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INTRODUCTIONHowtoprotectthedatabase ,thekernelre sourcesofinformationwarfare,isbecomingmoreandmoreimportantsincetherapiddevelopmentofcomputerandcommunicationtechnology .TheArtificialIntelligenceInstituteofZhejiangUni versityhasprototypedaDatabaseSecuritya…  相似文献   
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INTRODUCTIONAsasinkandaninnersourceofnutrients,sedimentsplayanimportantroleinlakeeutroph ication.TheeutrophicationstatusofWestLakeisstillcriticalinrecentyearsevenaftermostpollutionsourcesaroundWestLakehavebeencontrolled(Peietal.,1998) ,mainlythroughtherel…  相似文献   
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INTRODUCTIONConsiderableattentionhasbeenfocusedonthecontrolproblemofuncertaindynamicalnon linearsystemssubjecttoexternaldisturba  相似文献   
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INTRODUCTIONThearchedretainingstructure ,anewtypeofretainingstructureinfoundationpits(Caietal.,1 992 ) ,hasmanyvirtuessuchasmorereason ablestructureshape ,smallerdeformation ,lowercost,andsoon .Butithasnotoftenbeenusedinengineeringbecauseitsanalysismethodisnotr…  相似文献   
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INTRODUCTIONMostcountrieshaveimplementednewpoli ciesontheenergysavingandenvironmentpro tection.AmericanPresidentBushsigned“TheComprehensiveNationalEnergyPolicyAct”in1992statingthatnogeneral purpose ,three phaseinductionmotorswillbeallowedintoUnit edStat…  相似文献   
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INTRODUCTIONMoleculardynamics (MD)simulationwasfoundtobeanimportantmethodologyforstudyofcondensedmatter (Tsuzukietal.,1 996) .Kiselevan  相似文献   
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INTRODUCTIONCoronaryarterydisease (CAD)continuestobethemajorcauseofmorbidityandmortalityinourcountry .TheactivityofbloodcoagulationfactorshasbeenshowntobeanimportantriskindicatorforCAD .However,circulatinglevelsofcoagulationfactorsmaynotaccuratelyreflectt…  相似文献   
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INTRODUCTIONIthasbeenrecognizedthatlong spanbridg es ,cable supportedbridgesinparticular,aresubjecttothedynamicwindaction .Theaerody namicstability (flutter)ofsuspensionbridgesduringerectionisasubjectofmajorconcernforresearchersandengineers .Althoughtheperi…  相似文献   
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INTRODUCTIONWiththerapiddevelopmentofinformationtechnologyandtheinternet,widespreadapplica tionsofpersonalcomputers,thereliabilityofthepowersupplysystemshasbecomemoreimpor tant.SinceUPS (uninterruptedpowersup plies) ,withacorepart theCVCFPWMinvert er,play…  相似文献   
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INTRODUCTIONInChinaandinEnglandenvironmentaledu cationtakesmanyformsandisimplementedbymanyagencies,bothformallyandinformally.Developmentsinbothcountrieshavebeen ,andcontinuetobe,influencedbygovernmentpoli cy ,publicawarenessandsubjectsub cultures.Thisstud…  相似文献   
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