最值得背诵的英语文章精粹 40篇.docx
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最值得背诵的英语文章精粹 40篇.docx
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最值得背诵的英语文章精粹40篇
最值得背诵的英语文章精粹40篇不重复单词3174
1CellsandTemperature
Cellscannotremainaliveoutsidecertainlimitsoftemperatureandmuchnarrowerlimitsmarktheboundariesofeffectivefunctioning.Enzymesystemsofmammalsandbirdsaremostefficientonlywithinanarrowrangearound37C;adepartureofafewdegreesfromthisvalueseriouslyimpairstheirfunctioning.Eventhoughcellscansurvivewiderfluctuationstheintegratedactionsofbodilysystemsareimpaired.Otheranimalshaveawidertoleranceforchangesofbodilytemperature.
Forcenturiesithasbeenrecognizedthatmammalsandbirdsdifferfromotheranimalsinthewaytheyregulatebodytemperature.Waysofcharacterizingthedifferencehavebecomemoreaccurateandmeaningfulovertime,butpopularterminologystillreflectstheolddivisioninto“warm-blooded”and“cold-blooded”species;warm-bloodedincludedmammalsandbirdswhereasallothercreatureswereconsideredcold-blooded.Asmorespecieswerestudied,itbecameevidentthatthisclassificationwasinadequate.Afencelizardoradesertiguana—eachcold-blooded----usuallyhasabodytemperatureonlyadegreeortwobelowthatofhumansandsoisnotcold.Thereforethenextdistinctionwasmadebetweenanimalsthatmaintainaconstantbodytemperature,calledhome0therms,andthosewhosebodytemperaturevarieswiththeirenvironments,calledpoikilotherms.Butthisclassificationalsoprovedinadequate,becauseamongmammalstherearemanythatvarytheirbodytemperaturesduringhibernation.Furthermore,manyinvertebratesthatliveinthedepthsoftheoceanneverexperiencechangeinthedepthsoftheoceanneverexperiencechangeinthechillofthedeepwater,andtheirbodytemperaturesremainconstant.
2Sleep
Sleetispartofaperson’sdailyactivitycycle.Thereareseveraldifferentstagesofsleep,andtheytoooccurincycles.Ifyouareanaveragesleeper,yoursleepcycleisasfollows.Whenyoufistdriftoffintoslumber,youreyeswillrollaboutabit,youtemperaturewilldropslightly,yourmuscleswillrelax,andyourbreathingwellslowandbecomequiteregular.Yourbrainwavesslowandbecomequiteregular.Yourbrainwavesslowdownabittoo,withthealpharhythmofratherfastwaves1sleep.Forthenexthalfhourorso,asyourelaxmoreandmore,youwilldriftdownthroughstage2andstage3sleep.Theloweryourstageofsleep.sloweryourbrainwaveswillbe.Thenabout40to69minutesafteryouloseconsciousnessyouwillhavereachedthedeepestsleepofall.Yourbrainwillshowthelargeslowwavesthatareknownasthedeltarhythm.Thisisstage4sleep.
Youdonotremainatthisdeepfourthstageallnightlong,butinsteadabout80minutesafteryoufallintoslumber,yourbrainactivitylevelwillincreaseagainslightly.Thedeltarhythmwilldisappear,tobereplacedbytheactivitypatternofbrainwaves.Youreyeswillbegintodartaroundunderyourclosedeyelidsasifyouwerelookingatsomethingoccurringinfrontofyou.Thisperiodofrapideyemovementlastsforsome8to15minutesandiscalledREMsleep.ItisduringREMsleepperiod,yourbodywillsoonrelaxagain,yourbreathingwillslipgentlybackfromstage1tostage4sleep----onlytoriseonceagaintothesurfaceofnearconsciousnesssome80minuteslater.
3Bacteria
Bacteriaareextremelysmalllivingthings.Whilewemeasureourownsizesininchesorcentimeters,bacterialsizeismeasuredinmicrons.Onemicronisathousandthofamillimeter:
apinheadisaboutamillimeteracross.Rod-shapedbacteriaareusuallyfromtwotofourmicronslong,whileroundedonesaregenerallyonemicronindiameter.Thusifyouenlargedaroundedbacteriumathousandtimes,itwouldbejustaboutthesizeofapinhead.Anadulthumanmagnifiedbythesameamountwouldbeoveramile(1.6kilometer)tall.
Evenwithanordinarymicroscope,youmustlookcloselytoseebacteria.Usingamagnificationof100times,onefindsthatbacteriaarebarelyvisibleastinyrodsordots.Onecannotmakeoutanythingoftheirstructure.Usingspecialstains,onecanseethatsomebacteriahaveattachedtothemwavy-looking“hairs”calledflagella.Othershaveonlyoneflagellum.Theflagellarotate,pushingthebacteriathroughthewater.Manybacterialackflagellaandcannotmoveaboutbytheirownpower,whileotherscanglidealongoversurfacesbysomelittle-understoodmechanism.
Fromthebacteriapointofview,theworldisaverydifferentplacefromwhatitistohumans.Toabacteriumwaterisasthickasmolassesistous.Bacteriaaresosmallthattheyareinfluencedbythemovementsofthechemicalmoleculesaroundthem.Bacteriaunderthemicroscope,eventhosewithnoflagella,oftenbounceaboutinthewater.Thisisbecausetheycollidewiththewaterymoleculesandarepushedthiswayandthat.Moleculesmovesorapidlythatwithinatenthofasecondthemoleculesaroundabacteriahaveallbeenreplacedbynewones;evenbacteriawithoutflagellaarethusconstantlyexposedtoachangingenvironment.
4FolkCultures
Afolkcultureisasmallisolated,cohesive,conservative,nearlyself-sufficientgroupthatishomogeneousincustomandracewithastrongfamilyorclanstructureandhighlydevelopedrituals.Orderismaintainedthroughsanctionsbasedinthereligionorfamilyandinterpersonal.Relationshipsarestrong.Traditionisparamount,andchangecomesinfrequentlyandslowly.Thereisrelativelylittledivisionoflaborintospecializedduties.Rather,eachpersonisexpectedtoperformagreatvarietyoftasks,thoughdutiesmaydifferbetweenthesexes.Mostgoodsarehandmadeandsubsistenceeconomyprevails.Individualismisweaklydevelopedinfolkculturesasaresocialclasses.UnalteredfolkculturesnolongerexistinindustrializedcountriessuchastheUnitedStatesandCanada.PerhapsthenearestmodernequivalentinAngloAmericaistheAmish,aGermanAmericanfarmingsectthatlargelyrenouncestheproductsandlaborsavingdevicesoftheindustrialage.InAmishareas,horsedrawnbuggiesstillserveasalocaltransportationdeviceandthefaithfularenotpermittedtoownautomobiles.TheAmish’scentralreligiousconceptofDemut“humility”,clearlyreflectstheweaknessofindividualismandsocialclasssotypicaloffolkculturesandthereisacorrespondingstrengthofAmishgroupidentity.RarelydotheAmishmarryoutsidetheirsect.Thereligion,avarietyoftheMennonitefaith,providestheprincipalmechanismformaintainingorder.
Bycontrastapopularcultureisalargeheterogeneousgroupoftenhighlyindividualisticandapronouncedmanyspecializedprofessions.Secularinstitutionsofcontrolsuchasthepoliceandarmytaketheplaceofreligionandfamilyinmaintainingorder,andamoney-basedeconomyprevails.Becauseofthesecontrasts,“popular”maybeviewedasclearlydifferentfrom“folk”.Thepopularisreplacingthefolkinindustrializedcountriesandinmanydevelopingnations.Folk-madeobjectsgivewaytotheirpopularequivalent,usuallybecausethepopularitemismorequicklyorcheaplyproduced,iseasierortimesavingtouseorleadsmoreprestigetotheowner.
5Vision
Humanvisionlikethatofotherprimateshasevolvedinanarborealenvironment.Inthedensecomplexworldofatropicalforest,itismoreimportanttoseewellthattodevelopanacutesenseofsmell.Inthecourseofevolutionmembersoftheprimatelinehaveacquiredlargeeyeswhilethesnouthasshrunktogivetheeyeanunimpededview.Ofmammalsonlyhumansandsomeprimatesenjoycolorvision.Theredflagisblacktothebull.Horsesliveinamonochromeworld.lightvisibletohumaneyeshoweveroccupiesonlyaverynarrowbandinthewholeelectromagneticspectrum.Ultravioletraysareinvisibletohumansthoughantsandhoneybeesaresensitivetothem.Humansthoughantsandhoneybeesaresensitivetothem.Humanshavenodirectperceptionofinfraredraysunliketherattlesnakewhichhasreceptorstunedintowavelengthslongerthan0.7micron.Theworldwouldlookeerilydifferentifhumaneyesweresensitivetoinfraredradiation.Theninsteadofthedarknessofnight,wewouldbeabletomoveeasilyinastrangeshadowlessworldwhereobjectsglowedwithvaryingdegreesofintensity.Buthumaneyesexcelinotherways.Theyareinfactremarkablydiscerningincolorgradation.Thecolorsensitivityofnormalhumanvisionisrarelysurpassedevenbysophisticatedtechnicaldevices.
6ThesourceofEnergy
Asummaryofthephysicalandchemicalnatureoflifemustbegin,notontheEarth,butintheSun;infact,attheSun’sverycenter.ItisherethatistobefoundthesourceoftheenergythattheSunconstantlypoursoutintospaceaslightandheat.ThisenergyislibratedatthecenteroftheSunasbillionsuponbillionsofnucleiofhydrogenatomscollidewitheachotherandfusetogethertoformnucleiofhelium,andindoingso,releasesomeoftheenergythatisstoredinthenucleiofatoms.TheoutputoflightandheatoftheSunrequiresthatsome600milliontonsofhydrogenbeconvertedintoheliumintheSuneverysecond.ThistheSunhasbeendoingforseveralthousandsofmillionsofyear.
ThenuclearenergyisreleasedattheSun’scenterashigh-energygammaradiation,aformofelectromagneticradiationlikelightandradiowaves,onlyofverymuchshorterwavelength.ThisgammaradiationisabsorbedbyatomsinsidetheSuntobereemittedatslightlylongerwavelengths.Thisradiation,initsturnisabsorbedandreemitted.Astheenergyfiltersthroughthelayersofthesolarinterior,itpassesthroughtheX-raypartofthespectrumeventuallybecominglight.Atthisstage,ithasreachedwhatwecallthesolarsurface,andcanesc
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