多花黑麦草品种在湖南邵阳地区的引种适应性研究

通过对引进的多花黑麦草(Lolium multiflorum Lam.)品种在湖南邵阳地区进行引种栽培后发现,引进品种在鲜草及干草产量等特性上均显著优于对照品种,草产量最高的是安哥斯和MaxImus;鲜草产量分别为154375kg/hm2和149687.5kg/hm2,干草产量分别为25969.9kg/hm2和24290.7kg/hm2。综合各项指标得出安哥斯和MaxImus最适宜在邵阳地区推广种植。     

一年生黑麦草在南方地区引种示范及高产栽培研究

通过对引进的22个一年生黑麦草(Lolium multiflorum Lam.)品种在湖南邵阳地区进行引种栽培后发现,引进品种安哥斯1号、MaxImus、蓝天堂、牧谣、海湾这5个品种在物候期,鲜草及干草产量等特性上均显著优于对照品种和其他引进品种,在湖南邵阳地区适应性表现较优;并进一步通过正交试验摸索出这5个品种的高产栽培技术要点。     

基于数值模拟和风洞试验的分流对冲式集沙仪结构优化设计

集沙仪是研究土壤风蚀必不可少的仪器之一,为提高集沙效率和自动采集数据的准确性,需要不断地对集沙仪进行优化设计.该文以FLUENT软件和微型风洞为试验平台,对分流对冲式集沙仪风沙分离器的排气管直径、排气管长度、排沙口直径、排沙口收缩高度进行了优化设计.数值模拟和风洞试验的结果显示:改进型风沙分离器排气口和排沙口的降速性能与原风沙分离器相比有了明显的提高,强风条件(13.8 m/s)下,排气管直径、长度均为25 mm,排沙口直径、收缩高度分别为75、15ram时,气流对集沙仪自动采集传感器的冲击力最小,排气口最高风速比原风沙分离器降低了7.47％,排沙口最高风速比原风沙分离器降低了35.59％,改进后的集沙仪集沙效率比原集沙仪提高了1.56％.     

Identification of Actinobacillus pleuropneumoniae strains of serotypes 7 and 4 using monoclonal antibodies: demonstration of common LPS O-chain epitopes with Actinobacillus lignieresii

Monoclonal antibodies (Mabs) against Actinobacillus pleuropneumoniae serotype 7 were produced and characterized. Three Mabs directed against surface polysaccharides were selected. One of the Mabs was directed against a capsular polysaccharide epitope (CPS) of A. pleuropneumoniae serotype 7 whereas two other Mabs reacted with different epitopes of the LPS O-chain. One of the latter reacted with the reference strain of serotype 7 and the other one with serotypes 7 and 4. These three Mabs were used to test, by Dot-ELISA, 508 field strains of A. pleuropneumoniae. None of the strains belonging to other serotypes different from serotypes 4 and 7 were positive with the Mabs. Used in combination, the CPS and one of the LPS O-chain directed Mabs were shown to be suitable for serotyping since they detected 100% of serotype 7 strains. In this study, we confirm for the first time that A. pleuropneumoniae serotype 4 is present in North America. Finally, both O-chain specific Mabs also reacted with the O-chain of Actinobacillus lignieresii. The cross-reactivity between the two species was confirmed using sera from pigs experimentally infected with A. pleuropneumoniae serotype 7 and A. lignieresii, using immunoblotting and ELISA. This is the first report of a specific cross-reactivity between the LPS of these bacterial species.     

Modeling height–diameter relationship for <Emphasis Type="Italic">Populus euphratica</Emphasis> in the Tarim riparian forest ecosystem,Northwest China

Modeling height–diameter relationships is an important component in estimating and predicting forest development under different forest management scenarios. In this paper, ten widely used candidate height–diameter models were fitted to tree height and diameter at breast height(DBH)data for Populus euphratica Oliv. within a 100 ha permanent plots at Arghan Village in the lower reaches of the Tarim River, Xinjiang Uyghur Autonomous Region of China. Data from 4781 trees were used and split randomly into two sets:75 % of the data were used to estimate model parameters(model calibration), and the remaining data(25 %) were reserved for model validation. All model performances were evaluated and compared by means of multiple model performance criteria such as asymptotic t-statistics of model parameters, standardized residuals against predicted height,root mean square error(RMSE), Akaike’s informationcriterion(AIC), mean prediction error(ME) and mean absolute error(MAE). The estimated parameter a for model(6) was not statistically significant at a level of a = 0.05. RMSE and AIC test result for all models showed that exponential models(1),(2),(3) and(4) performed significantly better than others. All ten models had very small MEs and MAEs. Nearly all models underestimated tree heights except for model(6). Comparing the MEs and MAEs of models, model(1) produced smaller MEs(0.0059) and MAEs(1.3754) than other models. To assess the predictive performance of models, we also calculated MEs by dividing the model validation data set into 10-cm DBH classes. This suggested that all models were likely to create higher mean prediction errors for tree DBH classes[20 cm. However, no clear trend was found among models.Model(6) generated significantly smaller mean prediction errors across all tree DBH classes. Considering all the aforementioned criteria, model(1): TH ? 1:3 t a= e1 t b?eàc?DBHT and model(6): TH ? 1:3 t DBH2= ea t b?DBH t c ? DBH2T are recommended as suitable models for describing the height–diameter relationship of P. euphratica. The limitations of other models showing poor performance in predicting tree height are discussed. We provide explanations for these shortcomings.     

高职院校开展大学生技能大赛活动研究——以江苏农林职业技术学院为例

技能培养是职业院校的主要教育方式,开展技能大赛则是检验职业院校人才培养质量和教学水平的重要手段.文章以江苏农林职业技术学院开展技能大赛活动为例,分析了技能大赛成绩取得的经验,指出了开展技能大赛的不足,提出通过课堂教学渗透工匠精神、传播媒介宣扬工匠精神、科学备赛践行工匠精神等系列举措培育大学生的工匠精神,成为大学生日后成...     

Load-carrying Capacity Calculate and Analysis of Staging Stake

Falsework is a kind of scaffoldwork using load bearing. It has widely use in scaffoldwork and bridgework and steel construction. For assuring falsework safety on structure construction, it is very important to quickly and accurately calculate falsework. Load - carrying capacity of staging of should be calculate by special design, which is from common used single row or double rows falsework. The authors analyze all kinds of factor and failure mode related to carrying capacity and find the result of numerical list by ANSYS program and code when the parameter of staging is determinated. It has important gaidance role in erection of falsework pole.     

土壤中黄萎菌核的含量对转基因棉花发病趋势的影响

利用土壤稀释法对转基因棉花材料12花龄期、吐絮期、收获期棉花根际土壤0～20 cm耕作层中黄萎菌核的含量和转基因材料7月31日至9月11日每隔10 d的发病情况进行了调查与分析.结果表明,转基因棉花材料12发病情况在7月31日至8月11日表现明显的高温隐症,病指下降,从8月11日至9月11日发病呈一直上升的趋势;每隔10 d转基因材料的平均病情指数分别为44.53;、42.53;、54.50;、61.17;和64.03;,整个调查发病期间呈较明显的双峰趋势.从该材料的根际土壤中分离出的黄萎病菌菌落呈黑色放射状,土壤中菌核含量在调查时期则呈先降低后上升又降低的趋势,调查的三个时期1 g土壤含微菌核量分别为118.80、202.80和105.20个/g.土壤中黄萎菌核的含量与该材料的发病情况有直接的关系,这主要与黄萎菌核的病原特性有关.     

分流对冲式集沙仪设计与性能试验

集沙仪是观测风沙流结构和研究风沙移动规律的必备仪器。针对强风环境下集沙仪内部风沙的有效分离问题,提出了分流气体对冲法,设计了分流对冲式集沙仪,阐述了分流气体对冲法的设计原理和分流对冲式集沙仪的参数分析理论,并在利用Fluent软件对其风沙分离器进行数值模拟的基础上进行了风洞试验验证和性能分析。结果表明,采用该方法的分流对冲式集沙仪具备了较高的降速性能和抗强风性能,排气口风速降幅达88.44%,排沙口风速降幅达90%,保证了集沙仪内部风沙的有效分离,平均集沙效率达90.15%,等动力性达93.27%,符合集沙仪设计的基本原则,制作成本低,能较好地满足风洞试验和风蚀观测要求。