《高等数学》统考浅析

考试制度的改革是高等学校教学改革的主要内容之一。华北地区高等农林院校近几年举行了统一命题考试,对考试本身质量的科学评价是改革考试的依据,考试命题的研究及考卷的分析探讨是教学改革的重要课题。本文针对这个问题对河北林学院91级的《高等数学》试卷进行了分析,用考试的效度、信度、区分度和难易度等4个质量指标来评估考试的质量。同时认为通过统考与兄弟院校交流了信息和经验,从而激励和促进了该课程的教学工作,使4年统考成绩呈上升趋势,实际上反映了该课程的教学质量在逐步提高。     

尾张温柑挂树保鲜试验初报

于11月中旬,用200 ppm 2,4-D和150 ppm多菌灵处理果实,挂树保鲜120 d后,稳果率达100%,好果率达99%,果实平均增重4.63%,可溶性糖含量提高2.4%,净增利润1600元/t,但次年减产5.8%     

兔瘟快速诊断的试验研究

使用醛化人“O”型红细胞和白瓷板进行血凝(HA)和血凝抑制(HI)试验诊断兔瘟,1～2分钟即可判定结果,反应时间比常规法缩短60倍。具有快速定性、定量检测的特点。同时该法特异、快速、简易、经济,是一种易于在基层推广应用的新方法。     

Soundscape effects on visiting experience in city park: A case study in Fuzhou,China

The main objective of this study was to reveal the relationships between sound/soundscape perception and public visiting experience in city parks, based on a questionnaire survey of 146 park users in West Lake park in Fuzhou, China. The results indicated that, the three visiting experience indicators, i.e., soundscape tranquil degree (STD), landscape aesthetic degree (LAD) and visiting satisfaction degree (VSD) were positively related with each other, and LAD (correlation coefficients = 0.728, p < 0.01) was more associated with VSD than STD (correlation coefficients = 0.565, p < 0.01). Perception of certain individual sounds was found in close relationships with the three indicators. Specifically, STD showed the most significant relationships with harmonious degree of individual sounds, where perception of traffic sounds showed the most negative effects, while perception of music related sounds and water sound showed positive effects. LAD was more associated with perceived occurrences of individual sounds, where traffic sounds and music related sounds showed the most significant effects again. Both perceived occurrences and dominant degree of individual sounds showed the most and equal relationships with VSD. Specifically, mechanical sounds showed the most negative effects, and dog barking showed significant negative effects too, while music related sounds could be the only kind of sound positively contributed to VSD. Social/demographical/behavioral factors and visit motivations all showed significant relationships with individual sound perception and visiting experience. Considering the effects of all associated factors, key factors were detected for each of the visiting experience indicators. All the three visiting experience indicators showed negative relationships with certain traffic sounds, while tree rustling sound was the only sound showing positive relationship with STD. Age was the most important social/demographical/behavioral factor showing positive relationships with LAD and VSD. The research results provided theoretical references for management and design of soundscapes to contribute to more satisfied experiences in city parks.     

Study on the Characteristics and Interrelationship of Plant Community and Soil in Degraded Alpine Meadow北大核心CSCD

To explore the changes of vegetation and soil characteristics and their relationships in the alpine meadow at different stages of degradation, the plant biomass, species diversity index, soil nutrient, soil physical and chemical properties were measured by the combination of field sample survey and laboratory analysis. The results showed that vegetation coverage, above ground and below ground biomass decreased from slight to severe degradation, the species diversity index, Shannon-wiener diversity index, Evenness index and Simpson index of vegetation community all showed a decreasing trend, and the soil nutrient and physical and chemical properties tended to deteriorate, the decrease of soil moisture and the increase of soil bulk density led to the decrease of biomass. The interaction and interaction between biomass and soil properties can change plant community composition and soil properties and reduce soil nutrient loss in the moderate degradation stage, improving the stability of plant community structure and increasing the diversity of plant community will be beneficial to the restoration of degraded alpine meadow. This study will help to clarify the degradation pattern of alpine meadow in different degradation stages, and provide a scientific basis and theoretical basis for restoring degraded alpine meadow. © 2019 Authors. All rights reserved.     

甘肃牧区牧民对草原生态补奖政策满意度研究

在中国政府致力于完善草原生态补奖机制的背景下,如何权衡牧民禁牧减畜与收入减少之间的矛盾,提高牧民对政策的满意度,是完善草原生态补奖政策亟须解决的关键科学问题。第一轮草原生态补偿政策实施期(2011-2015年)已结束,第二期(2016-2020年)已经开始,评估牧民对第一期补偿政策的满意度,对完善第二期草原生态补偿机制具有重要的借鉴意义。本研究以甘南、肃南和天祝500户牧户为调查对象,采用探索性因子分析,选取牧民社会经济特征、牧民对草原生态补奖政策的感知质量和感知价值3个潜变量,构建牧民对草原生态补偿政策满意度结构方程模型。结果显示,牧民受教育水平越高,获得的草原生态补奖额度越高,其对草原生态补奖政策的满意度也越高。牧民生活与放牧地区自然灾害发生情况,以及水质和水量的下降情况从侧面反映该地区草原生态环境情况。因此,本研究从完善牧区教育机制,强化草原生态补奖政策配套措施建设,鼓励牧民对草场进行科学管理等方面提出增强牧民对草原生态补奖政策满意度的建议。     

高寒草甸退化对优势物种根际土壤微生物量及酶活性的影响

以祁连山东缘的4个不同退化程度(未退化、轻度退化、中度退化、重度退化)高寒草甸为研究对象,测定分析了高寒草甸退化对优势物种和土壤理化性质的影响,以及不同退化程度优势物种对根际土壤和非根际土壤中3大类微生物的数量、微生物生物量(碳、氮、磷)的含量以及酶活性的影响。结果表明:(1)随高寒草甸退化程度的加剧,植物群落多样性呈下降趋势,土壤中有机碳、全氮、全磷和速效磷的含量呈逐渐降低的趋势;(2)随退化程度的加剧,根际和非根际土壤中3大类微生物的数量呈逐渐降低的趋势,并且不同退化程度下根际和非根际土壤中微生物的数量均表现为,细菌>放线菌>真菌;(3)随退化程度的加剧,根际和非根际土壤中微生物生物MBC,MBN和MNP的含量和土壤蔗糖酶、蛋白酶、脲酶、过氧化氢酶的活性均呈逐渐降低的趋势,并且土壤中微生物生物量的含量和土壤酶的活性均表现为根际土壤高于非根际土壤。     

农作物病害流行程度划分标准的方法探讨

农作物病害流行程度划分标准是确定病害流行轻重的主要依据.在研究分析当前病害流行程度划分标准存在问题的基础上,提出病害流行程度划分标准应该由多项指标改为一项指标,分别以相应行政区域的加权病情指数或虫口密度来表示,并给出了其测算方法.同时提出行政区域范围的大小不同,病害流行程度分级标准的指标不同.行政区域小,分级指标值大;行政区域大,分级指标值小.从而解决了目前实际工作中病害流行程度分级标准不规范的问题.