首页
试卷库
试题库
当前位置：
X题卡
>
所有题目
>
题目详情
平行四边形ABCD中，M是BC的中点，若，则λ+μ＝（ ）
查看本题答案
包含此试题的试卷
高一下学期数学《》真题及答案
点击查看
你可能感兴趣的试题
平行四边形ABCD中E为CD的中点若在平行四边形ABCD内部随机取一点M则点M.取自△ABE内部的概
下列命题①一组对边平行另一组对边相等的四边形是平行四边形②对角线互相平分的四边形是平行四边形③在四边
0个
1个
3个
4个
空间四边形ABCD中若AB＝BC＝CD＝DA＝AC＝BCE.F.G.H.分别是AB.BC.CD.DA
平行四边形
长方形
菱形
正方形
已知在平行四边形ABCD中AB=4BC=6则此平行四边形的周长为.
如图四边形ABCD是平行四边形E.是AD中点F.是BC中点.求证四边形BEDF是平行四边形.
已知四边形ABCD下列说法正确的是
当AD=BC，AB//DC时，四边形ABCD是平行四边形
当AD=BC，AB＝DC时，四边形ABCD是平行四边形
当AC=BD，AC平分BD时，四边形ABCD是矩形
当AC=BD，AC⊥BD时，四边形ABCD是正方形
已知平行四边形ABCD对角线ACBD交于点O.1若AB=BC则平行四边形ABCD是_________
如图3-34所示E.F.分别为平行四边形ABCD中ADBC的中点G.H.在BD上且BG＝DH求证四边
如图在平行四边形ABCD中∠C.=60°M.N.分别是ADBC的中点BC=2CD.1求证四边形MNC
已知园边形ABCD中AC与BD交于点O.如果只给出条件AB∥CD那么还不能判定四边形ABCD为平行四
①②
①③④
②③
②③④
已知四边形ABCD下列说法正确的是
当AD=BC，AB∥DC时，四边形ABCD是平行四边形
当AD=BC，AB=DC时，四边形ABCD是平行四边形
当AC=BD，AC平分BD时，四边形ABCD是矩形
当AC=BD，AC⊥BD时，四边形ABCD是正方形
如图在四边形ABCD中AB//CD若加上AD//BC则四边形ABCD为平行四边形现在请你添加一个适当
已知四边形ABCD下列说法正确的是
当AD＝BC，AB∥DC时，四边形ABCD是平行四边形
当AD＝BC，AB＝DC时，四边形ABCD是平行四边形
当AC＝BD，AC平分BD时，四边形ABCD是矩形
当AC＝BD，AC⊥BD时，四边形ABCD是正方形
已知平行四边形ABCD的对角线交于点O则下列命题是假命题的是
若AC⊥BD，则平行四边形ABCD是菱形
若BO=2AO，则平行四边形ABCD是菱形
若AB=AD，则平行四边形ABCD是菱形
若∠ABD=∠CBD，则平行四边形ABCD是菱形
在四边形ABCD中AC与BD相交于点O.如果只给出条件AB∥CD那么还不能判定四边形ABCD为平行四
3个
4个
5个
6个
如图四边形ABCD是平行四边形E.是AD中点F.是BC中点.求证四边形BEDF是平行四边形.
在平行四边形ABCD中∠BAD=150°AB=8cmBC=10cm求平行四边形ABCD的面积.
如图在平行四边形ABCD中∠C=60°MN分别是AD.BC的中点BC=2CD.1求证四边形MNCD是
四边形ABCD中如果AB＝BCCD＝AD那么四边形ABCD是平行四边形
如图在平行四边形ABCD中E.F.分别是ADDC的中点若△CEF的面积为3则平行四边形ABCD的面积
热门试题
更多
ThismorningIwenttoschoolbyabicycleasusual.AsIamlisteningtomyfavoritemusicwithaheadphoneonmyheadIdidn'tnoticeacarparkedontheroadside.Iscratchedthecarandleftascaronit.ThinkthatIwouldhaveclassesIleftanotewithhisnameandaddresstoletthedriverknowwhathadhappened.Latelyintheafternoonwhenwewerehavingaclassmeetingourheadmasterledinastrangerthatwasthecarowner.Heexplainedtheclassthewholestorybutpraisedme.Myteacherandclassmatewereimpressedandproudofmyhonest.
AsInternetusersbecomemoredependentontheInternettostoreinformationarepeoplerememberless?Ifyouknowyourcomputerwillsaveinformationwhystoreitinyourownpersonalmemoryyourbrain?ExpertsarewonderingiftheInternetischangingwhatwerememberandhow. InarecentstudyProfessorBetsySparrowconductedsomeexperiments.SheandherresearchteamwantedtoknowtheInternetischangingmemory.Inthefirstexperimenttheygavepeople40unimportantfactstotypeintoacomputer.Thefirstgroupofpeopleunderstoodthatthecomputerwouldsavetheinformation.Thesecondgroupunderstoodthatthecomputerwouldnotsaveit.Laterthesecondgrouprememberedtheinformationbetter.Peopleinthefirstgroupknewtheycouldfindtheinformationagainsotheydidnottrytorememberit. InanotherexperimenttheresearchersgavepeoplefactstorememberandtoldthemwheretofindtheinformationontheInternet.Theinformationwasinaspecificcomputerfolder文件夹.Surprisinglypeoplelaterrememberthefolderlocation位置betterthanthefacts.WhenpeopleusetheInternettheydonotremembertheinformation.Rathertheyrememberhowtofindit.Thisiscalledtransactivememory交互记忆. AccordingtoSparrowwearenotbecomingpeoplewithpoormemoriesasaresultoftheInternet.Insteadcomputerusersaredevelopingstrongertransactivememoriesthatispeoplearelearninghowtoorganizehugequantitiesofinformationsothattheyareabletoaccessitatalaterdate.Thisdoesn'tmeanwearebecomingeithermoreorlessintelligentbutthereisnodoubtthatthewayweusememoryischanging. 1Thepassagebeginswithtwoquestionsto. A.introducethemaintopic B.showtheauthor'sattitude C.describehowtousetheInternet D.explainhowtostoreinformation 2Whatcanwelearnaboutthefirstexperiment? A.Sparrow'steamtypedtheinformationintoacomputer. B.Thetwogroupsrememberedtheinformationequallywell. C.Thefirstgroupdidnottrytoremembertheinformation. D.Thesecondgroupdidnotunderstandtheinformation. 3Intransactivememorypeople. A.keeptheinformationinmind B.changethequantityofinformation C.organizeinformationlikeacomputer D.rememberhowtofindtheinformation 4WhatistheeffectoftheInternetaccordingtoSparrow'sresearch? A.Weareusingmemorydifferently. B.Wearebecomingmoreintelligent. C.Wehavepoorermemoriesthanbefore. D.Weneedabetterwaytoaccessinformation.
Iranintoastrangerashepassedby.Ohexcusemepleasewasmy1.HesaidPleaseexcusemetooIwasn'twatchingforyou.Wewerevery2thisstrangerandI.Wewentonourwayandwesaidgoodbye.Butathomea3storyistold. LaterthatdaywhenIwascookingtheeveningmealmydaughterstoodbesidemevery4.WhenI5Inearlyknockedherdown.Moveoutofthe6Isaidwithafrown.Shewalkedawayherlittleheartbroken.Ididn't7howharshly严厉地I'dspoken. WhileIlayawakeinbedthateveningmyhusbandsaidtomeWhile8astrangeryouarepolitebutwiththegirlyouloveyouare9.Golookonthekitchenfloorandyou'llfindsomeflowersbythedoor.Thosearetheflowersshebroughtfor10.Shepickedthemherselfpinkyellowandblue.Shestoodquietlynotto11thesurpriseandyou12sawthetearsinhereyes. 13mytearsbegantofall.Iquietlywentandkneltdownbyherbed.WakeuplittlegirlIsaid.Aretheseflowersyoupickedforme?ShesmiledIfoundthemoutbythetree.Ipickedthem14they'reprettylikeyou.Iknewyou'dlikethemespeciallytheblue. IsaidDaughterI'msorryforthewayI15today.I16haveyelledatyouthatway. ShesaidOhMomthat'sokay.Iloveyouanyway. IsaidDaughterIloveyoutoo.AndIdoliketheflowersespeciallytheblue. Ihadgottheworld17again.I'd18tobepolitetopeopleinthestreet﹣good19makesocietywork.Butastrangerissomeonewemeetonceandthenneverseeagain﹣and20isforlife. 1A.response B.sentence C.answer D.speech 2A.careful B.serious C.polite D.unhappy 3A.Interesting B.different C.similar D.meaningful 4A.excited B.noisy C.upset D.still 5A.called B.turned C.returned D.removed 6A.way B.space C.house D.area 7A.prove B.care C.realize D.understand 8A.referringto B.dealingwith C.listeningto D.pickingup 9A.anxious B.patient C.disappointed D.unkind 10A.us B.you C.thefamily D.herfriends 11A.ruin B.expect C.announce D.handle 12A.seldom B.simply C.never D.even 13A.Bythistime B.Atonetime C.Foratime D.Atthesametime 14A.while B.so C.unless D.because 15A.considered B.developed C.acted D.performed 16A.mustn't B.couldn't C.wouldn't D.shouldn't 17A.clear B.right C.clean D.meaningful 18A.begin B.learn C.change D.continue 19A.manners B.habits C.lifestyles D.behaviors 20A.lover B.companion C.family D.friend
人体骨髓腔中的骨髓幼年时是红骨髓有造血功能成年后转化为黄骨髓失去造血功能．但一次性失血过多时成人的黄骨髓可转化为红骨髓重新恢复造血功能．下列叙述错误的是
TheDanishlifestyleconceptofhyggemeansmanyindescribablefeelingofcomfortablethingstomanypeople.Nowjoinusinvisitingsomeofthebesthyggeplaces. 1.ManhausenManshausenNorway Adventure﹣seekingpeopleneedn'tlookfurtherthanManhausena55﹣acreislandescapeinNorway'sGrotoyastrait.Nottobemissedthesaltwaterhottuboverlookingtheseaandfamily﹣stylemealsenjoyedfiresideatthemainhouse.Thebabysittingservicealsoavailable. Getmoreinformationhere. 2.CedarLakesEstatePortJervisNewYork Occupying500bucolicacresthisturn﹣of﹣the﹣centurysummercampnowhousesahostofluxurylodge﹣stylecabins.Bikethegroundspaddlethelakesswimintheoutdoorheatedpoolorheadtoanearbymountainforadayofskiing.Thenliedownwithagreatbookbeneathafurblanketturnonyourfireplaceandgetyoursnuggleon. Getmoreinformationhere. 3.SohoFarmhouse.OxfordshireEngland ThisOxfordshirecountrysidemembers﹣onlycluboffersupaBritishversionofhygge.AmongthesplendidpropertyscoziestofferingsthecommunityfarmyardandtheStudioCabinguestroomwhichboastsviewsofthelake. Getmoreinformationhere. 4.SaltHouseInn.ProvincetownMassachusetts Thischarmingcoastaltownnowboastsa19th﹣century﹣shingledcottageturnedhotel.Bookyourvisitduringthequietwindsweptoff﹣seasonJanuarythroughMarchforsomesaltyfreshaironthebeach. Getmoreinformationhere. 1Ifyouaretakingababywhichonemaysuityoubest? A.Manhausen. B.CedarLakesEstate. C.SohoFarmhouse. D.SaltHouseInn. 2WhatisspecialaboutSohoFarmhouse? A.Waterscenery. B.Limitedaccess. C.Outdooractivities. D.Family﹣stylemeals. 3Whereisthistextmostprobablytakenfrom? A.Amagazine. B.Abrochure. C.Atextbook. D.Awebsite.
在一定的光照强度和适宜的温度条件下甲乙两种植物的CO2吸收速率随环境CO2浓度变化趋势如下图所示．回答下列问题 1植物叶片光合作用产生的O2中的O来自于填物质当环境CO2浓度为a时O2除部分释放到外界以外还有部分可以参与细胞有氧呼吸与填“NADH”或“NADPH”结合释放出大量能量． 2当环境CO2浓度大于a时甲乙两种植物中对光能利用率较低的植物是．当CO2浓度大于c时限制植物甲光合作用的外界因素主要是． 3空气中CO2浓度为0.03%对植物的光合作用来说一般达不到最大光合速率．农业生产中常常把地块作成几个畦便于灌溉与排水畦是指用土埂沟或走道分隔成的作物种植小区．某地区夏季多为南风若植物甲为夏季生长的高秆经济类植物作畦的走向应为南北走向可以提高作物产量其依据是．
CenterforExcellenceinChildandAdolescentHealthResearch Ourresearchcenterwascreatedtopromotethehealthofbabieschildrenadolescentsandyoungadultsbyadvancingmeaningfulandcreativeclinical临床的research.Throughthiswebsitewebringsparticipantsfamiliesresearchershealthcareprovidersandthecommunityintoourresearchhomewherewecanlearnfromoneanother.Togetherwecanpromotethehealthofchildrenandyouthbyadvancingmeaningfulandinnovativeclinicalresearch. ForFamilies&Caregivers Currentlyguidelinesfortreatingchildrenareoftenbasedondatafromadultstudies.Toimproveclinicalcareofchildrenmorestudiesareneededfocusingonchildren'shealthwiththegoaltobetterdiagnosetreatandpreventthediseasesthatarespecifictochildren.Learnhowyoucanhelpdoctorsandnursesprovidethebestcare. ForTeens&YoungAdults Weneedadolescentsandyoungadultslikeyoutohelpdoctorsandnursesprovidethebestcaretheycan.Doctorsandnursesusewhattheylearnfromresearchstudiestotakecareofpatientsbutmostofthisresearchhasbeendonewithadults.Yourbodiesaredifferentfromolderadultsandyourhealthneedsaredifferenttoo!Weneedyoutohelpuslearnaboutthebesttreatmentsforteensandyoungadultsandyoucanmakeadifference. ForHealthCareProviders Consideringthestateofchildrentreatmentchildhealthresearchisthebestwaytoadvancemedicalcareforchildren.Weneedchildrenofdifferentagesgendersracesandneighborhoodstoparticipateinstudiessodoctorswillknowwhichtreatmentsworkbestforchildren. 1Howwillthecenterpromotethehealthofchildren? A.Byresearchingtheeffectsofadultmedicineonchildren. B.Bycomparingandlearningresearchresultsofthecommunity. C.Bymakingcreativeclinicalresearchaboutyoungpatients. D.Byconnectingwithfamiliesandcommunitiesregularly. 2Whatareguidelinesforchildrentreatmentbasedon? A.Informationfromadultstudies. B.Datafromchildrentoolongago. C.Statisticswithconnectionofparents. D.Experiencebuiltupthroughgenerations. 3Whodoesthepassageaskforhelpfortheresearch? A.Doctorsandresearchers. B.Teachersandresearchers. C.Socialhealthcareworkers. D.Teensandyoungadults.
已知垂体由腺垂体和神经垂体两部分组成分别参与不同的稳态调节过程如图下列有关叙述错误的是
An18﹣year﹣oldgirlAnnaMeierfromAustriaistakingherparentstocourtforpostingover500photosofheronFacebooksince2009withoutherpermission. Annahasapparentlybecomefedupwithherparents'refusaltotakedowntheembarrassingphotosofheratanearlyageandisnowseekingjusticeincourt.Shetoldthemagazinethatevilthoughshewas11yearsoldwhenherparentsstartedsharingherphotoswithseveralhundredsofFacebookfriendstheywentasfarastopostpicturesofherasababywithouteveraskingifitwasalrightwithher.Theyknewnoshameandnolimit﹣anddidn'tcarewhetheritwasapictureofmesittingonthetoiletorlyingnakedinmybed﹣everystagewasphotographedandthenmadepublicthegirlsaid. ThegirladdedthatshewasonlyabletoseethephotospostedonFacebookbyherparentswhenshewas14aftersettingupherownaccountonit.AgainandagainAnnaaskedherparentstoremovethephotosofherimmediatelybuttheyrefused.Angryandupsetshefeltthatshehadnootherwaybuttotakethemtocourtwhichshedidassoonassheturned18thisyear.I'mtiredofnotbeingtakenseriouslybymyparentsshesaid. Anna'slawyerclaimstheyhaveagoodchanceofwinningthecaseincourtifitcanbeproventhattheimageshaveviolatedherrightstoapersonallife.ButbasedonsimilarcasesandaccordingtoAustrianprivacylawsiftheparentslosetheymaybeforcedtopaytheirdaughterafineof€3000to€10000. ButAnna'sparentshoweverseenothingwrongwithpostingbabyphotosofher.Iconsideritmyrighttopublishthesephotosherfathersaid.Wehavepostednomorephotosofourdaughtersinceshestoppedallowingustophotographher.Wealsohavebabyphotosofherthatcanonlybeseenbyalimitedgroupof700Facebookfriends. It'sreportedthatAnnahasmovedoutofherparents'homeandislivingwithsomegirlMendsinarentedapartment. 1Whichofthefollowingistrueaccordingtothepassage? A.Annastartedtoaskherparentstoremove500photosat11. B.Around700ofherparents'Facebookfriendssharedthepictures. C.Alma'sparentsfeltshamelessforwhattheyhaddoneonFacebook. D.Anna'sparentsstartedtopostherpicturesonFacebookwhenshewas14. 2WhatmadeAnnadecidetotakeherparentstocourt? A.Thepicturesofhersittingonthetoilet. B.Herparents'attitudetowardsherrequest. C.Thehateforherparentssinceearlychildhood. D.Thecomments﹣ofherparents'Facebookfriends. 3IfAnna'sloseinthecasetheywillhavetopayafineofatleast. A.€3000 B.€4000 C.€8000 D.€10000 4Whatcanweinferfromthepassage? A.Thegirlwillsurelywinthecaseincourt. B.Thegirlandherparentshavemadepeace. C.Thegirlhasatenserelationshipwithherparents. D.Theauthorsupportsthegirlaccusingherparents.
假定英语课上老师要求同桌之间交换修改作文请你修改同桌写的以下作文.文中共有10处语言错误每句中最多有两处.每处错误仅涉及一个单词的增加删除或修改. 增加在缺词处加一个漏字符号∧并在其下面写出该加的词. 删除把多余的词用斜线\划掉. 修改在错的词下划﹣横线并在该词下面写出修改后的词. 注意1.每处错误及其修改均仅限一词 2.只允许修改10处多者从第11处起不计分. IoncepaidabriefvisitChinatenyearsagoanditwasmydreamtoreturnsomeday.Travelthelengthofthecountryfeltlikeadreamthen.Howeverin2017itfinallycametruly.Notforafewweeks'adventureandtoliveandworkforayear.Itwasanuniqueopportunitytoexperiencemanyaboutthemysteriouscountry.Iwouldcommunicatewithpeoplefromdifferentbackgroundsandhavelotsoffuns.IwaswarmlywelcomedthemomentwhenIarrivedatthecollege.IthoughtIamgoingtoenjoythis.Itreallygolikethis.IndeedmystudentsoftenaskBrucewhyarewealwayssmiling?WhatelsecouldIsay?
豌豆有较多易于区分的相对性状遗传学三大定律中有两大定律的发现都以豌豆作为实验材料．不考虑交叉互换的情况下回答下列问题 1遗传学三大基本定律分别是基因自由组合定律基因的连锁互换定律． 2孟德尔利用豌豆做杂交实验的整个过程中对母本的处理是． 3为了判断豌豆茎的高度高茎和矮茎豆英的形状饱满和不饱满花的位置腋生和顶生这三对相对性状的遗传是否遵循基因的自由组合定律．孟德尔分别让高茎豌豆与矮茎豌豆杂交饱满豆荚豌豆与不饱满豆英豌豆杂交花腋生豌豆与花顶生豌豆杂交所得F1进行自交F2中高茎矮茎＝31饱满不饱满＝31腋生顶生＝31． ①豌豆茎的高度豆荚的形状和花的位置中显性性状依次为． ②纯合高茎不饱满顶生豌豆与纯合矮茎饱满腋生豌豆杂交所得F1再自交若F2中与亲本表现型不同的个体占则表明控制这三对相对性状的基因遵循自由组合定律若控制豆英形状和花位置的基因不遵循自由组合定律但这两对等位基因均与控制茎高度的等位基因遵循自由组合定律则F2的表现型及其比例为．
假定你是学校广播站记者李华打算本周五下午3点与外教Mr.Brown在他办公室录制一期访谈节目交流如何选择阅读材料来促进英语学习.请给外教写一封电子邮件确认他能否接受访谈并说明相关事项. 注意 1.词数100左右 2.可以适当增加细节以使行文连贯.
Weknowthatchoosingacollegemajorcanbeveryhard.Buthavenofear!Yourchoiceofmajorwillnotlockyouintoaspecificcareerfortherestofyourlife.Here'swhatyouneedtoknowaboutcollegemajorsbeforeyoucommit. Whatisamajor? 1Beyondgeneralcollegerequirementsyou'llalsotakeagroupofcoursesinasubjectofyourchoosingsuchasChemistryLiteratureorPoliticalScience. Howimportantismymajor? Themajoryouchoosewillneitherpredictnorguaranteeyourfuture.Manygraduatesfindjobsthathavenothingtodowithwhattheystudiedincollege.Ifyouintendtoearnaprofessionaldegreeaftercollegeyouwillprobablyneedcertaincourses.2 WhendoIdeclareamajor? Thisvarieswidelyacrossschoolsandprograms.3Othersrequirethatyoudeclareuponamajorbythetimethatyousetfootinsideyourfirstclass. 4 Definitely.Oneofthemostexcitingaspectsofcollegelifeisthatitintroducesyoutonewsubjectsandarousesnewpassions.Howeverkeepthisinmindeverymajorhasnecessarycoursework.Ifyouchangeyourmajorlateinthegameitmaytakemorethanthetraditionalfouryearstoearnadegree. Whatareminorsanddoublemajors? Ifonefieldofstudydoesn'tsatisfyyourintellectualappetiteconsideraminor.Aminorissimilartoamajorinthatit'sanareaofacademicconcentration.5Adoublemajorprovidesyouwithanunderstandingoftwoacademicfields.Itallowsyoutobecomefamiliarwithtwosetsofvaluesandviewswhileitalsorequiresyoutofulfilltwosetsofrequirements. A.CanIchangemymind? B.Ismymajortime﹣consuming? C.It'syourspecializedareaofstudyincollege. D.Moststudentsfindonemajorismorethanenough. E.Someschoolsmaygiveyouoneyearormoretodecide. F.Butmanyfuturedoctorsmajorinnon﹣sciencerelatedfields. G.Theonlydifferenceisthatitdoesn'trequireasmanyclasses.
真核细胞部分蛋白质需在内质网中进行加工．研究发现错误折叠的蛋白质会通过与内质网中的伴侣蛋白结合而被“扣留”在内质网中直到正确折叠如图所示．下列叙述不正确的是
ThedevelopmentoftheInternethasmadeitpossible1purchaseclothesonline.Thewebsitesoffervarietiesofdressesforustosuitalltheoccasions.Dresses2arrangeneatlyaccordingtothecategory3wouldmakeyourselectioneasier.Apart4thecategorythesortingofthedressescanbebypricemodelorthedate5addtothewebsite.Whenyouclickonaparticulardresstherealsowouldbe6optiontoviewthedressinvariousangles. The71atesectionofthesewebsiteswouldfeaturethenewarrivalsondisplay.8visitthissectionwouldkeepyouupdatedaboutthefashion.Foraparticulardressinformationsuchasthematerial9commentaboutthestyleorthepriceofthedressisclearlymentioned. YoucanalsobeaVIPtothesewebsitesto10regularenjoydiscounts.Incaseyouarelookingatabulk批量purchasethesewebsitesalsoofferwholesaledressesatgreatprices.
2018年11月一对名为“露露”和“娜娜”的基因编辑婴儿的诞生引发了国内巨大的争议．基因编辑过程的实质是用特殊的引导序列将“基因剪刀﹣﹣Cas9酶”精准定位到所需修饰的基因上然后进行编辑．回答下列问题 1科学家用法将特殊的引导序列与“基因剪刀﹣﹣Ca9酶”导入目的细胞上述实例中目的细胞为． 2“露露”与“娜娜”其实也是试管婴儿试管婴儿需让成熟且的精子与成熟的卵细胞结合形成受精卵然后进行早期胚胎培养．该时期所用培养液中含有的物质有无机盐和有机盐类氨基酸维生素水和血清等． 3一个处于囊胚期的早期胚胎经过技术可形成两个甚至多个胚胎该技术操作的关键是要做到将若科学家想在早期胚胎时就知道“露露”的性别可通过实现．
油松种子表面含有脱落酸水洗可以去除种子表面的大部分脱落酸某实验小组探究了水洗和夹破种皮两种处理方式对油松种子萌发的影响实验结果如图所示下列叙述错误的是
鸢尾以其花大色艳花形奇特而在园林植物造景和城市绿化美化中备受青睐．表为IAA对莺尾种子萌发的影响有关叙述中错误的是 不同浓度IAA对鸢尾种子萌发的影响
咪唑喹啉衍生物BEZ和长春花碱VLB用于治疗卵巢癌肝癌等癌症为研究二者对肾癌的治疗效果研究人员进行了系列实验． 1体外培养癌细胞培养液中补充动物血清利于更好地模拟的成分．将肾肿瘤组织用处理后制成细胞悬浮液．将装有细胞悬浮液的培养瓶置于中培养． 2探究BEZ和VLB单独及联合使用对肾癌细胞凋亡的影响结果如图1所示． 该实验的自变量是实验结果表明． 3Caspase﹣3是细胞内促凋亡蛋白Mcl﹣1是Caspase﹣3基因表达的调控因子．为研究BEZ和VLB治疗肾癌的机制研究人员对各组细胞进行实验处理24小时后检测Mcl﹣1的mRNA和蛋白质含量结果如图2． ①图2中左图与右图GAPDH内参的化学成分填“相同”或“不同”．据图2推测BEZ和VLB通过影响Mcl﹣1蛋白含量． ②综合图1图2结果在下列箭头上标明“+”或“﹣”分别表示“促进”和“抑制”图示药物发挥作用的机理． 4请结合上述研究为治疗肾癌提出合理建议．
如图表示青藏高原的高寒草甸生态系统的部分成分字母以及相应的生理过程序号回答下列问题 1该生态系统的结构包括． 2若该图表示生态系统的能量传递图中所示的能量有种形式分别是．若该生态系统能维持稳定则A～D之间的能量依次为a～d大小关系是． 3若该图表示生态系统的物质循环则碳的主要存在形式是图中缺少的过程是用字母和箭头表示． 4高原雪兔能辨别其天敌赤狐的排泄物气味而及时进行躲避这体现了信息传递的功能是．
下列关于真核生物转录和翻译的叙述正确的是
纤维素是植物秸秆的主要成分可利用纤维素酶将其降解为葡萄糖再利用葡萄糖生产燃料酒精．某科研人员将纤维素酶固定在载体海藻酸钠上使它可以重复稳定使用提高其利用率．回答下列问题 1一般认为纤维素酶至少包括三种组分即． 2该科研人员将纤维素酶与海藻酸钠混合后滴加到一定浓度的氯化钙溶液中使液滴形成凝胶固体小球该固定化酶的方法称为．工业生产中若要将小分子酶固定化一般填“适宜”或“不适宜”采用该方法．与使用游离酶相比工业生产中使用固定化酶的优点是． 3该科研人员进一步探究纤维素酶固定化后的热稳定性变化．将固定化酶和游离酶置于60℃水浴中每20min测定一次其活力．结果如图所示酶活力每毫升酶液1min产生1mg葡萄糖为一个单位U． 据图分析纤维素酶固定后热稳定性判断依据是．根据游离酶的热稳定性的特点推测适宜在填“低温”“高温”或“最适温度”条件下保存酶．
InsideasecuredroominabeautifulcastlenearParisasmallmetalcylinder圆柱体restsonashelfbeneathadoublesetofbelljars.Ithaslainthereformorethanacenturyitsrestonlyoccasionallydisturbedwhentheroom'sthreekeyholdersperformacoordinatedopeningceremonytolettechniciansenterandcleanthispreciouspieceofmetal. Firstthecylinderisrubbedwithapieceofsoftalcohol﹣soakedcloth.Thenitissteamedwithpurewater.Finallythe1kgcylinderisreturnedcarefullytoitsrestingplace. Suchattentiontoalumpofmetalisunusualbuthasapurpose.ThecastlehousestheInternationalBureauofWeightsandMeasuresandthatpieceofshiningcircularmetalisitsholiestrelic.Itisthedefiningmass质量againstwhichallotherkilogramsaremeasured.Thisistheinternationalprototypeorstandardofthekilogram.TheIPKinshort. Dozensofcarefullyweightedcopiesoftheoriginalhavebeenmade.Theyarestoredaroundtheworldandusedtostandardizeindividualnations'weightsandmeasuressystems. ButthedaysoftheIPKinitscurrentformarenumbered.TheInternationalBureauofWeightsandMeasureshasdecidedtoreplacethissinglephysicalspecimenwithamorefundamentalmeasurement﹣basedonelectriccurrent﹣inordertodefinethemassofanobject.Thekingofkilogramsisabouttobedethroned. OnekeyreasonfordoingthisworkistoprovideinternationalsecuritysaysBureauspokesmanPaulRobinson.Ifthecastleburneddowntomorrowandthekilogramwasdestroyedwewouldhavenoreferenceleftfortheworld'smetricweightssystem.Therewouldbechaos.ThecurrentdefinitionofthekilogramistheweightofthatcylinderinParisafterall. AnothermajormotivationforthereplacementoftheIPKisthegrowingneedtobeabletocarryoutmoreandmoreprecisemeasurements.DrugcompanieswillsoonbewantingtouseingredientsthatwillhavetobemeasuredintermsofafewmillionthsorevenbillionthsofagramsaysRobinson.Weneedtobepreparedtoweighsubstanceswiththatkindofaccuracy. 1WhatdoweknowabouttheIPKfromthefirsttwoparagraphs? A.It'sthemostvaluablemetalintheworld. B.It'scaredforwithgreatdevotion. C.It'susedinreligiousceremonies. D.It'sbeautifullydesignedanddecorated. 2Whichofthefollowingbestexplainsdethronedunderlinedinparagraph5? A.rebuilt B.destroyed C.upgraded D.removed 3WhatisareasonforreplacingthecurrentIPK? A.Tosatisfytheincreasingdemandforexactness. B.Toprotectthemetalcylinderfromdamage. C.Tomaketakingmeasurementsmoreeconomical. D.Toprovideallcountrieswiththesamestandard. 4Whatcanbeasuitabletitleforthetext? A.Nomorekilos B.Aheavytechnology C.Thefutureofthekilo D.Thehistoryofmeasures
脱落酸ABA有“逆境激素”之称在植物对抗干旱等不利环境因素时起重要作用． 1ABA对植物的生命活动起作用其合成经过细胞内复杂的生物化学反应过程需要NCED1～NCED5等酶的作用． 2研究人员对水稻进行干旱胁迫4h及复水4h处理测定叶片中ABA含量及相关基因的mRNA含量结果如图1． ①由图1中甲图可知干旱胁迫下叶片ABA含量诱导叶片气孔减少水分散失． ②NCED1～NCED5基因的表达具有组织特异性如NCED4基因主要在根中表达．仅根据图1的结果能否确认NCED4基因不是干旱胁迫的响应基因．请做出判断并说明理由． 3研究人员将NCED3基因作为目的基因正向连接构建表达载体导入水稻细胞获得转基因幼苗Ⅰ反向连接构建表达载体转录NCED3基因的非模板链获得转基因水稻幼苗Ⅱ．将两种幼苗与野生型水稻幼苗一起培养干旱胁迫处理15天后检测植株相关生长指标及体内ABA含量部分结果如表和图2． ①据表中结果阐述干旱胁迫下野生型植株形态改变的生物学意义． ②图2中123组ABA含量无明显差异的原因是． ③综合上述研究分析第6组植株ABA含量低于第4组的原因是． 4干旱胁迫下野生型植株和NCED3基因敲除突变体中NGA1蛋白含量均增加．研究人员推测NGA1蛋白是干旱环境促进NCED3基因表达的调控因子．检测植株的NCED3基因表达量结果为实验组低于对照组初步支持上述推测．若要进一步验证推测应选择的实验材料实验组处理及预期结果包括填选项前的符号． a．NGA1基因敲除突变体 b．NCED3基因敲除突变体 c．导入含NGA1突变基因的表达载体 d．导入含NGA1基因的表达载体 e．导入空载体 f．正常供水环境 g．模拟干旱环境 h．NCED3﹣mRNA含量高于对照组 i．NCED3﹣mRNA含量低于对照组
下列关于构成生物体的N元素的叙述错误的是
MyfatherandIhavebeenseparatedforovertwoyears.HewasphysicallyviolentandemotionallyabusivetomethroughoutmychildhoodandIfeltthatIcouldn'tforgivehim.AndyetnowheisdyingunconsciousandstrugglingtobreathethroughanoxygentubeafteramajorstrokeallIcanthinkofishowmuchhelovedme. Howhewouldholdmyfringe刘海backandkissmeontheforeheadbeforeschool.Howheboughtmeapotterysetandrollerskatesalthoughwewerestrugglingbyonjusthissalaryandallowedmetoskatetoschool.HowhewouldplaychessandtenniswithmeandtakemetoendlesschessandtennistournamentseventhoughIneverwonanything.HowhewouldreadtheGuardianeverydayandfillinthequickcrosswordbutleaveafewcluesandpraisemeifIsolvedthem.HekepteveryoneofmyGuardiancolumnsandeveryarticleIeverhadpublishedevenduringourmanyestranged疏远periods.HegavemealotofhissavingstobuyaflatafterIbecameasinglemum.Andhesetmydateofbirthasthepasscodeonhisphone. YetI'mashamedtosayIblamedhimoftenforeverythingmyanorexia厌食症mycuttingmyanxietymydepression…HewasthereduringthetoughtimesyetallIcouldthinkwasthatthetoughtimeshappenedbecauseofhimforgettingthatthecausesofeventsarecomplexandthatplentyofpeoplewhohadhappychildhoodshavetodealwithmentalillnessanddomesticviolencetoo. IevenstoppedhimfromseeingmydaughterthenthreethethingthatbroughthimmosthappinessbecauseIwasscaredhewouldhurtherandthatherlifewouldbelikemine.Thatdecisionwouldmeanheneverspoketomeagain. Whenwespenttimetogetherinpreviousyearsmyfatherhuggedmealotyetnevertalkedmuch.Bornin1930sAmericaduringtheDepressionhewasamanoffewwordsasilentromanticwhosignedhisemptyValentine'scardstomymotherwithonlyhisfirstinitial.IknowhethoughtItalkedtoomuchironicallyInevertoldhimwhatIneededto.KnowinghewasoldItriedtogetbackintouchseveraltimestomakethingsrightbutmymothersaidhedidn'twanttohearfromme.Iunderstandthat.Whywouldhewanttohearfromthedaughterwhowasneverabletoforgivehimforhismistakeswhobroughtthemuptimeaftertimeunabletoaccepthisapologies?Whopreventedhimfromseeinghisgranddaughter?Whoscoldedhimforhisfaultsyetneveracknowledgedhisnumerouskindnesses? It'smuchtoolatenow.WhenIsitbyhishospitalbedandholdhislargewrinkledhandfartoowarmandaskhimtosqueezeitifhecanhearmehedoesn't.SoItellhimafewofthethingsIshouldhavetoldhimwhenhewasconsciousthoughit'shardtosaythewordsthatIlovehimverymuchandthatI'msorryabouttheestrangement.AnditremindsmeofwhatI'veknownforalongtimethatmydaddidn'tknowhowtobeafathertomewhenIwasyoungbecausehisfatherwasabusivetohimasachild.Hisfatherdiedestrangedfromhissonmyfatherisdyingestrangedfromhisdaughter. IneverthoughtthatI'dfeelthisbrokenatlosinghim.Ifantasizethathiseyeswillopenandthathewillbeconsciousagainforjustafewdays.IwillgivehimaletterthankinghimforallthethingsIhaverememberedwhilewritingthispieceandapologizingforallthewaysIhavewrongedhim.AndwhenIdelivertheletterIwillbringmyfive﹣year﹣olddaughterwithmesohecanseeherhappinessandsweetnessandlearnthatthechainofhurtthathasbeenpasseddownfromgenerationtogenerationhasfinallybeenbroken. 1TheseparationbetweenFatherandthedaughterismainlycausedby. A.Father'scrueltytowardsthedaughter. B.Father'sirresponsibilityforthefamily. C.thedaughter'smisunderstandingofherfather. D.thedaughter'sprotectionofherkidfromharm. 2Fatherrejectedhisdaughter'soffertogetintouchwithhimbecause. A.hewastooashamedtofacehisdaughter. B.hecouldn'tpardonhisdaughter'signorance. C.hecouldn'tsupporthisdaughteranymore. D.hewascontenttoliveawayfromhisdaughter. 3Theauthor'sfathercanbedescribedas. A.generouscoldandstubborn. B.strictcaringandstubborn. C.generousstrictandinconsiderate. D.caringcoldandinconsiderate. 4Whatmessagedoestheauthorwanttoconveyintheunderlinedpart? A.Thepreviouswayoffamilyeducationwillnolongercontinue. B.Thegranddaughterwillbreakthefamilychaintolivefreely. C.Therewillbenorestrictioninthefamilyfromthatmomenton. D.Fatherwillleavetheworldwithoutanyregretsandsufferings.
鸡的性别决定方式为ZW型ZW染色体存在同源区Ⅱ和非同源区ⅠⅢ如图所示．鸡的羽毛有斑纹和无斑纹是一对相对性状无斑纹由仅位于I区段的隐性基因a控制．回答下列问题 1若某性状是由位于Ⅱ区段的一对等位基因控制则该种群中雌鸡的基因型有只考虑该性状种该性状填“有”或“没有”与性别相关联的特点． 2若基因型ZAW属于纯合子用杂合的有斑纹鸡与无斑纹鸡杂交杂交亲本的基因型为． 3假设鸡的羽色黄色B对白__为显性这对基因所在的染色体是未知的．现有纯合黄色和纯合白色雌雄鸡若干只请用上述鸡为材料设计一个杂交实验验证基因B/b是位于常染色体上还是位于Z染色体的Ⅰ区段上要求只进行一次杂交实验写出实验思路预期结果及结论．．
常见的酿酒酵母只能利用葡萄糖而不能利用木糖来进行酒精发酵而自然界中某些酵母菌能利用酶A分解木糖产生酒精．回答下列问题 1在制备含琼脂的培养基和倒平板的过程中下列选项需要的是填序号． ①酒精灯②接种环③__蒸汽灭菌锅④培养皿 2将自然界收集的酵母菌菌株转接到仅以为碳源的培养基中在填“有氧”或“无氧”条件下培养一周后有些酵母菌死亡说明这些酵母菌不能利用木糖发酵． 3测定微生物数量常用的方法有活菌计数法和前者的统计结果一般用而不是用活菌数来表示． 4纯化后的酶A可以用电泳法检测其分子量大小．在相同条件下带电荷相同的蛋白质电泳速度越快说明． 5生产上常将酶A固定化以反复利用．部分操作如下将酶A固定在填“溶于水”或“不溶于水”的载体上将其装入反应柱内后需用蒸馏水充分洗涤固定化酶柱以除去未吸附的酶A．一般来说酶不适合采用法固定化．
ThisWaytoDreamland Daydreamingmeanspeoplethinkaboutsomethingpleasantespeciallywhenthismakesthemforgetwhattheyshouldbedoing.Daydreamershaveabadreputationforbeingunawareofwhat'shappeningaroundthem.Theycanseemforgetfulandclumsy.1Theyannoyusbecausetheyseemtobeignoringusandmissingtheimportantthings. Butdaydreamersarealsoresponsibleforsomeofthegreatestideasandachievementsinhumanhistory.2Canyouimaginewhatkindofworldwewouldhavewithoutsuchideasandinventions? Sohowcanyoucomeupwithbrilliantdaydreamsandavoidfallingovertreerootsorotherwiselookinglikeafool? Firstunderstandthatsomeopportunitiesfordaydreamingarebetterthanothers.Feelingsafeandrelaxedwillhelpyoutoslipintodaydreams.3Andifyouwanttoimproveyourchancesofhavingacreativeideawhileyou'redaydreamingtrytodoitwhileyouareinvolvedinanothertask﹣preferablysomethingsimpleliketakingashowerorwalkingorevenmakingmeaninglessdrawings. It'salsoimportanttoknowhowtoavoiddaydreamsforthosetimeswhenyoureallyneedtoconcentrate.Mindfulnessbeingfocusedisatoolthatsomepeopleusetoavoidfallingasleep.4 Finallyyouneverknowwhatwonderfulideamightstrikewhileyourmindhasmovedslowlyaway.5 Alwaysrememberthatyourbestideasmightcomewhenyourheadisactuallyintheclouds. A.Havinginterestingthingstothinkaboutalsohelps. B.Theystareoffintospaceandwanderbythemselves. C.Withoutwanderingmindswewouldn'thaverelativityCokeorPost﹣itnotes. D.Atonetimedaydreamingwasthoughttobeacauseofsomementalillnesses. E.Itinvolvesslowsteadybreathingforself﹣controlthathelpspeoplestaycalmandattentive. F.Daydreamsareoftenverysimpleanddirectquiteunlikesleepdreamswhichmaybehardtounderstand. G.Thereforeit'sagoodideatokeepanotebookorvoicerecordernearbywhenyou'reinthedaydreamzone.
农作物的籽粒成熟后大部分掉落的特性称为落粒性落粒性给水稻收获带来较大的困难．科研人员做了如图所示杂交实验下列说法不正确的是
热门题库
更多
高一下学期数学
教案备课库
高一上学期数学
高一上学期化学
教案备课库
教案备课库
教案备课库
高一上学期物理
教案备课库
教案备课库
教案备课库
教案备课库
教案备课库
教案备课库
教案备课库
教案备课库
湘公网安备 43130202000226号