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1.
煤的溶剂抽出剂中前沥青烯与沥青烯的质量之比随煤化程度增加而增加,原位热解红外光谱研究结果表明,它们的热稳定性与其结构参数有关,芳香度高,甲基取代结构多的前沥青烯比沥青烯的热稳定性好。前沥青烯与沥青烯在溶剂分级过程中表现出的溶解性与其结构参数无必然联系,而与其酸碱组分间的氢键强度有关。前沥青烯中酸碱组分间的氢键强度为5.15 ̄30.9kJ/mol;沥青烯为〈5.15kJ/mol。  相似文献   

2.
本文中用DNA热变性实验及荧光分析法研究了β-榄香烯与小牛胸腺DNA的结合作用.热变性实验表明β-榄香烯可使小牛胸腺DNA的热变性温度Tm值下降2℃,小牛胸腺DNA(30μg/ml)与β-榄香烯(20μg/ml)温育后.激发波长为3.4nm,发射波长为358nm,其荧光强度为0.315,此时小牛胸腺DNA(30μg/ml)的荧光强度仅为0.020,用酵母的t-RNA与-β-榄香烯实验也取得类似的结果。对β-榄香烯的抑癌机理用量子化学CNDO/2方法计算的结果进行了探讨。β-榄香烯的前沿轨道能级ELUMO=0.0168 au EHOMO=03239au鸟嘌呤的ELUMO=0.1629au其EHOMO=-0.25960au胸腺嘧啶的ELUMO=0.1324au.其EHUMO=0.3550au脲嘧啶的ELUMO-=0.0888au其EHOMO=-03940au。上述计算结果提示β-榄香烯与核酸碱基的前沿轨道之间的相互作用;因β-榄香烯上的一个甲基带有较正的静电荷,该甲基可能与核酸碱基上的氮原子存在分子间选择性疏水作用。  相似文献   

3.
研究了两种道路沥青老化动力学,计算得到有关动力学参数,揭示了沥青组成结构与其老化性能之间的关系。  相似文献   

4.
用DSC研究了BPPDPS改性BMI树脂固化反应动力学,获得固化反应级数n=1.4,活化能E=81.24kJ/mol,以及树脂的固化工艺:140℃,1h;190℃,2h;250℃,4h。测定了不同配比固化树脂的吸水率、玻璃化温度、热氧化性和弯曲性能,当树脂配比为1.5:1时,固化树脂表现优良的耐热性,特别是在耐热性方面,230℃弯曲强度保留达82.4%,并用Friedman法推导出固化树脂的热降解反应活化能为290kJ/mol,遵循一级反应。  相似文献   

5.
根据煤结构的不均匀性及煤液化中包含大量串联和并联反应的事实,提出了一模拟煤液化的数学模型。该模型把液化过程处理为两组不可逆反应的串联(即煤裂解生成沥青烯和前沥青烯;沥青烯和前沥青烯生成油),其中每组都包含一系列不同组分的平行反应,从理论上可认为这些反应的活化能服从高斯分布。这一模型能较好地描述同一煤中各组分液化难易程度的不同,也合理地解释了煤液化中表现反应活化能随转化率增加而上升的现象。由此得到的理论值不仅和实验数据一致,也和文献值较好符合。  相似文献   

6.
通过对文题的研究,发现反应初期为动力学控制,对[Fe2+]为三级反应,频率因子为3.87×10121min-1,活化能为109.8kJ/mo1;反应后期为传质控制,对[Fe2+]为一级反应,频率因子为5.87×106min-1,活化能为35.5kJ/mol。氧分压对宏观反应速率影响不显著,在整个反应过程中反应速率对[O2]为0.2级反应。还得到了氧化过程的优化串级温度序列。  相似文献   

7.
南非钩麻Harpagophytum procumbens DC.的镇痛、抗炎作用与其次生代谢产物中环烯醚萜苷和苯丙醇苷衍生物的结构多变有关。作者采用LC—DAD—MS/SPE—NMR联用技术对该植物根中微量的异环烯醚萜苷进行了检测。  相似文献   

8.
研究了两种不同结构道路沥青Shel70和PA100的老化过程。发现沥青的组成和结构对其老化性能有较大影响:具有较长烷基侧链的道路沥青,在一定的温度下,烷基侧链易于断裂形成自由基而引发氧化反应;沥青各组分结构上的不连续性导致其抗老化性能较差。在老化过程中,由于氧的介入生成了酮和亚砜等含氧官能团,使得沥青分子间相互作用力增加,破坏了原有沥青的组成与结构,导致沥青的针入度下降,各种性质发生明显变化。  相似文献   

9.
目的:评价氯烯雌酚醚对围绝经期及经经后妇女骨丢失的影响。方法:59例围绝经期及绝经后患者,随机分成氯烯雌酚醚组(38例)和对照组(21例)两组。治疗前及治疗后6个月各测1次血、尿骨代谢生化指标。在治疗前及治疗后2年时用DEXA测定股骨颈及腰椎的BMD。结果:治疗前两组间各指标差异无显著性(P>0.05)。治疗后氯烯雌酚醚组的血清BGP及尿HOP/Cr均较对照组为低,而MD较对照组为高,差异有显著性(P<0.05)。氯烯雌酚醚组治疗后血清BGP、尿HOP/Cr及BMD均较治疗前有所下降,除BMD外,均有统计学差异(P<0.01):对照组治疗后血清BGP、尿HOP/Cr水平较治疗前有所上升,BMD较治疗前有所下降,均有统计学差异(P<0.01,P<0.05)。结论:氯烯雌酚醚能抑制围绝经期及绝经后妇女的高骨转换状态,防治骨丢失。  相似文献   

10.
前胡丙素对肾血管性高血压大鼠脑肾ATP酶活力的影响   总被引:2,自引:0,他引:2  
用两肾一夹模型观察肾血管性高血压大鼠血压与脑,肾细胞膜ATP酶活力的变化及前胡丙素对上述变化的影响。两肾一夹术后16周大鼠血压由升至(27.1±1.8)kPa,脑,肾细胞膜Na^+k^+-ATP酶活力分别下降至(7.3±2.5)和(14.7±1.2)μmol/(mg.h),Ca^2+ATP活力下降至(15.8±2.8)和(16.1±2.3)μmol/(mg.h)。与高血压组相比,Pra-C「20m  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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