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41.
以川芎(Ligusticum chuanxiong Hort.)的根、茎、叶及其对应的愈伤组织为试验材料,研究不同浓度的卡那霉素对其诱导和生长的影响。不同的外植体对卡那霉素的敏感度不同,根的敏感度高于茎,茎的敏感度高于叶片。方差分析和总体观察的结果表明,在川芎的遗传转化中,卡那霉素的最佳抗性筛选浓度范围为20~40 mg/L。  相似文献   
42.
选用18只分3组处理(分别在鸡、狗日粮中添加蜂胶、芦荟粉和金霉素)的45日龄肉鸡、60日龄狗,停药(金霉素)12小时取样,对比研究抗生素及其替代品对其铬含量的影响。用石墨炉原子吸收法测定出用蜂胶、芦荟粉和金霉素饲喂的鸡(狗)肉中铬含量均低于我国无公害畜禽肉安全要求(GB18406.3—2001)中规定的铬的最高限量,且3组肉鸡(狗)中铬含量无显著性差异。  相似文献   
43.
The Representative Soil Sampling Scheme of England and Wales has recorded information on the soil of agricultural land in England and Wales since 1969. It is a valuable source of information about the soil in the context of monitoring for sustainable agricultural development. Changes in soil nutrient status and pH were examined over the period 1971–2001. Several methods of statistical analysis were applied to data from the surveys during this period. The main focus here is on the data for 1971, 1981, 1991 and 2001. The results of examining change over time in general show that levels of potassium in the soil have increased, those of magnesium have remained fairly constant, those of phosphorus have declined and pH has changed little. Future sampling needs have been assessed in the context of monitoring, to determine the mean at a given level of confidence and tolerable error and to detect change in the mean over time at these same levels over periods of 5 and 10 years. The results of a non‐hierarchical multivariate classification suggest that England and Wales could be stratified to optimize future sampling and analysis. To monitor soil quality and health more generally than for agriculture, more of the country should be sampled and a wider range of properties recorded.  相似文献   
44.
新疆不同河流斑重唇鱼(Diptychus maculates)形态特征比较研究   总被引:2,自引:0,他引:2  
运用聚类分析、单因子方差分析和主成分分析对伊犁河、塔什库尔干河和托什干河3个群体斑重唇鱼(Diptychus maculates)10个可数性状和11个可量性状进行比较分析.可数性状聚类分析显示塔什库尔干河群体与托什干河群体首先聚在一起.然后与伊犁河群体聚在一起.可量性状单因子方差分析和多重比较结果显示伊犁河群体与塔什库尔干河群体和托什于河群体分别在6个和8个变量上存在差异,要大于塔什库尔干河群体和托什干河群体之间4个变量的差异.对所有性状的主成分分析显示3个群体在主成分1上分化较明显,其中塔什库尔于河群体和托什干河群体关系较近,伊犁河群体与上述两群体关系相对较远.结果表明伊犁河与塔里木河水系的斑重唇鱼存在形态分化.  相似文献   
45.
The objective of this study is to clarify the performance of the Global Positioning System (GPS) in forested areas after selective availability (SA) was turned off. In this study, we conducted a field test on horizontal and vertical positional errors of GPS positioning at different points in forested areas. The precision and accuracy of GPS positioning at different points were then calculated and compared. Furthermore, the effect of differential GPS (DGPS) on precision and accuracy was analyzed using analysis of variance (ANOVA), and the necessity for DGPS after SA was turned off was discussed. As a result, the largest horizontal precision errors were found to be in the plantation forest, followed by the natural forest and forest road. On the other hand, precision errors were smallest at the landing, around which there were no obstacles. Horizontal accuracy errors were greatly improved by using the DGPS. Large vertical precision errors were produced in the plantation forest, on the forest road, and in the natural forest, while those at the landing were much smaller. Vertical accuracy errors were also relatively small at the landing. In conclusion, tree canopies greatly affected precision errors, and the DGPS improved not horizontal precision but horizontal accuracy. The autonomous GPS is sufficiently useful for purposes in which horizontal positional errors of a maximum of 10m are allowable. However, the DGPS should be used for surveying and mapping, for which higher accuracy is necessary.  相似文献   
46.
数量性状基因图谱构建方法的比较   总被引:24,自引:1,他引:24  
应用方差分析法(ANOVA)、区间作图法(IM)和复合区间作图法(CIM),分析玉米组合Ki3×CML139的F_2群体有关玉米螟抗性、株高和穗位高的数量性状基因(QTL)图谱。结果表明:(1)在同一显著水平下(。=0.0032),ANOVA共发现25个QTL,而IM为21个,CIM为23个。说明ANOVA虽然难以精确标定QTL的位置,但其发现能力仍可能是最高的。(2)在总共发现的30个QTL中,3种方法都发现的有15个,两种方法共同发现的有9个,仅由一种方法发现的有6个,说明3种方法的同一性仍是主要的。值得注意的是CIM法单独发现的QTL达4个之多,但其可重复性尚待验证。(3)3种方法估计的QTL的平均加性效应(?)和显性效应(?)均无显著差异,而且方法间变异大多小于方法内变异。(4)建议以几种方法构建QTL图谱,并优先标定共同发现的QTL;QTL的效应可以合并估计。  相似文献   
47.
We consider two questions important for applying analysis of variance (ANOVA): Should normality be checked on the raw data or on the residuals (or is it immaterial which of the two approaches we take)? Should normality and homogeneity of variance be checked using significance tests or diagnostic plots (or both)? Based on two examples, we show that residuals should be used for model checking and that residual plots are better for checking ANOVA assumptions than statistical tests. We also discuss why one should be very cautious when using statistical tests to check the assumptions.  相似文献   
48.
固定裸沙地粗糙度动力学特性的分析与研究   总被引:4,自引:0,他引:4  
主要利用曲线拟合的方法,结合野外实测数据计算固定裸沙地的粗糙度,对计算出的粗糙度和风速进行回归分析和方差分析,由此对粗糙度的动力学特性进行分析与研究,结果表明:在下垫面不发生改变的情况下,空气动力学粗糙度与风速的增长呈负相关关系,即粗糙度具有动力学特性。但是由于两者相关程度并不显著,因此在实际工作中可以忽略风速对粗糙度的影响。  相似文献   
49.
A tomato (Solanum lycopersicum L.) crop was grown in four greenhouses during the dry season 2005/06 in Central Thailand. Sidewalls and roof vents of two greenhouses were covered with nets and these greenhouses were mechanically ventilated when air temperature exceeded 30 °C (NET). The other two greenhouses were covered with polyethylene film and equipped with a fan and pad cooling system (EVAP). Overall mean air temperature was significantly reduced by 2.6 and 3.2 °C (day) and 1.2 and 2.3 °C (night) in EVAP as compared to NET and outside air, respectively. Temperature maxima in EVAP averaged about 4 °C lower than in NET and outside. The relative humidity was around 20 and 30% (day) and 10 and 15% (night) higher in EVAP than in NET or outside, respectively. Vapour pressure deficit averaged 0.25 kPa in EVAP, 1.03 kPa in NET and 1.48 kPa outside. The crop water-consumption was significantly lower in EVAP (1.2) than in NET (1.8 L plant−1 day−1), which is ascribed to reduced transpiration in EVAP. Total fruit yield was similar in NET (6.4 kg plant−1) and EVAP (6.3 kg plant−1). The quantity of undersized (mostly parthenocarpic) and blossom-end rot (BER)-affected fruits was reduced in EVAP. However, the proportion of marketable yield was significantly higher in NET (4.5 kg plant−1) than in EVAP (3.8 kg plant−1), owing largely to an increased incidence of fruit cracking (FC) in EVAP. Higher FC but lower BER incidence coincided with higher fresh weight and Ca concentration in the fruits in EVAP. It is concluded that in regions with high atmospheric relative humidity evaporative cooling without technical modifications allowing dehumidification will not improve protected tomato production.  相似文献   
50.
基于响应曲面法的女性假人颈部减速特性建模   总被引:1,自引:0,他引:1  
混Ⅲ5百分位女性假人颈部标定试验中,减速特性遇到问题较多,试验发现标定温度、蜂窝铝孔数及裁剪方式及碰撞速度均会影响颈部标定结果。本文利用中心复合设计,采用响应曲面法建立颈部减速特性模型,同时结合方差分析(ANOVA),详尽分析上述因素对标定结果的影响趋势。进而优化影响参数的选取,从而极大地提高标定效率。  相似文献   
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