农户视角的撤点并校政策认可度影响因素识别研究——基于陕西、宁夏与青海农村调研数据

基于农户视角,对农村中小学撤点并校进程中农户的认可度对该项政策实施效果产生显著的影响进行调研。选取陕西、宁夏和青海14个县共3 731位学生家长的调研数据,采用有序logistic模型,从个人特征、县级政策因素、空间变量以及教育成本4个维度解释农户对撤点并校认可度的影响因素,识别撤点并校进程中农户认可度的关键影响因素。研究结果显示:农户受教育程度和收入水平与政策认可度呈正相关;征求过意见的农户更加赞成学校合并;同时学生教育成本和家校距离的增加将显著降低农户对撤并政策的认可度。因此,考虑西部地区学生的经济承受能力,收入水平较低和距离过远的西部山区村最好能够恢复并保留村小和教学点,未来的学校布局调整需提升农户的参与度。     

石膏纤维板在建筑上的应用

本文结合工程实例对石膏纤维板材在建筑上的应用进行分析，并与现被限制使用的传统实心粘土砖材料进行对比，指出该板材在建材市场的广阔前景。     

边疆少数民族区域森林康养模式研究——以滇东南森林康养公园为例

为探索边疆地区森林康养典型模式,以滇东南森林康养公园为研究对象,调查分析该地开展森林康养活动的可行性,建立滇东南森林康养发展模式。结果表明,试验区的森林覆盖率、大气质量、水质、土壤质量、声音、人体舒适度指数等指标均达到森林康养指标;试验区的地理位置、自然资源、社区发展模式等均适合森林康养业的发展;试验区设计的森林康养模式内容包括森林步道区、森林沐浴区、自然教育区、生态保育区、观景平台区、管理服务区及其它辅助设施等功能区。在滇东南发展森林康养业将获得良好的社会效益、生态效益和经济效益。     

河北省新民居建设满意度影响因素实证分析

以河北省唐山、秦皇岛等地的调查数据为基础,通过排序选择模型,实证分析了河北省农民对新民居建设满意度的影响因素。结果表明:当地农民是否知道所在村整体发展目标、是否担任过村干部、家庭收入水平是其主要影响因素。调查得到的主要启示是:加强宣传力度、增加农民积极性和加大资金扶持力度,对农民的新民居建设满意度的提高有重要意义。     

正整数分拆成公差为偶数的等差分拆

讨论了将正整数n分拆成连续奇数或者连续偶数的分拆,给出了这类分拆数与正整数n的满足一定条件的因数个数之间的关系,并将这些结论作了推广,得到了正整数n分拆成公差为偶数的等差分拆数的结果.     

Partitioning and Prediction of Soil Moisture in Heilongjiang Province

为客观分析黑龙江省土壤水分的特点,以有效利用水资源,实现农业增产,利用黑龙江省32个气象站1981～2009年3～10月降水量、蒸发量、日照时间等气象资料和3～10月逢8观测的土壤重量含水率资料,对黑龙江全省进行土壤分区和土壤水分预报。结果表明：土壤水分的散失与降水、日照、风速等气象条件的变化有较大关系。利用模糊聚类法,划分出黑龙江省5个土壤水分分区;并尝试用逐步回归法建立了春季土壤水分预报方程,经试验预报准确率较高。     

西藏林地功能分区及差别化保护利用探讨

根据西藏的自然环境条件,结合林地保护管理现状,将全区林地划分为4个功能区,并就各区域林地的功能定位、差别化保护利用以及相应的管理措施进行探讨。     

反刍动物泌乳期的营养分配及其调控机制

泌乳期是哺乳动物的一个重要生理时期。随泌乳期开始,动物整体的营养分配和新陈代谢发生显著变化,以满足乳腺的需要。其净影响是乳腺新陈代谢速度和养分利用增加,非乳腺组织养分利用减少。泌乳期动物通过提高采食量或调用体贮来保证养分供给。随着泌乳期开始,肝脏糖异生速度显著提高,肝糖原被动员,葡萄糖氧化减少;脂质代谢速度增快,而脂肪组织中脂质合成速度下降。泌乳期营养分配的主要调节因子是激素。本文最后讨论了泌乳期各生理过程的协调作用,并举例说明了其重要性。     

Kinetics of Uptake and Metabolism of Atrazine in Model Plant Systems

The present work concerns atrazine absorption and metabolism by corn (Zea mays.) seedlings immersed in an aqueous medium in comparison with Acer pseudoplatanus cell cultures. At the point of equilibrium, the apparent concentration inside the A. pseudoplatanus cells (with a moderate lipid content: 0·17% of dry weight) was about twice that of the medium. This equilibrium was probably due to a simple partition process; part of the atrazine was dissolved in the cell water and reached the same concentration as in the external medium while the rest was concentrated inside the cellular lipids. The theoretical calculation of the lipid/water partition, taking into account the value of log P measured not with the lipids but with octanol (log P=2·5), gave a value of 1·5 for concentration inside the plant material. Such an equilibrium, resulting from a partition process between water and lipids, was also obtained in non-living corn seedlings. In living seedlings, an over-concentration of radioactivity due to [¹⁴C]atrazine derivatives was rapidly obtained inside roots and shoots giving concentrations respectively 7- and 12-fold higher than that of atrazine in the external medium. This was due to very rapid chemical transformation of atrazine into its hydroxy derivatives, especially hydroxyatrazine. This hydrolysis of atrazine in corn was due to the presence of high levels of benzoxazinone derivatives in corn seedling cells. The hydroxylated metabolites were able to concentrate in the cells very rapidly and were unable to diffuse freely into the external medium. As a consequence, this process facilitated the penetration of large quantities of atrazine which became rapidly hydroxylated, allowing therefore the passive penetration of atrazine to be further improved, since the concentration C₁ in the receiver compartment was always close to zero. The passive transfer of atrazine, following Fick's law: dq/dt=-Pa (C₀–C₁), was therefore optimized. © 1997 SCI.     

Vegetable production under COVID-19 pandemic in China: An analysis based on the data of 526 households

The COVID-19 pandemic had an enormous impact on the vegetable supply chain in China. Effective evaluation of the pandemic's influences on vegetable production is vital for policy settings to enhance the security of vegetable supply. Based on first-hand data from 526 households, we explored regional differences in different types of loss and potential factors affecting the severity farmer households suffered during the pandemic. The results underline that sales contraction and price volatility in the context of interruption of supply chain dominate the total losses during the pandemic. Such losses differ across provinces and are more substantial in provinces with stricter confinement measures. Farmer households' participation in local market and modern marketing methods helps mitigate the negative effects of the COVID-19 shock, while labor hiring and facilities adoption in production widen the losses due to the shortage in the workforce. In the future, the vegetable industry practitioners and relevant government departments should work together to coordinate the development of short and long supply chains and strengthen the stability and security of the vegetable supply chain.