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1.
用双(N-间乙炔基苯基邻苯二甲酰亚胺)醚(DAIE)改性苯乙炔基硅氧硼烷(PESB)制得复合材料基体树脂(PESBDAIE)。通过FT-IR、DSC和TG研究了PESBDAIE的固化反应及耐热性。将PESBDAIE与纤维复合制得复合材料,研究了该材料的耐热性、弯曲强度及断面形貌。研究结果表明,固化物在氮气气氛下质量损失5%时的温度(T5%)为576 °C,空气气氛下T5%为507 °C。复合材料在500 °C下放置10 min后质量保留率为97.0%,弯曲强度为176 MPa。  相似文献   

2.
用聚甲基二间苯二乙炔基硅烷树脂(PSA)改性二氧化双环戊二烯(R122环氧树脂)得到R122/PSA树脂体系,并以该树脂为基体制备了玻璃纤维复合材料。通过FTIR、DSC和TGA研究了R122/PSA树脂的固化反应及其耐热性能,同时研究了R122/PSA基复合材料的力学性能、耐热性能、介电性能和耐水性能。结果表明:改性树脂在高温下保持了良好的耐热性能,mPSA/mR122=02的固化物在800 °C下质量保留率比纯R122树脂的提高了30%。所制备的复合材料常温下弯曲强度达到735 MPa,220 °C下的弯曲强度达到4184 MPa,不仅保留了良好的力学性能,而且耐热性能得到了很好的提升,同时其浸泡96 h后的吸水率仅为065%,耐水性能优异。  相似文献   

3.
将双(N-间乙炔基苯基邻苯二甲酰亚胺)醚(DAIE)和双酚A型氰酸酯(CE)分别加到聚苯乙炔基苯基硅氧硼烷(PSOB)和三苯乙炔基苯基硅烷(PTPES)混合体系中进行改性,制得两种纤维增强复合材料PSOB-PTPES-DAIE和PSOB-PTPES-CE。研究了固化后树脂的热稳定性能、力学性能、介电性能和耐水性能。结果表明:两种改性树脂高温下均保持了良好的耐热性能,在氮气中质量损失5%时的温度(T5%)最高可达534 °C,800 °C下质量保留率最高可达62.9%。所制备的两种复合材料体系常温下弯曲强度可达250 MPa以上,240 °C下的弯曲强度最高可达202 MPa。饱和吸水率最低可达1.4%,耐水性能优良。不同处理条件下的复合材料介电常数与介电损耗角正切值变化较小,介电性能良好。  相似文献   

4.
制备了双(N-间乙炔基苯基邻苯二甲酰亚胺)醚(BE)改性甲基二苯乙炔基硅烷(MDPES)(BE/MDPES)。研究表明,选择BE/MDPES的固化温度时,必须同时考虑网络的形成反应和BE中醚键的断裂反应。当最终固化温度控制在300℃时,mBE/mMDPES=4/5的玻璃纤维复合材料的弯曲强度高达275MPa,235℃时的高温弯曲强度为241MPa,保留率达88.5%,且优异的耐热性能与介电性能保持不变。  相似文献   

5.
用一种硅炔杂化树脂聚(甲基硅烷-二乙炔基苯)(PSP)改性有机硅树脂(HS),通过FT-IR和TGA研究了树脂体系的固化反应及耐热性,并对制备的复合材料进行力学性能、耐热性能和介电性能研究。结果表明:当HS与PSP的质量比为5∶5时综合性能最优,树脂体系在氮气氛围下质量损失5%时的温度(Td5)为691 °C,1 000 °C时质量保留率为88%;HS-PSP树脂短切玻纤复合材料冲击强度为21 kJ/m2,弯曲强度为65 MPa,200 °C时的弯曲强度高温保留率为78%,介电常数为4.6,介电损耗因数为7.9×10-3,体积电阻为6.7×1013 Ω。改性后的复合材料具有优异的力学、耐热和介电性能。  相似文献   

6.
甲基二苯乙炔基硅烷(MDPES)是一种新型耐高温有机硅树脂,由于主链中含有硅原子单元、乙炔单元和苯基,因此具有优良的耐热性能和介电性能。经双马来酰亚胺(BMI)改性后,MDPES/BMI复合材料不仅保留了良好的耐热性能和介电性能,而且力学性能也得到了极大的改善。  相似文献   

7.
以四氯化锆、苯乙炔和间乙炔基苯胺(APA)为原料,通过先驱体合成法制备新型含锆有机先驱体树脂——含Zr聚乙炔基苯胺树脂(ZAPA)。通过FT-IR表征了其结构,利用DSC及FT-IR研究了其固化反应,通过TG研究了其固化物的耐热性能,采用XRD和EDS研究了其固化物的烧结性能。结果表明:ZAPA树脂可以发生固化交联反应,其固化物相对于APA的固化物具有更好的耐热性能,在N2气氛下,ZAPA树脂固化物失重5%的温度为445 °C,1 000 °C下的质量残余率为43.7%;在空气气氛中,1 000 °C下烧结5 h后,可形成ZrO2晶体。  相似文献   

8.
利用非等温差示扫描量热法(DSC)得到了二甲基-二(3-乙炔基苯胺)硅烷(DMEAS)的特征固化参数,采用Kissinger和Ozawa法计算得到DMEAS固化反应表观活化能(ΔE)分别为100.6、113.0 kJ/mol;通过FT-IR研究了DMEAS固化前后的结构变化,采用TGA分析了其固化物的耐热性。结果表明:DMEAS固化反应主要是乙炔基发生交联反应,形成空间网状结构;在氮气中,DMEAS固化物的热降解起始温度(Td5)为563℃,900℃时的质量残留率为84.0%。  相似文献   

9.
将热致性乙炔基封端液晶单体(MPBE)与含硅芳炔树脂(PSA)进行共聚,制得乙炔基封端液晶改性含硅芳炔树脂(PSA-MPBE)。采用FT-IR在线表征了PSA-MPBE树脂固化过程的结构变化,用裂解-气相色谱-质谱联用仪(Py-GC-MS)分析了其高温裂解产物,研究了其固化机理,用偏光显微镜(POM)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)分析了共混树脂的相结构、断裂形貌和微观结构。结果表明:MPBE与PSA发生了共聚反应,使介晶域固定在交联网络中,形成结构均匀的以介晶相为小岛的海岛结构,PSA-MPBE树脂的断裂行为从典型的脆性断裂转变为微塑性断裂。  相似文献   

10.
通过格氏试剂反应制得了改性硅炔杂化树脂(GMD)。采用DSC、TGA等分析方法研究了GMD的固化反应及耐热性能。结果表明:GMD固化物在氮气气氛下质量损失5%时的温度(Td5)为631 °C,1 000 °C时的质量残留率为59%。所制备的玻璃纤维增强复合材料在常温下的弯曲强度为320 MPa,在240 °C的弯曲强度保留率高达90%,空气条件下经500 °C处理7 min后,质量保留率仍达到99.7%。该复合材料的玻璃化温度大于400 °C,具有优异的耐热性能、力学性能及介电性能。  相似文献   

11.
Objective: To evaluatel the value of D-dimers in patients with acute aortic dissection (AAD). Methods: This study consisted of 16 patients with AAD and 27 non-AAD patients. Serum D-dimets were measured by Sta-Liatest D-DI immunoturbidimetric assay. Results: D-dimer level was higher (P < 0.001) in patients with AAD(7.91 ± 5.52 μg/ml) than that in non- AAD group(1.57±1.24 μg/ml). D-dimer was positive (>0.4 μg/ml) in all patients with AAD and in 10 control group patients (37%). Among patients with acute AAD, D-dimers tended to be higher in Stanford A than in Stanford B (8.67 ± 4.31 μg/ml vs. 3.24±1.27 μg/ml, P <0.01). D-dimer values tended to be higher in more extended disease(3.84 ± 1.65 μg/ml, 8.57 ± 3.58 μg/ml and 11.87 ± 5.69 μg/ml in thoracic aorta, thoracic and abdominal aorta, thoracic and abdominal aorta and iliacal arteries, respectively, P < 0.05 for both 8.57 ± 3.58 and 11.87 ± 5.69 vs. 3.84 ± 1.65 ). Including the control group into the analysis, we found a sensitivity of 100%, a negative predictive value of 100%, and a specificity of 66% and a positive predictive value of 64% for D-dimer in diagnosis of AAD in our patients with suspected AAD. Conclusion: D-dimer was elevated in patients with AAD. A negative D-dimer test result could be useful in excluding AAD.  相似文献   

12.
Objective: To set up a simple and reliable rat model of combined liver-kidney transplantation. Methods: SD rats served as both donors and recipients. 4℃ sodium lactate Ringer's was infused from portal veins to donated livers,and from abdominal aorta to donated kidneys, respectively. Anastomosis of the portal vein and the inferior vena cava (IVC) inferior to the right kidney between the graft and the recipient was performed by a double cuff method, then the superior hepatic vena cava with suture. A patch of donated renal artery was anastomosed to the recipient abdominal aorta. The urethra and bile duct were reconstructed with a simple inside bracket. Results: Among 65 cases of combined liver-kidney transplantation, the success rate in the late 40 cases was 77.5%. The function of the grafted liver and kidney remained normal. Conclusion: This rat model of combined liver-kidney transplantation can be established in common laboratory conditions with high success rate and meet the needs of renal transplantation experiment.  相似文献   

13.
Objective To observe blood pressure change with age in salt-sensitive teenagers whose salt sensitivity were determined by repeated testing.Methods Salt sensitivity was determined through intravenous infusion of normal saline combined with volume-depletion by oral diuretic furosemide in 55 teenagers. After five years, salt sensitivity was re-examined and subject blood pressure was followed up. Blood pressure changes in salt-sensitive teenagers were compared to that of non-salt sensitive teenagers over five years.Results After 5 years, the repetition rate of salt sensitivity determined by intravenous saline loading is 92.7%. In teenagers with salt sensitivity on the baseline, both the systolic blood pressure increments and increment rates were much higher than non-salt sensitive teenagers (12.7±12.1 mmHg vs. 2.8±5.2 mmHg, P< 0.01; 12.2%± 12.0% vs. 2.5% ±4.4%, P< 0.001,respectively). There was a similar trend for diastolic blood pressure (8.4 ± 6.4 mmHg vs. 3.7 ± 6.4 mmHg, P = 0.052; 13.2% ±10.6 % vs. 6.8%± 10.1%, P = 0.053, respectively).Conclusions Salt sensitivity determined by intravenous saline loading showed good reproducibility. Blood pressure increments with age were much higher in salt-sensitive teenagers than non-salt sensitive teenagers, especially in terms of systolic blood pressure.  相似文献   

14.
目的:评价使用安心颗粒对急诊经皮冠状动脉介入术(PPCI)术后生活质量的影响.方法:将160例接受PPCI的急性ST段抬高型心肌梗死患者随机分为安心颗粒组(术前顿服安心颗粒8.8g,术后安心颗粒4.4 g/次,每日2次)和对照组(仅接受基础药物治疗).所有患者均服用阿司匹林、氯吡格雷和阿托伐他汀.分别在入院时、出院前1d、出院后180 d时,应用心肌梗死多维度量表(MIDAS)、中文版SF-36评价量表对患者生活质量评分.并观察术后30 d以内的出血并发症、血小板减少症发生情况.结果:入院时和出院前1d,两组患者的心肌梗死MIDAS、SF-36量表评分比较无差异(P>0.05);出院后180 d时,与对照组比较,安心颗粒组MIDAS、SF-36评分明显减低(P<0.05);组内与入院时比较,两组出院前1d、出院后180 d时,MIDAS、SF-36评分均降低(P<0.05).两组患者在随访期间均无大量出血、少量出血、重度和极重度血小板减少症发生,安心颗粒组有4例、对照组有7例发生不明显出血(P>0.05).两组发生轻度血小板减少症的患者数比较无差异(P>0.05).结论:PPCI使用安心颗粒,能改善急性ST段抬高型心肌梗死患者的生活质量,且不增加出血风险.  相似文献   

15.
Objective:To investigate the influences of urapidil and nicardipine on rabbit sinus function,atrio-ventricular node function and hemodynamics.Methods:Thirty-two Angora's rabbits were selected and randomly divided into four groups.U1 group:urapidil 0.25 mg/kg;U2 group:urapidil 0.5 mg/kg;N1 group:nicardipine 10 μg/kg;N2 group:nicardipine 20 μg/kg.All these medicine were administrated within 30 seconds.Measurements were taken before and after the administration of urapidil or nicardipine for the following data:mean blood pressure(MAP),heart rate(HR),sino-atrial conduction time(SACT),maximal sinoatrial recovery time(SNRTmax)corrected sinus node recovery time(CSNRT),index of sinus node recovery time(SNRTI),Wenckebach A-V conduction frequency (WB),and P-R interval.Results:Significant MAP and HR changes were identified in all of the four groups before and after administration of both urapidil and nicardipine.No significant changes could be found in the rest of the parameters.Intergroup analysis showed that SACT and CSNRT of N1 and N2 groups were shorter than those of the U2 group(P<0.01);the MAP decreased(P<0.01)and the HR increased drastically(P<0.01).Conclusions:Neither urapidil(0.25 mg/kg,0.5 mg/kg)nor nicardipine(10μg/kg,20μg/kg)has any significant influence on rabbit sinus function or rabbit atrio-ventricular node function.Nicardipine could be a better choice than urapidil for parafunctional sinus node patients.  相似文献   

16.
Objective:To investigate the gene expression of osteoprotegerin(OPG) and osteoclast differentiation factor(ODF) in the bone tissue of patients with hip fracture due to osteoporosis. Methods:OPGmRNA and ODFmRNA in the bone tissue in 50 cases of osteoporosis sufferers(over 50 years old) with hip fracture(Observer Group) and 30 cases of hip facture sufferers with no osteoporosis(Control group) were analyzed with the Semi-Quantitative RT-PCR method. Results:The mRNA expressed of ODF, OPG were both high in the patients with hip fracture. In the control group, the expression of OPG mRNA was observed, while the expression of ODF mRNA was very slight. Conclusion:Aged patients contained all signals including OPG, ODF that are essential for inducing osteoclastogenesis and promoting bone resorption.  相似文献   

17.
Objective:To investigate the clinical features, pathological characteristics and immunophenotype of solid-pseudopapillary tumor of the pancreas(SPTP). Methods:Nine surgically treated cases of SPTP were retrospectively reviewed. Hematoxylin and Eosin(HE) staining and immunohistochemical staining were used to analyze all cases, and the general clinical data was collected. Results:Six patients were asymptomatic except for a palpable mass. Two patients complained of vague-epigastric pain. One patient appeared jaundice. The tumor was encapsulated and solid tissues alternately with cystic tissues. Histologically, the histological structure of solid portion was pseudopapillary with a fibrovascular core. Tumor cells were uniform and medium-sized which were arranged in sheets ets or nests or pseudopapillary patterns. Immunohistochemical studies demonstrated that SPTP proved positive in vimentin(9/9 cases), AAT(9/9 cases), NSE(9/9 cases), ACT(7/9 cases), CK20(2/9 cases), CgA(1/9 cases), S-100(3/gcases), PR(4/gcases), Syn(3/9 cases) and CD56(5/9cases), negative in CEA and ER. Conclusion:SPTP is a tumor predominantly occurring in young women frequently without special symptoms. This tumor has various characteristical histological patterns with different immunophenotype.  相似文献   

18.
Objective:To probe into the influence of changes of ovarian hormones on the pathogenesis of the specific sub-type premenstrual syndrome(PMS)and reveal partial microcosmic mechanisms of adverse flow of liver-qi.Methods:Estradiol(E2)and progesterone(P)levels in serum were determined at different phases of menstrual cycle by radioimmunoassay.Results:In the group of PMS with adverse flow of liver-qi.the secretive peak value Of E2 and P at the follicular phase significantly decreased,and the secretive peak value at the luteal phase did not come into being.Conclusions:Low E2 and P secretive peak at the follicular phase and absence of secretive peak at the luteal phase is one of the microcosmic mechanisms of PMS with adverse flow of liver-qi.One of the pathophysiologic mechanisms of specific sub-type PMS is probably the continuous low level of E2and P.  相似文献   

19.
Real-time three-dimensional echocardiography (RT3DE)is a new ultrasound technique that enables dynamic threedimensional visualization and quantification of the heart in real time. Investigation of feasibility and methodology of RT3DE in determining left ventricular (LV) and right ventricular (RV) volumes, RT3DE was performed in 35 normal adults using Philips SONOS 7500 system with a 2-4 MHz matrix array transducer. The 60°×60° "pyramid" volume database was obtained and analyzed on a TomTec echo workstation. Both LV and RV volumes were calculated with four 3DE methods (i.e. apical 2, 4, 8, and 16-plane) through manually tracing ventricular endocardial borders in end diastole and end systole. Stroke volumes were then calculated. LV volume was also measured by 2DE Simpson's rule using GE VIVID 7 ultrasound machine.  相似文献   

20.
Increasing maternal age is the only etiological factor unequivocally linked to Down's syndrome in humans. The occurrence rate of newborns with Down's syndrome is about 1/220 in women over 35 years old. However, the occurrence rate in embryos fertilized in vitro, of the elder woman is unclear. Using FISH we screened the number of chromosome 21 in preimplanted embryos of 5 elderly women (average age, 38.4 years) to study the feasibility and necessity of screening trisomy 21 in embryos in patients over 35 years old at the in vitro fertilization (IVF) center.  相似文献   

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