播种机参数和打穴铲结构对投种影响的计算机仿真

根据铲式成穴器与倾斜圆盘勺式排种器组合设计成的打穴播种机的结构特点,建立了种子下落过程中运动轨迹的参数方程。以此为基础分析了播种机双向倾角、排种器投种角和打穴铲结构参数对种子在打穴铲内自由下落过程的影响,进而确定了打穴铲几何尺寸的设计原则。     

Comparison of population estimators and indices for monitoring house mice in sorghum crops

House mice (Mus musculus domesticus Schwarz & Schwarz, 1943) are monitored in Australia and China to track changes in mouse population densities and forecast their potential damage to cereal crops. The present study compared population indices based on the number of different mice caught and overall trap success from live-trapping with an oil card index (OC) and a tracking index (T) for monitoring mice in sorghum crops immediately before crop maturation. T was measured as the percentage of track board covered with mouse footprints night⁻¹, and OC as the percentage of card removed by mice night⁻¹. The reliability of these abundance indices was quantified by Pearson correlation coefficient with the trappable population size (Ñ), which was estimated by capture–recapture over eight consecutive nights on 175 × 5 trapping grids, in sorghum crops on two properties on the Darling Downs, Queensland. Because of differences among individual mice in capture probability, Model M_h of program MARK was used to account for such heterogeneity and to estimate the size of each mouse population. The number of individual animals caught was more strongly correlated with Ñ than trap success and, therefore, might be a more reliable index; the data suggest that three trapping occasions provide optimal precision for this index. T correlated significantly with Ñ only at sites where the canopy of sorghum plants was closed, and its use should, therefore, be restricted to this habitat. OC did not correlate with Ñ because none or very little of the cards was eaten at low to moderate mouse densities. T and the number of animals caught over three trapping nights are recommended for monitoring mice in sorghum crops immediately prior to crop maturation.     

我国普通高校田径课程改革的国际化趋势

田径运动课程是世界各国大学体育教育中的重要内容,我国大学更是将田径作为体育教育的基础课程予以开设,但由于教育理念和教学方法等诸方面的原因,田径运动课程并没有受到学生的普遍欢迎。因此,吸取国外大学田径课程改革的成功经验,走国际化的田径课程改革方向就显得十分必要和迫切了。学习和借鉴田径课程改革中国际上的通行做法和积极进行国际间的课程交流是田径课程国际化改革的方向。     

横县茉莉花电子交易与质量安全溯源平台研究

针对横县茉莉花传统交易现状,在分析平台建设需求的基础上,提出了茉莉花电子交易与质量安全溯源平台,通过开发电子交易系统、信息采集发布平台、种植管理系统尧追溯编码系统和追溯查询系统,构建统一安全体系和集成标准体系,实现平台系统间的集成和数据间的无缝对接,对横县取得茉莉花茶市场话语权、规避国内外贸易市场风险、推动横县茉莉花产业健康发展具有重要意义。     

Use of a 3D dynamometric horseshoe to assess the effects of an all‐weather waxed track and a crushed sand track at high speed trot: Preliminary study

Reasons for performing study: Track surface quality is considered a risk factor of musculoskeletal injuries. Ground reaction force (GRF) measurement is a relevant approach to study the interaction between the hoof and the ground. Force plates are not adapted to compare different surfaces at high speed. A 3D dynamometric horseshoe (DHS), using 4 triaxial piezoelectric sensors, has been developed and validated. Objectives: To use the DHS to compare the effects of 2 track surfaces, an all‐weather waxed track and a crushed sand track, on the GRF in trotter horses under training conditions. Methods: The right forelimb of 3 French Trotters was equipped with the DHS. Two tracks were tested in a straight line: a crushed sand track (S) and an all‐weather waxed track (W). For each session, trials were repeated 3 times in a Latin square design. The speed of the runs was set at 10 m/s and recorded synchronously. For each trial, data acquisition was performed at 600 Hz and 10 consecutive strides were analysed. Statistical differences were tested using a general linear model procedure. Results: The amplitude of the maximal longitudinal braking force (Fx) was significantly lower on W compared to S. This event happened about 6% later in the stance phase on W. The magnitude of the GRF at impact decreased on W. The average speed and the mean stance phase duration were not statistically different on both surfaces. The stride length was about 6 cm longer on S. Conclusion and potential relevance: This study demonstrates the ability and sensitivity of the DHS to discriminate track surfaces by measuring the GRF at high speed. These preliminary results show that the loading rate, the amplitude of horizontal braking and shock at impact are attenuated on W, which suggests a reduction of stresses in the distal limb.     

广西百色市“种植-沼气-养殖+灯”生态农业循环模式研究

在总结各地生态型循环农业模式的基础上,探讨了"种植-沼气-养殖 灯"模式的概念、生产流程与循环路径。该模式以种养业为龙头,以沼气为纽带,串联种、养、加工等产业,建立沼气肥全程利用的综合性生态农业生产方式。生产流程包括养猪、养鱼、沼气、果树、诱虫灯、果实套袋等6个环节,循环路径体现了生物链间的联动协调,六位一体,每个环节在空间上互相链接。以百色市右江区四塘镇保安村那利屯作为案例,剖析了这种模式的具体实践与成效,提出了相应的政策启示与建议。     

南岭南坡中段不同群落林下幼树的生物多样性及分布

2008年中国南方特大冰雪灾害对南岭森林生态系统产生严重的影响,冰雪灾害4 a后通过对南岭树木园内不同群落类型林下幼树的调查,分析不同群落林下幼树生物多样性和分布的差异。结果表明:林下幼树胸径主要集中分布在0.61.8 cm间,使群落垂直分层现象更为明显;各群落林下幼树物种的丰富度(S)显著(P>0.05)大于乔木物种的,林下幼树的pielou均匀度指数(J)基本处于0.50.6间,与乔木层无显著差异,乔木层物种丰富度和分布均匀度直接影响林下幼树的生物多样性指标;不同群落类型林下幼树数量分布表现出明显的差异,落叶阔叶林林下幼树株数平均8 870株·hm^-2,常绿阔叶林林下幼树株数平均7 160株·hm^-2,针阔混交林林下幼树株数平均5 920株·hm^-2,其中,鸭公树幼树分别占30.0%,13.3%、9.5%。减去鸭公树种子萌发产生的幼树外,不同群落类型林下幼树株数差异并不显著(P>0.05),动物传播使外源性树种鸭公树的种子在不同群落间散布,而以南酸枣为主要优势种的落叶阔叶林能够引入更多的种子。不同群落林下幼树均呈现聚集分布,其中,大规模聚集的鸭公树和牛耳枫在落叶阔叶林中趋于Poisson分布,而群落内部乔木树种通过种子散布萌发和根蘖萌条产生的幼苗,聚集强度较大。     

柑橘品种抗寒性生理指标的比较研究

在叶片气孔密度、束缚水/自由水和电解质渗透率3个生理指标上对12个柑橘品种进行了抗寒性比较测定。结果表明,气孔密度比较宫本、光明13号、太田柑、大浦抗寒性较强;束缚水/自由水比较宫本抗寒性最强;电解质渗透率比较光明13号抗寒性最强。综合3项指标,光明13号、宫本的抗寒性较强;以叶片电解质渗透率作指标来衡量柑橘的抗寒性,操作较简单、方便,测定结果能准确反映样品抗寒性。     

黄河中下游地区耕地轨迹演变及驱动机制研究——以河南省为例

为探究黄河中下游地区耕地轨迹演变规律,以河南省沿黄地区和非沿黄地区为例,运用变化轨迹方法、景观格局指数和Logistic回归模型进行耕地轨迹演变及其驱动机制的对比分析。结果表明：沿黄地区耕地扩张和缩减幅度高于非沿黄地区,扩张型耕地在沿黄地区主要沿黄河两岸分布,非沿黄地区分布均匀。非沿黄地区缩减型耕地向各行政区的中心集聚,沿黄地区缩减型耕地明显向郑州集聚。耕地是河南省优势景观类型,沿黄地区扩张型耕地和缩减型耕地聚集程度和连通性高于非沿黄地区,但连通聚集增长率低于非沿黄地区。Logistic分析表明,沿黄地区与非沿黄地区的耕地轨迹转化驱动因素略有差异,沿黄地区耕地的扩张对黄河水的依赖性强,非沿黄地区受经济发展和社会生活的影响较大。缩减型耕地在沿黄地区和非沿黄地区的驱动因子基本一致,区别主要在于贡献率的不同。研究结果为保障国家粮食安全及黄河流域高质量发展提供理论依据。     

"刘翔现象"给中国田径的思考与启迪

从刘翔的成功,论述了中国田径运动的发展不能受"人种论"思想的束缚,人种与体育之间的关系服从"人体工效学"的原理。"刘翔现象"为中国田径市场开发、青少年田径运动科学化训练、田径后备人才的培养实行"体教结合"诸方面提供了可借鉴经验和深层次的思考。