进口自走式插秧机最适盘土厚度研究

试验通过对进口自走式插秧机的最佳育苗盘土厚度进行研究,分设1.8、2.0、2.5 cm的3个盘土厚度,通过试验比较,得出最适盘土厚度是2.0 cm,该处理的水稻秧苗素质最好,而且机械插秧效果最好,水稻产量最高,产量达到568.7kg/667 m2。     

便携式烟叶厚度电子测量仪的研制

为准确测量烟叶厚度,可靠判别烤烟身份,解决长期以来依靠试验人员感官测量烟叶厚度问题,设计集高精度、小型化和便携于一体的烟叶厚度电子测量仪。该仪器包括机械测量装置和测控仪表,采用智能传感器技术以及后续硬件电路、软件系统实现烟叶厚度的测量。标定传感器,对烟叶厚度仪进行校准试验,接着对烤烟烟叶厚度进行了一天连续测量。结果显示：（1）该传感器的线性度小于1.2%;（2）仪器最大示值误差为4 μm,回程误差为2 μm;（3）叶片厚度值在9∶00左右开始下降,在13∶30-15∶30左右出现极值,在晚间叶片厚度值基本无变化。该烟叶测厚仪能够满足试验人员户外对烟叶厚度的准确测量。     

粒径和包膜厚度对控释肥肥效的影响研究

筛选出适宜制造控释肥料的核芯肥料粒径和包膜厚度,以便达到节省包膜材料用量,降低包膜控释肥生产成本的目的。通过玉米盆栽试验探讨核芯肥料粒径、包膜厚度对玉米地上部生物量、含氮量和氮素利用率、控释肥料肥效的影响。粒径和厚度只有在第一、二造时对玉米地上部含氮量有显著性影响,第三造时无显著影响;粒径和厚度对单造以及三造累计氮素利用率都有显著影响,且包膜控释肥料处理的玉米氮素利用率要高于或显著高于复合肥处理的。核芯肥料粒径对玉米生物量无显著影响,大颗粒可代替小颗粒。包膜处理能显著提高玉米生物量,相对于未包膜的复合肥处理,平均提高了32.6%。     

越南甜竹纤维形态特征的研究

对甜竹原料、甜竹浆的纤维形态进行了研究。结果表明:甜竹原料纤维平均长度为2.37 mm、平均宽度17.91μm、长宽比值132.40;纤维平均壁厚为8.13μm、平均腔径为2.57μm、壁腔比值6.33。研究了在蒸煮过程中纤维形态的变化。结果表明,在蒸煮过程中甜竹纤维长度不断变小,从2.37 mm(原料)到1.79 mm(全浆),减少24%;蒸煮过程中纤维长宽比值也不断缩小,从132.40(原料)到98.89(全浆)。与青皮竹浆、桉木浆(阔叶木)、马尾松浆(针叶木)和麦草浆(草类)的纤维形态相比,甜竹浆纤维长度大于麦草浆纤维,小于马尾松浆纤维,与青皮竹浆和桉木浆纤维长度基本相近,因此甜竹浆纤维属于长纤维范围,是一种优良的造纸原料。     

Field litter thickness assessed by gamma-ray spectrometry

The relationship between forest litter thickness and gamma-ray emissions were investigated using portable field spectrometer measurements along two sites located within the boreal forest of Québec, Canada. Results show that total gamma-ray emissions provide a covariable that is linearly related to litter thickness. This secondary information can be used to increase the precision of the estimations obtained from a cokriging process. Thus, gamma-ray measurements can be incorporated into experimental designs to compensate for a scarcity of measurements.     

纤维板尺寸稳定性研究进展

结合当前纤维板工业迅速发展的实际情况和生产中存在的问题,阐述了纤维板尺寸稳定性差的原因.根据国内外学者的相关研究成果,从原料的酸碱性、胶粘剂、蒸汽处理、水分、热压工艺等方面入手,介绍了干法纤维板尺寸稳定性研究概况.     

弱光胁迫下黄瓜苗期下胚轴性状的遗传分析

【目的】阐明弱光胁迫下黄瓜下胚轴性状的遗传特点。【方法】以耐弱光黄瓜品系M22与不耐弱光黄瓜品系M14及其F1、F2、回交世代（B1、B2）为试验材料,应用F2群体分离分析方法与主基因+多基因模型分析法,于2007和2008年对弱光（日平均光强为100μmol/（m2.s））条件下黄瓜的下胚轴长与下胚轴粗进行遗传分析。【结果】群体分离分析结果表明,黄瓜F2代群体中下胚轴粗和下胚轴长性状遗传变异幅度均较小,其中下胚轴粗在2007和2008年的变异幅度分别为0.258和0.226cm,下胚轴长分别为8.5和4.5cm;广义遗传力较低,其中下胚轴粗在2007和2008年的广义遗传力分别为0.54和0.62,下胚轴长为0.60和0.69,表明不宜在F2代进行性状选择。主基因-多基因遗传分析表明,黄瓜下胚轴粗的遗传受1对加性主基因-加性-显性多基因模型（D₂）控制,B1、B2、F2世代主基因遗传率分别为27.03%,56.25%和60.38%。下胚轴长遗传受加性-显性-上位性多基因（C₀）控制,B1、B2、F2代多基因遗传率分别为74.38%,63.29%和83.37%。【结论】下胚轴粗遗传以主基因遗传为主;下胚轴长性状主要由微效多基因控制,受环境影响很大,不宜进行早代选择。     

Antibacterial properties of PLA nonwoven medical dressings coated with nanostructured silver

In this paper, magnetron sputtering was applied to deposit nano-structured silver films on the surfaces of polylactic acid (PLA) nonwovens, which were used in medical dressings. The influence of the coating thickness of the nano-structured sliver films on the antibacterial property of the nonwovens was studied. The antibacterial properties of the medical dressings were measured by shake flask test. The surface morphology of nano-structured silver films and the grain sizes of silver agglomerates were analyzed by atomic force microscope (AFM). Energy dispersive X-ray (EDX) was employed to analyze the surface elemental compositions. The study revealed that the antibacterial properties were improved as the film thickness increased. AFM images of the coated samples indicated that as the sputtering time prolonged, the film thickness was increased, the film became compacter, and the specific area of the film was also increased. Thus, the release rate of silver ions increased, leading to the improved antibacterial property. It was found that the reduction percentage of both tested bacteria-Staphylococcus aureus and Escherichia coli reached 100 % as the coating thickness exceeded 1 nm.     

管道穿越低等级砂石公路埋深的确定方法

通过对车辆荷载作用下路基的受力分析,提出了管道穿越低等级砂石路时的覆土厚度应大于路基工作区深度。经对不同载重量的车辆荷载所产生的附加应力等指标的计算分析,建议管道穿越低等级公路时应考虑增加管顶的覆土厚度。     

薄果皮甜玉米自交系的鉴定与分级

甜玉米果皮厚度直接决定了子粒的柔嫩度,果皮越厚,柔嫩度越差。因此可以通过测量果皮厚度来间接判断甜玉米的柔嫩度,并通过选育薄果皮的品种提高甜玉米品质。本试验对65份普甜、127份超甜玉米自交系进行了初步果皮厚度测定和筛选,并提出了广州地区甜玉米果皮厚度四级分级标准:薄(X≤75μm)、较薄(75μm95μm),供育种者参考应用。