tpo133阅读原文翻译

TradewasthemainstayoftheurbaneconomyintheMiddleEast,ascaravansnegotiatedthesurroundingdesert,restrictedonlybyaccesstowaterandbymountainranges.Thishasbeensosinceancienttimes,partlyduetothegeologyofthearea,whichismostlylimestoneandsandstone,withfewdepositsofmetallicoreandotherusefulmaterialsAncientdemandsforobsidian(ablackvolcanicrockusefulformakingmirrorsandtools)ledtotradewithArmeniatothenorth,whilejadeforcuttingtoolswasbroughtfromTurkistan,andthepreciousstonelapislazuliwasimportedfromAfghanistan.OnecantracesuchexpeditionsbacktoancientSumeria,theearliestknownMiddleEasterncivilization.RecordsshowmerchantcaravansandtradingpostssetupbytheSumeriansinthesurroundingmountainsanddesertsofPersiaandArabia,wheretheytradedgrainforrawmaterials,suchastimberandstones,aswellasformetalsandgems.Relianceontradehadseveralimportantconsequences.Productionwasgenerallyinthehandsofskilledindividualartisansngpieceworkunderthetuageofamasterwhowasalsotheshopowner.Intheseshopsdifferencesofrankwereblurredasartisansandmasterslaboredsidebysideinthesamemodestestablishment,wereusuallymembersofthesameguildandreligioussect,livedinthesameneighborhoods,andoftenhadassumed(orreal)kinshiprelationships.Theworkerwasboundtothemasterbyamutualcontractthateitheronecouldrepudiate,andtherelationshipwasconceptualizedasoneofpartnership.Thismodeofcraftproductionfavoredthegrowthofself- erningandideologicallyegalitariancraftguildseverywhereintheMiddleEasterncity.Thesewereessentiallyprofessionalassociationsthatprovidedforthemutualaidandprotectionoftheirmembers,andallowedforthemaintenanceofprofessionalstandards.Thegrowthofindependentguildswasfurtheredbythefactthatsurpluswasnotaresultofdomesticcraftproductionbutresultedprimarilyfrominternationaltrading;theernmentleftworkingpeopleto ernthemselves,muchasshepherdsoftribalconfederacieswereleftalonebytheirleaders.Inthemultiplicityofsmall-scalelocalegalitarianorquasi-egalitarianorganizationsforfellowship,worship,andproductionthatflourishedinthislaissez-faireenvironment,individualscouldin ctwithoneanotherwithinacommunityofharmonyandideologicalequality,followingtheirownpopularlyelectedleadersanderningthemselvesbysharedconsensuswhileminimizingdistinctionsofwealthandpower.Themercantileeconomywasalsocharacterizedbyapeculiarmoralstancethatistypicalofpeoplewholivebytrade—anattitudethatisindividualistic,calculating,risktaking,andadaptivetocircumstances.Asamongtribespeople,alrelationshipsandacarefulweighingofcharacterhavealwaysbeencrucialinamercantileeconomywithlittleregulation,whereone'swordisone'sbondandwhereinformaltiesoftrustcementtogetheraninternationaltradenetwork.Norhavemerchantsandartisanseverhadmuchtoleranceforaristocraticprofessionsofmoralsuperiority,favoringinsteadanegalitarianethicoftheopenmarket,wheresteadyhardwork,theloyaltyofone'sfellows,andentrepreneurialskillmakeallthedifference.And,likethepastoralists,MiddleEasternmerchantsandartisansunhappywiththeirenvironmentcouldsimplypackupandleaveforgreenerpastures—anactofself-assertionwhollyimpossibleinmostothercivilizationsthroughouthistory.Dependenceonlong-distancetradealsomeantthatthegreatempiresoftheMiddleEastwerebuiltbothli llyandfigurativelyonshiftingsand.Thecentralstate,thoughoftenveryrichandverypopulous,wasintrinsicallyfragile,sincethedevelopmentofnewinternationaltraderoutescouldunderminethemonetarybaseanderodestatepower,asoccurredwhenEuropeanseafarerscircumventedMiddleEasternmerchantsafterVascodaGama'svoyagearoundAfricainthelatefifteenthcenturyopenedupasouthernroute.Theecologyoftheregionalsopermittedarmedpredatorstoprowlthesurroundingbarrens,whichwerealmostimpossibleforastatetocontrol.Peripheralpeoplesthereforehadagreatadvantageintheirdealingswiththecenter,makingernmentauthorityinsecureandanxious.

东地区与北方的亚美尼亚的贸易，与土耳其的玉石进口贸易，以及与铺的监视下通过工匠手工完成所需要的工序。在这样的中，阶层的这种有益于制度成长的生产模式和人人的的工坊在中东的城 这种重商形式的经济模式也通过处在浓厚氛围中的人们所标榜的特定道德对远距离的贸易的依赖也意味着中东伟大的得以建立在这片飘忽不定却又 点，因为新的国际贸易线路的出现是会动摇经济基础并腐蚀国家权力，15世纪周，这些地区几乎无法被控制。外边的人们因此得到了一个应对绝好的机会，这一切使的主导地位风雨飘摇。Theperiodictableisachartthatreflectstheperiodicrecurrenceofchemicalandphysicalpropertiesoftheelementswhentheelementsarearrangedinorderofincreasingatomicnumber(thenumberofprotonsinthenucleus).Itisamonumentalscientificachievement,anditsdevelopmentillustratestheessentialinterybetweenobservation,prediction,andtestingrequiredforscientificprogress.Inthe1800'sscientistsweresearchingfornewelements.Bythelate1860'smorethan60chemicalelementshadbeenidentified,andmuchwasknownabouttheirdescriptivechemistry.Variousproposalswereputforthtoarrangetheelementsintogroupsbasedonsimilaritiesinchemicalandphysicalproperties.Thenextstepwastorecognizeaconnectionbetweengroupproperties(physicalorchemicalsimilarities)andatomicmass(themeasuredmassofanindividualatomofanelement).Whentheelementsknownatthetimewereorderedbyincreasingatomicmass,itwasfoundthatsuccessiveelementsbelongedtodifferentchemicalgroupsandthattheorderofthegroupsinthissequencewasfixedandrepeateditselfatregularintervals.Thuswhentheseriesofelementswaswrittensoastobeginanewhorizontalrowwitheachalkalimetal,elementsofthesamegroupswereautomaticallyassembledinverticalcolumnsinaperiodictableoftheelements.Thistablewastheforerunnerofthemoderntable.WhentheGermanchemistLotharMeyerand(independently)theRussianDmitryMendeleyevfirstintroducedtheperiodictablein1869-70,one-thirdofthenaturallyoccurringchemicalelementshadnotyetbeendiscovered.Yetbothchemistsweresufficientlyfarsightedtoleavegapswheretheirysesofperiodicphysicalandchemicalpropertiesindicatedthatnewelementsshouldbelocated.MendeleyevwasbolderthanMeyerandevenassumedthatifameasuredatomicmassputanelementinthewrongceinthetable,theatomicmasswaswrong.Insomecasesthiswastrue.Indium,forexample,hadpreviouslybeenassignedanatomicmassbetweenthoseofarsenicandselenium.Becausethereisnospaceintheperiodictablebetweenthesetwoelements,Mendeleyevsuggestedthattheatomicmassofindiumbechangedtoacompleydifferentvalue,whereitwouldfillanemptyspacebetweencadmiumandtin.Infact,subsequentworkhasshownthatinaperiodictable,elementsshouldnotbeorderedstrictlybyatomicmass.Forexample,luriumcomesbeforeiodineintheperiodictable,eventhoughitsatomicmassisslightlygreater.Suchanomaliesareduetotherelativeabundanceofthe"isotopes"orvarietiesofeachelement.Alltheisotopesofagivenelementhavethesamenumberofprotons,butdifferintheirnumberofneutrons,andhenceintheiratomicmass.Theisotopesofagivenelementhavethesamechemicalpropertiesbutslightlydifferentphysicalproperties.Wenowknowthatatomicnumber(thenumberofprotonsinthenucleus),notatomicmassnumber(thenumberofprotonsandneutrons),determineschemicalbehavior.MendeleyevwentfurtherthanMeyerinanotherrespect:hepredictedpropertiesofsixelementsyettobediscovered.Forexample,agapjustbelowaluminumsuggestedanewelementwouldbefoundwithpropertiesogoustothoseofaluminum.Mendeleyevdesignatedthiselement"eka-aluminum"(ekaistheSanskritwordfor"next")andpredicteditsproperties.Justfiveyearslateranelementwiththeproperatomicmasswasisolatedandnamedgalliumbyitsdiscoverer.TheclosecorrespondencebetweentheobservedpropertiesofgalliumandMendeleyev’spredictionsforeka-aluminumlentstrongsupporttotheperiodiclaw.Additionalsupportcamein1885wheneka-silicon,whichhadalsobeendescribedinadvancebyMendeleyev,wasdiscoveredandnamedgermanium.Thestructureoftheperiodictableappearedtolimitthenumberofpossibleelements.ItwasthereforequitesurprisingwhenJohnWilliamStrut(LordRayleigh,discoveredagaseouselementin1894thatdidnotfitintothepreviousclassificationscheme.Acenturyearlier,HenryCavendishhadnotedtheexistenceofaresidualgaswhenoxygenandnitrogenareremovedfromair,butitsimportancehadnotbeenrealized.TogetherwithWilliamRamsay,Rayleighisolatedthegas(separatingitfromothersubstancesintoitspurestate)andnameditargon.Ramsaythenstudiedagasthatwaspresentinnaturalgasdepositsanddiscoveredthatitwashelium,anelementwhosepresenceintheSunhadbeennotedearlierinthespectrumofsunlightbutthathadnotpreviouslybeenknownonEarth.RayleighandRamsaypostulatedtheexistenceofanewgroupofelements,andin1898othermembersoftheseries(neon,krypton,andxenon)wereisolated.

当德国化学家lotharMeyer和（彼此独立的）的门在1869年第一次Meyer大胆的多，他甚至设想如果以原子的质量为排列标准所排出的周期表中元完全不同的体积而改变了，而这积的改变使得硒可以放置在镉和锡之间空着的数目（中质子的数量）而不是原子的质量决定着化学性。门在另一个研究上也比Meyer更加深入：他预测了六种元素的性质已经将这个元素定义为“次铝”（eka这个词在梵语中的意思是“下一个”）而且（，在1894年发现了气态元素不能适应之前的元素表。一个世纪以前，哈里许就宣称当氧气和氮气从空气中被移除后仍然有剩余的气体存在，但在于自然界中的气体元素氦，这种元素存在于中，并且早在光谱出现前就被注意到，但是之前并没有在地球上找到过。和假定了一组新的元素，而且这组元素中的其他成员也在1898年被成功分离出来（氖，氪，氙。netsinOurSolarTheSunisthehubofahugerotatingsystemconsistingofninenets,theirsalites,andnumeroussmallbodies,includingasteroids,coets,and Anestimated99.85percentofthemassofoursolarsystemiscontainedwithintheSun,whilethenetscollectivelymakeupmostofthereaining0.15percent.Thenets,inorderoftheirdistancefromtheSun,areMercury,Venus,Earth,Mars,Jupiter,Saturn,Uranus,Neptune,andPluto.UnderthecontroloftheSun'sgravitational,eachnetmaintainsanellipticalorbitandallofthemtravelinthesamedirection.Thenetsinoursolarsystemfallintotwogroups:theterrestrial(Earth-like)nets(Mercury,Venus,Earth,andMars)andtheJovian(Jupiter-like)nets(Jupiter,Saturn,Uranus,andNeptune).Plutoisnotincludedineithercategory,becauseitsgreatdistancefromEarthanditssmallsizemakethisnet'struenatureamystery.ThemostobviousdifferencebetweentheterrestrialandtheJoviannetsistheirsize.Thelargestterrestrialnet,EarthhasadiameteronlyonequarterasgreatasthediameterofthesmallestJoviannet,Neptune,anditsmassisonlyoneseventeenthasgreat.Hence,theJoviannetsareoftencalledgiants.Also,becauseoftheirrelativelocations,thefourJoviannetsareknownastheouternets,whiletheterrestrialnetsareknownastheinnernets.Thereappearstobeacorrelationbetweenthepositionsofthesenetsandtheirsizes.Otherdimensionsalongwhichthetwogroupsdiffermarkedlyaredensityandcomposition.Thedensitiesoftheterrestrialnetsaverageabout5timesthedensityofwater,whereastheJoviannetshavedensitiesthataverageonly1.5timesthedensityofwater.Oneoftheouternets,Saturn,hasadensityofonly0.7thatofwater,whichmeansthatSaturnwouldfloatinwater.Variationsinthecompositionofthenetsarelargelyresponsibleforthedensitydifferences.Thesubstancesthatmakeupbothgroupsofnetsaredividedintothreegroups—gases,rocks,andices—basedontheirmeltingpoints.Theterrestrialnetsaremostlyrocks:denserockyandmetallicmaterial,withminoramountsofgases.TheJoviannets,ontheotherhand,containalargepercentageofthegaseshydrogenandhelium,withvaryingamountsofices:mostlywater,ammonia,andmethaneices.TheJoviannetshaveverythickatmospheresconsistingofvaryingamountsofhydrogen,helium,methane,andammonia.Bycomparison,theterrestrialnetshavemeageratmospheresatbest.Anet'sabilitytoretainanatmospheredependsonitstemperatureandmass.Simplystated,agasmoleculecan"evaporate"fromanetifitreachesaspeedknownastheescapevelocity.ForEarth,thisvelocityis11kilometerspersecond.Anymaterial,includinga,mustreachthisspeedbeforeitcanleaveEarthandgointospace.TheJoviannets,becauseoftheirgreatermassesandthushighersurfacegravities,havehigherescapevelocities(21-60kilometerspersecond)thantheterrestrialnets.Consequently,itismorediffi