排序方式: 共有23条查询结果,搜索用时 15 毫秒
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结构精确的两亲性星型-梳型共聚物具有特殊的结构和性能,有广阔的潜在应用前景,因而受到广泛的关注.本文综合利用阴离子开环聚合技术(AROP)、可逆-加成断裂链转移自由基聚合技术(RAFT)和配位-插入开环聚合技术(CROP)设计并合成了结构精确新颖的两亲性星型-梳型共聚物PEO_4-6-[P(St-co-HEMA)-g-PCL]_4.我们对各步产物进行了核磁和GPC表征,对各个聚合过程的可控性都进行了深入研究,证明了两亲性星型-梳形共聚物中每个链段的分子量都是可控的,而且分子量分布窄,符合可控聚合的特点. 相似文献
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Comparison of total dose effects on SiGe heterojunction bipolar transistors induced by different swift heavy ion irradiation 下载免费PDF全文
The degradations in NPN silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) were fully studied in this work, by means of 25-MeV Si, 10-MeV C1, 20-MeV Br, and 10-MeV Br ion irradiation, respectively. Electrical parameters such as the base current (IB), current gain (β), neutral base recombination (NBR), and Early voltage (VA) were investigated and used to evaluate the tolerance to heavy ion irradiation. Experimental results demonstrate that device degradations are indeed radiation-source-dependent, and the larger the ion nuclear energy loss is, the more the displacement damages are, and thereby the more serious the performance degradation is. The maximum degradation was observed in the transistors irradiated by 10-MeV Br. For 20-MeV and 10-MeV Br ion irradiation, an unexpected degradation in Ic was observed and Early voltage decreased with increasing ion fluence, and NBR appeared to slow down at high ion fluence. The degradations in SiGe HBTs were mainly attributed to the displacement damages created by heavy ion irradiation in the transistors. The underlying physical mechanisms are analyzed and investigated in detail. 相似文献
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烯类单体与聚酰胺(尼龙)纤维接枝共聚合已有报道.Varma等人研究了Ce4+引发丙烯腈、丙烯酰胺分别与尼龙纤维的接枝共聚反应。Lenka发表了用P2O48-引发甲基丙烯酸甲酯(MMA)与尼龙6纤维接枝共聚合的研究结果.Nayak等人报道了用乙酰丙酮锰为引发剂使MMA与尼龙6接枝共聚合.本文以二甲基苯胺(DMA)/硫酸铜为引发体系,用MMA接枝尼龙66纤维丝,研究了Cu2+浓度等因素对该接枝共聚反应的影响. 相似文献
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对于相同制作工艺的NPN锗硅异质结双极晶体管(SiGe HBT), 在不同辐照剂量率下进行60Co γ射线的辐照效应与退火特性的研究. 测量结果表明, 两种辐照剂量率下, 随着辐照总剂量增加, 晶体管基极电流增大, 共发射极电流放大倍数降低, 且器件的辐照损伤、性能退化与辐照剂量率相关, 低剂量率下辐照损伤较高剂量率严重. 在经过与低剂量率辐照等时的退火后, 高剂量率下的辐照损伤仍较低剂量率下的损伤低, 即待测SiGeHBT具有明显的低剂量率损伤增强效应(ELDRS). 本文对相关的物理机理进行了探讨分析.
关键词:
锗硅异质结双极晶体管
低剂量率辐照损伤增强
辐照效应 相似文献
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超高效液相色谱-串联质谱法快速测定猪尿液中30种不同种类“瘦肉精”药物残留 总被引:4,自引:0,他引:4
建立了超高效液相色谱-串联质谱快速简单地同时测定猪尿液中30种不同种类“瘦肉精”药物(赛庚啶、可乐定及28种β-受体激动剂类)残留的方法.对液相色谱分离条件、MS/MS检测参数及样品前处理方式进行了优化.试样经5000 r/min离心5 min后直接经MCX柱净化,分别用3 mL水和3 mL甲醇淋洗,5%氨化甲醇进行洗脱,N2吹干后以流动相进行复溶,UPLC-MS/MS进行测定.结果表明,30种药物可在5.0 min内有效分离;各药物在0.1 ~ 10μg/L范围内呈良好的线性关系,相关系数均大于0.992;方法的检出限为0.1 μg/L,定量限为0.3 μg/L.在3个浓度水平下的平均回收率为67.6% ~ 103.2%,日内、日间相对标准偏差分别为2.8% ~ 16.8%和2.6% ~15.8%. 相似文献
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