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.
采用MRGC-80型高压微反色谱联合装置,在400~470℃、3MPa下研究了文题。建立了数学模型,得到了反应速率常数和失活速率常数、反应级数和失活级数、反应和失活表观活化能。结果表明,催化剂失活为独立失活,失活级数随过程变化。从失活级数推测其失活机理为平行连串失活,反应物甲苯、产物苯和二甲苯均能引起催化剂失活。反应压力在一定范围内对催化剂失活速率无明显影响,故可在较低的反应压力下研究催化剂失活动力学。温度对催化剂失活速率的影响不大,表明在所用温度范围内提高反应温度,对甲苯歧化反应过程是有利的。  相似文献   

2.
讨论了甲苯和均三甲苯烷基转移与歧化反应制备二甲苯过程中Hβ负载磷钨酸系列催化剂的催化性能。结果表明:反应主要为甲苯烷基转移和均三甲苯歧化反应;随着催化剂中Hβ上磷钨酸负载量的增加,均三甲苯转化率、二甲苯选择性和收率均先增加后减少,当磷钨酸质量分数为10%时,总酸量达到最大,总转化率、二甲苯收率及二甲苯选择性也分别达到最大值,即77.0%、38.5%和51.1%。催化剂XRD图谱显示负载的磷钨酸高度分散于Hβ分子筛表面,对载体晶体结构无影响。  相似文献   

3.
对甲苯歧化与三甲苯烷基转移反应体系中不同温度和进料条件下的平衡组成,平衡转化率,平均选择论进行了详细计算,结果表明:(1)随温度的升高,甲苯与三甲苯的芳烃平衡转化率降低,二甲苯的平衡选择率亦降低;(2)降低进料中的甲苯与三甲苯摩尔比(Tol:TMB从9降到1),甲苯和三甲苯的芳烃平衡转化率降低,而二甲苯的平衡选择率明显上升,然后,在改性的β沸石催化剂上进行了不同工艺条件下的反应,通过对实验数据与平衡数据的比较和分析表明,反应温度升高,芳烃转化率上升且越来越接近平衡转化率,而二甲苯的选择率迅速下降;进料 中Tol:TMB存在一个最佳点,即60:40(m:m),此时芳烃转化率最高,二甲苯的选择率亦最高。  相似文献   

4.
以三氯化磷为催化剂,针对氟甲苯在不同的温度及光照条件下进行侧链氯化取代反应。其连串反应产物分布规律在一定的氯化深度范围内符合一级反应动力学。反应产物组成分布受到光照及温度的影响,α,α-二氯-对氟甲苯的收第在68%~75%。  相似文献   

5.
研究了含乙烯基和硅氢键的聚硅氮烷(ViHPSZ)在氯铂酸催化下的交联过程。用FTIR、TG-DSC研究了其热行为并对结构进行了表征,同时考察了陶瓷产物的致密性。结果表明,氯铂酸催化剂经活化处理可催化ViHPSZ交联。交联主要以硅氧化反应方式进行,聚硅氮烷在交联过程中重量损失少,产物密度较高。  相似文献   

6.
用马来酸二丁酯(DBM)对乙丙三元胶(EPDM)进行了功能化,在烃链上导入极性基团,以改善EPDM与含极性基团聚合物的相容性.红外光谱表明功能化反应确已发生.用电子顺磁共振波谱仪(ESR)研究了热引发的机理,产物的功能化率由皂化水解反应测定;产物交联程度由凝胶量间接表征;用凝胶渗透色谱法(GPC)表征产物的分子量分布。研究了反应温度、反应时间、单体用量和引发剂用量等对产物功能化率和凝胶量的影响。  相似文献   

7.
利用测定凝胶含量的方法 ,对SBS热塑性弹性体在紫外光辐照下的交联反应进行了研究。研究表明 ,SBS经光交联剂的引发能很好地发生交联 ,在所采用的光引发剂蒽醌、苯芴酮、三硝基芴酮、安息香乙醚中 ,安息香乙醚的交联效果最佳。另外 ,通过红外光谱对交联反应动力学进行了研究 ,结果发现SBS中乙烯双键含量的增加对交联反应影响不大 ,因为乙烯双键含量的增加 ,只会加速分子内反应 ,对分子间的交联反应没有贡献。辐照膜的差示扫描量热及热失重分析表明 ,交联后的SBS膜热稳定性增大 ,且随交联程度的增加 ,热稳定性增大 ,并用扫描电镜对交联膜的微观结构进行了表征  相似文献   

8.
利用测定凝胶含量的方法 ,对SBS热塑性弹性体在紫外光辐照下的交联反应进行了研究。研究表明 ,SBS经光交联剂的引发能很好地发生交联 ,在所采用的光引发剂蒽醌、苯芴酮、三硝基芴酮、安息香乙醚中 ,安息香乙醚的交联效果最佳。另外 ,通过红外光谱对交联反应动力学进行了研究 ,结果发现SBS中乙烯双键含量的增加对交联反应影响不大 ,因为乙烯双键含量的增加 ,只会加速分子内反应 ,对分子间的交联反应没有贡献。辐照膜的差示扫描量热及热失重分析表明 ,交联后的SBS膜热稳定性增大 ,且随交联程度的增加 ,热稳定性增大 ,并用扫描电镜对交联膜的微观结构进行了表征  相似文献   

9.
研究了用于挥发性有机化合物催化燃烧的金属与催化层一体化催化剂,探讨了孔径对催化剂性能的影响。根据Langm uir吸附理论,建立了催化燃烧反应动力学模型,得到了甲苯、二甲苯、环己烷在空气中催化燃烧反应动力学方程。  相似文献   

10.
用马来酸二丁酯(DBM)为接枝单体,过氧化二枯基(DCPO)为引发剂,对低密度聚乙烯(LDPE)进行了熔融接枝功能化。样品的红外光谱表明接枝反应确已发生。通过对样品中酯基的皂化水解测定产物的接枝率,对产物进行萃取,用凝胶量间接表征产物的交联程度;用溶液的特性粘度从侧面显示样品的支化或降解情况。实验结果表明,产物的接枝率和凝胶量可以通过选择反应条件(温度、时间及反应混合物的组成)来控制;过量的DCPO是引起交联产生凝胶的主要原因;向体系中添加DMF可阻止交联反应的发生,但产物的接枝率也有所下降,以自由基机理对上述结果进行了讨论。  相似文献   

11.
Dr.Zhang Ren,the chief physician,is the chairman of Shanghai Acupuncture and Moxibustion Association.Having been engaged in medicine for about 40 years,he is experienced in treating various intractable diseases.In his long years of clinical practice,he advocates taking the TCM differentiation as the basis to seek for the acupuncture method for treatment of modern intractable diseases.The author of this essay had the fortune to follow Dr.Zhang in study.The following is a summary of Dr.Zhang's experience in the acupuncture treatment for different intractable diseases with the same therapeutic principle.  相似文献   

12.
CASE HISTORY A female patient, 46 years old, head of the foreign affairs department of a certain university in Beijing, paid her first visit on October 9, 2006, with the chief complaint of vomiting for one month. She got vomiting after meals in early September. Before that, she had discomfortable sensation in the stomach due to angry with others, but she didn't pay much attention. Later, it developed into vomiting after eating. After the vomiting, the discomfort would be relieved, but with slight hypodynamia. She was once diagnosed as having 'neurogenic vomiting'. Having taken some western and Chinese drugs, the above symptoms were a little bit improved, but she would have nausea upon eating and with regurgitation. Because of the fear for vomiting, she did not dare to have food intake, with body weight reduction of 6 kilos in one month.  相似文献   

13.
Objective: Early complications were analyzed in those with Evans Ⅲ type of intertrochanteric fracture treated with operation or nonoperative approaches. Methods:59 cases with Evans Ⅲ type of intertrochanteric fracture between June, 1999 to July, 2006 were admitted in our department. 38 patients were complicated with cardiovascular diseases, such as hypertension and arrhythmia. All the cases were operated. Results:58 cases were operated successfully. One died of pulmonary interstitial fibrosis. Grade data of different age brackets indicated that early infective complications had apparent differences between the operation and the control group. Compared with the control group, the operation group had benefits such as fewer complications, especially the infective complications, and incidence of lower extremities venous thrombosis, and the results showed notable differences. Conclusion:In elderly patients with Evans Ⅲ type of intertrochanteric fracture, the incidence of pulmonary infection was the highest. Venous thrombosis in lower extremities was the most serious complication. So it will be helpful to perform the quadriceps femories function exercise. The postoperative effect is also related with the operation approach.  相似文献   

14.
Objective: To investigate the histomorphological change in auto-extremity artery following transplantation. Methods: 50 New Zealand rabbits were randomly divided into 5 groups(postoperative 1 d, 3 d, 7 d, 14 d, 56 d, n = 10). Femoral artery was harvested and end-to-side anastomosed with carotid in order to build the auto-extremity arterial graft animal model. On the postoperative 1^st, 35^nd, 7^th, 14th and 56^th days, grafts for morphometric analysis under the Image analysis system were obtained; and electron microscope was scanned to observe endothelial cells. In addition, Immunostaining of sections were performed with the mouse monoclonal antibody of the a -smooth muscle isoform of actin and proliferating cell nuclear antigen antibody. Results: Overall patency rate for all conduits was 86%.The intimal hyperplasia was first observed in the 7^th day group, and continued to increase in the 56^th day group(183.21 ± 111.74) μ m, P 〈 0.01. Additionally, the luminal narrowed(32.43 ± 18.28)% in the 56^th day group. Smooth muscle cells were the mainly hyperplastic components. The most active proliferation of cells was detected in the 14^th day group, where the extracellular matrix gradually deposited in the intima. Conclusion: Moderate intimal hyperplasia occurred in arterial conduits and vascular structure experienced constrictive remodeling after auto-transplantation.  相似文献   

15.
Objective:To investigate the optimum screening conditions of associated proteins in human psoriasis vulgaris by serum proteomics technique, and to screen the different expression proteins related with psoriasis vulgaris. Methods:Serum samples of peripheral blood were collected from newly diagnosed psoriasis vulgaris patients in the clinic, and 20 matched healthy persons. Serum albumin IgG was removed by filtering with ProteoExtract Albumin/IgG. After comparative proteomics analysis the different protein spots were identified using 2-DE and MS. Results :Electrophoresis figures with high resolution and reproducibility were obtained. Three different expression proteins were found only in the serum from psoriasis vulgaris patients, while nine other different proteins expressing from healthy volunteers. Conclusion:The protein expression was different in the serum between the psoriasis vulgaris patients and healthy volunteers. It was hoped that we could find the biomarkers related to psoriasis vulgaris by using proteomics.  相似文献   

16.
17.
采用记录大鼠伤害性屈肌反射积分肌电图的方法,观察了鞘内注入Carbachol(Car,胆硷能M受体激动剂)及吗啡引起的抗痛作用,并分析了纳洛酮(μ受体阻断剂)、优降糖(KATP通道阻断剂)及阿托品对上述药物抗痛作用的影响,结果显示:①鞘内注入Car引起剂量依赖性的抗痛作用;②Car的抗痛作用可被鞘内予先注入纳洛酮或优降糖阻断;③鞘内注入吗啡引起的抗痛作用可被优降糖阻断,但不能被阿托品所阻断。这些结果提示:内源性阿片肽和KATP通道介导了Car或乙酰胆硷引起的脊髓抗痛作用,在此过程M受体的激活引起内源性阿片肽的释放,后者通过打开KArp通道实现镇痛。  相似文献   

18.
Objective To explore methods of preventing and reversing rejection after simultaneous pancreas-kidney (SPK) tran splantation. Methods Seventeen patients underwent SPK transplantation from September 1999 to September 2003 were reviewed retrospectively. Immunosuppression was achieved by a triple drug regimen consisting of cyclosporine, mycophenolate mofteil (MMF), and steroids. Three patients were treated with anti-CD3 monoclone antibody (OKT3, 5 mg· d-1) for induction therapy for a mean period of 5-7 days. One patients received IL-2 receptor antibodies (daclizumab) in a dose of 1 mg· kg-1 on the day of transplant and the 5th day posttransplant. One patient was treated with both OKT3 and daclizumab for induction. Results No primary non-functionality of either kidney or pancreas occurred in this series of transplantations. Function of all the kidney grafts recovered within 2 to 4 days after transplantation. The level of serum creatinine was 94 ± 11 μmol/L on the 7th day posttransplant. One patient experienced the accelerated rejection, resulting in the resection of the pancreas and kidney grafts because of the failure of conservative therapy. The incidence of the first rejection episodes at 3 months was 47.1% (8/17). Only the kidney was involved in 35.3% (6/17); and both the pancreas and kidney were involved in 11.8% (2/17). All these patients received a high-dose pulse of methylprednisone (0.5 g·d-1) for 3 days. OKT3 (0.5 mg·d-1) was administered for 7-10 days in two patients with both renal and pancreas rejection. All the grafts were successfully rescued. Conclusion Rejection, particularly acute rejection, is the major cause influencing graft function in SPK transplantation. Monitoring renal function and pancreas exocrine secretion, and reasonable application of immunosuppressants play important roles in the diagnosis and treatment of rejection.  相似文献   

19.
20.
Objective To investigate the expression of cytochrome C in perihematomal brain tissue and its relationship with the histopathological change and formation of cerebral edema in patients with hypertensive cerebral hemorrhage.Methods Thirty four patients(23 male,11 female) of hypertensive cerebral hemorrhage in hospital from Sep.2001 to Sep.2002 were selected with a mean age 55.6± 10.2 years(from 35 to 75 years).The mean volume of hemorrhagic blood was 50.4±11.6 ml(from 25 to 85 ml).The perihematomal brain tissue was obtained from the minimally invasive surgery.Histopathological change and expressions of cytochrome C in perihematomal brain tissue was detected by histopathological and immunohistochemical techniques.The volume of perihematomal cerebral edema was determined by computed tomographic scan before operation.The results of staining and the volume of perihematomal cerebral edema were analyzed with double blind fashion.Results Perihematomal cerebral edema were found 12-72h after cerebral hemorrhage.Myelin sheath degeneration,condensation of nucleus and typical apopototic body were observed in perihematomal brain tissue.Expression of cytochrome C in perihematomal brain tissue was observed at 4 h and reached peak around 48-72 h after cerebral hemorrhage.Cytochrome C expressed higher positively in 16 patients and lower positively in 13 patients.Cytochrome C expression was not detected only in 5 patints.There were significant differences in volume of perihematomal cerebral edema with different expression of cytochrome C in perihematomal brain tissue(P<0.01).Conclusions Cytochrome C expression was upregulated in perihematomal brain tissue in patients with hypertensive cerebral hemorrhage.Cytochrome C might involve in the histopathological change and the formation of perihematomal cerebral edema  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