. Rijal Erwin Appel Ulrich Blaha 《Environmental pollution (Barking, Essex : 1987)》2010,158(5):1756-1762
Sediments affected by fluctuations of hydrocarbon contaminated groundwater were studied at a former military site. Due to remediation, groundwater table fluctuation (GWTF) extends over approximately one meter. Three cores were collected, penetrating through the GWTF zone. Magnetic parameters, sediment properties and hydrocarbon content were measured. We discovered that magnetic concentration parameters increased towards the top of the GWTF zone. Magnetite is responsible for this enhancement; rock magnetic parameters indicate that the newly formed magnetite is in a single domain rather than a superparamagnetic state. The presence of hydrocarbons is apparently essential for magnetite to form, as there is clearly less magnetic enhancement in the core, which is outside of the strongly contaminated area. From our results we conclude that the top of the fluctuation zone has the most intensive geomicrobiological activity probably responsible for magnetite formation. This finding could be relevant for developing methods for simply and quickly detecting oil spills. 相似文献
60.