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1.
梯形导向浮阀塔板具有良好的流体力学和传质性能。本文探讨了该塔板的流体力学模型,得出梯形导向浮阀塔板的阀孔临界气速,塔板压降,雾沫夹带和泄漏点孔速的关联式,可代价 梯形导向浮阀塔板设计之用。  相似文献   

2.
应用空气-水系统,在1600mm×400mm的矩形塔内,对梯形导向浮阀塔板的流体力学进行了实验研究,测定了阀孔临界气速,塔板压降,雾沫夹带和泄漏。应用空气-水-CO2系统,测定了梯形导向浮阀塔板的效率。实验结果表明,梯形导向浮阀塔板具有良好的流体力学和传质性能。  相似文献   

3.
对高开孔率、大孔径筛板复合塔板在喷射状态下的流体力学性能进行了测定及关联,提供了必要的流体力学参数。结果表明,该塔板具有阻力低、雾沫夹带量小、操作上限速度大等特点,特别适合那些要求气相负荷大、液相负荷低的过程。  相似文献   

4.
在φ2.8m大型冷模塔板上,研究了双溢流扩张流和收缩流两种情况下塔板液体流动状况。考察了液流强度,堰径比,外堰高,降液管下口高等对板面液体流动的影响。实验表明,扩张流塔板存在严重回流和滞流现象,收缩流塔板面液体停留时间有明显差异。  相似文献   

5.
在大型冷模试验装置上,研究了液流强度、外堰高、降液管下口高和堰径比等因素对大型塔板板面液体流动状况的影响。实验表明:大型塔板上液体存在严重的不均匀流动,堰径比较大时,液体流动的不均匀性有所减弱;液流强度、外堰高和降液管下口高对板面液流分布的状况共同构成影响;在外堰高和降液管下口高一定的情况下,存在一个适合的液流强度,使板面液体回流区面积最小。  相似文献   

6.
简要的说明了筛板塔的操作性能以及如何布置筛板塔板。对计算筛板塔的各项性能:干板压降、净液高度、雾沫夹带、塔板的效率的某些公式进行了比较,推荐一些比较适当的公式。编制了计算筛板塔流体力学以及塔板设计参数、塔板效率的软件‘SieveTray’,对特定的条件进行演练以说明其用法。  相似文献   

7.
对一种穿流式固阀塔板进行了流体力学冷态实验考察。采用常温、常压下的空气和水作为实验介质,测试了不同操作条件下塔板的干板压降、全板压降和清液层高度,比较了不同的塔板结构参数对流体力学性能参数的影响。实验结果表明,塔板压降和清液层高度均随着孔中心距和开孔率的减小而增大,而随着孔径的增大而增大。气液两相在穿流塔板上为逆流流动,且随着气液流量的变化呈现出4种不同的流动形态。建立了清液层高度的经验式,且计算值与实验测量值吻合良好。推导了描述穿流塔板独特的流动形态的参数即气体流通分率的数学表达式,计算结果表明,该分率随着孔中心距的减小而减小,并随着孔径和开孔率的增大而减小。  相似文献   

8.
在500mm×300mm的矩形有机玻璃实验塔中,用水-空气体系对组合式角钢塔板的流体力学性能及传质性能进行实验研究,并以筛孔塔板作对比实验。结果表明组合式角钢塔板是一种结构简单,压降低,压降低,操作弹性宽,处理能力大和板效率较高的新型塔板。  相似文献   

9.
利用双头电导探针测定了固阀塔板上密集鼓泡区气泡的运动速度,考察了密集鼓泡区不同轴向高度的气泡速度分布规律及其分形特征,分析了塔板上密集鼓泡区的气泡运动行为。研究结果表明:不同轴向高度处气泡速度沿同方向的分布具有相似性,近塔中心区域气泡速度变化平缓,呈弱双峰分布;塔板上气泡速度分布具有分形特征,分形维数为1.04~1.25,且随轴向高度的增加均先减小后增大;深层鼓泡区内气泡速度分布的分形维数可以较好地表征气泡运动的湍动强度,两者之间存在线性关系,气泡流湍动强度及分形维数与泡沫层高度间存在指数函数关系。  相似文献   

10.
定向一喷射式塔板在该塔板上,排列有许多舌形板瓣和横向隔板,后者与气液流接触时,能在隔板表面附近产生附加的两相接触区,塔板的结构如图所示。这种塔板经试验台试验和工业性试验,已成功地投入硅有机化合物生产中使用。它比泡罩式塔板具有以下几个优点:生产能力增加50~100%,制造简单,金属消耗量少,安装容易,当有固相沉淀时易于清洗,在塔停止操作进行检查时,液体可以完全流出。因此可以广泛推广于工业中应用。  相似文献   

11.
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   

12.
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   

13.
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   

14.
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   

15.
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   

16.
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   

17.
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   

18.
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   

19.
Objective To measure Derpl and Blot5 allergen levels in asthmatics' homes in Hongkong.Methods Seventy houses were enrolled for a mite indoor environment study. Dust samples were obtained from two sites of each patients' house: bed and floor. Derpl and Blot5 levels were quantified by a two-site monoclonal antibody-based ELISA technique.Results The levels of Derpl allergens found in bed (geometric mean (GM) 3.43 μg/g of dust; 95%CI, 1.89-4.96 μg/g)and on the floor (GM 1.12 μg/g of dust; 95%CI, 0.71-1.53 μg/g) indicated significant differences (P=0.005). However, the levels of Blot5 allergens found in bed (GM 19.00 μg/g of dust; 95%CI, 0.89-38.90 μg/g) and on the floor (GM 6.14 μg/g of dust; 95%CI, 0.40-11.90 μg/g) showed no statistically significant difference. In addition, in regards to the exposure index for Derpl and Blot5 allergens found in bed and on the floor, 17.6% in bed and 8.6% on the floor had levels of Blot5 ≥ 10 μg/g of dust, higher than those obtained for Derp1 (7.2% and 0% in bed and on the floor respectively, P< 0.05); higher percentages in bed and on the floor (25.0% and 35.7%) were observed for levels of Blot5 =0 μg/g of dust as compared with Derpl in bed and on the floor (4.3% and 14.5% respectively, P< 0.05).Conclusions Derpl and Blot5 are the major allergens found in this regional study, Blot5 is a more potent allergen in Hongkong, probably reflecting the high level of exposure to Blomia tropicalis (Bt). Bt and Dermatophagoides pteronyssinus (Dp) allergens should be included for precise diagnosis and effective immuno-therapeutic treatment of mite allergy in Hongkong.  相似文献   

20.
ANTI-PROLIFERATION EFFECT OF ORIDONIN ON HL-60 CELLS AND ITS MECHANISM   总被引:4,自引:0,他引:4  
Objcetive To investigate the anti-proliferation effect of oridonin on leukemic HL-60 cells and its mechanism. Methods HL-60 cells in vitro in culture medium were given different concentrations of oridonin. The inhibitory rate of cells were measured by microculture tetrazolium (MTT) assay, cell apoptotic rate was detected by flow cytometry (FCM), morphology of cell apoptosis was observed by hoechst 33258 fluorescence staining, and the activity of telomerase was detected using telomere repeat amplification protocol (TRAP) PCR-ELISA before and after apoptosis occurred. Results Oridonin could decrease telomerase activity, inhibit growth of HL-60 cells, and cause apoptosis significantly. The suppression was both in time- and dose-dependent manner. Marked morphological changes of cell apoptosis including condensation of chromatin and nuclear fragmentation were observed clearly by hoechst 33258 fluorescence staining especially after cells were treated 48-60 hours by oridonin. Conclusions Oridonin has apparent anti-proliferation and apoptotic effects on HL-60 cells in vitro, decreasing telomerase activity of HL-60 cells may be one of its most important mechanisms. These results will provide strong laboratory evidence of oridonin for clinical treatment of acute leukemia.  相似文献   

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