Utilizing a DUALEM‐421 and inversion modelling to map baseline soil salinity along toposequences in the Hunter Valley Wine district

In the oldest commercial wine district of Australia, the Hunter Valley, there is the threat of soil salinization because marine sediments underlie the area. To understand the risk requires information about the spatial distribution of soil properties. Electromagnetic (EM) induction instruments have been used to identify and map the spatial variation of average soil salinity to a certain depth. However, soils vary with depth dependent on soil forming factors. We collected data from a single‐frequency and multiple‐coil DUALEM‐421 along a toposequence. We inverted this data using EM4Soil software and evaluated the resultant 2‐dimensional model of true electrical conductivity (σ – mS/m) with depth against electrical conductivity of saturated soil pastes (EC_p – dS/m). Using a fitted linear regression (LR) model calibration approach and by varying the forward model (cumulative function‐CF and full solution‐FS), inversion algorithm (S1 and S2), damping factor (λ) and number of arrays, we determined a suitable electromagnetic conductivity image (EMCI), which was optimal (R² = 0.82) when using the full solution, S2, λ = 3.6 and all six coil arrays. We conducted an uncertainty analysis of the LR model used to estimate the electrical conductivity of the saturated soil‐paste extract (EC_e – dS/m). Our interpretation based on estimates of EC_e suggests the approach can identify differences in salinity, how these vary with parent material and how topography influences salt distribution. The results provide information leading to insights into how soil forming factors and agricultural practices influence salinity down a toposequence and how this can guide soil management practices.     

谷物冷却机回风利用与节能

分析了谷物冷却机采用回风型冷却的节能原理及优点，回风型冷却具有重要的节能意义。     

丰本生力酵素饲喂肉猪试验研究

选用60日龄杜洛克、长白仔猪，Ⅰ组为试验组，Ⅱ组为对照组。对照组饲养基础日粮，试验组在对照组的基础上添加1％的丰本生力酵素。结果表明：平均日增重试验组均高于对照组，其增长幅度杜洛克为13．1％，长白猪为8．12％。饲料转化率差异不显著，但瘦肉率试验组比对照组提高了13．1％。经济效益明显提高，杜洛克试验组比对照组提高了4．8％，长白猪试验组比对照组提高了5．3％。     

环境温度和饲粮营养浓度对生长期母兔代谢能利用率的影响

选用6只9周龄新西兰母兔,评定环境温度和饲粮营养浓度对生长期母兔代谢能利用率的影响。试验在密闭式的小动物呼吸测热柜中进行。分别对处于环境温度为20±2℃和30±2℃,采食两种不同营养浓度的试兔进行测试。饲粮营养水平实测值,分别为12.22kJ ME/g和13.49kJ ME/g;粗蛋白质(CP)分别为17.3％和21.6％;中性洗涤纤维(NDF)分别为23.7％和16.5％。结果表明:环境温度影响试兔的能量平衡,它与采食量间存在着显著的相关。20±2℃时,相关系数r=0.798;30±2℃时,相关系数r=0.875。在本试验设计范围内,饲粮营养浓度并不影响代谢能食入量(ME_I),热增耗(HP)和能量平衡(EB)。当环境温度为20±2℃和30±2℃时,表观代谢能转化率(NE/ME)分别为51％和71％;每天每兔每千克代谢体重代谢能维持需要分别为396 kJ和361 kJ。试验结果认为:环境温度影响营养物质消化率(P相似文献   

不确定度评定方法在汽车事故再现中的应用

介绍了不确定度理论及其评定方法，结合车辆碰撞事故的具体特点，给出了基于能量守恒的车速计算表达式．通过选择适当的输入参数作为不确定因子，分别计算各分量等效速度标准不确定度．考虑不确定度累积和传播，得到车速输出结果的合成标准不确定度和展伸不确定度，以此检验事故再现结果的准确程度．通过具体事故案例的分析计算和计算机检验，验证该方法的适用性．     

不同能量水平对羊生产性能及激素水平的影响

选用山羊和绵羊各21只,研究能量水平对羊采食量(DMI)、日增重(ADG)、饲料转化率(FCR)、胰岛素、生长激素和孕酮浓度的影响。结果表明:绵羊的DMI显著大于山羊的(P<0．05),低能量水平下,绵羊的DMI显著大于山羊的(P<0．05)。绵羊的ADG显著高于山羊的(P<0．05),高能量水平下两种羊的ADG显著高于低能量水平的(P <0．05),FCR在绵羊与山羊之间、不同能量水平之间及互作之间都不显著(P>0．05)。试验前期山羊血清胰岛素水平显著大于绵羊的(P<0．05),在低能量水平下,山羊的血清胰岛素浓度显著高于绵羊的(P<0．05)。试验前期山羊的孕酮水平显著高于绵羊的(P<0．05),高能量水平下的孕酮极显著地高于中、低能量水平下的孕酮(P<0．01),中等能量水平下,山羊的孕酮浓度显著高于绵羊的(P<0．05)。     

不同进食水平对生茸期梅花鹿能量代谢的影响

本试验采用梯度饲养试验、消化代谢试验及呼吸测热试验等方法 ,对成年梅花鹿生茸期能量代谢规律进行了研究。结果指出 :①随着能量进食水平的提高 ,梅花鹿体沉积能显著增加 ;②梅花鹿日产热量与进食能量水平呈强直线相关 ;③甲烷能产生量随着能量进食水平的增加而增加。     

Reproductive roles predict sexual dimorphism in internal and external morphology of lake whitefish,Coregonus clupeaformis

Abstract – The different reproductive roles of the sexes can predict the direction and magnitude of sexual dimorphism of external and internal morphology. Males should have enlarged structures that enhance the acquisition of mating opportunities, whereas females are predicted to have enlarged organs that are associated with the production of eggs. We tested these predictions in male and female lake whitefish, a species in which both sexes have similar overall body size and shape. After controlling for body size, male lake whitefish had significantly longer jaws and pectoral and pelvic fins, larger hearts, and more muscle than females. Sexual dimorphism in relative muscle mass may be one of the most fundamental morphological differences between males and females. Females had relatively heavier livers than males. Because the liver is important for the breakdown of fats and vitellogenesis, selection should favour an enlarged liver in females for the processing of energy and the production of large numbers of eggs.     

永丰草地的类型及其生产力评估

本文描述了甘肃省天祝县永丰草地的主要草地类型、生产能力及利用模式。研究工作显示,草地改良措施,对不同植被的生物量分布,将产生显著的效果。灌溉和施肥,将促进河谷草甸的地下生物量向地上生物量的转化过程。灌溉可使河谷草甸中禾草组分的增加超过50％,使产草量增加50％～100％。上年秋天和当年春天土壤的含水量,是全年产草量的决定因素,其对产草量的重要性超过全年平均降水量的影响。除了植被组分、产草量的变化外,河谷草地在可消化粗蛋白、可消化能、代谢能等方面也有重大变化,9月份与4月份相比,这三项指标分别高出376％、86％和86％。不同年龄组的绵羊饲料消耗显示,7岁羊的饲料消耗是10月龄羊的17倍;但是7岁羊的胴体重量仅是10月龄羊的2倍。根据永丰滩草地、饲草、家畜的这些特点,当地的畜牧业,不应当在毫无经济意义的情况下,保持太多的牲畜头数,优化畜产品生产的最好方法,就是实行季节畜牧业。季节畜牧业(其中繁殖母羊数达67％)与其他草地改良措施相结合,将使该地区单位面积上的绵羊的产肉量提高4.9倍。     

水稻中系8541与中系8240光合特性的比较研究

本文通过光合作用参数的测定,详细的研究了中系8541和8240两种不同产量水平的水稻品种的光合特性.论述了在含等量叶绿素的条件下,中系8541和中系8240之间在对光谱的吸收、叶片的光合作用量子转化效率,叶绿体的PSⅡ(光系统Ⅱ)潜在活性(Fv/F_0)和原初光能转化效率(Fv/Fm等的主要区别.实验结果说明,上述各光合作用参数中系8541都优于中系8240.不仅如此.在Mg~(2+)作用下,Fv/Fo和Fv/Fm比值的提高以及Mg~(2+)对两个光系统激发能分配的调节能力中系8541也强于中系8240.