种植密度对贵州春玉米茎秆抗倒伏性能及籽粒产量的影响

为了明确密植条件下春玉米茎秆特性和产量的变化及其相互关系,为贵州春玉米密植高产提供理论依据和实践指导。以贵州广泛种植的玉米品种先玉1171和新中玉801为材料,设置3.0、4.5、6.0、7.5、9.0和10.5万株hm-26个密度,于2018—2019年开展田间试验,研究种植密度对春玉米茎秆形态特征和力学特性、空秆率、倒伏率和产量的影响。结果表明:(1)春玉米株高和穗位高随密度增加先增高后降低;增密后第3节长增幅最大,第3节单位茎长干重、穿刺强度和抗折力,第7节茎粗、干重和横截面积下降幅度最大;密度对茎秆横截面扁率影响不显著。品种之间比较,先玉1171节间长,第3、5节的节间干重和第3节穿刺强度显著高于新中玉801,第7节干重、节间粗、单位茎长干重、节间横截面积、横截面扁率和抗折力显著低于新中玉801。(2)倒伏率和空秆率随密度增加而增大,增密后先玉1171倒伏率显著高于新中玉801,空秆率显著低于新中玉801。(3)产量随密度增加先增加后降低,先玉1171和新中玉801分别在9.3万株hm^-2和8.6万株hm^-2时产量最高。增密后先玉1171比新中玉801增产10.28%,有效穗数和穗粒数更高。(4)相关和多元回归分析表明,株高、穗位高与倒伏率显著正相关,节间粗和单位茎长干物质对玉米茎秆抗折力的正向影响显著。产量与茎秆性状密切相关,株高对产量的正向影响最大。可见,不同春玉米茎秆抗倒伏性能和籽粒产量对密度的响应有差异,新中玉801增密后茎秆节间短而粗,单位茎长干重较大,抗倒伏能力较强。而先玉1171由于在高密度下空秆率比新中玉801低,有较高的有效穗数和穗粒数,因此高密度下产量更高。综合考虑茎秆性状和产量,先玉1171和新中玉801在贵州适宜密度分别为9.0万株hm^-2和8.5万株hm^-2。     

A Constitutive Model for Structured Clays based onTwo Different Types of Overconsolidation

Structure has a major influence on the stress strain relation of soil, which implies that the constitutive model should reflect the its structure. Based on the investigation , the over consolidation (OC) of the soils was made up of two different types, which were structure induced OC and stress induced OC. And then the structure induced OC and stress induced OC were united. Structure induced OC index was used to represent the degree of structure and the cam clay model was extended. The shape of the yield surface was the same as cam clay model, whise the size was equal to the sum of the structure induced OC and stress induced OC. And the change in size of the yield surface was decerminated by the volume harden function and the structural damage function. The associated flow rule was adopted in the model. Afterwards constitutive model for structured clays was presented. The concept of the model is clear and the parameters are simple. The ability of the model is good by firstly application and it can describe the character of the structured soils.     

Thermal Performance and Energy Analysis of Green Roof

Energy consumption and thermal parameters of green roof and bare roof were measured in the air conditioned and nature indoor environment in summer.It was found that the heat flow of green roof was reduced about 70%, and additional equivalent thermal resistance of green roof was about 1.0 m2·K/W in the air conditioned,cooling efficiency of green roof was about 111% in the nature condition.     

Analysis of plastic flow characteristics based on bridge steel 16Mn ratcheting

Abstract:The analysis of the plastic flow characteristics on the basis of the ratcheting experimental results for the bridge steel 16Mn are carried out by calculatig the plastic modulus H and the angle θ between the backstress rate deviator and the plastic flowdirection. The different mechanisms causing uniaxial andmultiaxial non proportional ratchetting are illustrated, that is, the starting and evolution of uniaxial ratchetting is due to the different values of the plastic modulus H at the symmetric loading points with respect to the mean stress. On the other hand, the staring and evolution of multiaxial non proportional ratcheting is driven by H and θ variations. The influence of loading history on ratchetting is the result of the influence of loading history on the angle θ.     

表没食子儿茶素没食子酸酯对大豆分离蛋白凝胶的影响

为改善大豆分离蛋白(SPI)凝胶的强度,在SPI热诱导或酶诱导形成凝胶过程中添加表没食子儿茶素没食子酸酯(EGCG),制备EGCG/SPI凝胶体系.通过表面疏水性、自由巯基含量、内源荧光光谱和圆二色谱分析体系中SPI的结构改变,发现EGCG的添加提高了SPI的表面疏水性和自由巯基含量,蛋白质链展开,出现松弛和拉伸,分子柔性增加.圆二色谱结果表明无序结构(β-转角和无规卷曲)含量明显增加,β-折叠含量明显减少.进一步研究了热诱导和酶诱导下EGCG/SPI凝胶体系的形成作用力、凝胶强度、流变学特性、持水力及表面形貌的变化,结果表明,EGCG的添加增强了热凝胶中的氢键、疏水相互作用和二硫键,EGCG/SPI凝胶具有更高的持水力、凝胶强度和储存模量,以及更为紧密的三维网络结构.     

不同矿化度咸水灌溉对小麦生长及产量的影响研究

为了研究小麦对不同矿化度咸水灌溉的综合反应,于2007-2008和2008-2009年度在河北省农林科学院旱作农业研究所试验站,分别采用1(CK),2,4,6,8 g/L 5个矿化度咸水对石家庄8号、衡观35、山融3号、衡观136和沧6004 5个小麦品种进行灌溉研究。结果表明,小麦的株高、生物量、叶面积和群体随灌溉水矿化度增高而降低;比叶重(叶片厚度)、叶绿素含量以及千粒重随灌溉水矿化度增高而呈现升高趋势。这一研究结果表明,可以利用适度的咸水一定程度上塑造合适的株型。灌溉水的盐分对小麦群体的影响是造成产量降低的重要原因,采用具有一定株高和分蘖成穗率强的小麦品种,适当加大播量是提高咸水灌溉小麦产量的重要手段。     

Web和“3S”技术在森林防火指挥中的应用研究

森林防火的信息化、网络化、数字化已成为当今森林防火工作发展趋势。笔者介绍了利用Web和3S技术,结合森林防火专业知识,在森林防火指挥中的应用。     

显齿蛇葡萄组培育苗试验

为增加显齿蛇葡萄的繁殖速度,通过组培试验培养显齿蛇葡萄无病毒苗,结果表明:显齿蛇葡萄外植体脱分化以MS+6-BA1.5mg.L-1的浓度的愈伤组织生长最快;在显齿蛇葡萄分化芽的过程中,不同处理组合中以MS+6-BA1.5mg·L-1+NAA0.05mg·L-1表现最好;在显齿蛇葡萄生根培养中,不同处理以1/2N6+6-BA1.5mg·L-1+NAA0.15mg·L-1表现最好。     

广州市龙洞公园的设计理念和特色

基于广州市龙洞公园的悠久历史和区位优势,其设计理念强调挖掘本土文化风韵、开发文化景观、延续生态脉络,在公园设计中包括用地布局、功能结构、景观特色、道路设计、绿地种植、生态工程等方面,均展示了地域文化、生态及艺术的大地景观。     

冲压发动机C/SiC喷管承压失效研究

新型三维编织碳/碳化硅复合材料存在较强的各向异性,而各个方向的性能数据积累不足,复合材料的强度计算方法尚不完善,为了发现新型三维编织碳/碳化硅复合材料在冲压发动机喷管中应用可能遇到的问题,并找到相应地解决措施,开展了这种复合材料应用于冲压发动机喷管的承压强度计算和承压实验研究。对承压实验中出现的低压破坏情况进行了分析,分析了低压破裂的原因,提出了改进措施。分析结果表明:C/SiC喷管喉部密度较低,导致强度较低,承载能力下降,是首次强度验证实验过程中该局部破坏的原因;为提高喷管强度,需要通过其形状设计并控制沉积流场,保证其喉部的沉积密度达到1.9g/cm³以上。对改进后的喷管进行了实验验证,实验结果与计算结果基本一致,满足要求。因此,在实际应用中应对喷管喉部和纵向密度的分布进行工业CT无损检测,确保喷管密度的分布均匀。 