时域反射仪测定高含盐土壤盐分研究

采用室内试验的方法,通过使用时域反射仪(TDR100)测定不同含盐量及不同含水率土样的电导值,与采用电导率仪测定的土壤溶液电导值及烘干法测得的含水率值进行比较。结果表明,它们之间存在显著的线性关系。并根据测定结果得到标定公式,提出使用TDR测定高含盐量土壤含盐量的方法。试验结果可为河套灌区野外测定土壤含盐量提供参考。     

220kV降压变电所电气部分初步设计

变电所是电力系统极其重要的组成部分,其合理设计与建设可以保证供电的可靠性和满足远期负荷的要求。设计一个220kV地区性降压变电所,主要向地方负荷供电。介绍该变电所的原始资料,阐述其电气部分主变压器的选择和电气主接线的拟定设计,为此类变电所的设计提供理论参考。     

Effects of dietary levan on growth performance,nonspecific immunity,pathogen resistance and body composition of orange‐spotted grouper (Epinephelus coioides H.)

This study investigated the effects of levan produced by Bacillus licheniformis FRI MY‐55 on growth performance, intestinal count of viable bacteria, immune status, pathogen resistance and body composition of orange‐spotted grouper (Epinephelus coioides). Orange‐spotted grouper were fed diets supplemented with levan at concentrations of 0 (control), 5.0, 10.0, 25.0 and 50.0 g kg^?1 for 12 weeks. The final weight and per cent weight gain were significantly higher in the 25.0 g kg^?1 levan‐supplemented group than in the control group (p < 0.05). All levan‐supplemented diets significantly decreased the count of total viable aerobic bacteria and Vibrio spp. in the intestines of groupers (p < 0.05). Serum total protein levels, globulin levels, lysozyme activity and survival rate of orange‐spotted grouper after challenge with V. harveyi were significantly higher in the 25.0 g kg^?1 levan‐supplemented group than in the control group (p < 0.05). This study also found that the 10.0, 25.0 and 50.0 g kg^?1 levan‐supplemented diets significantly increased the crude protein level in the body composition of orange‐spotted grouper. Overall, the results of this study indicate that dietary levan (25.0 g kg^?1) could be an effective method for enhancing the growth performance and disease resistance in orange‐spotted grouper.     

高酸海棠苗木抗寒性生理指标的分析

为了研究高酸海棠栽种适宜区域,用高酸海棠新品种‘冰心1 号’、‘红勋1 号’与现有品种‘新苹1号’进行抗寒性比较,以枝条作为试验材料进行低温处理,并根据外渗电导法、脯氨酸及丙二醛(MDA)含量的变化,研究了各样品的抗寒性能。通过试验测定结果可判定3 个样本的相对电导率大小依次为‘新苹1 号’＞‘红勋1 号’＞‘冰心1 号’,脯氨酸含量由高到低的顺序依次为‘冰心1 号’＞‘红勋1 号’＞‘新苹1 号’,MDA含量大小的总体趋势依次为‘红勋1 号’＞‘新苹1 号’＞‘冰心1 号’。总体而言,‘冰心1号’的抗寒性最强,3 个品种的抗寒顺序依次为‘冰心1 号’＞‘红勋1 号’＞‘新苹1 号’。其中‘冰心1 号’与‘红勋1号’都具有较强的耐寒能力,适宜栽种于新疆天山以北及其他寒冷区域。     

高职电工技术教学模式改革的探索

高职院校现已将电工技术这门课程为基础专业课程。掌握好这门课程的基础知识和实践技能,对于高职学生以后进一步学习和以后的发展,将起到非常重要的作用。因此根据当前电工技术这门课程发现比较普遍和严重的问题,结合现实的课程教学内容,笔者将从课程的内容和教学方法、以及教学实践这几方面考虑做出比较符合现在需求的研究和探索。     

中职机电专业理实一体化教学模式探究

笔者阐述了中职机电专业实施“理实一体化”教学的背景和必要性,进而解析了“理实一体化”教学的内涵和作用,针对性提出了中职机电专业进行“理实一体化”教学的策略,以期推动中职机电专业教学的改革。     

The influence of nitrogen and phosphorous status on glyphosate hormesis in Lemna minor and Hordeum vulgare

The herbicide glyphosate has been shown to stimulate growth and photosynthetic capacity of barley and other plant species. The growth increase, however, only takes place under certain, yet undefined, growth conditions. We hypothesise that glyphosate growth stimulation only takes place, when growth is nutrient limited. Nutrient limitation was induced in this study by limiting nitrogen and phosphorous availability. The experiments were performed on hydroponically grown lesser duckweed and barley and on barley in the field. Hydroponic duckweed and barley grown under a range of N- and P-availabilities displayed glyphosate induced growth increases in plants which were slightly stressed by N-deficiency, but not in response to P-deficiency in the case of barley. The growth increase found for P-deficient duckweed was hypothesised to be caused by glyphosate derived P, acting as a nutrient source. No growth increase was found in the 2012 field experiment, which was in contrast to earlier year’s findings. Our hypothesis that nutrient limitation makes plants susceptible to glyphosate induced growth was only confirmed for nitrogen but not for phosphorous and not under field conditions in 2012. Mechanisms related to high C:N ratios might be of importance, as this trait varies depending on N- and P-availability during plant growth.     

传感器不均匀分布对电阻层析成像检测原木内缺陷的影响1）

为研究传感器平面内的分布对电阻层析成像（ ERT）检测原木内部缺陷准确度的影响,以大青杨和杉木原木作为试验材料,改变传感器的分布对原木内部缺陷进行检测,并结合平面几何学和统计学分析实验数据。结果表明：传感器分布的均匀度与图像拟合度呈正相关关系;当均匀度超过0．91时,变异系数小于0．15,图像的拟合度均值达到0．83,所以要提高检测精度需精确均匀布置传感器。     

五种冬季宿果植物抗寒性及电导率变化规律研究

对平枝栒子、小叶栒子、北美海棠、美洲南蛇藤、北海道黄杨5种冬季宿果植物于冬季进行电导率测定。结果表明:各参试树种在整个冬季的电导率呈现明显不同的变化趋势;春季与秋季电导率差值可反映出植物在冬季的受害情况;电导率波动反映出植物对低温受害的调节情况。北海道黄杨抗寒性较强,小叶栒子抗寒性差,平枝栒子、北美海棠、美洲南蛇藤抗寒性一般。