都市餐饮企业的净菜需求影响因素分析——以北京市为例

净菜的广泛使用能提高餐饮企业的出餐率,减少其后厨面积、劳动用工和厨余垃圾。基于北京地区708份餐饮企业净菜需求的问卷调查样本,运用垄断竞争市场理论和二元选择模型分析了影响餐饮企业净菜使用行为的具体因素。研究发现,对净菜了解程度不够和净菜价格偏高是制约餐饮企业使用净菜的主要因素,具有不同个体特征和环境特征的餐饮企业选择净菜的倾向性不同。建议在餐饮业大力开展净菜宣传科普工作;大力扶持净菜加工企业和发展相关技术支撑体系以降低净菜价格。     

面向园艺专业的园艺植物育种学总论SPOC在线课程建设

小规模在线课程(SPOC)是大规模在线开放课程(慕课,MOOC)与传统线下课堂教学融合的新型混合教学模式。园艺植物育种学总论是研究园艺植物新品种选育与良种繁育原理和方法的一门学科,是园艺本科专业的核心课程。根据园艺专业培养目标,以育种途径为核心,从课程设计理念、课程特点与目标、内容设计、课程考核等方面探讨园艺植物育种学总论SPOC教学的改革与创新。     

农林产品营销理论的形成与发展

农林产品营销理论随着市场营销理论的发展而丰富。分析农林产品营销在西方的形成、发展过程,以及农林产品营销理论在中国的发展与应用,指出我国农林产品营销理论在微观、中观和宏观方面的发展趋势。     

青岛老城区里院街区空间解析——基于城市设计基础理论的分析

“里院”是青岛老城一种特有的居住形式,文章运用图底理论,行为场所理论这些当代城市设计的基础理论,对里院街区空间和里院街区开敞空间进行了分析。保护里院街区空间也不应仅仅停留在物质形态,重点也是要考虑居民的需求,以尊重他们的行为方式作为前提,在此基础上提高他们的生活品质。     

A Study on Urban Land Structure Optimization Model

As far as the urban land structure is mentioned, it means the distribution of urban land among the different industries of the city. The problem of urban land structure is referred as unreasonable allocation of urban land caused by several factors, including the decision making mechanism of old economy and urban development policies. Different from using Fractal theory, Entropy theory and Functional theory, in this paper, with reference to Dissipative Structure Theory, one dynamic, systematic and historical optimization model of Max f(J_i, X_i) with two parameters of J_i and X_i will mainly be set up. This model can be used for analyzing the key factors determining the optimization of urban land structure.     

气候相似理论在引种中的应用与探讨

本文依据《中华人民共和国种子法》对引种的法律界定，并参阅了相关的法律及科技专业书籍，通过在引种实际工作中的不断探索研究，在气象等相关部门的通力合作下，成功地将气候相似理论导入引种中，为科学引种提供了一个思路。     

改进Hargreaves模型估算川中丘陵区参考作物蒸散量

为提高Hargreaves-Samani(HS)模型参考作物蒸散量(ET0)计算精度,该文基于贝叶斯原理利用川中丘陵区1954-2002年逐日资料对其温度指数、温度系数和温度常数进行改进,并使用2003-2013年资料以Penman-Monteith(PM)模型为标准评价HS改进模型计算精度与适应性。结果表明:HS改进模型参数在川中丘陵区各区均小于联合国粮农组织推荐值,并呈现出随纬度上升而增大的趋势;与PM模型计算结果相比,HS改进模型计算的ET0相对误差在川中丘陵区北部从14.2%~60.9%降至-1.1%~33.4%、中部从40.6%~92.6%降至16.9%~61.1%、南部从31.3%~96.0%降至8.5%~64.4%、整个川中丘陵区从32.1%~82.7%降至9.5%~52.6%;相关性分析表明,HS改进模型和PM模型计算的ET0回归曲线的斜率更接近于1(北部1.16、中部1.02、南部0.99、全区1.13),决定系数均达到0.85(P0.01)以上;趋势分析表明,HS改进模型和PM模型计算的ET0变化一致,年内均呈开口向下的抛物线状,年际均呈微小上升趋势。因此,基于贝叶斯原理改进的HS模型在川中丘陵区不同区域变异性较小,适应性较强,具有较高的计算精度,可作为川中丘陵区参考作物蒸散量简化计算的推荐模型。     

Allelopathy variation in dryland winter wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) accessions grown on the Loess Plateau of China for about fifty years

In this study, we investigated the genetic variation of allelopathic potential, its grey correlation with important agronomic characters, and rank analysis on allelopathic stability of fifteen wheat accessions commonly grown in arid regions of the Loess Plateau in China. The genetic variation of allelopathic property in dryland winter wheat showed significant differences between accessions. Allelopathic effects exhibited high heritability (55–95%) throughout the life cycle of wheat. Heritability was highest in the tillering stage and weakest in the seed filling stage. Allelopathic potential varied and was discontinuous throughout the wheat life cycle. Grey correlation analysis indicated a close relationship between allelopathic potential dependant on growth phase and agronomic characters. Allelopathic expression during some growth periods induced a partial correlation effect on some important agronomic characters that affected wheat yield. Allelopathic heritability and its degree of influence on yield were more evident in the vegetative growth stage compared to the reproductive stage. A multiple linear regression was built between allelopathic potential during different growth periods and agronomic characters pursued in wheat breeding. Allelopathic potential had a linear effect on production traits cultivated in wheat breeding. When allelopathic intensity varied from 0 to 1 in the reproductive stage, plant height ranged from 44 to 108 cm, spike length from 6.4 to 9.2 cm, number of spikelets with seeds from 13.4 to 21.0, mean seed number per spike from 41.5 to 50.3 and thousand seed weight from 36.2 to 38.3 g. Based on rank analysis, we concluded that there was a synergistic relationship between allelopathic potential in wheat and genetic, chemical and ecological factors. Triticum aestivum L. ‘No 6 Lankao’ and T. aestivum L. ‘No 22 Xiaoyan’ were identified as stable and relatively strong allelopathic accessions, whereas T. aestivum L. ‘Lankao 95–25’ was a stable but relatively weak allelopathic cultivar. Other varieties showed unstable allelopathic potential.     

中国古代土壤耕作理论和技术的历史演进

“耕为农事之首”,“欲求足食之道,先明力耕之法”。我国古代就高度重视土壤耕作在农业增产中的重要作用,先民们在长期的农业生产实践中,积累了丰富的土壤耕作的经验,并把直观经验上升为土壤耕作理论和技术,本文以历史时代为线索,对我国古代土壤耕作理论和技术的产生和发展及其基本内容进行一些分析和探讨,以期对当今土壤耕作科学具有借鉴意义。     

非统计理论在灰色建模中的应用

为了解决灰色建模过程中利用残差模型来修正原灰色模型的繁琐工作,提出利用稳健估计理论对灰色建模的数据序列进行分析、筛选,找出数据列中存在的不确定信息,并达到直接建立灰色模型的目的。针对数据中存在不确定信息的实际情况,利用非统计理论对所研究的数据序列进行分析,对不确定信息中是否含有误差有一个确切的结论。进而找到一个比较方便而准确的建立灰色模型的方法。