非负特征图的列表不完全染色的研究

每一个顶点u∈V(G),若任意给定k种颜色的列表,G都存在一个L-染色,使得G的每个顶点至多有d个邻接点与其染相同的颜色,则称图G为(k,彩*-可选的.文章证明了每个可以嵌入到非负特征曲面的图,若不包含4-圈和7-圈,G是(3,1)*-可选的.     

基于纹理南疆红枣外观品质应用研究

红枣分级技术主要依靠人工分级,造成了生产效率低下,分级精度低。随着无损检测技术发展,利用计算机技术实现红枣的自动分级,已成为较优的红枣分级方法。以南疆红枣外部品质特征为研究对象,应用MATLAB的数字图像处理技术,寻求红枣外部品质特征参数的采集以及分级方法。采用灰度化对红枣图像作预处理以及图像的特征提取,结果表明,该方法可以实现红枣外部特征参数的采集,进而实现南疆红枣的纹理分级,具有实际应用价值,且对今后逐步实现基于机器视觉的红枣外观品质综合分级研究具有指导意义。     

基于学习曲线的生物质成型燃料补贴政策研究

通过对中国生物质成型燃料产业的调研与分析,结合该产业的发展轨迹和国家相关的规划目标,构造中国生物质成型燃料的学习曲线,利用该曲线来预测中国固体成型燃料成本的变化趋势。在此基础上,研究如果2020年我国生物质成型燃料利用量要达到5 000万吨的规模,应该如何量化并制定政府的补贴政策。结果表明,若要在2020年实现将生物质成型燃料的商业化并达到5 000万吨的利用量,生物质成型燃料的成本需降低至462元/吨,此时学习系数为0.509,学习率为70.2%。为促使生物质成型燃料的技术进步和产业化发展,需要在2020年以前对该产业进行财政补贴,最大补贴规模为2016年的6亿元,从2012年到2020年的累计补贴为41.24亿元。     

河西走廊东部初、终霜冻日和无霜期变化特征分析

为了引进适宜作物品种,合理调整种植结构,提高农业产业水平。利用1961—2014年河西走廊东部4个气象站初、终霜冻日（最低地温≤0℃）和年气温资料,采用气候诊断方法,对河西走廊东部初、终霜冻日及无霜期的变化进行了研究。结果表明,在时间变化上,初霜冻日显著推迟,终霜冻日显著提早,无霜期显著延长。初、终霜冻日和无霜期时间序列分别存在8~10年、9~11年和9~10年准周期变化。初、终霜冻日和无霜期均发生了气候突变。受海拔高度、地形地势和植被覆盖的影响,在空间分布上,初霜冻日为山区早于荒漠区早于绿洲平原区,终霜冻日为山区晚于荒漠区晚于绿洲平原区,无霜期为山区短于荒漠区短于绿洲平原区。初霜冻日、终霜冻日和无霜期与年气温和海拔显著相关。     

国家级茶树良种的烘青及炒青绿茶适制性探讨

为筛选适宜制作烘、炒青绿茶的茶树品种,试验分析了‘翠峰’、‘迎霜’、‘舒茶早’、‘凫早二号’和‘祁门槠叶种’等5个国家级良种烘、炒青绿茶的适制性。结果显示：（1）呈味物质含量在5个品种之间存在显著性差异;其中,‘祁门槠叶种’和‘凫早二号’的咖啡碱含量较高,但‘凫早二号’烘青绿茶滋味醇厚,且香气突出;‘迎霜’品种有着较高的酚氨比和酚碱比,其加工为炒青绿茶后,滋味醇厚较爽,且香气较好;‘舒茶早’品种的茶多酚和水浸出物含量较低,虽然其烘青滋味较好,但香气不佳;5 个茶树品种中,烘、炒青绿茶适制性最好的是‘翠峰’品种;（2）本试验分析得出了呈味物质与审评得分的相关性,为今后茶树品种的适制性研究提供一定的经验。     

有机生态型无土栽培的现状与展望

有机生态型无土栽培技术,是无土栽培技术的一种,其能适应当前生态农业及绿色食品发展的需要,只有大力推广有机生态型无土栽培,才能实现传统农业向现代化农业的转变。     

农田土壤水分特征曲线参数拟合及其剖面变异特性研究

在天津农学院西校区和山西大同阳高试验基地,采用环刀取原状土方法分层、分垂直和水平2个方向取土样,采用高速离心机(CR22GⅡ)方法得到了土壤水分特征曲线数据,利用Van Genuchten模型对实测数据进行了拟合,并运用Excel软件规划求解与模式搜索法交替迭代进行参数拟合优化求解。结果表明,根据实测数据所选的参数初始值和优化值之间有明显差异,以残余含水率差异最大,参数n差异最小;参数优化过程中不同参数随迭代次数的增加有不同的变化规律;不同深度的参数优化值有显著差异,不同方向参数值有一定差异;取样误差对参数的优化结果也有一定的影响。     

应用型粮食工程专业特色化发展的思考

介绍粮食工程专业应用型人才的培养目标与要求,从人才培养方案的设计与完善、教学模式的深化和改革、实践教学体系的建立及优化、行业企业共同培养学生新模式的探索及设立、应用型教师队伍的打造及培养等方面,探讨应用型粮食工程专业特色化发展的思路。     

Quantification of Dry-Matter Accumulation and Nutrient Uptake Pattern of Short Day Onion (Allium cepa L.)

Understanding the physiology of dry-matter accumulation and nutrient uptake pattern of an onion crop is an essential criteria for optimizing fertilizer practices. An experiment was conducted to estimate the dry-matter accumulation and nutrient uptake pattern of short day onion. The dry-matter accumulation and nutrient uptake followed the sigmoid growth curve pattern. Uptake of nitrogen and potassium was slow for the first 15 days followed by rapid uptake from 15 to 60 days after transplanting and accounted for 76.2–78.2% of total uptake. Takeup of phosphorus, sulfur, manganese, zinc, and copper uptake was greater during 30 to 75 days after transplanting and accounted for 64.9–70.6% of total uptake. The deficiency of nutrients during these period reduces the crop yield significantly. The dry-matter accumulation and nutrient-uptake pattern reported in this study provide an opportunity for optimizing quantity and timing of nutrient application through fertilizers for short day onions.     

Plant-available water and integral energy for Medicago sativa and Bromus tomentellus in texturally different soils

Soil water availability is very crucial for pasture plants because their growth solely depends on the soil water storage. While plant-available water (PAW) is successfully related to plant growth, it is the energy required per unit mass of water, integrated over the PAW range, named the integral energy (E_I) that determines how easily plants can take up water from the soil. The soil water retention function was integrated over the PAW range to calculate the E_I. PAW and E_I were determined for Medicago sativa (alfalfa, a legume) and Bromus tomentellus (a grass) species in five texturally different soils of semi-steppe rangeland in central Zagros, western Iran. The PAW was calculated as the difference between field capacity and permanent wilting point (nominal h of 15,000 hPa or actual h obtained from PWP value determined in greenhouse). E_I values were calculated for the nominal and actual PAW values. M. sativa PAW and E_I values were more than those from B. tomentellus, indicating that M. sativa was able to tolerate higher soil matric suctions at similar conditions. Results showed predicting E_I only from basic soil properties is not accurate. PAW and E_I are dependent on plant species and soil type interactions, and environmental compatibility.