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.
水解对MCM-41分子筛的结构破坏作用   总被引:3,自引:0,他引:3  
详细考察了SiMCM-41、AlMCM-41和HAlMCM-41在不同环境中的水解和结构破坏情况.空气和水蒸汽中短期高温焙烧对全硅型SiMCM-41的结构影响较小,但在潮湿空气中长期放置可因Si—O—Si键发生水解而造成结构的严重破坏.AlMCM-41的抗水解能力优于SiMCM-41的,但因其结构中包含一定量的Na+离子,降低了高温焙烧时结构的热稳定性和水热稳定性.HAlMCM-41的热稳定性和水热稳定性均优于AlMCM-41.分子筛水热晶化过程中的盐析效应被证实是导致AlMCM-41和HAlMCM-41抗水解能力增强的原因,因此在合成原料中加盐可显著改善MCM-41分子筛的抗水解能力和稳定性  相似文献   

2.
中孔MCM—41分子筛在微孔沸石ZSM—5上附晶生长的研究   总被引:15,自引:2,他引:15  
首次在微孔沸石ZSM5表面进行了MCM41分子筛的附晶生长,并首次提出中孔材料MCM41分子筛静电组配理论的新形式(XS+I);同时利用XRD、TEM、BET等测试手段表征了合成样品,并讨论了微孔沸石表面附晶生长中孔分子筛MCM41的合成化学,考察了F离子效应、pH值及表面活性剂CTAB(十六烷基三甲基溴化铵)的影响。  相似文献   

3.
用原子吸收光谱法测定了70例健康老年人、30例健康成年人和30例老年高血压病人血清中Cu、Zn、Fe、Mn、Ca、Mg6种元素的含量.结果表明,健康老年人组与健康成年人组(对照组)相比,除Fe以外,Cu、Zn、Mn、Ca、Mg均有显著性差异;与老年高血压病人组相比,除Mg以外,Cu、Zn、Fe、Mn、Ca均有显著性差异.我们认为稳定的Cu/Zn比值及较高的血Mg水平是健康老年人未发生心血管疾病及糖尿病的重要原因之一,而高Cu、高Ca及显著偏高的Cu/Zn比值,则是发生高血压的一个重要原因。  相似文献   

4.
合成了一系列结构为层状ABO3的复合氧化物La4BaCu5-xMxO13(M=Mn,Co),并利用XRD、X射线能谱、氧程序升温脱附和化学分析方法对它们的结构和活性氧种进行了研究。XRD分析结果表明:它们的结构为五层的ABO3结构。活性氧种的研究表明La4BaCu5O13中掺杂Mn或Co之后,样品中明显存在的MCu(M=Mn,Co)之间的协同作用,并且CuMn之间协同作用明显比CuCo的强。  相似文献   

5.
合成了一系列结构为层磁状ABO3的复合氧化物La4BaCu5-xMxO13(M=Mn,Co),并利用XRD、X射线能谱、氧程序升温脱附和化学分析方法对它们的结构和活性氧种进行了研究。XRD分析结果表明:它们的结构为五层的ABO3结构。玫瑰中a4BaCu5O13中掺Mn或Co之后,样品中明显存在的M-Cu(M=Mn,Co)之间的协同作用,并且Co-Mn之间协同作用明显比Cu-Co的强。  相似文献   

6.
在凝胶体系NaX(F、Cl、Br)Na2OAl2O3SiO2CTAB(十六烷基三甲基溴化铵)H2O中,研究了水热合成中孔MCM41的合成条件。实验证明,在398K下晶化8~16d,NaX/SiO2介于0.01~0.05时,均可合成出MCM41分子筛;NaF的加入,可以加快MCM41分子筛的晶化速度;NaBr的加入,对形成MCM41分子筛有阻碍作用。采用XRD、SEM、TGDTA和N2吸附对合成样品加以表征,证明合成样品具有介孔分子筛特性。  相似文献   

7.
Cu修饰的MCM—41的合成,表征及对芳烃羟化反应催化作?…   总被引:15,自引:1,他引:14  
利用MCM-41形成过程中协同自组装特点,在合成过程中引入Cu(NH3)4^2+,制备出过渡金属表面修饰的纯硅介孔分子筛Cu-MCM-41,采用XRD,ICP,ESR,N2吸附等手段确定Cu处于MCM-41的表面,取代了端羟基中氢的位置,与骨架桥氧和硅羟基中的氧配位,利用苯酚羟化反应为探针,考察了Cu-MCM-41的催化活性。结果表明,Cu-MCM-41具有很高的苯酚羟化活性,与TS-1分子筛的催  相似文献   

8.
陈本美  夏晓波 《分析化学》1996,24(4):422-425
本文对高效液相色谱法(HPLC)测定眼组织中丝裂霉素(Mitomycin C,MMC)的条件进行了优选。研究了PH值及温度对MMC稳定性的影响。以乙腈作为从结膜和巩膜中提取MMC的溶剂,乙酸乙酯作为从房水中提取MMC的溶剂,在较大浓度范围内0.1-400μg/g),其回收率为49%-92%。  相似文献   

9.
Cu对Cu—Mn—Ce—O和Cu—Mn—Ce—Pd—O催化剂三效性能的影响   总被引:1,自引:0,他引:1  
利用火焰脉冲-微反装置考察了Cu-Mn-Ce-O和Cu-Mn-Ce-Pd-O两类催化剂的三效活性。结果表明Cu的加入有利Cu-Mn-Ce-O的NOx和CO的转化,而不利于Cu-Mn-Ce-Pd-O的NOx和HC的转化。XRD分析结果表明在Cu-Mn-Ce-O中加入Pd,原来的CuMn2O3消失,生成新相MnAl2O4;TPR分析结果表明Cu使Mn-Ce-O样品表面氧量增加,表面易于还原,而使Mn-  相似文献   

10.
采用火焰原子吸收法检测了两种溃疡性结肠炎中药制剂中Mn、Cr、K、Na、Ca、Mg等金属元素的含量。结果显示,肠炎宁灌肠散中Mn、Cr、Na、Mg元素含量均明显高于肠炎宁口服胶囊中含量,而K元素则明显低于口服胶囊中含量。结果提示,中药肠炎宁疗效与金属元素含量有一定关系。  相似文献   

11.
在检测中药材黄芪中黄芪甲苷含量时,将高效液相色谱的二极管阵列检测器和蒸发光散射检测器串联使用,并结合光谱和质谱分析技术,对黄芪甲苷的伴生组分进行了研究.结果表明,不同产地的黄芪样品中,黄芪甲苷的含量差别较大,其伴生组分的种类和含量也有很大不同.此项研究对于深入评估黄芪的品质具有一定的参考价值.  相似文献   

12.
A method was developed for the simultaneous identification of astragalosides (AGs) and isoflavonoids (IFs) in the roots of Astragalus membranaceus and Astragalus mongholicus by HPLC coupled with atmospheric pressure chemical ionization MS/MS (HPLC-APCI-MS/MS). Diagnostic fragment ions of AGs and different group of IFs were obtained with one AG and eight IF standards analyzed by CID-MS, which were adopted as characteristic MS/MS fingerprints for further identification of these compounds in the two Astragalus species by using HPLC-APCI-MS/MS. A total of 20 IFs and 10 AGs were identified or tentatively identified. Among them, six IFs were detected in A. membranaceus for the first time and five IFs were firstly identified in A. mongholicus. The results indicate that HPLC-APCI-MS/MS is a powerful tool for the simultaneous characterization of IFs and AGs in complex matrix.  相似文献   

13.
对不同产地中药黄芪中铁、锰、铜及锌4种痕量元素存在的形态及其含量进行研究。文中叙述了分离各种形态的方法及其试液,包括样品中测定痕量元素总量的试液,水煎液的可溶态和悬浮态的试液,可溶态试液中有机形态、无机形态、稳定形态和不稳定形态的试液,以及水煎药渣中4种元素测定溶液等8种试液的制备方法。采用电感耦合等离子体原子发射光谱法测定了各试液中4种痕量元素的含量。以可溶无机形态的试液为基体,用标准加入法作回收试验,测得4种元素的回收率在97.6%~102.0%之间。  相似文献   

14.
A selective and sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the determination of three triterpenoid saponins isolated from Astragalus membranaceus leaf extract. In this article, a method for simultaneous determination of Huangqiyenin A, Huangqiyenin E, and Huangqiyenin K was established for the first time. The method was successfully applied to the pharmacokinetic study of Astragalus membranaceus leaf extract after oral administration. Liquid–liquid extraction was applied to plasma sample preparation. Multiple reaction monitoring mode with an electrospray ion source in positive electrospray ionization was chosen to quantify the analytes. Chromatographic separation was performed on a Waters HSS T3 column, using gradient elution with a mobile phase composed of acetonitrile and 5 mM ammonium acetate/water. The pharmacokinetic results showed that all three compounds had the characteristics of rapid absorption-slow metabolism trend. The time of maximum plasma concentration of Huangqiyenin A is higher than Huangqiyenin E and Huangqiyenin K. And the maximum plasma concentration of Huangqiyenin A is higher as well. The pharmacokinetic results revealed the pharmacokinetic characteristics of the three analytes in rat plasma, which could provide a helpful reference for the further study of Astragalus membranaceus leaf extract.  相似文献   

15.
Two new cycloartane-type triterpenoid saponins were isolated from the roots of Astragalus membranaceus (FISCH.) BGE. (Leguminosae) cultivated in Kangwon province, Korea. These saponins were named astramembranosides A and B and were established to be cycloastragenol 6,25-di-O-beta-D-glucopyranoside (astramembranoside A) and cyclocanthogenin 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-xylopyranoside (astramembranoside B) on the basis of chemical and spectral evidence. In addition, 12 known saponins were also isolated from the same materials. Although cycloastragenol 3-O-xyloside and agroastragalosides I and II have already been isolated from A. membranaceus adventitious roots, these three saponins together with brachyoside B and azukisaponin V methyl ester were isolated for the first time from this plant.  相似文献   

16.
五种补肾中成药物中微量铝分析   总被引:1,自引:0,他引:1  
用Al-CAS-OP-10分光光度法测定了五种补肾中成药中铝含量。结果表明,五种中成药中铝含量有一定的差异。本实验结果为进一步研究铝与补肾中成药的功效关系提供了有用数据。  相似文献   

17.
贵州省白酒中糠醛含量初探   总被引:5,自引:0,他引:5  
测定了贵州省白酒中糠醛含量,结果显示,贵州白酒中均含糠醛,但不同香型白酒中糠醛含量差异较大。  相似文献   

18.
建立了一种机械力化学提取法和实时直接分析质谱(DART-MS)分析相结合的中草药多糖分析方法,同时测定了黄芪、银耳、百合、茯苓、鼓槌石斛、金钗石斛、铁皮石斛和党参8种中草药多糖。比较了机械力化学提取(MCE)法与传统方法的提取效果,并优化了MCE法的提取参数。通过体积排阻色谱分离中草药多糖,建立分子质量校准曲线,估算了多糖分子质量。利用DART-MS直接裂解多糖大分子,可瞬时获得m/z<350的碎片离子,不同的中草药多糖得到的特征性的质谱离子峰可用于多糖样品的有效区分。该方法具有简单、快速、高通量、无需预消化的特点,是直接从复杂多糖大分子中获取特征指纹图谱的有力工具。  相似文献   

19.
The preparation of chloroprene–methyl methacrylate copolymers in the presence of Lewis acids (Et1.5AlCl1.5) in hydrocarbon solvent and the effect of Lewis acids concentration on copolymer composition are described. 13C NMR spectra were obtained on these copolymers. In samples of high MMA content, tactic placements of MMA were observed as well as several different kinds of sequences for chloroprene and MMA. In samples of low MMA content, no tactic placements of MMA were found but several different kinds of chloroprene sequences were observed. From the analysis of the 13C NMR spectra of the different copolymers examined, it is apparent that all the various kinds of chloroprene sequences in these copolymers can be determined.  相似文献   

20.
灵芝孢子的微量元素含量和药理应用分析   总被引:22,自引:0,他引:22  
为了更深入研究灵芝孢子的药理作用和治疗功效,用电感耦合高频等离子体光谱法测定了四种不同产地、不同等级的灵芝孢子中的20种元素含量。结果表明,四种孢子成分基本不受产地和等级的影响,其中以钴(Co)、铬(Cr)、硒(Se)含量最高,从而更证实了灵芝孢子是抗肿瘤、降血糖、保护心脑血管、提高身体素质的一种健康营养品。  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