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121.
中国畜禽温室气体排放量估算 总被引:26,自引:2,他引:24
为探明中国畜禽温室气体排放量及其趋势,该研究在政府间气候变化专家委员会(IPCC,2006)最新公布的畜禽温室气体排放系数和计算方法的基础上,结合中国畜牧业发展实际,估算了全国2000-2007年和各省区2007年畜禽温室气体的排放量。结果表明,全国年平均排放甲烷总量1 002.7万t,氧化亚氮总量57.7万t;2000-2007年期间全国畜禽温室气体排放量总体呈下降的趋势,黄牛甲烷排放量最大,生猪氧化亚氮排放量最大;各省区畜禽温室气体排放量呈现区域集中特点,居前2位的是四川省和河南省。要减少中国畜禽温室 相似文献
122.
对线性回归模型的参数给出了一种新的有偏压缩估计,简称BC估计,并证明了BC估计的许多优良性质。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):264-270
Three field teams undertook a survey of crown transparency in Switzerland in 1993. A fourth team (control) also visited a subset of the trees that had already been visited by the field teams and reported estimates for the same. The problem of estimating the proportion (Pc) of trees with total crown transparency at least equal to a (fixed) level c is addressed. The method assumes that the control team estimate is an unbiased estimate of Pc and therefore if the expected difference between a field team estimate and the control team estimate is non‐zero then the field team estimate is biased. This assumption is most likely to be met in those countries or areas where the control team consists of the instructors. When this assumption cannot be met, as long as the bias of the control team remains the same over the years, the estimates of Pc from different years can still be used to study, for example, whether there is any temporal trend in Pc . A weighted average of the bias‐corrected field team estimates is used to determine the confidence limits. The method is applied to the Swiss national forest damage inventory data from the year 1993. The same approach can also be taken for estimating the proportion of cases where a random variable X, qualitative (such as the social position of a tree) or quantitative (such as the diameter of a tree at breast height), assumes values in a particular set. 相似文献
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Rong-Cai Yang Mohan R. Thiagarajah Vipan K. Bansal Gary R. Stringam M. Habibur Rahman 《Euphytica》2006,148(3):217-225
Summary The segregation and linkage between glufosinate (transgenes ‘Rf3’ and ‘T177’) and blackleg resistance genes in canola (Brassica napus L.) were assessed using F1 microspore-derived doubled haploid (DH) populations from four crosses including reciprocals, two involving the transgene ‘Rf3’ and the other two involving the transgene ‘T177’. To relax the assumption of no segregation distortion required for the conventional analysis of segregation and linkage, we employed Bailey's analysis that allows detecting segregation distortion at linked loci. The significant departures from the 1:1 segregation were detected in the crosses involving the transgene ‘T177’ but not in the crosses involving the transgene ‘Rf3’. The apparent deficit of the herbicide tolerant DH lines in the crosses with the transgene ‘T177’ is likely due to differential selection against the gametes carrying ‘T177’ during microspore culture. The linkage was strong between blackleg resistance and the transgene ‘Rf3’ but weak or absent between blackleg resistance and the transgene ‘T177’, suggesting that the two transgenes are probably inserted into distant regions of the genome. The observed linkage offers an opportunity to develop new canola cultivars with both glufosinate tolerance conferred by transgene ‘Rf3’ and blackleg resistance. 相似文献
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Summary Better understanding of the physiological and genetic basis of wheat grain protein will contribute to breeding efforts for this characteristic. This study provides information about plant protein distribution in high and low grain protein winter wheats (Triticum aestivum L.) at different growth stages and its relation to grain protein. Field experiments involved two winter wheats with high grain protein, Redwin and Lancota, and two with low grain protein, Centurk and Brule in two years. Protein content in the head, the upper three leaves, the first and second leaf, and the peduncle were estimated with Near Infrared Reflectance Spectrophotometer (NIR) at five growth stages. High protein cultivars had higher leaf protein at ripe and higher protein content in the heads at most growth stages than low grain protein cultivars. High protein cultivars had lower protein content in the peduncle than low protein cultivars at ripe. Correlation coefficients between plant-part protein and grain protein ranged from 0.48 to 0.87 for the heads, from –0.45 to –0.79 for the peduncle, and from 0.55 to 0.84 for the leaves. A combination of head, peduncle, and first leaf protein at heading was significantly related to grain protein (R2=0.71). Indirect selection for head, peduncle, and first leaf (flag leaf) protein at heading should result in increased grain protein. Recurrent selection for increased grain protein, with parent selectionbefore anthesis and hybridization should be successful. 相似文献
128.
改进Hargreaves模型估算川中丘陵区参考作物蒸散量 总被引:3,自引:2,他引:3
为提高Hargreaves-Samani(HS)模型参考作物蒸散量(ET0)计算精度,该文基于贝叶斯原理利用川中丘陵区1954-2002年逐日资料对其温度指数、温度系数和温度常数进行改进,并使用2003-2013年资料以Penman-Monteith(PM)模型为标准评价HS改进模型计算精度与适应性。结果表明:HS改进模型参数在川中丘陵区各区均小于联合国粮农组织推荐值,并呈现出随纬度上升而增大的趋势;与PM模型计算结果相比,HS改进模型计算的ET0相对误差在川中丘陵区北部从14.2%~60.9%降至-1.1%~33.4%、中部从40.6%~92.6%降至16.9%~61.1%、南部从31.3%~96.0%降至8.5%~64.4%、整个川中丘陵区从32.1%~82.7%降至9.5%~52.6%;相关性分析表明,HS改进模型和PM模型计算的ET0回归曲线的斜率更接近于1(北部1.16、中部1.02、南部0.99、全区1.13),决定系数均达到0.85(P0.01)以上;趋势分析表明,HS改进模型和PM模型计算的ET0变化一致,年内均呈开口向下的抛物线状,年际均呈微小上升趋势。因此,基于贝叶斯原理改进的HS模型在川中丘陵区不同区域变异性较小,适应性较强,具有较高的计算精度,可作为川中丘陵区参考作物蒸散量简化计算的推荐模型。 相似文献
129.
基于四维变分和集合卡尔曼滤波同化方法的冬小麦单产估测 总被引:1,自引:5,他引:1
为了通过数据同化方法提高冬小麦的估产精度,以陕西省关中平原为研究区域,采用标定的CERES-Wheat模型模拟8个典型样点冬小麦整个生育期的叶面积指数(LAI),通过四维变分(4DVAR)和集合卡尔曼滤波(En KF)2种同化算法同化CERES-Wheat模型模拟的LAI和遥感数据反演的LAI,获得单点尺度的LAI同化数据,将单点尺度的LAI同化值扩展到区域尺度,对两种同化方法的单点尺度和区域尺度的同化结果进行对比与分析。结果表明,两种同化方法均能综合遥感反演LAI和模型模拟LAI的优势,使LAI同化值更符合冬小麦LAI的实际变化规律;在单点尺度和区域尺度上,En KF-LAI均更能反映关中平原冬小麦的实际生长状况。采用En KF-LAI构建关中平原冬小麦估产模型估测2008年和2014年的冬小麦单产,通过实测单产对估产模型进行验证,结果表明,2008年样点估测单产与实测单产的相对误差均小于15%,部分县估测单产与实测单产的相对误差均小于10%;与2014年模拟单产与实测单产间的相对误差相比,估测单产与实测单产间的相对误差降低0.57%~9.30%,RMSE降低217 kg/hm2,其中,8个样点的估产精度达到94%以上,表明组合估产模型的估产精度较高。 相似文献
130.