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1.
为了考察煤灰中的化学组分对熔融特性温度的贡献,借助我国69种重要的商业用煤的灰熔融特性温度和灰中SiO2和Al2O3等6种主要化学组分的测试数据,利用多项式模型的偏回归函数分析方法,对煤灰的熔融特性温度进行一至四阶多项式模型回归分析,获得了各化学组分的偏回归函数。研究结果表明:各化学组分的偏回归函数能够表现熔融温度对应于该组分变化的趋势;同一组分偏回归函数不同,该组分对变形温度、软化温度和熔融温度的影响存在较大的差异;CaO和TiO2的偏回归函数反映熔融温度变化趋势的可信度最高。实验为进一步研究煤灰熔融特性温度的数学模型和参数选择提供参考。  相似文献   

2.
以高灰熔点鲍店煤和南屯煤为对象,利用X射线衍射(XRD)、扫描电镜(SEM)和FactSage软件等方法,研究了添加CaO和Fe2O3助熔剂对煤灰中矿物高温熔融行为的影响和助熔机理。结果表明:两种助熔剂都能有效降低煤灰熔融温度,助熔效果与助熔剂种类和添加量有关。  相似文献   

3.
选择3种不同灰熔融温度的煤,在弱还原性气氛下,利用XRD考察不同加热温度下煤灰熔融过程中的矿物演变过程,并对煤灰的熔融机理进行探讨。结果表明:3种煤中的晶体矿物主要有高岭石、石英、方解石、石膏和黄铁矿等,煤中高岭石和石英的含量与煤灰熔融温度成正相关影响。煤中方解石、黄铁矿和石膏含量与煤灰熔融温度成负相关影响。815 ℃煤灰中晶体矿物主要为石英、硬石膏和赤铁矿等。随着加热温度的升高,煤灰中石英、硬石膏等结晶矿物含量逐渐减少,生成新的矿物。莫来石的生成是导致煤灰熔融温度高的主要原因。低灰熔融煤灰在加热过程中,1 100 ℃时少量铁钙辉石的生成起到了降低煤灰熔融的作用。  相似文献   

4.
利用灰熔点测定仪和高温旋转黏度计,研究了鲍店煤和混配煤的两种煤灰和经气化炉高温熔融后熔渣的熔融特性和黏温特性。在高温条件下,煤灰和熔渣的黏度变化规律相似;根据煤灰和熔渣的组成及其在Al2O3-SiO2-CaO-FeO四元相图中的位置和在临界黏度附近矿物质的变化规律,分析了煤灰和熔渣熔融特性和黏温特性差异的原因,分析结果与实验结果吻合良好。  相似文献   

5.
研究了钙基助熔剂对皖北刘桥二矿混煤(AQ007)灰熔融特征的影响,并采用XRD和红外光谱分析了钙基助熔剂添加前后不同热处理温度下AQ007煤灰的矿物组成。结果表明:1 000 ℃以上形成的莫来石是导致AQ007煤灰熔点高的主要原因,加入钙基助熔剂可以降低AQ007煤灰的熔融温度。这是因为添加钙基助熔剂后,高温下含钙化合物间容易形成钙长石、钙黄长石等低温共熔化合物,从而使煤的灰熔点下降。  相似文献   

6.
尿液渗透压(Uosm)测定是评价肾功能的主要参考指标;Uosm/Posm渗比(浓缩指数),虽可直接反映肾小管重吸收功能,但常因少尿存在影响结果;而自由水清除率(CH2O),目前认为是最理想的肾浓缩功能检查。目前国内渗透压仪的使用还限于少数大医院,用折射仪通过测定尿折射率计算Uosm极为方便,已普遍使用,再以公式推算Posm(血浆渗透压),并代入公式计算CH2O,我们探索设计了简易3小时禁水法测定CH2O。实验方法如下。  相似文献   

7.
覃明 《广东医学》2021,42(4):449-453
目的 探讨呼气末气道正压(PEEP)与ICU老年患者肠内营养不耐受(FI)的相关性,为临床肠内营养治疗提供参考。方法选取行气管插管机械通气治疗的80例老年患者作为研究对象,于肠内营养(EN)前及EN后连续7 d测量腹内压(IAP),评估患者EN过程中FI(腹泻、便秘、呕吐/返流、胃肠道出血)发生情况,采用偏相关分析PEEP与IAP的相关性、IAP与FI的相关性,确定PEEP预测FI的最佳临界值和IAP预测FI的最佳临界值。结果研究对象的IAP基线水平较低,以0级为主,没有Ⅱ级及以上者。EN开始后7 d内IAP的平均水平以0级和Ⅰ级为主,Ⅱ级和Ⅲ级腹内压频数明显增多,无Ⅳ级腹内压。患者腹内压基线水平与EN后7 d内腹内压平均水平比较,差异有统计学意义(P<0.05)。FI发生率为72.5%,FI主要表现为腹泻(40%)。相关分析显示PEEP与IAP呈正相关(P<0.05),PEEP判断FI的受试者工作特征(ROC)曲线下面积(AUC)为0.94(95%CI:0.869~1.0),其预测FI的最佳临界点为3.0 cmH2O。IAP基线水平和EN 7 d IAP均值预测FI的AUC分别为0.929(95%CI:0.835~1.0)和0.995(95%CI:0.982~1.0),其预测FI的最佳临界点分别为7.75 mmHg(1 mmHg=0.133 kPa)和11.05 mmHg。结论PEEP与ICU老年机械通气患者FI呈正相关,IAP与FI呈正相关,当PEEP≥3 cmH2O、IAP基线水平≥7.75 mmHg、EN 7 d IAP≥11.05 mmHg时,要警惕FI的发生。  相似文献   

8.
目的:探讨住院早产儿喂养不耐受(feeding intolerance,FI)的临床特征及其危险因素,为临床早期识别及有 效防治FI提供实证依据。方法:选择2016年7月至12月入住四川大学华西第二医院新生儿科符合纳入标准的116例早产 儿作为研究对象。采用自行设计的《早产儿喂养不耐受临床观察表》,观察早产儿FI的临床特征,寻找早产儿发生 FI的主要危险因素。结果:1)共62例发生FI,发生率为53.45%(62/116),男婴发生率为44.93%(31/69),女婴发生率为 65.96%(31/47),差异有统计学意义(P<0.05);极低出生体重儿FI发生率为48.57%(34/70),超低出生体重儿FI发生率为 88.89%(8/9),差异有统计学意义(P<0.05)。FI主要发生在开奶48~72 h内,以腹胀、胃潴留、呕吐和胃内咖啡色样物为 临床表现,其中腹胀为最主要的临床表现。2)logistic 多因素回归分析显示:出生体重<1 000 g(P<0.05)、使用枸橼酸咖 啡因(P<0.05)和配方奶喂养(P<0.05)是FI发生的主要危险因素。结论:FI在早产儿中发生率高。出生体重<1 000 g以及 使用枸橼酸咖啡因和配方奶开奶是早产儿发生FI的主要危险因素。  相似文献   

9.
目的 在反应范围模型指导下探讨住院早产儿喂养不耐受(FI)发生的风险因素,构建风险预测模型,为有效防治早产儿FI提供实证依据。方法 采用横断面研究,选择2014年8月至2015年1月入住新生儿科的早产儿。在反应范围模型指导下设计临床观察表,从预测性稳态、反应性稳态、稳态超负荷及稳态失败等方面对发生FI及未发生FI者进行分析,通过logistic回归分析建立早产儿FI发生风险预测模型,并检验模型的有效性。结果 ①207例早产儿中,男性125例,女性82例,胎龄27+2~37周,平均(33.48±1.66)周;出生体质量830~3 120 g,平均(2 019.55±334.38) g。早产儿FI发生率为33.8%;FI主要发生在开奶72 h内,早期早产儿FI的临床表现以胃潴留为主,晚期早产儿FI则以呕吐为主要临床表现。②单因素分析显示,胎龄、出生体质量、宫内窘迫、宫内感染、氨茶碱应用、母乳喂养及两次大便间隔时间与早产儿FI有关;logistic回归分析显示,胎龄与出生体质量是FI的保护因素,胎龄越大,出生体质量越重,FI发生的风险越低。宫内窘迫、氨茶碱应用、两次大便间隔时间超过3 d是FI发生的高危因素。③经回代预测,回归方程的回代率为92.73%,预测FI的敏感度为97.14%,特异度为88.32% ,准确度为91.30%。 结论 胎龄低、出生体质量低、宫内窘迫、使用氨茶碱及两次大便间隔超过3 d是FI发生的重要风险因素,适用于logistic回归构建预测FI发生风险模型;该模型能够为临床确定FI的高危人群和及时进行干预提供客观可靠的依据。  相似文献   

10.
罗海良  许文艳  黄敏 《当代医学》2021,27(7):117-119
目的 分析非瓣膜性心房颤动患者纤维蛋白原(FI)、血小板平均体积(MPV)、左房内径(LAD)与脑梗死的关系.方法 选取本院2017年3月至2019年3月收治的非瓣膜性心房颤动合并脑梗死患者75例作为观察组,另选取同期非瓣膜性心房颤动未合并脑梗死患者75例作为对照组.并比较两组临床资料,并进一步采用Logistic多因素回归分析探讨非瓣膜性心房颤动发生脑梗死的危险因素.结果 观察组FI、MPV、LAD、脂蛋白(a)高于对照组(P<0.05);经Logistic多因素回归分析,FI、MPV、LAD是非瓣膜性心房颤动发生脑梗死的独立危险因素(P<0.05).结论 FI、MPV、LAD是非瓣膜性心房颤动发生脑梗死的危险因素,临床应及时检测,为临床脑梗死早期预防、治疗提供参考依据.  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.
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   

16.
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   

17.
A clinical guideline for the therapeutic interventions of integrative medicine may be defined as a written document which states a series of recommendations on therapeutic interventions of integrative medicine for a special disease or condition. The guideline may provide assistance to medical professionals in making clinical decisions aimed at improving the clinical outcome of patients and reducing the costs of medical care(~'4~. Recommendations issued by a guideline should be based on the best available evidence in both Western and Chinese medicine. For fulfilling this purpose, the development of clinical guidelines for therapeutic interventions in the field of integrative medicine should follow scientific principles and undergo a rigorous processes.  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.
Journal of Nanjing Medical University (English Edition) JNMU, sponsored by Nanjing Medical University, was established in 1987. It is a bimonthly comprehensive English medical journal published locally and abroad.Since 2007, Journal of Nanjing Medical University (English Edition )was granted Elsevier the full publishing and distribution rights worldwide for the Electronic Edition, excluding the People's Republic of China.  相似文献   

20.
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   

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