共查询到20条相似文献,搜索用时 93 毫秒
1.
用abinitio方法研究2,4-二甲基-1,3-戊二烯各种构象异构体的结构,找到s-trans和s-cis两种稳定构象,且s-trans更稳定.对稳定构象的几何结构、电荷分布进行了研究,讨论了不同的电子基组对优化几何的影响,并计算了稳定构象的热力学常数,与实验结果进行了比较. 相似文献
2.
用过渡态理论和AM1方法,对8-二甲基-7-甲氧基-5-烯-壬腈氧化物分子内环加成反应机理进行了研究。结果表明,存在两种产物的平行反应,对两个反应的速率常数比值的计算,得到反式和顺式的产率比为90.5:9.5,与实验产率比值(≥85:15)结果接近。标题物立体专一选择性由活化焓和活化熵共同决定。 相似文献
3.
4.
α-[(1H-1,2,4-三唑-1-基)甲基]-β-芳基-β-芳硫基取代苯丙醇的合成及生物活性研究 总被引:1,自引:0,他引:1
利用1,3-二芳基-2-[(1H-1,2,4-三唑-1-基)甲基]-2-丙烯-1-酮7与取代硫酚进行1,4-亲核加成,经重排得到化合物4,将化合物4用NaBH4还原,得到目标化合物5,其结构经元素分析、^1H NMR和红外光谱所确证,并测试化合物5对小麦锈病的活性,结果发现大部分化合物的杀菌活性均较低。 相似文献
5.
6.
ICP—AES测定钯—钡合金中常量钡 总被引:1,自引:0,他引:1
本文采用ICP-AES法测定钯-钡合金中常量钡。考察了其体及无机酸的存在对钡发射线强度的影响,采用标准曲线法对含量分别为0.59%和26.04%的两个试样进行了测定,结果满意。 相似文献
7.
4-烷基环己基苯甲酸酯类液晶合成工艺研究 总被引:2,自引:0,他引:2
以环己烯为原料,经烷基环己基苯甲酸和烷基酚合成了4-烷基环己基苯甲酸酯类液晶(nmAEAH)。并对烷基环己基苯甲酸的合成工艺进行了改进和优化,使成本降低、可以进行批量生产。测试并收集了nmAEAH的物理性能参数;熔点、沸点、清亮点;气相、液相、红外、核磁、差热分析结果等,为此类液晶单体进一步的基础研究和应用研究奠定了基础。 相似文献
8.
9.
本文采用ICP-AES法测定钯-钡合金中常量钡。考察了基体及无机酸的存在对钡发射线强度的影响。采用标准曲线法对含量分别为0.59%和26.04%的两个试样进行了测定,结果满意。 相似文献
10.
液晶基元直接竖挂于主链上的液晶共聚物的研究 总被引:2,自引:0,他引:2
合成了含液晶基元的单体,4+4'-(对甲氧基-苯甲酰氧基)-苯甲酸氧基]-苯基-甲基丙烯酸酯,以及由此单体与苯乙烯,通过自由基共聚合反应合成了一系列含液晶性和非液晶性两种序列结构的共聚物.采用DSC、偏光显微镜和X-衍射方法研究了共聚物的液晶行为,发现单体和所有的共聚物(除CP—9外)均有很好的热致液晶性及较宽的液晶态温度范围;随苯乙烯单体单元摩尔百分含量的增加,共聚物的分子量、相转变温度和热失重温度基本上呈下降趋势.通讯联系人0.sg/dl的溶液,于40oC用乌氏粘度计测定.l·2单体合成合成路线如下:化合物I、11、Ill和IV的制备按文献l’]的方法进行.化合物1、11、Ill和IV经元素分析、‘H—NMR和MS等表征,结果与其化学结构~致.1.3聚合物的合成聚合反应和共聚物结构式表示如下:按单体(IV)与苯乙烯不同摩尔比,以DMF为溶剂,AIBN为引发剂(相当于单体摩尔数的0.50).通过封管聚合,在60oC水浴中反应36h,升温至70oC反应12h,抽滤,用DMF和甲醇洗,真空干燥.2结果与讨论2.l含液晶基元的单体(I)化合物1、11、Ill和IV经测试分析结果与其化学结构一致.由表1可见,单体? 相似文献
11.
12.
卷烟内在质量的气相色谱-数学聚类法研究 总被引:2,自引:0,他引:2
采用吸附丝色谱方法采集和分析了红塔山牌卷烟的挥发性成分,对 10个真品进行 R型聚类分析和 R型因子分析,从 26个组分提取出对卷烟质量起主导作用的 7个特征变量(组分),并对其丰度进行了讨论,进而建立了红塔山卷烟的质量数学模型,用 2个真品和 2 个假冒品对模型进行了检验,结果令人满意。 相似文献
13.
Forty wines of Vitis Vinifera var. 'Pinot Noir' were analyzed for their elemental and organic compositions by atomic emission spectrometry and glass-capillary gas chromatography, respectively. Their sensory quality was evaluated by a panel of judges. Average overall quality scores were used to rank these wines. Stepwise regression analysis and principal component factor analysis were used to investigate correlations between objective chemical measurements and subjective sensory evaluations. Compounds which were found to be related to overall quality of wine were identified. 相似文献
14.
Jacobsen S Grove H Jensen KN Sørensen HA Jessen F Hollung K Uhlen AK Jørgensen BM Faergestad EM Søndergaard I 《Electrophoresis》2007,28(8):1289-1299
Practical approaches to the use of multivariate data analysis of 2-DE protein patterns are demonstrated by three independent strategies for the image analysis and the multivariate analysis on the same set of 2-DE data. Four wheat varieties were selected on the basis of their baking quality. Two of the varieties were of strong baking quality and hard wheat kernel and two were of weak baking quality and soft kernel. Gliadins at different stages of grain development were analyzed by the application of multivariate data analysis on images of 2-DEs. Patterns related to the wheat varieties, harvest times and quality were detected on images of 2-DE protein patterns for all the three strategies. The use of the multivariate methods was evaluated in the alignment and matching procedures of 2-DE gels. All the three strategies were able to discriminate the samples according to quality, harvest time and variety, although different subsets of protein spots were selected. The explorative approach of using multivariate data analysis and variable selection in the analyses of 2-DEs seems to be promising as a fast, reliable and convenient way of screening and transforming many gel images into spot quantities. 相似文献
15.
Zhang J Rodila R Watson P Ji Q El-Shourbagy TA 《Biomedical chromatography : BMC》2007,21(10):1036-1044
Sirolimus, an effective immunosuppressive agent, is used for drug eluting stents. During stent development, an analytical method for the determination of sirolimus in tissue needs to be established. Normally, tissue samples are homogenized and then analyzed against the calibration standards prepared in a tissue homogenate. This approach provides insufficient control of the homogenization process. In this paper, tissue quality control samples were introduced for the optimization of the homogenization process during method development, but also allowance for the performance evaluation of the entire analytical process. In addition, a new approach using rabbit blood as a homogenization medium was developed to stabilize sirolimus in rabbit tissue homogenates. Calibration standards and quality controls were prepared by spiking different sirolimus working solutions into rabbit blood. Homogenization quality control samples were prepared by injecting other sirolimus working solutions into empty test tubes and pre-cut arteries within pre-defined masses. A high-throughput homogenization procedure was optimized based on the specific chemical properties of sirolimus. The linear dynamic range was between 49.9 pg/mL and 31.9 ng/mL to accommodate the expected artery homogenate concentrations. Additionally, quality controls in rabbit blood were also used in the extraction to support the calibration standards. The accuracy and precision of the quality controls in rabbit blood reflect the extraction performance and the accuracy and precision of the homogenization tissue quality controls reflect the overall performance of the method. The mean bias was between -4.5 and 0.2% for all levels of quality controls in the blood and between 4.8 and 14.9% for all levels of the homogenization tissue quality controls. The CVs of all concentration levels were < or =5.3% for the quality controls in blood and < or =9.2% for the homogenization tissue quality controls. The method was successfully applied to determine the concentration of sirolimus in the rabbit arteries. 相似文献
16.
《Arabian Journal of Chemistry》2022,15(12):104296
Mailuoshutong pill (MLSTP) is a traditional Chinese medicine compound preparation used for the treatment of thromboangiitis obliterans. However, component responsible for those effects are not yet identified, nor with their accurate contents and in-vivo movement, which means the quality markers of MLSTP are still unknown. The aim of this study was to discovery quality markers of MLSTP by developing a new multi-dimensional network strategy based on “Content-Pharmacokinetics-Pharmacology”. 40 analytes were determined by UHPLC-MS/MS in 8 min and the average contents in 11 batches of commercial MLSTP samples were used as the content dimension, the pharmacokinetics and pharmacology dimension were evaluated by five variables based on ADME Prediction and Prediction of Activity Spectra. Each dimension of the characteristic network was quantified by multivariate statistical analysis, and a three-dimensional network was constructed. Finally, Liquiritin, Calycosin-7-glucoside and Albiflorin with larger regression area were preferred as quality markers of MLSTP, which had satisfactory comprehensive properties of content, pharmacokinetic properties and pharmacological activity. In summary, the potential quality markers of MLSTP were identified by multi-dimensional characteristic network of content, pharmacokinetics and pharmacology. Also, the new strategy established in this work provided a valuable perspective for the selection of quality control indicators from compound formula. 相似文献
17.
The study was designed to explore the potential applications of the real-time cell electronic analysis technology in the quality evaluation of natural medicines. The natural medicinal Flos Carthami was discussed as a methodological example and the specific time/dose-dependent cell response profiles (TCRPs) were produced by the real-time cell electronic analysis technology. The similarity and bioactivity were obtained by analyzing all TCRPs. Meanwhile, an HPLC method according to the Chinese Pharmacopeia (edition 2010) was used to evaluate the quality of Flos Carthami. The correlation was obtained by comparing the results produced by the two different approaches. By analyzing the data, five different samples ofFlos Carthami can produce remarkably similar TCRPs. The quality ofFlos Carthami was evaluated by both the HPLC and the TCRPs analysis-based approaches and similar results were obtained. The results suggest that the same natural medicine from different locations could produce similar TCRPs. By analyzing the TCRPs, the bioactivity and quality evaluation of natural medicines can be obtained. This technology is a physiologically relevant approach for the quality evaluation of natural medicines. The ultimate aim of our study is to establish a new standard for quality evaluation. 相似文献
18.
The aim of this study was to evaluate the primary experience of implementing a quality system in a clinical laboratory. The
second interrelated aim was to evaluate the quality and financial indicators needed for continuous measurement of quality,
decision making in the laboratory management and everyday process control in analytical work. The quality process itself should
be evaluated because the building up of a quality system requires a considerable amount of resources. The most effective and
practical ways of using a quality system as a management tool should be found and the need for financial appraisal when the
quality system is implemented is stressed. According to our study, when the effects of the quality system were evaluated,
the managers of the laboratory had not considered the appropriate financial indicators. The quality indicators considered
to be the best were internal quality control, external quality assessment and customer satisfaction surveys. The first benefits
of the quality system evaluated by the personnel were other than the purely financial benefits, they include a more systematic
and empowering approach to laboratory management, better working instructions, better knowledge of the methods and equipment,
and fewer errors. The financial evaluation of a quality process in a public-owned clinical laboratory is complicated due to
the fact that financial indicators are not as far developed and diverse as in industrial organisations. When starting to implement
a quality system, it is important to pay attention to all measures that motivate the staff and help them benefit from the
practical effects of the system.
Received: 10 November 1999 / Accepted: 12 January 2000 相似文献
19.
Yating Lei Yuanqing Wang Zhicheng Sun Meiyu Lin Xiong Cai Dan Huang Kun Luo Shihan Tan Ye Zhang Jianye Yan Xinhua Xia 《Journal of separation science》2020,43(7):1382-1392
The present study aimed to develop a strategy involving quantitative analysis of multicomponents by single marker in combination with high‐performance liquid chromatography fingerprint qualitative analysis for performing the quality control of Aurantii Fructus. The content of 12 components (eriocitrin, neoeriocitrin, narirutin, naringin, hesperidin, neohesperidin, meranzin, poncirin, naringenin, nobiletin, tangeretin, and auraptene) in samples was determined using reliable relative correction factors that were obtained using naringin as an internal reference standard. The new method demonstrated good applicability, and no significant differences were observed between the external standard method and the new method as determined by calculating standard method difference. Qualitative evaluation of samples was conducted using similarity analysis, hierarchical cluster analysis, and quality fluctuation analysis. Chromatographic fingerprint data were divided into three groups by similarity and hierarchical cluster analyses, and seven components may have a more significant impact on the quality of Aurantii Fructus in quality fluctuation analysis. Overall, the study suggests that the qualitative and quantitative analyses of multicomponents using quantitative analysis of multicomponents by single marker combined with chromatographic fingerprinting can be considered good quality criteria for performing quality control and providing technical support for the further pharmacological and pharmaceutical research of Aurantii Fructus. 相似文献