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原位共聚阻燃聚酰胺66的结构与性能 被引量:3
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作者 付琪轩 蔡信民 +2 位作者 陈勇伟 冯新星 张华 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2022年第8期59-65,共7页
采用原位共聚合方法将含磷阻燃剂引入聚酰胺66(PA66)分子链中进行阻燃改性,制备得到了原位共聚阻燃聚酰胺66(FR-PA66),经测试所有样品均通过了UL-94的V-0级别,且阻燃剂质量分数为6%时,LOI值提高到28%。同时,运用傅里叶变换红外光谱分析... 采用原位共聚合方法将含磷阻燃剂引入聚酰胺66(PA66)分子链中进行阻燃改性,制备得到了原位共聚阻燃聚酰胺66(FR-PA66),经测试所有样品均通过了UL-94的V-0级别,且阻燃剂质量分数为6%时,LOI值提高到28%。同时,运用傅里叶变换红外光谱分析、X射线衍射分析、差示扫描量热分析、力学性能分析和偏光显微镜等方法,表征了阻燃改性后FR-PA66的结构、结晶行为变化及力学性能。研究表明,由于阻燃剂的引入,FR-PA66分子链受苯环的空间位阻影响,柔性有所降低,导致FR-PA66结晶速度减慢、结晶温度降低,形成晶粒尺寸较小,而晶型结构并未改变;随着阻燃剂含量的增加,FR-PA66的结晶能力和力学性能有进一步下降的趋势。 展开更多
关键词 阻燃 聚酰胺66 结构 结晶
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Clinical characteristics and prognosis of 69 cases of neonatal appendicitis 被引量:1
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作者 Yong Zhao Caihan Tang +6 位作者 Jinshi Huang Junmin Liao Yichao Gu Kaiyun Hua Yanan Zhang yongwei chen Shuangshuang Li 《Pediatric Investigation》 CAS CSCD 2023年第2期95-101,共7页
Importance:Neonatal appendicitis(NA)is a rare and potentially fatal neonatal disease.However,misdiagnosis is common owing to atypical clinical manifestations and non-specific laboratory tests.Objective:The aim of this... Importance:Neonatal appendicitis(NA)is a rare and potentially fatal neonatal disease.However,misdiagnosis is common owing to atypical clinical manifestations and non-specific laboratory tests.Objective:The aim of this study was to summarize the clinical characteristics,treatments,and prognoses of infants with NA.Methods:This retrospective analysis included 69 patients diagnosed with NA admitted to Beijing Children’s Hospital between 1980 and 2019.The patients were divided into surgical and non-surgical groups based on whether surgery was performed.Their clinical characteristics were analyzed using the chi-square test,t-test,or the Mann-Whitney U test.Results:The study included 47 males and 22 females with NA.The primary symptoms were abdominal distension(n=36,52.2%),fever(n=19,27.5%),refusal to feed or decreased feeding(n=16,23.2%),and vomiting(n=15,21.7%).Sixty-five patients underwent abdominal ultrasound examinations;43 had definite appendiceal abnormalities,10 had right lower abdominal adhesive masses,and 14 had neonatal enterocolitis manifestations.Twenty-nine and 40 patients were in the surgical and non-surgical groups,respectively.No statistically significant differences were observed between the groups regarding sex,age at onset,birth weight,admission weight,or hospitalization time.However,parenteral nutrition was prolonged in the surgical group(P=0.001).Additionally,two patients(2.9%)died.Interpretation:NA is a rare neonatal disease with atypical clinical manifestations.Abdominal ultrasonography may aid in the diagnosis.Similarly,appropriate treatment can improve the prognosis. 展开更多
关键词 Acute appendicitis DIAGNOSIS NEONATAL THERAPY
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RMB Appreciation, Output Growth, and Inflation 被引量:2
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作者 yongwei chen DONG LI 《Economic and Political Studies》 2013年第2期3-17,共15页
Following Dibooglu and Kutan(2005),we construct a structural VAR model to investigate the impact of RMB(the Chinese currency)appreciation on growth and inflation in China.The empirical results show that RMB appreciati... Following Dibooglu and Kutan(2005),we construct a structural VAR model to investigate the impact of RMB(the Chinese currency)appreciation on growth and inflation in China.The empirical results show that RMB appreciation has negative effects on output growth and inflation while neither effect is statistically significant.However,exchange rate shocks are important in the fluctuations of output growth and inflation.We also simulate the scenario of a sharp currency appreciation compared to the gradual approach adopted by the Chinese government.In the counterfactual analysis we find that a sharp appreciation would lead to more violent shocks in economic growth and inflation compared to the gradual approach. 展开更多
关键词 GROWTH INFLATION RMB STRUCTURAL VAR
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