Gram行列式在欧氏空间中几个重要结论

文章利用Gram行列式刻画了Euclid空间中的一系列重要的度量概念如向量到线性子空间的距离,向量与子空间的夹角,向量到线性流形的距离.     

日本水稻生产现况及其启示

日本是发达的工业国家,其农业生产总值仅占国民生产总值的1.5%.但水稻生产在日本仍具有重要的意义,在过去的几十年里,日本政府对水稻生产采取严格的保护与支持政策.在贸易自由化、经济全球化的背景下,日本水稻政策面临着巨大的挑战.为了提高日本稻米的国际竞争力,日本政府开始改革国内水稻支持政策,取消了价格管制,更多地采用了市场化的手段来管理水稻生产.本文讨论了日本水稻生产的现况及其支持政策,并就我国的水稻生产支持政策的制定提出了建议.     

PROVENANCE TEST OF SCA-BUCKTHORN GEOGRAPHY

INTRoDUCTIONSca-buckthorn(HtwopherhamnoidesL,)isashrubofoleastorfamily(Elaeagnaceae)'Thereareabout7OoOOhm2naturalforestinthe#threenorth'areaofChina.Nowartificialforestisdevel-opingatthespeedof7oooohm'everyyear,whichp1aysaimportantpartinimprovingthe1ocaleco-environment.Distributionofsca-buckthorniswideinChina.Becauseofdifferentgeographicandecologicconditions,manydifferentpopulationswereformed.Itisdutyofprovenancetesttocompareandchoosethesepopulations.Chinesescholarshavestudiedbiologica…     

Effects of physical attributes and chemical composition of novel foods on food selection by Norway rats (Rattus norvegicus)

An organism’s food is a fundamental aspect of its survival niche. Free-ranging rodents are presented regularly with different types of novel food. To investigate the novel food selection process in Norway rats concerning chemical and physical characteristics, 288 laboratory bred Norway rats (Rattus norvegicus) were tested with a 2-h free choice for each animal. First, rats were tested against eight kinds of novel foods: corn, beans, broiler ration, soybeans, peanuts, rice, potatoes, and millet. Rats preferred corn over the other novel food types, and there was a significant positive correlation between the selective coefficient and carbohydrate content; rats chose novel food with highest energy content. Rats also appeared to be less neophobic to foods of high sugar content. Regarding physical characteristic, rats effectively differentiated between spectral colors of different wavelengths, and red-colored food was more attractive for rats than foods of four other colors. Small-sized food received the highest numbers of visits and longest feeding bouts compared to other sizes. These results suggest that the carbohydrates content, red color, and small size of novel food play a role in the novel food selection of Norway rats.     

核桃专用生物-有机-无机复混肥对核桃种植的影响

目前核桃专用肥以复混肥搭配有机肥为主,肥料利用率较低,且会造成肥料浪费,增加施肥成本;本研究结合核桃需肥规律和核桃主产区土壤养分情况,针对核桃专用肥的施用现状在云南核桃主产区进行生物-有机-无机复混肥的应用研究,旨在提高肥料利用率、减少肥料施用量和提高核桃产区土壤微生物活性;在肥料施用期间检测土壤微生物情况以及功能菌株...     

小作物用农药登记管理研究

本文研究了小作物概念及重要性,国外小作物分类及小作物用农药登记管理现状,指出了我国在此领域的现状与存在差距,并提出了建议。     

利用生物性状检测青蒿的遮阴性能

试验采取盆栽,三次重复,以2个不同青蒿为材料,在遮阴和正常两个条件下,利用生物性状检测青蒿的遮阴性能。结果表明,遮阴条件下,青蒿地上部干重、地下部干重、株高、叶面积、叶绿素含量、类胡萝卜素含量和青蒿素含量均减少,经过方差分析,2个青蒿材料各项指标遮阴和正常两个条件下差异显著, 青蒿叶片青蒿素与地上部干重、叶绿素含量和类胡萝卜素达1%显著相关。     

棉花产量育种的数量性状分析

产量是棉花育种的主要目标之一，为提高棉花产量育种效率，本文从产量结构模式、产量与其构成因素的相关关系两方面，分析了与棉花产量育种有关的数量性状，并讨论了提高棉花产量遗传潜力的可能性     

浙江大盘山国家级自然保护区野果资源食用开发价值评价

为对野果资源的食用开发提供评价和筛选依据,应用层次分析法构建野果资源食用开发价值综合评价模型,并对浙江大盘山国家级自然保护区常见的40种可食用野果进行评价和筛选。结果表明,野果资源食用开发价值的标准层指标的综合权重值为风味口感(0.2674)>营养保健(0.1245)>贮藏难度(0.0884)>结果产量(0.0733)>适应能力(0.0658)>驯化技术(0.0658)>观赏价值(0.0590)>资源储量(0.0442)=新颖程度(0.0442)>产品卖相(0.0368)=食用风险(0.0368)>繁育特性(0.0329)>采食时间(0.0314)>药用价值(0.0295)。经筛选,三叶木通(Akebia trifoliata)、南五味子(Kadsura japonica)、蓬蘽(Rubus hirsutus)等5种野果被评为I级开发利用对象;插田泡(Rubus coreanus)、木通(Akebia quinata)、中华猕猴桃(Actinidia chinensis)等14种野果被评为II级开发利用对象;北枳椇(Hovenia dulcis)、君迁子(Diospyros lotus)、珍珠栗(Castanea henryi)等9种野果被评为III级开发利用对象;高梁泡(Rubus lambertianus)、野山楂(Crataegus cuneata)、山樱花(Cerasus serrulata)等12种野果被评为IV级开发利用对象。