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1、医学重点1．X线特性：穿透性、荧光作用、摄影作用、电离作用2．X线影像形成的原理：(1)X线的三个特性：穿透性荧光作用摄影作用(2)人体组织有密度与厚度的区别：X线穿透过人体后，经过不同组织的吸收,产生了X线量的差别，在荧光屏及照片上产生不同密度的影像3．X线检查方法和选择原则（1）了解各种X线检查方法的适应症、禁忌症和优缺点（2）选择安全、准确、简便而经济的方法（3）由简到繁,先透视而后拍平片及造影（4）根据病情,灵活应用4．X线分析病变的原则①病变的位置及分布②病变的数目③病变的形状④病变的边缘⑤病变的密度⑥邻近器官及组织的改变⑦器官功能的改变5．CT图象特点1．空间分辨力q
2、ualityegg,chicken,...Developmentofpoultryindustrywilloccupyacertainareaofland,thereisamodernproductwithcomprehensiverollupof50,000chickenslayinghens,coversanareaof14.87hectares(233acres)more(includingOfficeofhatching,broodrearing,andlayingHouse,eggs,feedprocessingworkshop,Office,etc).Thepoult
3、ryindustryshouldworkinlandconservation,notaccountedfororlesscultivatedland,wasteland,theprincipleofslopeland.Whenthechickenfarmshouldgenerallynotavailabletolocalarablelandareatodetermineanappropriatelevelofbreedingsizeandnot,asinthepast,firstdeterminethesize,thengototheexpropriation.3.energy-
4、saving,water-savingawarenessinthe1970ofthe20thcentury,thepigandchickenfarmmechanizationinourcountryforwardundertheslogan,thecountrystartedbuildingamodernlargechickenfarmsintheclimax.Wasbuiltasthefullyenclosedintensivechickenfarms,usingartificiallight,mechanicalfeedingandmandatoryventilation,a
5、smallnumberofchickenfarmsalsousemechanicalsetseggsandmanure.Accordingtostatistics,fullyenclosedchickencoopperchickenwhentheannualelectricityconsumptionof10-kilowatt•,halfopenedthehenhousewhen•2~5kW(open),whentheentireopeningis0.5kW•,rollingopenshedsat0.45kW•.Henhousetypes,powerconsumptiondiff
6、erenceisverybig,adifferenceof10~20.China'senergysupplyisinshortsupply.Therefore,indeterminingthebreeding,poultryequipmentselectionshouldtakefullconsiderationofenergysavingissues.LackoffreshwaterresourcesinChina,theaverageannualprecipitationis600mm.19882474cubicmetersofwaterpercapitainChina,on
7、ly1/4ofthepopulationallovertheworld,nowreducedto2300cubicmeters.Hendailywaterintaketoabout1.5~2times,sowhenyou?单位面积中所含象素的大小和多少?象素越小,数目越多,构成的图象越细致,空间分辨力越高?CT图象空间分辨力不如X线图象高2．密度分辨力?辨别两个象素最小密度之差的能力?两个象素密度之差越小,密度分辨力越高?CT图象的密度分辨力较X线图象高5．CT值定义：在CT图象
