基于结构相似度的关中平原旱情空间分布特征

季节性干旱是影响关中平原农业生产最主要的灾害,研究气候变化背景下的关中平原旱情空间分布特征和变化规律具有重要的科学意义与应用价值。基于关中平原2003—2014年每年3月上旬—5月下旬的旬时间尺度条件植被温度指数(VTCI)的干旱监测结果,采用结构相似度(SSIM)研究关中平原VTCI的空间变化特征及其影响因子。结果表明:关中平原VTCI的空间变化特征具有明显的区域差异性和空间异质性,结构性因素是VTCI空间变化的主要影响因子,总体上受水热、地形分布格局等因素的结构性影响,但微地貌、下垫面覆盖的不同及变化和人为因素导致其主体产生变化。当微地貌、下垫面覆盖类型和人为因素成为主导因子时,结构相似度与其高度相关,对其变化的响应非常敏感。与利用某些指数直接作为干旱的指示因子或构建统计模型分析干旱特征相比,引入研究图像的结构信息的参量SSIM实现了定量、准确、形象地描述干旱的空间分布特征和变化规律。     

田间土壤特性的空间相关结构分析及其分布描述

本文对雄县试区试验田的土壤特性空间变异性进行经典统计分析，并利用地质统计学半方差分析法定量描述土壤特性的空间相关结构，然后使用Ｋｒｉｇｉｎｇ最优内插估值法得到了田间土壤特性参数的空间分布等值图。分析结果表明，该试验田０～１００ｃｍ土壤范围内的平均含水量不仅在整个空间分布上而且在纵横曲型剖面上都呈现出弱变异性，空间相关结构显著，相关距离约６０～８０ｍ。采用上述结论和等值图不但能减少样本采样的数量和密度，还能根据田间含水量的空间分布特征合理布点采样，实施土壤墒情的科学监测。     

邛海盆地土壤氮素空间变异特征与影响因素研究

以西昌市邛海盆地为研究区域,随机均匀布点采集386个耕作层土壤样点,分析化验土壤理化性质,运用地统计学方法和GIS技术研究邛海盆地表层土壤氮素含量的空间变异特征,利用方差分析、缓冲区分析和回归分析定量分析区域内土壤氮素空间变异的影响因素。研究结果表明,研究区表层土壤全氮和速效氮含量分别为(1.85±0.51)g/kg和(138.5±47.7)mg/kg,属较丰富水平,变异系数分别为27.52%和32.24%,属中等差异强度;土壤全氮和速效氮具有中等程度的空间相关性,空间变异均以随机变异为主,具有各向异性特征,在西北-东南方向上空间变异相对剧烈;研究区土壤全氮和速效氮含量总体上呈条带状或斑块状分布特征,高值区主要位于西昌市的东南郊区,并以此高值中心向南、向东和向北3个方向逐步递减,低值区主要出现在邛海北面近湖岸地带。影响因素分析结果表明,土地利用方式、土壤母质、土壤质地、土壤p H值、城镇、河流、邛海湖对土壤全氮和速效氮空间变异具有显著影响,而道路对土壤氮素空间变异影响不显著。     

An entropy approach to spatial disaggregation of agricultural production

While agricultural production statistics are reported on a geopolitical – often national – basis we often need to know the status of production or productivity within specific sub-regions, watersheds, or agroecological zones. Such re-aggregations are typically made using expert judgments or simple area-weighting rules. We describe a new, entropy-based approach to making spatially disaggregated assessments of the distribution of crop production. Using this approach, tabular crop production statistics are blended judiciously with an array of other secondary data to assess the production of specific crops within individual ‘pixels’ – typically 25–100 square kilometers in size. The information utilized includes crop production statistics, farming system characteristics, satellite-derived land cover data, biophysical crop suitability assessments, and population density. An application is presented in which Brazilian state level production statistics are used to generate pixel level crop production data for eight crops. To validate the spatial allocation we aggregated the pixel estimates to obtain synthetic estimates of municipality level production in Brazil, and compared those estimates with actual municipality statistics. The approach produced extremely promising results. We then examined the robustness of these results compared to short-cut approaches to allocating crop production statistics and showed that, while computationally intensive, the cross-entropy method does provide more reliable estimates of crop production patterns.     

基于距离反比法的土壤盐分三维空间插值研究

以新疆兵团一块面积约70 hm2的盐碱地为研究对象,采用EM38与土钻取样相结合的方法得到了126个点不同土层(0~200 cm)的1 386个土壤盐分数据,应用三维距离反比法(3D-IDW)对土壤盐分进行了空间插值,探讨了垂向坐标扩大倍数和搜索点数对插值结果精度的影响。结果表明,研究区0~140 cm土层盐分平均含量较高,为1.84~2.11 g/kg,盐分变异较大,而140~200 cm土层盐分平均含量较低,为1.74~1.79 g/kg。所有土层盐分含量的统计特征值(平均值、标准差和变异系数等)均随土层加深而呈现递减的趋势。土壤盐分实测值和估计值的均方根误差随垂向坐标扩大倍数的增大而减小,随搜索点数的增加而增大,其值在0.1~0.4 g/kg范围内变化,当垂向坐标扩大300倍、搜索点数为6个时,插值效果较优。采用确定的参数对研究区的土壤盐分进行了三维空间插值,结果表明土壤盐分空间分布特征与实测值比较吻合,大部分区域土壤盐分含量小于2.5 g/kg,靠近北部和南部边界区土壤含盐量较低,属于非盐化土区,而大于4 g/kg盐化土主要分布在中间和南部局部区域。研究区80%土壤为非盐化土和轻度盐化土,20%为中度和重度盐化土。影响该区盐化土分布的主要因素有灌溉、局部地形、粘土层位置、地下水埋深和矿化度。当不同方向的取样间距相差很大时,选取合适的垂向坐标扩大倍数和搜索点数对保障3D-IDW法的插值结果精度至关重要。     

云南楚雄黑井古镇景观空间形态解析

黑井古镇在其特有的自然环境和历史发展过程中,形成了独特的自然景观、建筑文化及精神文化。基于黑井古镇的历史沿革,分析了黑井古镇自然景观、总体格局、人工建筑的总体景观特征,同时揭示出黑井古镇＂千年盐都＂的历史地位。从黑井古镇的自然环境空间,人工建筑（包括街巷、建筑、节点）空间,精神文化空间3个方面,描述与剖析了古镇的空间形态以及给人的感受。这将对认识黑井古镇,研究明清时期商业重镇的建设及发展有一定的参考价值。     

Complexity of indica-japonica varietal differentiation in Bangladesh rice landraces revealed by microsatellite markers

To understand the genetic diversity and indica-japonica differentiation in Bangladesh rice varieties, a total of 151 accessions of rice varieties mostly Bangladesh traditional varieties including Aus, Boro, broadcast Aman, transplant Aman and Rayada varietal groups were genotyped using 47 rice nuclear SSRs. As a result, three distinct groups were detected by cluster analysis, corresponding to indica, Aus and japonica rice. Among deepwater rice varieties analyzed some having particular morphological features that mainly corresponded to the japonica varietal group. Some small seeded and aromatic varieties from Bangladesh also corresponded to the japonica varietal group. This research for the first time establishes that the japonica varietal group is a prominent component of traditional varieties in Bangladesh, particularly in deepwater areas.     

Effect of Different Plant Growth Regulators on Callus Induction and in vitro Rapid Propagation of Wild Petunia Juss.

In this study,the seeds of wild Petunia Juss.were used as explants to investigate the optimal condition for tissue culture.Several different kinds and concentrations of growth regulators were adopted to produce more multiple bud clumps,callus or roots in this study.The experiments may provide experimental foundation for the rapid propagation technology and establishment of tissue culture system for wild Petunia Juss.     

山新杨高效组培再生体系的建立

以山新杨(P.davidiana×P.bolleana)叶片为外植体,1/2MS为基本培养基,对适合山新杨叶片再生的生长调节剂6-BA和NAA进行研究。结果表明:适宜山新杨叶片分化培养基是1/2MS+NAA 0.05 mg/L+6-BA 0.5 mg/L;继代抽茎培养基是1/2MS+NAA 0.08 mg/L+6-BA 0.1 mg/L;最佳生根培养基是1/2MS+IBA 0.3 mg/L。     

警惕我国高校教师待遇分化趋向——基于高校行政化、学科分化和资本互化的视角

目前，我国高校教师群体内部不同程度地出现了经济收入和权利地位等待遇分化趋向。高校教师的待遇分化主要体现在“官民”之别、文理之差和资历之异上，其源于高校管理“行政化”、学科分化和个体资本互化等因素合力作用的结果。可以通过“去行政化”、完善考评分配制度等措施来缩小高校内部不同群体间的待遇分化。