水稻茎秆对稻田净灌水量测量值的影响     

刘德斌  邹玉田  王小寅 《节水灌溉》2016,(5):48-50

为快速准确测算稻田净灌水量,采取小区试验与大田同步验证的方法,分析直接量测与观测分析2种方法所得小区净灌水量间的差异及原因,并引入偏差系数K(即用2种方法测量值的比值表示直接量测法的偏差程度)。结果表明:水稻茎秆对田面水层的填充作用,会对直接量测法所测净灌水量产生影响;与观测分析法相比,直接量测法所测稻田单次净灌水量偏大1.4%~11.7%,且此偏差在水稻生育初期较小,至生育末期逐渐增加至最大;茎面积指数SAI与K成明显线性关系,采用SAI对直接量测法所测结果进行校准,可减少稻田总净灌水量测算偏差2.3%~6.3%。  相似文献   

基于最小偏差的林分生长组合预测模型及其应用     

李际平  刘素青 《中南林业科技大学学报(自然科学版)》2004,24(5):80-83

根据Bates J M 和Granger C W J 的组合预测方法的概念,提出了基于最小偏差的林分生长组合预测模型,并介绍了模型求解的方法.由实例证明,组合预测模型能大大地改善预测效果,是一个理想的模型,在应用上具有重要意义.  相似文献   

Analysis on Deviation of the Urbanization from Economy Development in China     

《保鲜与加工》2003,(5):118-122127

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家蚕种克卵粒数容许差距的测算方法   总被引：1，自引：0，他引：1  

王林芳  徐世清  李掌林  陶鸣  潘丽芬 《蚕业科学》2006,32(1):132-134

控制样本间克卵粒数的差距是保证家蚕种良卵率检测准确性的关键。通过调查和理论分析,认为家蚕卵粒质量的分布服从正态分布。在置信概率为95%下,3次重复间样本卵粒数的容许差距估计公式为d=0.191 3×n3/2×10-3。当克卵粒数在1 600~1 699、1 700~1 799、1 800~1 899、1 900~2 000区间时,容许差距分别为13、14、15、16粒。  相似文献   

浅析《黑人奴隶弗雷德里克·道格拉斯的生平自述》中的语言偏离现象     

裴莎莎 《信阳农业高等专科学校学报》2012,22(4)

弗雷德里克·道格拉斯在其自传体小说《黑人奴隶弗雷德里克.道格拉斯的生平自述》中,借助语法偏离和书写偏离等语言偏离手段,以艺术的形式为自己构建了一个自由的深度空间,在精神与灵魂的自由中突破了话语权力的藩篱,表现了自我与自主,彰显了主体和个性。  相似文献   

A Method for Numerical Simulating Density Distribution in Sand Packing     

XIANG Qun yin  OHNAKA Itsuo 《保鲜与加工》1999,(3):9-14

Various cost simulation software packages are extensively used in the construction industry today. There are some differences in the problems to which they are applied,but it is essential that users select suitable known distributions and estimate the parameter values for cost elements before starting any simulation. The accuracy and reliability of the simulation results depend on such selections. This paper proposes a practical and accurate selection method based upon the least differences of expected values and standard deviations between a known distribution and an estimated cost probability histogram.  相似文献   

Density-dependent growth of young-of-the-year Atlantic salmon (Salmo salar) revisited     

I. Imre  J. W. A. Grant  R. A. Cunjak 《Ecology of Freshwater Fish》2010,19(1):1-6

Imre I, Grant JWA, Cunjak RA. Density-dependent growth of young-of-the-year Atlantic salmon ( Salmo salar ) revisited. Ecology of Freshwater Fish 2010: 19: 1–6. © 2009 John Wiley & Sons A/S
Abstract –  The length of individual young-of-the-year (YOY) Atlantic salmon ( Salmo salar ) in Catamaran Brook decreases with increasing population density following a negative power curve. Because most of this decrease in growth rate occurs at low densities (<1 fish·m⁻²), ( Imre et al. 2005 ; Journal of Animal Ecology, 74: 508–516) suggested that exploitation competition for drifting prey rather than space limitation might be responsible for this pattern. Recently, ( Ward et al. 2007 ; Journal of Animal Ecology, 76: 135–138) showed that the negative power curve of growth rate versus density can be caused by other mechanisms and suggested that Imre et al.'s evidence for density-dependent growth would have been stronger if we had analysed final size versus initial density rather than final density. We examined (i) whether the negative power curve of size versus density was also apparent in an analysis of final size versus initial density and tested two predictions that emerge from Ward et al.'s model, (ii) the variance in body size increases with population density, and (iii) the maximum fish size at a site is density-independent. The final size of YOY salmon decreased with increasing initial density following a negative power curve. Our data did not provide strong support for the above predictions emerging from Ward et al.'s model. Our analyses of different years, sites and seasons were consistent with the hypothesis of density-dependent growth of YOY salmon.  相似文献   

作物品种适应性和产量稳定性问题探讨   总被引：36，自引：0，他引：36  

俞世蓉 《南京农业大学学报》1989,(3)

对品种适应性和产量稳性的概念和含义、参数估计及其存在问题和应用作了综述与讨论。以品种平均产量为参照数所估计出的变异系数或标准差比数可看作稳定性参数,以环境指数为参照数所估计出的回归系数可看作适应性参数。如何获得环境估计值问题,还需进一步研究。建议以标准差比数a_i度量产量稳定性,以回归系数b度量品种适应性,以相关系数γ度量b的可靠性。  相似文献   

Variability of duration of pre-anthesis phases as a strategy for increasing wheat grain yield     

Guillermo A. García  Román A. SerragoMaría L. Appendino  Lucio A. Lombardo  Leonardo S. VanzettiMarcelo Helguera  Daniel J. Miralles 《Field Crops Research》2011,124(3):408-416

In wheat, stem elongation phase (SEP) duration is critical for grain number (GN) per unit of area determination, as it is the phase in which the spikes grow. Lengthening SEP, for instance by photoperiodic sensitivity, without altering the cycle to anthesis (AT) has been proposed as an alternative way to increase spike dry weight, and in turn GN. As most works supporting this idea have modified only SEP by artificial manipulation (e.g. photoperiod extensions), it is relevant to evaluate this hypothesis in populations segregating for this attribute in natural conditions. The aim of this work was to analyse the variability in SEP duration relative to AT in two F4 populations; in order to select contrasting phenotypes to evaluate the impact of this attribute on grain yield components and to analyse the selection response of this attribute. These segregating populations (Las Rosas INTA × Triguero 230 (A) and Klein Estrella × ProINTA B. Alazán (B)) were derived from parental lines with similar flowering time but different relative duration of their pre-anthesis phases. Two field experiments with previous vernalization treatment in cool chamber were carried out. In 2006, F4 populations were characterized and from one of them (population B, which presented higher variability) four groups were selected, which presented contrasting phenotypes in the attribute under study. Progenies of these groups (F5), together with remnant F4 full-sib of each one, were studied during 2007. Grain yield per plant was higher, due to GN increases, when duration of the SEP was lengthened. However, selection response to longer SEP with similar cycle to AT could not be found, possibly as the result of a high environmental influence on this attribute. The phenotypic variability evidenced in this attribute was not clearly associated with major adaptation genes evaluated (i.e. Ppd and/or Vrn), suggesting that other minor genes could be associated.  相似文献   

渔用柴油补贴政策实施中的利益关系与政策执行偏差问题探析     

同春芬  张凤 《现代渔业信息》2014,(3):167-171

渔用柴油补贴政策是近年来一项重要的支渔惠渔政策,也是渔业发展历史上国家对渔业最大的一项扶持政策。该政策的实施对于降低渔业生产成本,加强渔政管理,促进渔民增收、渔业增效和渔区稳定等均具有积极作用。然而,政策实施过程中相关利益主体表现出不同程度的自利倾向,并诱发了骗补、套补、坐吃空饷等问题。对此,建议相关部门应予以重视,并在完善政策本身的同时加强监管,协调好相关利益主体之间的利益关系,形成良性的监督制约机制,切实维护好渔民权益。  相似文献