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对 32 P的切仑科夫计数法及液闪测量作了比较 ,同时对于不同样品瓶和闪烁液对 32 P计数效率的影响进行了实验比较 ,指出提高 32 P测量效率的途径 相似文献
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本文介绍 OEIC 器件,侧重于基于 GaAs 和 InP 材料的、应用于光纤通信的 OEIC 发射器、接收器和中继器的发展现状、器件性能和各种关键新工艺,并探讨了其发展动向。 相似文献
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To bring the excellent abrasion-resistant po-tential of carbide into full play,composites of casttungsten carbide(CTC)grains based on mainlyplate martensite and high Cr,W white cast iron aremade on substrate of grey iron by cast-in-placehardfacing process.Results of high-stresstwo-body and three-body abrasion show that:(1)Base alloy microstructures have overwhelmingdominating effects on abrasion resistances of thecomposites in two-body and especially three-bodyabrasion systems.(2)All composites have very ex-cellent abrasion-resistances which increase drasti-cally with the increase of CTC grain size.In case ofthe same CTC grain size,composite based onmartensite white cast iron is much morewear-resistant than that based on mainly platemartensite although the volume fraction of CTCgrains in the latter is considerably larger than thatin the former.In three-body abrasion system,loadhas little effect on wear rate for composites basedon martensite white cast iron,but wear rate ofconventional wear-resistant materials increaseslinearly in a very steep slope as the nominal stressincreases. 相似文献
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The effect of compressive deformation testedabove the M_s temperature on the martensitemorphology in Fe-Ni-C alloys has been studied.Inthe Fe-30Ni-0.12C alloy,the M_s temperature is-50℃ The cylindrical specimens werecompressively deformed at -40℃.The strain rateswere 10,20,30 and 40%.X-ray analysis andmetallographic examination showed that nostrain-induced martensite was found.After quench-ing to -53℃,some thin plates and unusualmorphologies of lenticular martensites with bentand/or broken mid-ribs were observed.In theFe-30Ni-0.34C alloy,the M_s temperature is-120℃.Compressive deformation with differentstrain rates were carried out at room temperature.After quenching to the liquid nitrogen temperature,some bent thin plate matensites(unbroken)occur-red.The transformed twins in bent plate were alsobent and nearly parallel to the γ-α'interfaces.Orientation relationship between austenite and bentmartensite has been examined by means of trans-mission electron microscope.It was proved thatthese unusual morphologies are inherent in thecompressive pre-deformed austenite. 相似文献
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根据红外分析、顺磁共振、光电子能谱及化学分析结果,我们提出了氟塑料—46的辐射交联反应机理。交联点不一定如Bowers等由理论分析推断的在氟塑料—46的—CF_3侧链上。我们认为可以由 CF_3链侧自由基如—CF_2—CF—CF_2—,—CF_2—C—CF_2—,直接复合成交联键,H型交联;或由链侧自由基和链端自由基复合通过支化而交联,即T型或Y型交联。后者机率更多些。 相似文献
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The crack growth rates of A537 c1.1 steeland its weld metal have been investigated bothin air and in artificial sea water.The effectsof stress ratio,frequency,residual stressof welds as well as corrosion products on cor-rosion fatigue crack growth rate have been exa-mined.Some electrochemical reactions occurredduring tests and models for describing the cor-rosion fatigue crack growth process in lowstrength of offshore structural steel werediscussed. 相似文献