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1、FromradartonuclearmagneticresonanceRobertV.PoundDepartmentofPhysics,HarvardUniversity,Cambridge,Massachusetts02138[S0034-6861(99)00502-4]AswarengulfedEuropefromSeptember1939,andtherebyannounced.ForscaleitisworthnotingthatintheAxispowersoverranmostofthewesternEuropeanthecorrespon
2、dingmonthofJanuary1996,thePhysicalcountriesin1940,theUnitedStatesundertooktobuildReviewpublishednearly8000pagesinitsseveralparts.upquicklyitsmilitarycapabilities.Bylate1940,afullAlthoughtheRadiationLaboratorywaseminentlyyearbeforetheU.S.wasdrawnintowarasacombatant,successfulinit
3、stechnicalgoalsandiswidelyrecognizedtherebeganamassivemoveofscientists,especiallyashavingcontributedimportantlytotheAlliedvictory,physicists,temporarilyintoneworganizationssetuptotherewereseverallessgenerallyrecognizedeffectsondeveloptechnologicallyadvancedweapons.Oneofthethepos
4、twarworldofphysics.Manyphysicistsnotprevi-®rstofthese,destinedtobecomeoneofthelargest,wasouslygreatlyconcernedwithelectronicinstrumentationthe``RadiationLaboratory,''sonamedwithanintenttodevelopedamuchdeeperunderstandingespeciallyofobscureitspurpose,attheMassachusettsInstituteof
5、thefundamentallimitstoinstrumentalsensitivitysetbyTechnology,establishedinNovemberof1940bytheNa-varioussourcesofinterfering``noise.''Beyondatmo-tionalDefenseResearchCommittee(NDRC).Itsmis-sphericnoise,oftencalled``static,''widerrecognitionofsionwastodevelopradiodetectionandrangi
6、ng(tobe-shoteffectnoise,fromtheelectronicgranularityofelec-comeknownasRadar),inspiredbythestartlingtricalcurrents,andthermalnoise,explainedbytheeq-performanceofthepulsedcavitymagnetronrevealedtouipartitiontheoremofstatisticalmechanics,weremoreU.S.militaryof®cersandmembersoftheNa
7、tionalDe-widelyunderstood.ItwasdemonstratedquiteearlythatfenseResearchCommitteebytheBritish``TizardMis-themostsensitivedevicefortheinitialsignaldetectionsion.''Althoughmagnetronsasgeneratorsofelectro-inamicrowave(wavelength10cmandless)receiverwasmagneticenergyofshortwavelengthha
8、dbeenadevelopedversionofthearchaic``crystaldiod
