简介：Aredsoil,afluvo-aquicsoilandapermeablepaddysoilwereusedinalong-terminvestigationtostudychangesinnitrificationwithtreatments:1)soilincubation,2)liquidincubationinoculatedwithsoilsamples,and3)liquidincubationinoculatedwithammonia-oxidizingbacteria(AOB)fromthesoils.Thereweresignificantdifferences(P＜0.001)innitrificationratesamongthethreesoilswhenmeasuredfor28daysbyadding(NH4)2SO4attherateof154mgNkg-1drysoiltofreshsoil.However,theamountsofnitrifyingbacteriainthethreesoilswerenotrelatedtosoilnitrificationcapacity.WhenthesoilsamplesortheisolatesofAOBenrichedfromthecorrespondingsoilwereincubatedinliquidwithpH5.8,7.0and8.0buffersand10mmolL-1ammoniumnitrogen,therewerenosignificantnitrificationdifferencesinthesamesoiltypeateachpH.TheabilitytooxidizeammoniathroughAOBfromdifferenttypesofsoilsinahomogeneousculturemediumwassimilar,andthesoilnitrificationcapacitycouldreflecttheinherentpropertiesofasoil.AlteringtheculturemediumpHofindividualsoiltypealsoshowedthatacidificationofanalkalinefluvo-aquicsoildecreasednitrificationcapacity,whereasalkalinizationoftheacidicredsoilandpermeablepaddysoilincreasedtheirnitrification.Forabetterinsightintofactorsinfluencingsoilnitrificationprocesses,soilpropertiesincludingtextureandclaycompositionshouldbeconsidered.

简介：ThegeneticdifferentiationofKoreanpine(Pinuskoraiensis)indifferentaltitudesinChangbaiMountainwasanalyzedbyISSRtechnique,anditwasfoundthatthelevelofgeneticdiversityofKoreanpinereducesalongwithaltitudeincreasinginChangbaiMountain.ThevariationofKoreanpineismainlyfromintra-populationandthereisapositiverelativitybetweengeneticdistanceandverticalgeographicdistanceofKoreanpineindifferentaltitudes.ThegeneticcoherenceshowsthataltitudehaslessinsulationtoKoreanpine.Therefore,itisdeducedthattheterrainformationofverticaldistributionofKoreanpineisaresultofdiffusionfromloweraltitudetohigheraltitudeinthecourseofenlargingitsadaptability.

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简介：Basedonthestrongchelatingpropertyofbathophenanthrolinedisulfonicacid(BPDS)withFe(Ⅱ),rootFe(Ⅲ)chelatereductaseactivityisusuallymeasuredwithaspectrophotometerusingMES(2-morpholinoethanesulfonicacid)orHEPES(2-(4-(2-Hydroxyethyl)-1-piperazinyl)ethanesulfonicacid)bufferinthedarkbecauseofhighautoreductionrateofFe(Ⅲ)inthepresenceoflight.However,theexclusionoflightisinconvenient,especiallywhenanalyzingalargenumberofsamples.TheobjectiveofthisstudywastodevelopanewmethodfordeterminationofrootreductaseactivityundernormallaboratoryconditionsusingasuitablebuffercompositionandFe(Ⅲ)concentrationtoeliminatetheautoreductionofFe(Ⅲ).AmodifiedmethodusingaTris(2-amino-2-hydroxymethyl-1,3-propanediol)bufferatpH7.5insteadofMESorHEPESbufferandadecreasedFeEDTA(Feethylenediaminetetraaceticacid)concentrationof50μmolL-1wasdeveloped.TheautoreductionofFe(Ⅲ)usingtheTrisbufferwasundetectablefortemperaturesat4and28℃andwasalsomuchlowerthanthatusingtheotherbuffersevenwithsunlightduringmeasurementofFe(Ⅲ)reduction.Furthermore,thedifferencesinFe(Ⅲ)reductaseactivityamong5plantspeciesand14redclovercultivars(TrifoliumpratenseL.)couldbeeasilydetectedwiththemodifiedmethod.ThemethoddevelopedinthisstudytomeasurerootFechelatereductaseactivitywasnotonlyeffectiveandreliablebutalsoeasilymanagedundernormallaboratorylightconditions.

简介：异形．英文名称为Pleco，通称是指分类上属于鲶形目（Siluriformes),鲶形亚目（Siluroide),吸甲鲶科(Loncariidae)的鱼而言；在分类上，他们也是不容易鉴定的鱼类之一，除了幼鱼的成长会随着时间的不同而不同，就算是同一种的民鱼，雌雄间的形体．体色花纹．也是差距甚远。

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简介：Effectofdifferentshadinglevels(no-shading,80%shading,and40%shading)onphotosyntheticandstomatalresponsesincottonleaveswereinvestigatedunderconditionsofdifferentsoilwatercontentsinsummermidday.Allcottonleavesexhibitedsimilarbasicresponsestoshading,includingdecreasednetphotosyntheticrates,atendencytodecreaseintranspirationrates,andincreasedstomatalconductanceandintercellularCO2concentration.Theleafconductanceof80%shadedand40%shadedplantsincreasedby28%and16.7%comparedwithno-shadedplantsathighwater,respectively,butthenetphotosyntheticratesof80%shadedand40%shadedplantsdeclinedby50%and14.73%,respectively,Resultsshowedthatcombinedeffectofsoilmoistureandshadingonphotosyntheticandstomatalresponsesincottonleaveswasveryremarkable.

简介：豫石榴四号、五号,是由作者与河南石榴研究协作组继1995年选出豫石榴一、二、三号后,又经过近10年的努力选育出来的2个石榴新品种.豫石榴四号、五号,2004年9月10日在巩义市南河渡镇通过省级专家现场考察鉴定,2005年6月通过河南省林木品种审定委员会审定.目前,已在生产上正式推广应用.

简介：本文描述了研究区吉林省东部山区的地文景观特点和自然植被状况,阐述了生态土地分类的定义、基本特点及发展。根据研究区的地形图和卫片结合试点的劲松林场480个样点植被现状的调查数据,探讨了基于坡度、坡向、植被和海拔的四个分类因素下的5类和15类生态土地类型图。生态分类系统是确定、描述和绘制生态系统类型图的方法。本文研究是生态分类系统在吉林省东部针阔混交林区试验应用的一部分。图5表1参14。

简介：Effectsofcolumntemperatureandflowrateonseparationoforganicacidswerestudiedbydeterminingninelow-molecular-weightorganicacidsonreversed-phaseC18columnusinghighperformaceliquidchromatography(HPLC)withawavelengthofUV(ultraviolet)214nmandamobilephaseof18mmolL^-1KH2PO4buffersolution(pH2.1).Thethermalstabiltiyoforganicacidswasdeterminedbycomparingtherecoveriesoforganicacidsindifferenttemperaturetreatments.Therelationshipsbetweencolumntemperature,flowrateorsolventpHandretentiontimewereanalyzed.AtlowsolventpH,separatioinefficiencyoforganicacidswasincreasedbyraisingtheflowrateofthesolventbecauseofloweringtheretentiontimeororganicacids.Highcolumntemperaturewasunfavorablefortheseparationoforganicacids.Theseparatingeffectcanbeenhancedthroughreducingcolumntemperatureinorganicaciddeterminationduetoincreasingretentiontime.Highthermalstabilityoforganicacidswithlowconcentrationswasobservedattemperatureof40℃-45℃,SensitivityandseparationeffectoforganicaciddeterminationbyHPLCwereclearlyimprovedbyacombinationofraisingflowrateandloweringcolumntemperatureatlowsolventpH.

简介：轰动山东寿光、青州、昌乐的黄皮辣椒好品种，熟性早且果个大，果长28～32cm，单果重120～150g，适于春秋大棚，春拱棚栽培。

简介：Methodsfordeterminingnienelowmolecular-weightoragnicacidsinrootexudatesweredevelopedbyusingreversed-phasehighperformanceliquiedchromatographywithUV(ultraviolet)detectionat214nm.Themobilephasewas18mmolL^-1kH2PO4adjustedtopH2.25withphosporicacidndtheflowratewas0.3mLmin^-1,Theanalyticalcolumnwasareversed-phasesilicabasedC-18column(shim-packCLC-ODS).Therootexudateswerecollectedthroughsubmergingthewholerootsystemintoaerateddeionizedwaterfor2hours,Thefilteredexudatesolutionswereconcentratedtodrynessbyrotaryevaporationat40℃,dissolvedin10mLmobilephase.Thechromatoraphicconditionsoforganicaciddeterminationwereanalyzed.Theresultsshowedthattherewasahighselectivityandsensitivityintheorganicaciddeterminationbyreversed-phasehighperformanceliquidchromatography.Coefficientsofvariationfororganicacieddeterminationwerelowerthan10%exceptlacticacid.Therecoverieswereconsistentlybetween80.1%to108.3%.Detectionlimitswereapproximately0.05to4.5mgL^-1fororganicacidsexceptsuccinicacidwiththedetectionlimitof7.0mgL^-1.Phosphorusdeficiencymaycontributetothereleaseoforganicacidsinsoybeanrootexudatesespeciallymalic,lacticandcitricacids.

简介：2月9日,国务院新闻办公室召开新闻发布会,邀请中央财经领导小组办公室副主任陈锡文就2004年中央1号文件--的有关问题发表谈话.陈锡文说,此次公布的的文件,有两点特别引入注目:一是尽管会议研究了农民增收、粮食安全、农村改革等一系列问题,但文件却突出了促进农民增收这一主题.二是该文件的序号是中共中央2004年第1号文件.这都实际反映了党中央、国务院对农民增收问题的重视程度.

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简介：城市生态廊道是城市生态绿地系统中的重要组成部分，目前我国对于城市生态廊道的概念及其分类体系上还没有统一而明确的说法。因此，本文在明确城市生态廊道的概念基础上，提出城市生态廊道的分类体系，这将对我国城市生态廊道建设具有一定的指导意义。

简介：根据综合顺序分类法，将乐都县天然草地划分为四个类，九个亚类，二十六个草地型。草地类随海拔升高，依次分布着微温微干－微温微润－冷温潮湿－寒温潮湿类草地，呈明显的垂直分布规律。

简介：许多花卉除种名外,还有一类颇受人们喜爱的朗朗上口的别名。这些别名是人们根据花卉的生物学特性通过形象化,具体化,通俗化概括而得出的名称。对一个花卉爱好者来说,了解和掌握花卉别名对认识花卉的开花习性及形态特征有其独到意义。第一类是根据花的形状来取名

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简介：大蒜可分为两个变种,6个品种群,两个变种是双层蒜衣变种和单层蒜衣变种.双层蒜衣变种包括抽薹大蒜品种群,不安全抽薹大蒜品种群及春蒜品种群;单层蒜衣变种包括长叶大蒜品种群,短叶大蒜品种群及多层蒜瓣大蒜品种群.对抽薹大蒜品种群进一步分类可形成3个品种亚群.

简介：丰田2号(试验号浙9102)和丰田5号(试验号浙465),是由浙江省农科院蚕桑研究所20世纪90年代初育成的桑树人工多倍体新品种.据育种单位和浙江桐乡市田间栽培及室内生物测试,丰田2号等多倍体品种的产叶量和养蚕成绩名列前茅,成为当地蚕农竞相推广的首选良种.为将多倍体桑品种新技术成果尽快转化为经济效益,江油从1998年起,从浙江省农科院蚕桑研究所等科教单位引进30余个近年来育成的桑树三、四倍体新品种,近年多年多点的实用经济性状的选拔试验.第一批(1999～2003)8个供试新品种中,以丰田2号和丰田5号达到桑叶增产能力强,养蚕效益高的选拔目标.现简介如后.