首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
由熔融法制得聚丙烯接枝甲基丙烯酸β-羟乙酯,用毛细管流变仪、示差扫描量热计、广角X-射线衍射仪、结晶速率仪、偏光显微镜等对接枝物的流变性能和结晶性能进行了定性、定量表征,比较了接枝前后聚合物结晶形态的变化。  相似文献   

2.
由熔融法制得聚丙烯接枝甲基现人烯酸β-羟乙酯,用毛细管流变仪,示差扫描量热计、广角X-射线衍仪,结晶速率仪、偏光显微镜等对接枝物的流变性能和结果性能进行了定性,定量表征 ,比较了接枝前后聚合物结晶形态的变化。  相似文献   

3.
系统研究了甲基丙烯酸缩水甘油酯与聚丙烯的固相接枝反应,探讨了反应温度,引发剂浓度,单体浓度和反应时间等因素对接枝反应的影响。采用红外光谱表征了PP-g-GMA,并用WAXD,结晶速率仪等研究了接枝物的结晶性能。  相似文献   

4.
用固相接枝法合成了聚丙烯接枝马来酸锌离聚物(PP-g-MAZn)。利用X光、PLM和DSC研究了它的结晶行为。结果表明:PP-g-MAZn能促进β-型结晶的形成;接枝物形成的球晶尺寸变小,而且球晶不规整;接枝物的起始结晶温度移向高温,结晶速率加快;等温结晶动力学的研究表明接枝物结晶的成核方式不发生改变。  相似文献   

5.
采用溶液法制备了离聚物聚丙烯蜡接枝丙烯酸钠,对其热稳定性和结晶性能进行了表征。将聚丙烯蜡接枝丙烯酸钠与聚对苯二甲酸乙二醇酯(PET)熔融共混,利用差示扫描量热仪(DSC)和扫描电镜(SEM)研究了该类离聚物对PET的结晶性能和形态的影响。结果表明:聚丙烯蜡接枝丙烯酸钠的加入促进了PET的成核,使PET的熔融结晶温度由196.9 ℃升高到210.6 ℃,而冷结晶温度由135.5 ℃降低到124.2 ℃。与PET/聚丙烯蜡相比,聚丙烯蜡接枝丙烯酸钠与PET有更好的相容性。  相似文献   

6.
为了表明马来酸酐接枝聚烯烃后对聚酰胺的相容作用,本文研究了聚酰胺1010(PA1010)/聚乙烯-马来酸酐接枝共聚物(PE-g-MAH)共混物在不同MAH接枝量下的结晶性与力学性能。研究表明,MAH的存在导致PE-g-MAH-co-PA1010共聚物的形成,而该共聚物在标题共混物中起着相容剂的作用。共混物的结晶性能变化显示了共混组分间存在一定程度的混溶性。在一定的MAH含量内,标题共混物具有协同效应。  相似文献   

7.
采用溶融共混法制备了PBT和甲基丙烯酸缩水甘油酯功能化改性SBS的共混物,用FTIR、WAXD,DSC,MI等方法对共混物进行了表征,探讨了熔融共混过程中PBT和SBS-g-GMA的反应机理,研究了SBS-g-GMA对共混体系相容性,结晶性能,热性能和流变性能的影响。  相似文献   

8.
以过氧化二异丙苯(DCP)为引发剂,甲基丙烯酸缩水甘油酯(GMA)为活性单体,高抗冲苯乙烯(HIPS)通过熔融接枝制得了动能化的高抗冲聚苯乙烯接枝物(HIPS-g-GMA)。用红外光谱和电子能谱对其结构进行了表征。HIPS-g-GMA的红外谱图,证明GMA已经接枝到HIPS上。电子能谱分析也提供了相似的结论。研究了单体浓度和DCP用量对产物接枝率的影响,并用化学滴定方法测定了接枝物的接枝率。用DSC、SEM、WAXD、DMA等研究了PBT/HIPS和PBT、HIPS-g-GMA的结晶、形态结构、动态力学性能及力学性能随组成的变化。SEM及DMA分析表明增容后体系的相容性得到改善,力学性能有较大提高。  相似文献   

9.
研究聚氧化乙烯 R- 150 辐射接枝聚乙烯醇所形成的水凝胶膜的理化性能,结果显示,聚氧化乙烯接枝水凝胶的交联密度与辐射剂量呈正相关,与混合物质量分数呈负相关,与聚乙烯醇的接枝比例未见明显相关性。聚氧化乙烯 R- 150 接枝水凝胶的交联密度明显低于单纯聚乙烯醇水凝胶。其膨胀度与辐射剂量和聚乙烯醇接枝比例呈负相关,与其混合物浓度呈正相关,并且明显高于单纯聚乙烯醇。聚乙烯醇水凝胶膜的硬度与辐射剂量呈正相关,聚氧化乙烯 R- 150 接枝水凝胶膜的硬度与其浓度呈负相关,而与聚乙烯醇的接枝比例呈正相关。结果表明,聚氧化乙烯 R- 150 接枝水凝胶的交联密度主要受聚乙烯醇的影响,平衡水含量主要受聚氧化乙烯 R- 150 的影响,膜的硬度则受二者的双重影响。  相似文献   

10.
详细地研究了LDPE熔融接枝马来酸镧(MALa)的反应。产物LDPE-g-MALa的IR表明在波数1549cm-1和1628cm-1处出现了羧酸盐的C=0伸缩振动峰,说明MALa已接枝在LDPE上;WAXD衍射结果则表明在2θ=17.20°、14.20°处出现了新的衍射峰—离子峰。为了控制熔融接枝过程,考察了各种瓜条件对接枝率的影响。同时,DSC的结果表明离聚物中离子微区的存在在结晶过程中可以起到较好的成核作用。  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   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号