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111.
The relationship between the physicochemical properties (molar volume, partition coefficient, and dissociation constant) of slow-acting systemic postemergence xenobiotics and their uptake and translocation to the sites of action was investigated using the nonlinear, dynamic simulation model ERMESSE. When the pKa was held constant at 4.0, the model enables the prediction of the uptake of a systemic xenobiotic as a function of its partition coefficient and molar volume. The model also considered the effects of the physicochemical properties of a systemic xenobiotic on its long-distance translocation within the vascular tissues. For instance, when the log Kow and pKa were held constant at 1.5 and 6.0, respectively, the model predicted a higher translocation rate (55%) for molecules with a small (e.g., MV = 100 cm3 mol−1) as opposed to a large (e.g., MV = 300 cm3 mol−1, 33%) molar volume. In addition, the theoretical predictions from the ERMESSE model showed that any xenobiotic with a molar volume not exceeding 300 cm3 mol−1 could provide an uptake ?50% and a translocation rate ?25% when its log Kow is between −0.5 and 2.5 and its pKa is between 0.0 and 8.0. 相似文献
112.
SHEN Hong CHEN Mingjie ZHAO Yongchang PAN Yingjie Key Laboratory of Agricultural Genetics Breeding of Shanghai 《食用菌学报》2007,(2)
Fourteen Morchella samples (eleven from Yunnan and three from Zhejiang Provinces) were selected on the basis of differences in fruit body morphology. Ribosomal DNA internal transcribed spacers (ITS) were amplified in each case using the universal primer pair, ITS-1 and ITS-4, and the amplification products were purified and sequenced. Comparisons with sequence data in GenBank revealed that the 11 Morchella isolates collected from Yunnan belonged to four species: Morchella elata, Morchella conica, Morchella crassipes and Morchella costata. The three isolates collected from Zhejiang Province (M12, M13 and M14) were designated as unknown Morchella species. When Verpa conica (AJ544206) (from the genus Verpa belonging to the same family as Morchella) was taken as the outgroup, the 14 isolates formed three groups, M. elata, M. costata (Group 1); Morchella esculenta, M. conica (Group 2); and M. crassipes, M12, M13 and M14 (Group 3). 相似文献
113.
微孔草的分布及植物群落特征研究 总被引:5,自引:0,他引:5
采用定量样地法,对孔微草这一特种油料植物的群落结构、群落变异以及群落特征进行了研究。结果表明,微孔草干物质生产量占总量的比率,休闲地为9.16%、撩荒地为16.90%、油草地为15.32%、燕麦地为10.66%、青稞地为5.97%;群落系数相应为87.09%、87.91%、91.82%、95.65%、93.60%;优势度相应为9.60%、13.45%、11.99%、16.61%、7.13%。经主分 相似文献
114.
矩形薄壁侧堰水力特性试验研究 总被引:2,自引:2,他引:0
侧堰作为一种量水设施,精度较高、结构简单、安装和拆卸方便,较易在灌区应用和推广,有很大的研究价值。对不同宽度和高度的矩形侧堰在缓流条件下进行了试验,分析了各工况下矩形渠道侧堰上、下游水面线、能量分布、流量系数等水力因素。结果表明,主渠道侧堰段能量基本保持不变,符合De Marchi的恒定能量假定;主渠道靠近侧堰边壁、中心线以及另一边壁三处的水面波动程度不同,说明侧堰对堰前水流产生影响;基于De Marchi假定和无量纲分析原理得到的流量公式最大相对误差均在±10%以内,满足灌区量水精度要求。 相似文献
115.
116.
Simulation of transpiration, drainage, N uptake, nitrate leaching, and N uptake concentration in tomato grown in open substrate 总被引:3,自引:0,他引:3
M. Gallardo J.S. Rodríguez M.D. Fernández J.J. Magán 《Agricultural Water Management》2009,96(12):1773-1784
Free-drainage or “open” substrate system used for vegetable production in greenhouses is associated with appreciable NO3− leaching losses and drainage volumes. Simulation models of crop N uptake, N leaching, water use and drainage of crops in these systems will be useful for crop and water resource management, and environmental assessment. This work (i) modified the TOMGRO model to simulate N uptake for tomato grown in greenhouses in SE Spain, (ii) modified the PrHo model to simulate transpiration of tomato grown in substrate and (iii) developed an aggregated model combining TOMGRO and PrHo to calculate N uptake concentrations and drainage NO3− concentration. The component models simulate NO3−-N leached by subtracting simulated N uptake from measured applied N, and drainage by subtracting simulated transpiration from measured irrigation. Three tomato crops grown sequentially in free-draining rock wool in a plastic greenhouse were used for calibration and validation. Measured daily transpiration was determined by the water balance method from daily measurements of irrigation and drainage. Measured N uptake was determined by N balance, using data of volumes and of concentrations of NO3− and NH4+ in applied nutrient solution and drainage. Accuracy of the two modified component models and aggregated model was assessed by comparing simulated to measured values using linear regression analysis, comparison of slope and intercept values of regression equations, and root mean squared error (RMSE) values. For the three crops, the modified TOMGRO provided accurate simulations of cumulative crop N uptake, (RMSE = 6.4, 1.9 and 2.6% of total N uptake) and NO3−-N leached (RMSE = 11.0, 10.3, and 6.1% of total NO3−-N leached). The modified PrHo provided accurate simulation of cumulative transpiration (RMSE = 4.3, 1.7 and 2.4% of total transpiration) and cumulative drainage (RMSE = 13.8, 6.9, 7.4% of total drainage). For the four cumulative parameters, slopes and intercepts of the linear regressions were mostly not statistically significant (P < 0.05) from one and zero, respectively, and coefficient of determination (r2) values were 0.96-0.98. Simulated values of total drainage volumes for the three crops were +21, +1 and −13% of measured total drainage volumes. The aggregated TOMGRO-PrHo model generally provided accurate simulation of crop N uptake concentration after 30-40 days of transplanting, with an average RMSE of approximately 2 mmol L−1. Simulated values of average NO3− concentration in drainage, obtained with the aggregated model, were −7, +18 and +31% of measured values. 相似文献
117.
猴头菌产量与培养料含氮量的动态关系 总被引:2,自引:0,他引:2
选用20种配方进行猴头菌的栽培试验。培养料配方为棉籽壳、木屑和麦麸,其含N量为0.22% ̄1.42%。试验结果表明,猴头菌子实体干物质绝对生物学效率(ABE%=y1),经济效益(y2)与培养料含N量(N%=x1)之间的动态关系符合Logistic方程:y1=10.00/(1+3.4242e^-2.3215x1),r’y1x1=-0.8648^**,P〉0.01;y2=3.00/(1+8.6791e 相似文献
118.
孙枫林 《湖南农业大学学报(自然科学版)》2000,27(2)
人才,是经济社会活动诸多要素中最主要,最活跃的要求,结构合理的人才队伍才有可能产生高的效率和效益。本文应用灰关联度分析方法,以通信产业人才队伍为例进行分析,为制定合理的人才队伍结构提供了一种评价方法。 相似文献
119.
为了分析玻璃退火过程中永久应力的形成规律以及应力值的大小,基于玻璃永久应力的成因分析,建立了弹性体数值模型,给出了永久应力的计算方法和步骤。根据所建模型,利用ansys软件模拟了玻璃退火过程中结构应力和残余温差应力的形成过程,发现结构应力产生于膨胀系数开始发生变化的温度567℃,停止于膨胀系数稳定时的温度480℃。并根据模拟结果,计算出了玻璃中永久应力值的大小:边部压应力1.022MPa,中部张应力0.602MPa。模拟过程比较准确地反应了实际玻璃退火过程中应力的形成过程,根据模拟值求出的应力值大小基本符合玻璃实际应力值情况。 相似文献
120.
利用流量计几何形状确定流量系数初探 总被引:1,自引:0,他引:1
在使用文丘里流量计之前,最关键的工作是对流量系数μ的率定,其工作复杂。本文采用了利用流量计的几何断面尺寸来确定流量系数。只要确定了断面流动要素及尺寸,就可以精确地计算出管道流量。 相似文献