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应用肽疫苗或T细胞疫苗的理论依据是

不同HLA分子可选择性地与结合具有不同锚定位的锚定残基同一HLA可结合多种抗原肽同一家族的不同成员可识别和结合相同的锚定残基一种HLA等位基因产物只能识别一种抗原肽以上均错

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Tight-lippedeldersusedtosayIt’’snotwhatyouwantinthisworldbutwhatyouget. Psychologyteachesthatyoudogetwhatyouwantifyouknowwhatyouwantandwanttherightthings. Youcanmakeamentalblueprintofadesireasyouwouldmakeablueprintofahouseandeachofusiscontinuallymakingtheseblueprintsinthegeneralroutineofeverydayliving.Ifweintendtohavefriendstodinnerweplanthemenumakeashoppinglistdecidewhichfoodtocookfirstandsuchplanningisanessentialforanytypeofmealtobeserved. Likewiseifyouwanttofindajobtakeasheetofpaperandwriteabriefaccountofyourself.Inmakingablueprintforajobbeginwithyourselfforwhenyouknowexactlywhatyouhavetoofferyoucanintelligentlyplanwheretosellyourservices. Thisaccountofyourselfisactuallyasketchofyourworkinglifeandshouldincludeeducationexperienceandreferences.Suchanaccountisvaluable.Itcanbereferredtoinfillingoutstandardapplicationblanksandisextremelyhelpfulinpersonalinterviews.Whiletalkingtoyouyourcould-beemployerisdecidingwhetheryoureducationyourexperienceandotherqualificationswillpayhimtoemployyouandyourwaresandabilitiesmustbedisplayedinanorderlyandreasonablyconnectedmanner. Whenyouhavecarefullypreparedablueprintofyourabilitiesanddesiresyouhavesomethingtangibletosell.Thenyouarereadytohuntforajob.Getallthepossibleinformationaboutyourcouldbejob.Makeinquiriesastothedetailsregardingthejobandthefirm.Keepyoureyesandearsopenanduseyourownjudgement.Spendacertainamountoftimeeachdayseekingtheemploymentyouwishforandkeepinmind:Securingajobisyourjobnow. WhatdotheeldersmeanwhentheysayIt’’snotwhatyouwantinthisworldbutwhatyouget.
AreportconsistentlybroughtbackbyvisitorstotheUSishowfriendlycourteousandhelpfulmostAmericansweretothem.TobefairthisobservationisalsofrequentlymadeofCanadaandCanadiansandshouldbestbeconsideredNorthAmerican.Thereareofcourseexceptions.Small-mindedofficialsrudewaitersandill-manneredtaxidriversarehardlyunknownintheUS.Yetitisanobservationmadesofrequentlythatitdeservescomment. Foralongperiodoftimeandinmanypartsofthecountryatravelerwasawelcomebreakinanotherwisedullexistence.Dullnessandlonelinesswerecommonproblemsofthefamilieswhogenerallyliveddistantfromoneanother.Strangersandtravelerswerewelcomesourcesofdiversionandbroughtnewsoftheoutsideworld. Theharshrealitiesofthefrontieralsoshapedthistraditionofhospitality.Someonetravellingaloneifhungryinjuredorilloftenhadnowheretoturnexcepttothenearestcabinorsettlement.Itwasnotamatterofchoiceforthetravelerormerelyacharitableimpulseonthepartofthesettlers.Itreflectedtheharshnessofdailylife:ifyoudidn’’ttakeinthestrangerandtakecareofhimtherewasnooneelsewhowould.Andsomedayrememberyoumightbeinthesamesituation. Todaytherearemanycharitableorganizationswhichspecializeinhelpingthewearytraveler.YettheoldtraditionofhospitalitytostrangersisstillverystrongintheUSespeciallyinthesmallercitiesandtownsawayfromthebusytouristtrails.IwasjusttravelingthroughgottalkingwiththisAmericanandprettysoonheinvitedmehomefordinner―amazing.SuchobservationsreportedbyvisitorstotheUSarenotuncommonbutarenotalwaysunderstoodproperly.ThecasualfriendlinessofmanyAmericansshouldbeinterpretedneitherassuperficialnorasartificialbutastheresultofahistoricallydevelopedculturaltradition. AsistrueofanydevelopedsocietyinAmericaacomplexsetofculturalsignalsassumptionsandconventionsunderliesallsocialinterrelationships.Andofcoursespeakingalanguagedoesnotnecessarilymeanthatsomeoneunderstandssocialandculturalpatterns.Visitorswhofailtotranslateculturalmeaningsproperlyoftendrawwrongconclusions.ForexamplewhenanAmericanusesthewordfriendtheculturalimplicationsofthewordmaybequitedifferentfromthoseithasinthevisitor’’slanguageandculture.Ittakesmorethanabriefencounteronabustodistinguishbetweencourteousconventionandindividualinterest.YetbeingfriendlyisavirtuethatmanyAmericansvaluehighlyandexpectfrombothneighborsandstrangers. Intheeyesofvisitorsfromtheoutsideworld___________.
下列哪种维生素是辅酶A的成分
已知某种酶的Km值为25mmol/L欲使酶促反应达到最大反应速度的50%该底物浓度应为
Atthestartofthe20thcenturyimmigrantlaborandinnovationhelpedturntheU.S.intoapowerfulmanufacturingnation.Todayforeign-bornengineersjamthecorridorsofSiliconValleyhelpingAmerica’’sinformation-technologyboom.Andasthe21stcenturydawnsyetanotherwaveofimmigrantswillonceagainhelptransformtheeconomy. 46DuringthenextdecadeexceptingachangeingovernmentpolicynearlyamillionimmigrantsareexpectedtoarriveintheU.S.everyyearmostofwhombothlegalandillegalwillcontinuetocomefromLatinAmericaandSoutheastAsiabuteveryforeignlandwillberepresented. Asdomesticbirthratesstagnateonlyforeign-bornworkerwillkeepthelaborpoolgrowing.By2006infactimmigrantswillaccountforhalfofallnewU.S.workers;overthenext30yearstheirsharewillriseto60%. 47EvenatcurrentlevelsofimmigrationaccordingtotheLaborDept.thenumberofpeopleavailabletoworkwillincreasebyamere0.8%peryearbetween1996and2006-halftherateofthepreviousdecade.WithoutimmigrantsaccordingtoanewstudytheU.S.workforcewouldactuallybegintoshrinkby2015. 48It’’snotallaboutsheernumbersofcourse:ToliftproductivityandspurgrowthimmigrantsmustprovidecreativityentrepreneurialenergyorsimpleinitiativethatAmericacouldn’’tfindotherwise.IfallyoudidwasbringinpeoplewhoareexactlythesameasthosewehaveheretherewouldbenoeconomicbenefitsaysRandCorp.economistJamesP.SmithYou’’djusthavemorepeople. Justascrucialthearrayofeducationandskillsimmigrantsbringcouldfitneatlywiththesupplyofjobsoverthenextdecade.AccordingtoLindaLevineattheCongressionalResearchService60%ofthejobscreatedthrough2005willrequiresomepost-secondaryeducation.Butsheaddslow-skilljobswillstillrepresentabouthalfoftotalemployment.49Yetimmigrantsalsoare50%morelikelythanAmericanstohaveagraduatedegreeandanunbelievable23%ofU.S.residentsholdingPhDsinscienceandengineeringareforeign-bornaccordingtotheNationalScienceFoundation. Indeedforeign-bornworkershaveshownanextraordinaryabilitytoassimilateandflourish.Certainlysomelessskilledworkerswillremainatthebottomeconomicrungalltheirlives.50Yetotherswillcatchupquicklyandwithinadecadeoftheirarrivalthewell-educatedwillgofrommakingbarelyhalfthatofnative-bornAmericansincomparableworktonearly90%accordingtoarecentstudy. Thatofcoursewillraiseimmigrants’’livingstandards.Moreimportantitwillhelpdriveinnovationandentrepreneurshipkeyenginesofthe21stCenturyEconomy.
以下哪种氨基酸是含硫的氨基酸
Industrialsafetydoesnotjusthappen.Companies________lowaccidentratesplantheirsafetyprogramsworkhardtoorganizethemandcontinueworkingtokeepthem________andactive.Whentheworkiswelldonea________ofaccident-freeoperationsisestablished________timelostduetoinjuriesiskeptataminimum. Successfulsafetyprogramsmay______greatlyintheemphasisplacedoncertainaspectsoftheprogram.Someplacegreatemphasisonmechanicalguarding.Othersstresssafeworkpracticesby______rolesorregulations.______othersdependonanemotionalappealtotheworker.Buttherearecertainbasicideasthatmustbeusedineveryprogramifmaximumresultsaretobeobtained. Therecanbenoquestionaboutthevalueofasafetyprogram.Fromafinancialstandpointalonesafety________.Thefewertheinjury________thebettertheworkman’’sinsurancerate.Thismaymeanthedifferencebetweenoperatingat________orataloss.
Tight-lippedeldersusedtosayIt’’snotwhatyouwantinthisworldbutwhatyouget. Psychologyteachesthatyoudogetwhatyouwantifyouknowwhatyouwantandwanttherightthings. Youcanmakeamentalblueprintofadesireasyouwouldmakeablueprintofahouseandeachofusiscontinuallymakingtheseblueprintsinthegeneralroutineofeverydayliving.Ifweintendtohavefriendstodinnerweplanthemenumakeashoppinglistdecidewhichfoodtocookfirstandsuchplanningisanessentialforanytypeofmealtobeserved. Likewiseifyouwanttofindajobtakeasheetofpaperandwriteabriefaccountofyourself.Inmakingablueprintforajobbeginwithyourselfforwhenyouknowexactlywhatyouhavetoofferyoucanintelligentlyplanwheretosellyourservices. Thisaccountofyourselfisactuallyasketchofyourworkinglifeandshouldincludeeducationexperienceandreferences.Suchanaccountisvaluable.Itcanbereferredtoinfillingoutstandardapplicationblanksandisextremelyhelpfulinpersonalinterviews.Whiletalkingtoyouyourcould-beemployerisdecidingwhetheryoureducationyourexperienceandotherqualificationswillpayhimtoemployyouandyourwaresandabilitiesmustbedisplayedinanorderlyandreasonablyconnectedmanner. Whenyouhavecarefullypreparedablueprintofyourabilitiesanddesiresyouhavesomethingtangibletosell.Thenyouarereadytohuntforajob.Getallthepossibleinformationaboutyourcouldbejob.Makeinquiriesastothedetailsregardingthejobandthefirm.Keepyoureyesandearsopenanduseyourownjudgement.Spendacertainamountoftimeeachdayseekingtheemploymentyouwishforandkeepinmind:Securingajobisyourjobnow. Accordingtothepassageonemustwriteanaccountofhimselfbeforestartingtofindajobbecause_______________.
Industrialsafetydoesnotjusthappen.Companies________lowaccidentratesplantheirsafetyprogramsworkhardtoorganizethemandcontinueworkingtokeepthem________andactive.Whentheworkiswelldonea________ofaccident-freeoperationsisestablished________timelostduetoinjuriesiskeptataminimum. Successfulsafetyprogramsmay______greatlyintheemphasisplacedoncertainaspectsoftheprogram.Someplacegreatemphasisonmechanicalguarding.Othersstresssafeworkpracticesby______rolesorregulations.______othersdependonanemotionalappealtotheworker.Buttherearecertainbasicideasthatmustbeusedineveryprogramifmaximumresultsaretobeobtained. Therecanbenoquestionaboutthevalueofasafetyprogram.Fromafinancialstandpointalonesafety________.Thefewertheinjury________thebettertheworkman’’sinsurancerate.Thismaymeanthedifferencebetweenoperatingat________orataloss.
WhenitcomestotheslowingeconomyEllenSperoisn’’tbitinghernailsjustyet.Butthe47-year-oldmanicuristisn’’tcuttingfilingorpolishingasmanynailsasshe’’dliketoeither.Mostofherclientsspend＄12to＄50weeklybutlastmonthtwolongtimecustomerssuddenlystoppedshowingup.Speroblamesthesofteningeconomy.I’’magoodeconomicindicatorshesays.Iprovideaservicethatpeoplecandowithoutwhenthey’’reconcernedaboutsavingsomedollars.SoSperoisdownscalingshoppingatmiddle-browDillard’’sdepartmentstorenearhersuburbanClevelandhomeinsteadofNeimanMarcus.Idon’’tknowifotherclientsaregoingtoabandonmetooshesays. EvenbeforeAlanGreenspan’’sadmissionthatAmerica’’sred-hoteconomyiscoolinglotsofworkingfolkshadalreadyseensignsoftheslowdownthemselves.FromcardealershipstoGapoutletssaleshavebeenlaggingformonthsasshopperstempertheirspending.Forretailerswholastyeartookin24percentoftheirrevenuebetweenThanksgivingandChristmasthecautiousapproachiscomingatacrucialtime.Alreadyexpertssayholidaysalesareoff7percentfromlastyear’’space.Butdon’’tsoundanyalarmsjustyet.Consumersseemonlymildlyconcernednotpanickedandmanysaytheyremainoptimisticabouttheeconomy’’slong-termprospectsevenastheydosomemodestbelt-tightening. Consumerssaythey’’renotindespairbecausedespitethedreadfulheadlinestheirownfortunesstillfeelprettygood.Homepricesareholdingsteadyinmostregions.InManhattanthere’’sanewgoldrushhappeninginthe＄4millionto＄10millionrangepredominantlyfedbyWallStreetbonusessaysbrokerBarbaraCorcoran.InSanFranciscopricesarestillrisingevenasfrenziedoverbiddingquiets.Insteadof20to30offersnowmaybeyouonlygettwoorthreesaysJohnTealdiaBayAreareal-estatebroker.Andmostfolksstillfeelprettycomfortableabouttheirabilitytofindandkeepajob. Manyfolksseesilverliningstothisslowdown.Potentialhomebuyerswouldcheerforlowerinterestrates.Employerswouldn’’tmindalittlefewerbubblesinthejobmarket.Manyconsumersseemtohavebeeninfluencedbystock-marketswingswhichinvestorsnowviewasanecessaryingredienttoasustainedboom.Dinersmightseeanupsidetoo.GettingatableatManhattan’’shotnewAlainDucasserestaurantusedtobeimpossible.Notanymore.ForthatGreenspan&Co.maystillbeworthtoasting. Towhichofthefollowingistheauthorlikelytoagree
磺胺类药物能竞争抑制二氢叶酸还原酶是因为其结构相似于
酶与一般催化剂相比不同点有
AreportconsistentlybroughtbackbyvisitorstotheUSishowfriendlycourteousandhelpfulmostAmericansweretothem.TobefairthisobservationisalsofrequentlymadeofCanadaandCanadiansandshouldbestbeconsideredNorthAmerican.Thereareofcourseexceptions.Small-mindedofficialsrudewaitersandill-manneredtaxidriversarehardlyunknownintheUS.Yetitisanobservationmadesofrequentlythatitdeservescomment. Foralongperiodoftimeandinmanypartsofthecountryatravelerwasawelcomebreakinanotherwisedullexistence.Dullnessandlonelinesswerecommonproblemsofthefamilieswhogenerallyliveddistantfromoneanother.Strangersandtravelerswerewelcomesourcesofdiversionandbroughtnewsoftheoutsideworld. Theharshrealitiesofthefrontieralsoshapedthistraditionofhospitality.Someonetravellingaloneifhungryinjuredorilloftenhadnowheretoturnexcepttothenearestcabinorsettlement.Itwasnotamatterofchoiceforthetravelerormerelyacharitableimpulseonthepartofthesettlers.Itreflectedtheharshnessofdailylife:ifyoudidn’’ttakeinthestrangerandtakecareofhimtherewasnooneelsewhowould.Andsomedayrememberyoumightbeinthesamesituation. Todaytherearemanycharitableorganizationswhichspecializeinhelpingthewearytraveler.YettheoldtraditionofhospitalitytostrangersisstillverystrongintheUSespeciallyinthesmallercitiesandtownsawayfromthebusytouristtrails.IwasjusttravelingthroughgottalkingwiththisAmericanandprettysoonheinvitedmehomefordinner―amazing.SuchobservationsreportedbyvisitorstotheUSarenotuncommonbutarenotalwaysunderstoodproperly.ThecasualfriendlinessofmanyAmericansshouldbeinterpretedneitherassuperficialnorasartificialbutastheresultofahistoricallydevelopedculturaltradition. AsistrueofanydevelopedsocietyinAmericaacomplexsetofculturalsignalsassumptionsandconventionsunderliesallsocialinterrelationships.Andofcoursespeakingalanguagedoesnotnecessarilymeanthatsomeoneunderstandssocialandculturalpatterns.Visitorswhofailtotranslateculturalmeaningsproperlyoftendrawwrongconclusions.ForexamplewhenanAmericanusesthewordfriendtheculturalimplicationsofthewordmaybequitedifferentfromthoseithasinthevisitor’’slanguageandculture.Ittakesmorethanabriefencounteronabustodistinguishbetweencourteousconventionandindividualinterest.YetbeingfriendlyisavirtuethatmanyAmericansvaluehighlyandexpectfrombothneighborsandstrangers. Familiesinfrontiersettlementsusedtoentertainstrangers___________.
肝中富含的LDH同工酶是
核酸的最大紫外光吸收值一般在哪一波长附近
核酸变性后可产生的效应是
用凝胶过滤层析交联葡聚糖凝胶柱分离蛋白质时下列哪项是正确的
下列选项中符合tBNA结构特点的是
有关变构酶的叙述哪项是错误的
Atthestartofthe20thcenturyimmigrantlaborandinnovationhelpedturntheU.S.intoapowerfulmanufacturingnation.Todayforeign-bornengineersjamthecorridorsofSiliconValleyhelpingAmerica’’sinformation-technologyboom.Andasthe21stcenturydawnsyetanotherwaveofimmigrantswillonceagainhelptransformtheeconomy. 46DuringthenextdecadeexceptingachangeingovernmentpolicynearlyamillionimmigrantsareexpectedtoarriveintheU.S.everyyearmostofwhombothlegalandillegalwillcontinuetocomefromLatinAmericaandSoutheastAsiabuteveryforeignlandwillberepresented. Asdomesticbirthratesstagnateonlyforeign-bornworkerwillkeepthelaborpoolgrowing.By2006infactimmigrantswillaccountforhalfofallnewU.S.workers;overthenext30yearstheirsharewillriseto60%. 47EvenatcurrentlevelsofimmigrationaccordingtotheLaborDept.thenumberofpeopleavailabletoworkwillincreasebyamere0.8%peryearbetween1996and2006-halftherateofthepreviousdecade.WithoutimmigrantsaccordingtoanewstudytheU.S.workforcewouldactuallybegintoshrinkby2015. 48It’’snotallaboutsheernumbersofcourse:ToliftproductivityandspurgrowthimmigrantsmustprovidecreativityentrepreneurialenergyorsimpleinitiativethatAmericacouldn’’tfindotherwise.IfallyoudidwasbringinpeoplewhoareexactlythesameasthosewehaveheretherewouldbenoeconomicbenefitsaysRandCorp.economistJamesP.SmithYou’’djusthavemorepeople. Justascrucialthearrayofeducationandskillsimmigrantsbringcouldfitneatlywiththesupplyofjobsoverthenextdecade.AccordingtoLindaLevineattheCongressionalResearchService60%ofthejobscreatedthrough2005willrequiresomepost-secondaryeducation.Butsheaddslow-skilljobswillstillrepresentabouthalfoftotalemployment.49Yetimmigrantsalsoare50%morelikelythanAmericanstohaveagraduatedegreeandanunbelievable23%ofU.S.residentsholdingPhDsinscienceandengineeringareforeign-bornaccordingtotheNationalScienceFoundation. Indeedforeign-bornworkershaveshownanextraordinaryabilitytoassimilateandflourish.Certainlysomelessskilledworkerswillremainatthebottomeconomicrungalltheirlives.50Yetotherswillcatchupquicklyandwithinadecadeoftheirarrivalthewell-educatedwillgofrommakingbarelyhalfthatofnative-bornAmericansincomparableworktonearly90%accordingtoarecentstudy. Thatofcoursewillraiseimmigrants’’livingstandards.Moreimportantitwillhelpdriveinnovationandentrepreneurshipkeyenginesofthe21stCenturyEconomy.
Industrialsafetydoesnotjusthappen.Companies________lowaccidentratesplantheirsafetyprogramsworkhardtoorganizethemandcontinueworkingtokeepthem________andactive.Whentheworkiswelldonea________ofaccident-freeoperationsisestablished________timelostduetoinjuriesiskeptataminimum. Successfulsafetyprogramsmay______greatlyintheemphasisplacedoncertainaspectsoftheprogram.Someplacegreatemphasisonmechanicalguarding.Othersstresssafeworkpracticesby______rolesorregulations.______othersdependonanemotionalappealtotheworker.Buttherearecertainbasicideasthatmustbeusedineveryprogramifmaximumresultsaretobeobtained. Therecanbenoquestionaboutthevalueofasafetyprogram.Fromafinancialstandpointalonesafety________.Thefewertheinjury________thebettertheworkman’’sinsurancerate.Thismaymeanthedifferencebetweenoperatingat________orataloss.
在280nm波长附近具有最大光吸收峰的氨基酸是
WhenitcomestotheslowingeconomyEllenSperoisn’’tbitinghernailsjustyet.Butthe47-year-oldmanicuristisn’’tcuttingfilingorpolishingasmanynailsasshe’’dliketoeither.Mostofherclientsspend＄12to＄50weeklybutlastmonthtwolongtimecustomerssuddenlystoppedshowingup.Speroblamesthesofteningeconomy.I’’magoodeconomicindicatorshesays.Iprovideaservicethatpeoplecandowithoutwhenthey’’reconcernedaboutsavingsomedollars.SoSperoisdownscalingshoppingatmiddle-browDillard’’sdepartmentstorenearhersuburbanClevelandhomeinsteadofNeimanMarcus.Idon’’tknowifotherclientsaregoingtoabandonmetooshesays. EvenbeforeAlanGreenspan’’sadmissionthatAmerica’’sred-hoteconomyiscoolinglotsofworkingfolkshadalreadyseensignsoftheslowdownthemselves.FromcardealershipstoGapoutletssaleshavebeenlaggingformonthsasshopperstempertheirspending.Forretailerswholastyeartookin24percentoftheirrevenuebetweenThanksgivingandChristmasthecautiousapproachiscomingatacrucialtime.Alreadyexpertssayholidaysalesareoff7percentfromlastyear’’space.Butdon’’tsoundanyalarmsjustyet.Consumersseemonlymildlyconcernednotpanickedandmanysaytheyremainoptimisticabouttheeconomy’’slong-termprospectsevenastheydosomemodestbelt-tightening. Consumerssaythey’’renotindespairbecausedespitethedreadfulheadlinestheirownfortunesstillfeelprettygood.Homepricesareholdingsteadyinmostregions.InManhattanthere’’sanewgoldrushhappeninginthe＄4millionto＄10millionrangepredominantlyfedbyWallStreetbonusessaysbrokerBarbaraCorcoran.InSanFranciscopricesarestillrisingevenasfrenziedoverbiddingquiets.Insteadof20to30offersnowmaybeyouonlygettwoorthreesaysJohnTealdiaBayAreareal-estatebroker.Andmostfolksstillfeelprettycomfortableabouttheirabilitytofindandkeepajob. Manyfolksseesilverliningstothisslowdown.Potentialhomebuyerswouldcheerforlowerinterestrates.Employerswouldn’’tmindalittlefewerbubblesinthejobmarket.Manyconsumersseemtohavebeeninfluencedbystock-marketswingswhichinvestorsnowviewasanecessaryingredienttoasustainedboom.Dinersmightseeanupsidetoo.GettingatableatManhattan’’shotnewAlainDucasserestaurantusedtobeimpossible.Notanymore.ForthatGreenspan&Co.maystillbeworthtoasting. Whenmentioningthe＄4millionto＄10millionrangeLine3Paragraph3theauthoristalkingabout
Atthestartofthe20thcenturyimmigrantlaborandinnovationhelpedturntheU.S.intoapowerfulmanufacturingnation.Todayforeign-bornengineersjamthecorridorsofSiliconValleyhelpingAmerica’’sinformation-technologyboom.Andasthe21stcenturydawnsyetanotherwaveofimmigrantswillonceagainhelptransformtheeconomy. 46DuringthenextdecadeexceptingachangeingovernmentpolicynearlyamillionimmigrantsareexpectedtoarriveintheU.S.everyyearmostofwhombothlegalandillegalwillcontinuetocomefromLatinAmericaandSoutheastAsiabuteveryforeignlandwillberepresented. Asdomesticbirthratesstagnateonlyforeign-bornworkerwillkeepthelaborpoolgrowing.By2006infactimmigrantswillaccountforhalfofallnewU.S.workers;overthenext30yearstheirsharewillriseto60%. 47EvenatcurrentlevelsofimmigrationaccordingtotheLaborDept.thenumberofpeopleavailabletoworkwillincreasebyamere0.8%peryearbetween1996and2006-halftherateofthepreviousdecade.WithoutimmigrantsaccordingtoanewstudytheU.S.workforcewouldactuallybegintoshrinkby2015. 48It’’snotallaboutsheernumbersofcourse:ToliftproductivityandspurgrowthimmigrantsmustprovidecreativityentrepreneurialenergyorsimpleinitiativethatAmericacouldn’’tfindotherwise.IfallyoudidwasbringinpeoplewhoareexactlythesameasthosewehaveheretherewouldbenoeconomicbenefitsaysRandCorp.economistJamesP.SmithYou’’djusthavemorepeople. Justascrucialthearrayofeducationandskillsimmigrantsbringcouldfitneatlywiththesupplyofjobsoverthenextdecade.AccordingtoLindaLevineattheCongressionalResearchService60%ofthejobscreatedthrough2005willrequiresomepost-secondaryeducation.Butsheaddslow-skilljobswillstillrepresentabouthalfoftotalemployment.49Yetimmigrantsalsoare50%morelikelythanAmericanstohaveagraduatedegreeandanunbelievable23%ofU.S.residentsholdingPhDsinscienceandengineeringareforeign-bornaccordingtotheNationalScienceFoundation. Indeedforeign-bornworkershaveshownanextraordinaryabilitytoassimilateandflourish.Certainlysomelessskilledworkerswillremainatthebottomeconomicrungalltheirlives.50Yetotherswillcatchupquicklyandwithinadecadeoftheirarrivalthewell-educatedwillgofrommakingbarelyhalfthatofnative-bornAmericansincomparableworktonearly90%accordingtoarecentstudy. Thatofcoursewillraiseimmigrants’’livingstandards.Moreimportantitwillhelpdriveinnovationandentrepreneurshipkeyenginesofthe21stCenturyEconomy. Atthestartofthe20thcenturyimmigrantlaborandinnovationhelpedturntheU.S.intoapowerfulmanufacturingnation.Todayforeign-bornengineersjamthecorridorsofSiliconValleyhelpingAmerica’’sinformation-technologyboom.Andasthe21stcenturydawnsyetanotherwaveofimmigrantswillonceagainhelptransformtheeconomy. 46DuringthenextdecadeexceptingachangeingovernmentpolicynearlyamillionimmigrantsareexpectedtoarriveintheU.S.everyyearmostofwhombothlegalandillegalwillcontinuetocomefromLatinAmericaandSoutheastAsiabuteveryforeignlandwillberepresented. Asdomesticbirthratesstagnateonlyforeign-bornworkerwillkeepthelaborpoolgrowing.By2006infactimmigrantswillaccountforhalfofallnewU.S.workers;overthenext30yearstheirsharewillriseto60%. 47EvenatcurrentlevelsofimmigrationaccordingtotheLaborDept.thenumberofpeopleavailabletoworkwillincreasebyamere0.8%peryearbetween1996and2006-halftherateofthepreviousdecade.WithoutimmigrantsaccordingtoanewstudytheU.S.workforcewouldactuallybegintoshrinkby2015. 48It’’snotallaboutsheernumbersofcourse:ToliftproductivityandspurgrowthimmigrantsmustprovidecreativityentrepreneurialenergyorsimpleinitiativethatAmericacouldn’’tfindotherwise.IfallyoudidwasbringinpeoplewhoareexactlythesameasthosewehaveheretherewouldbenoeconomicbenefitsaysRandCorp.economistJamesP.SmithYou’’djusthavemorepeople. Justascrucialthearrayofeducationandskillsimmigrantsbringcouldfitneatlywiththesupplyofjobsoverthenextdecade.AccordingtoLindaLevineattheCongressionalResearchService60%ofthejobscreatedthrough2005willrequiresomepost-secondaryeducation.Butsheaddslow-skilljobswillstillrepresentabouthalfoftotalemployment.49Yetimmigrantsalsoare50%morelikelythanAmericanstohaveagraduatedegreeandanunbelievable23%ofU.S.residentsholdingPhDsinscienceandengineeringareforeign-bornaccordingtotheNationalScienceFoundation. Indeedforeign-bornworkershaveshownanextraordinaryabilitytoassimilateandflourish.Certainlysomelessskilledworkerswillremainatthebottomeconomicrungalltheirlives.50Yetotherswillcatchupquicklyandwithinadecadeoftheirarrivalthewell-educatedwillgofrommakingbarelyhalfthatofnative-bornAmericansincomparableworktonearly90%accordingtoarecentstudy. Thatofcoursewillraiseimmigrants’’livingstandards.Moreimportantitwillhelpdriveinnovationandentrepreneurshipkeyenginesofthe21stCenturyEconomy.
Aninvisibleborderdividesthosearguingforcomputersintheclassroomonthebehalfofstudents’’careerprospectsandthosearguingforcomputersintheclassroomforbroaderreasonsofradicaleducationalreform.Veryfewwritersonthesubjecthaveexploredthisdistinction--indeedcontradiction--whichgoestotheheartofwhatiswrongwiththecampaigntoputcomputersintheclassroom. Aneducationthataimsatgettingastudentacertainkindofjobisatechnicaleducation.Justifiedforreasonsradicallydifferentfromwhyeducationisuniversallyrequiredbylaw.Itisnotsimplytoraiseeveryone’’sjobprospectsthatallchildrenarelegallyrequiredtoattendschoolintotheirteens.RatherwehaveacertainconceptionoftheAmericancitizenacharacterwhoisincompleteifhecannotcompetentlyassesshowhislivelihoodandhappinessareaffectedbythingsoutsideofhimself.Butthiswasnotalwaysthecasebeforeitwaslegallyrequiredforallchildrentoattendschooluntilacertainageitwaswidelyacceptedthatsomewerejustnotequippedbynaturetopursuethiskindofeducation.Withoptimismcharacteristicofallindustrializedcountrieswecametoacceptthateveryoneisfittobeeducated.Computer-educationadvocatesforsakethisoptimisticnotionforapessimismthatbetraystheirotherwisecheeryoutlook.Bankingontheconfusionbetweeneducationalandvocationalreasonsforbringingcomputersintoschoolscomputer-educationadvocatesoftenemphasizethejobprospectsofgraduatesovertheireducationalachievement. Therearesomegoodargumentsforatechnicaleducationgiventhefightkindofstudent.ManyEuropeanschoolsintroducetheconceptofprofessionaltrainingearlyoninordertomakesurechildrenareproperlyequippedfortheprofessionstheywanttojoin.Itishoweverpresumptuoustoinsistthattherewillonlybesomanyjobsforsomanyscientistssomanybusinessmensomanyaccountants.Besidesthisisunlikelytoproducetheneedednumberofeverykindofprofessionalinacountryaslargeasoursandwheretheeconomyisspreadoversomanystatesandinvolvessomanyinternationalcorporations. Butforasmallgroupofstudentsprofessionaltrainingmightbethewaytogosincewell-developedskillsallotherfactorsbeingequalcanbethedifferencebetweenhavingajobandnot.Ofcoursethebasicsofusinganycomputerthesedaysareverysimple.Itdoesnottakealifelongacquaintancetopickupvarioussoftwareprograms.Ifonewantedtobecomeacomputerengineerthatisofcourseandentirelydifferentstory.Basiccomputerskillstake--attheverylongest--acoupleofmonthstolearn.Inanycasebasiccomputerskillsareonlycomplementarytothehostofrealskillsthatarenecessarytobecominganykindofprofessional.Itshouldbeobservedofcoursethatnoschoolvocationalornotishelpedbyaconfusionoveritspurpose. Itcouldbeinferredfromthepassagethatintheauthor’’scountrytheEuropeanmodelofprofessionaltrainingis____________.
下列关于酶活性中心的叙述中正确的是
WhenitcomestotheslowingeconomyEllenSperoisn’’tbitinghernailsjustyet.Butthe47-year-oldmanicuristisn’’tcuttingfilingorpolishingasmanynailsasshe’’dliketoeither.Mostofherclientsspend＄12to＄50weeklybutlastmonthtwolongtimecustomerssuddenlystoppedshowingup.Speroblamesthesofteningeconomy.I’’magoodeconomicindicatorshesays.Iprovideaservicethatpeoplecandowithoutwhenthey’’reconcernedaboutsavingsomedollars.SoSperoisdownscalingshoppingatmiddle-browDillard’’sdepartmentstorenearhersuburbanClevelandhomeinsteadofNeimanMarcus.Idon’’tknowifotherclientsaregoingtoabandonmetooshesays. EvenbeforeAlanGreenspan’’sadmissionthatAmerica’’sred-hoteconomyiscoolinglotsofworkingfolkshadalreadyseensignsoftheslowdownthemselves.FromcardealershipstoGapoutletssaleshavebeenlaggingformonthsasshopperstempertheirspending.Forretailerswholastyeartookin24percentoftheirrevenuebetweenThanksgivingandChristmasthecautiousapproachiscomingatacrucialtime.Alreadyexpertssayholidaysalesareoff7percentfromlastyear’’space.Butdon’’tsoundanyalarmsjustyet.Consumersseemonlymildlyconcernednotpanickedandmanysaytheyremainoptimisticabouttheeconomy’’slong-termprospectsevenastheydosomemodestbelt-tightening. Consumerssaythey’’renotindespairbecausedespitethedreadfulheadlinestheirownfortunesstillfeelprettygood.Homepricesareholdingsteadyinmostregions.InManhattanthere’’sanewgoldrushhappeninginthe＄4millionto＄10millionrangepredominantlyfedbyWallStreetbonusessaysbrokerBarbaraCorcoran.InSanFranciscopricesarestillrisingevenasfrenziedoverbiddingquiets.Insteadof20to30offersnowmaybeyouonlygettwoorthreesaysJohnTealdiaBayAreareal-estatebroker.Andmostfolksstillfeelprettycomfortableabouttheirabilitytofindandkeepajob. Manyfolksseesilverliningstothisslowdown.Potentialhomebuyerswouldcheerforlowerinterestrates.Employerswouldn’’tmindalittlefewerbubblesinthejobmarket.Manyconsumersseemtohavebeeninfluencedbystock-marketswingswhichinvestorsnowviewasanecessaryingredienttoasustainedboom.Dinersmightseeanupsidetoo.GettingatableatManhattan’’shotnewAlainDucasserestaurantusedtobeimpossible.Notanymore.ForthatGreenspan&Co.maystillbeworthtoasting. ByEllenSperoisn’’tbitinghernailsjustyetLine1Paragraph1theauthormeans
Aninvisibleborderdividesthosearguingforcomputersintheclassroomonthebehalfofstudents’’careerprospectsandthosearguingforcomputersintheclassroomforbroaderreasonsofradicaleducationalreform.Veryfewwritersonthesubjecthaveexploredthisdistinction--indeedcontradiction--whichgoestotheheartofwhatiswrongwiththecampaigntoputcomputersintheclassroom. Aneducationthataimsatgettingastudentacertainkindofjobisatechnicaleducation.Justifiedforreasonsradicallydifferentfromwhyeducationisuniversallyrequiredbylaw.Itisnotsimplytoraiseeveryone’’sjobprospectsthatallchildrenarelegallyrequiredtoattendschoolintotheirteens.RatherwehaveacertainconceptionoftheAmericancitizenacharacterwhoisincompleteifhecannotcompetentlyassesshowhislivelihoodandhappinessareaffectedbythingsoutsideofhimself.Butthiswasnotalwaysthecasebeforeitwaslegallyrequiredforallchildrentoattendschooluntilacertainageitwaswidelyacceptedthatsomewerejustnotequippedbynaturetopursuethiskindofeducation.Withoptimismcharacteristicofallindustrializedcountrieswecametoacceptthateveryoneisfittobeeducated.Computer-educationadvocatesforsakethisoptimisticnotionforapessimismthatbetraystheirotherwisecheeryoutlook.Bankingontheconfusionbetweeneducationalandvocationalreasonsforbringingcomputersintoschoolscomputer-educationadvocatesoftenemphasizethejobprospectsofgraduatesovertheireducationalachievement. Therearesomegoodargumentsforatechnicaleducationgiventhefightkindofstudent.ManyEuropeanschoolsintroducetheconceptofprofessionaltrainingearlyoninordertomakesurechildrenareproperlyequippedfortheprofessionstheywanttojoin.Itishoweverpresumptuoustoinsistthattherewillonlybesomanyjobsforsomanyscientistssomanybusinessmensomanyaccountants.Besidesthisisunlikelytoproducetheneedednumberofeverykindofprofessionalinacountryaslargeasoursandwheretheeconomyisspreadoversomanystatesandinvolvessomanyinternationalcorporations. Butforasmallgroupofstudentsprofessionaltrainingmightbethewaytogosincewell-developedskillsallotherfactorsbeingequalcanbethedifferencebetweenhavingajobandnot.Ofcoursethebasicsofusinganycomputerthesedaysareverysimple.Itdoesnottakealifelongacquaintancetopickupvarioussoftwareprograms.Ifonewantedtobecomeacomputerengineerthatisofcourseandentirelydifferentstory.Basiccomputerskillstake--attheverylongest--acoupleofmonthstolearn.Inanycasebasiccomputerskillsareonlycomplementarytothehostofrealskillsthatarenecessarytobecominganykindofprofessional.Itshouldbeobservedofcoursethatnoschoolvocationalornotishelpedbyaconfusionoveritspurpose. Theauthorthinksthepresentrushtoputcomputersintheclassroomis____________.
下列哪一种氨基酸是亚氨基酸
蛋白质二级结构中存在的构象为

锚定残基

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