The Non-Linear Finite Element Analysis of Cable Structures Based on Four-Node Isoparametric Curved Element

In this paper,based on the geometric nonlinear behavior of cable structures,a finite element method with four-node isoparametric element was presented,the third order polynomial was used as displacement functions and initial curve of the element.By means of the principle of virtual work and the updated Lagrangian method,the authors derived the finite element equations,and solved them by Newton-Raphson method.The proposed model leads to high precision and can meet the engineering requirements.The model presented in this paper can be applied in the analysis of long-span tension structures,such as cable structures,cable domes and so forth.     

红壤旱地不同农田生态系统结构对玉米病虫害的影响

红壤旱地不同农田生态系统结构对玉米病虫害的影响研究表明,间作、套种可减轻玉米病虫害。晚玉米间作绿豆,玉米纹枯病和玉米小斑病的发病率和病情指数均低于清种玉米。玉米蚜、玉米螟、黄足蠼螋和出尾虫是玉米生长中后期的主要害虫,尤其是玉米螟、黄足蠼和出尾虫直接危害穗部,对产量影响较大。油菜||紫云英／玉米／玉米||绿豆模式玉米害虫种类和数量少,害虫天敌总数多,主要玉米害虫危害率低,适于红壤旱地推广应用。     

山东石灰岩山地的植被结构特征

阐述了石灰岩山地植被结构特征,初步提出了适宜石灰岩山地植被恢复和重建的植物种类。研究结果表明:高位芽植物是灌木层中的优势层片;地面芽植物是草本植物的优势层片;卷柏是地被层的唯一植物,在侧柏纯林和混交林中分布都很广,在林下植物中占有重要地位。沂源县的石灰岩山地以黄荆 酸枣 胡枝子—结缕草为建群种,博山区的石灰岩山地以黄荆 酸枣 胡枝子—结缕草 荩草 白羊草为建群种。在数量和功能上占优势的是灌草丛,这些种类的绝大多数为旱中生植物。两个地区的侧柏混交林与侧柏纯林林下植物种类贫乏,在植物种类组成上,侧柏纯林与混交林没有明显的不同,但也存在某些差异,即同一种植物在不同林分中的重要性不同,具体表现为重要值的排列次序不同。喜光耐旱的植物种类在纯林中的重要程度大,中生的比较耐阴的植物种类在混交林中的重要程度大。     

马铃薯渣果胶多糖分离纯化及结构初探

[目的]初步探索马铃薯渣果胶多糖的一级结构。[方法]采用阴离子交换柱分离,交联葡聚糖凝胶柱纯化,气相色谱,高效凝胶色谱,紫外扫描和红外光谱、高碘酸氧化和Smith降解等方法,对马铃薯渣果胶多糖的一级结构进行了初步推测。[结果]马铃薯渣果胶多糖由酸性糖和中性糖组成,其中大部分为酸性糖,酸性糖分子量为41 161 Da,其中不含蛋白、肽链和核酸,既有五碳糖也有六碳糖,既有吡喃糖又有呋喃糖,其结构分枝很少,既有α-糖苷键又有β-糖苷键,戊糖是以1→2或1→4位键合的,己糖则是以1→4或1→3位键合的。[结论]马铃薯渣果胶多糖是一种结构复杂的以糖醛酸为主的酸性杂多糖。     

大蒜溶液对小鼠小肠黏膜结构、上皮内淋巴细胞和杯状细胞的影响

用组织学和组织化学方法研究不同浓度的大蒜素溶液对小鼠小肠黏膜结构及部分黏膜免疫相关细胞分布与数量的影响.试验选用8周龄BALB/C雄鼠50只,分为5组,每组10只,每组分别饲喂5种不同浓度的大蒜素溶液,每天80ml,实验期为10天.结果显示,1%大蒜素溶液对小鼠小肠肠绒毛长度、V/C比值、黏膜厚度,黏膜免疫相关细胞数量影响最大,对改善和增强小鼠小肠的消化吸收功能,提高肠道的防御能力效果最佳.     

Effect of different carbohydrates on the functional properties of black rice glutelin (BRG) modified by the maillard reaction

The objective of this study was to investigate the effects of the glycosylation of BRG on its structures and functional properties. The glycosylation of BRG was achieved via Maillard reactions with four carbohydrates, including arabinose (AN), sodium alginate (SA), maltodextrin (MD), and lactose (LT), and the corresponding conjugates were named BRG-AN, BRG-SA, BRG-MD, and BRG-LT, respectively. The formation of the BRG conjugates was confirmed by changes in the BRG amino groups, conjugation degree, as well as molecular weight. BRG-AN and BRG-MD presented a significantly higher conjugation degree and lower amino group levels compared to the other two conjugates. Circular dichroism (CD) analysis indicated that all the conjugated BRG displayed markedly decreased levels of β-sheets and increased levels of α-helixes. However, only BRG-AN increased significantly in irregular loops. Results from the Fourier Transform Infrared Spectroscopy (FTIR) analysis indicated that the most apparent changes in the structures of BRG conjugates were evident as absorption peaks at 3389 cm⁻¹, 1528 cm⁻¹, 1230 cm⁻¹, and 953–1180 cm⁻¹. After glycosylation, the solubility, emulsion activity index (EAI), and emulsion stability index (ESI) of BRG were significantly improved. After glycosylation of the BRG, induced by Maillard reactions with four carbohydrates, the denaturation temperature (T_d) and enthalpy (ΔH) change values increased substantially from 90.16 °C to 124.28 °C and 11.01 J/g to 18.43 J/g, respectively. The results indicated that BRG-AN exhibited better solubility, EAI, and ESI than the other BRG conjugates.     

中黑盲蝽在几种寄主植物上取食行为的比较研究

【目的】明确中黑盲蝽在主要寄主植物上的取食刺探行为,为评价寄主抗虫性和寄主选择习性提供方法和依据。【方法】通过EPG技术研究中黑盲蝽在菜豆、苜蓿、甘蓝和小麦以及棉花的生长点、子叶、真叶等器官上的取食特征。【结果】 中黑盲蝽在各寄主上的刺探电位波形由Ⅰ波、Ⅱ波、Ⅲ波和Ⅳ波4部分组成。Ⅰ波表示口针的刺入;Ⅱ波表示口针在撕裂植物组织和细胞,并向外分泌唾液;Ⅲ波表示取食;Ⅳ波表示口针的拔出。中黑盲蝽取食苜蓿和棉花生长点的每次刺探时间、每次刺探中的Ⅲ波时间均显著长于其它测试植物或器官。【结论】发现并定义了中黑盲蝽的四类刺探波（Ⅰ波、Ⅱ波、Ⅲ波、Ⅳ波）。通过比较EPG参数,发现在几种测试植物中,中黑盲蝽喜欢取食苜蓿,而在棉花植株上喜欢取食生长点。     

制图标准中剖面区域、剖切面后结构及断面表示法的商榷

在机械制图的教学实践和机械制图教材的编写过程中,发现技术制图、机械制图标准在剖面区域的表示法不够清晰,相交剖切面后的结构的画法不方便画图以及断面图画法易产生异义等问题,并对此进行了分析,提出自己新的想法.     

掺硅粉水泥与硅质集料界面结构的初步探讨

通过一系列实验数据和曲线说明,掺硅粉水泥与集料的界面结构有所变化,并闸述了变化的原因。实验结果表明:掺硅粉水泥与集料胶结的粘结强度高于硅酸盐水泥与集料胶结的粘结强度;界面区的最薄弱层并不在界面表层,而是在距界面十几微米处。     

落叶松木屑快速热解炭制备活性炭工艺及结构表征

以落叶松木屑快速热解炭为原料,采用水蒸气活化法制备了活性炭,其最佳活化工艺为:温度800℃,时间20 min.该条件下活化得率为51%,活性炭亚甲基蓝吸附值为232 mg/g,碘吸附值为968 mg/g,脱色性能优异.微观结构分析表明,快速热解炭主要由微孔组成,外表面包裹沉积吸附层,活化过程中活化剂能够有效去除沉积吸附...