“葫芦克星”对恶性杂草水葫芦的几个生理指标的影响

采用盆栽试验方法,研究了“葫芦克星”对水葫芦几个生理指标的影响,探讨“葫芦克星”控制恶性杂草水葫芦的机制。研究结果表明,喷施“葫芦克星”后,水葫芦叶片的过氧化物酶（POD）活性、多酚氧化酶（PPO）活性和丙二醛（MDA）含量与水葫芦的胁迫反应是相关的。喷药后,水葫芦叶片POD活性一直处于下降趋势且比清水对照POD活性低,而PPO活性和MDA含量则是先上升后下降且比清水对照高。     

利用链接分析发现中国大学网站的权威网页和中心网页

从中国大学排名前100位的大学中选取36所综合性大学，利用Alltheweb搜索引擎收集网站链接数据，单纯从大学间的网站链接关系出发，得到了权威网页和中心网页。     

软枣猕猴桃新品系—‘蜜玉’的选育

‘蜜玉’是从混合实生后代中筛选出的优良资源,经无性繁殖系统选育出的软枣猕猴桃新品系。果实椭圆形,果皮绿色,光滑无毛,平均单果重12.1 g。果肉绿色,可溶性固形22.5 %,总糖13.4 %,总酸1.06 %,维生素C1050.0 mg?kg-1。口感较甜,香气浓郁,抗寒、抗病能力较强。在吉林左家地区,6月中旬开花,9月初成熟。果实在常温条件下第7天开始软熟,低温（2～4℃）条件下第24天开始软熟。     

夏玉米产量时空变化及气候年型分析

定量分析夏玉米同一品种产量及产量构成要素时空变化,探讨造成产量时空差异的气候年型组合变化特征。基于2004～2013年夏玉米种植区郑单958多点田间试验数据分析表明,夏玉米区域平均产量为9 055 kg/hm~2,年际差为1 635 kg/hm~2,变幅为18.1%;地点差4 258 kg/hm~2,变幅为47.1%。夏玉米区域平均千粒重为313 g,年际变幅为13.1%;地点变幅为27.8%。夏玉米区域平均穗粒数为479,年际变幅为18.0%,地点变幅为38.7%。千粒重的增加导致夏玉米产量显著增加。穗粒数显著降低和时空差异大是造成产量波动和时空差异变幅大的主要原因。夏玉米产量和产量构成要素,低产点受各气候要素变化的影响显著;平产点受温度和日最高温度大于33℃的天数影响显著;高产点受降水影响显著。     

Evolution of spatial structure patterns of city networks in the Yangtze River Economic Belt from the perspective of corporate pledge linkage

The pledge of stock rights is a method for measuring the external horizontal connections of enterprises, which is more suitable to represent the city network compared with the vertical connections of enterprises. Meanwhile, it is greatly significant to express the relationships of regional spaces. The paper characterizes and explores the evolution of urban spatial structure with complex network research methods to enrich the relevant works on city networks in the Yangtze River Economic Belt from 2011 to 2017. The results are as follows: First, from 2011 to 2017, the pledge of stock rights among cities was enhanced significantly, and the trend of the city networks' characteristics become strengthened and more complicated. Second, cities in the Yangtze River Delta have relatively high connection values, however, cities in the western area are holding peripheral positions within the city network. Third, due to the advantages of economic agglomeration and radiation, the provincial capital have become the core nodes in the city network. Fourth, Shanghai, Hangzhou, and Nanjing have dominant positions within city networks in the Yangtze River Economic Belt. Particularly, Shanghai, as one of the leading financial centers in China, has a growing influence on other cities and gradually evolved into a regional growth pole city and the first core city.     

Effects and mechanisms of rural E-commerce clusters on households' entrepreneurship behavior in China

The vigorous development of rural E-commerce reveals a powerful pattern of economic clustering. Recently, many Taobao Villages have formed in more than 80% of the provinces in rural China, and increasingly households are using E-commerce for entrepreneurial innovation in Taobao Villages. However, the effect and mechanism of the Taobao Village model on households' entrepreneurship behavior remain unclear. Using survey data and structural equation modeling, we analyzed the factors of households' entrepreneurship behavior and investigated the mechanism of rural E-commerce clustering on the households' entrepreneurship behavior in Taobao Villages. The results show that: (1) rural E-commerce clusters stimulated entrepreneurial enthusiasm and increased entrepreneurial behavior; (2) local resource endowment, entrepreneurial atmosphere and culture, threshold for entrepreneurship, and demonstrative leadership had significant positive effects on households' entrepreneurship behavior; (3) external environmental support, including government, and external business environment support had significant positive effects on E-commerce development. All these results indicate that rural E-commerce clusters promote households' entrepreneurship behavior.     

PEG-6000模拟干旱胁迫下不同基因型 小麦品种萌发期抗旱性的综合鉴定

为了研究不同基因型小麦品种萌发期的抗旱性,以20个小麦品种为材料,采用质量分数为20%的PEG-6000溶液处理模拟干旱胁迫,测定了芽长、主胚根长、芽鲜质量、根鲜质量、发芽率、发芽势、发芽指数和萌发抗旱指数等指标,通过主成分分析和综合评价值(F值)法对供试材料的抗旱性进行综合评价,并通过测定相关生理指标对评价结果进行了验证。结果表明,PEG-6000胁迫处理后的芽长、主胚根长、芽鲜质量、根鲜质量、发芽率、发芽势、发芽指数均受到抑制,但不同品种的降幅存在显著差异。主成分分析表明,晋麦47、运旱618、长治6406、石4185和旱选10号抗旱性明显强于F值较低的京冬18、石家庄4号、石优20、郑麦366和郑麦9023。相关生理指标测定结果表明,F值较高的晋麦47、运旱618和长治6406的抗旱性要显著高于F值较低的京冬、石家庄4号和郑麦366。这说明基于形态指标的综合评价值法可以有效地对小麦萌发期抗旱性进行鉴定,供试材料中抗旱性较强的品种有:晋麦47、运旱618、长治6406、石4185和旱选10号,抗旱性较差的品种有:京冬18、石家庄4号、石优20、郑麦9023和郑麦366。