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221.
222.
Hiroshi Tachimori Toshio Masuda 《Journal of polymer science. Part A, Polymer chemistry》1995,33(12):2079-2085
1-(p-N-Carbazolylphenyl)-2-phenylacetylene (p-CzDPA) was polymerized by TaCl5–co-catalyst systems (cocatalysts: n-Bu1Sn, Et3SiH, and 9BBN) to produce acetone-insoluble polymers in about 60-70% yields. Poly(p-CzDPA) was a yellowish-orange solid, most part of which was soluble in toluene, chloroform, etc., and its weight-average molecular weights were around 4×105. This polymer formed a tough film by solution casting, and was thermally very stable (the onset temperature of weight loss in TGA in air 470°C). The oxygen per-meability coefficient of the polymer at 25°C was lower than two barrers. The present polymer showed photoconductivity and redox activity. © 1995 John Wiley & Sons, Inc. 相似文献
223.
224.
CFB煤燃烧/热解双反应器中热解室对立管内气固流动特性的影响 总被引:4,自引:0,他引:4
考察了循环流化床煤燃烧/热解双反应器系统中热解室的存在对立管内的压力分布及气固流动状况的影响。提升管的内径100 mm、高6 m,立管的内径44 mm、高3 m,热解室的截面积200 mm×200 mm、高770 mm。结果表明,随着提升管内表观气速Ur的增加,有无热解室立管内均为负压差流动,负压差梯度随着Ur的增加而减小。有热解室时,热解室内要保持一定的料位高度,整个立管内固体颗粒的流动为负压差移动床流动;没有热解室时,立管内为稀相流动和移动床流动同时存在,立管内平衡料柱高度随Ur的增加而升高。随着循环量Gs的增加,两种类型的立管内负压差梯度均随之增大,也存在着流动形态的差别。循环量Gs的增加会引起立管内平衡料柱高度的降低。立管内气固相对滑移速度也随着循环量Gs的增加而增大。 相似文献
225.
K. Grob 《Journal of separation science》1980,3(6):286-290
The sensitivity of an FID may change when the carrier gas flow rate changes during a chromatographic run. Sample parts which are eluted at reduced FID sensitivity produce a reduced peak area, hence are discriminated as compared to other components. Sensitivity changes were studied for hydrogen as carrier gas. For the detector tested, differences in the carrier gas flow rates of 1 ml/min shifted the FID sensitivity by 1 to 5% (depending on the fuel gas supply). Thus the stability of the sensitivity is no longer ensured as soon as the carrier gas flow rate is changed manually or by an automatic programmer during an analysis. Sensitivity drifts may also occur during temperature programmed runs with a pressure regulated carrier gas supply since the gas flow through the capillary drops with increasing temperature. Such shifts in the response became noticeable as soon as relatively high carrier gas flow rates combined with long range temperature programmes were used. The typical patterns of such discriminations are shown, closing with a discussion on the possibilities for minimizing such undesired effects. 相似文献
226.
Marcos J Pascual JA de la Torre X Segura J 《Journal of mass spectrometry : JMS》2002,37(10):1059-1073
A fast and sensitive method for the comprehensive screening of anabolic agents and other banned doping substances using gas chromatography/tandem mass spectrometry (GC/MS/MS) with an external ionization ion trap mass spectrometer is presented. The method takes advantage of the resolving power of MS/MS to eliminate background interferences, thus speeding up the chromatographic analysis. For each compound, different fragmentation reactions were studied and their collision energies optimized to obtain the best sensitivity in terms of their signal-to-noise ratio (S/N). A dramatic reduction in overall analysis time was achieved compared with other common approaches. More than 50 substances could finally be monitored in less than 7.4 min with detection limits (S/N >3) lower than 0.5 ng ml(-1) for most of the compounds with special sensitivity requirements according to the International Olympic Committee (IOC). A validation procedure for qualitative analysis was performed. The selectivity of the method showed that no interfering peaks were observed at the retention time of the analytes. Good intermediate precision, below 25% for most of the compounds, and robustness were observed. The optimized method was successfully applied to analyse more than 100 real human urine samples with optimum sensitivity and specificity rates. 相似文献
227.
建立火焰原子吸收光谱法测定天然气转化催化剂中氧化钾的分析方法。该方法将催化剂样品和助溶剂四硼酸锂熔融后再用盐酸溶解定容,采用火焰原子吸收光谱仪对样品溶液进行测定。在优化的实验条件下,钾离子的质量浓度在0.05~0.50 mg/L范围内与吸光度呈良好线性关系,相关系数为0.9995。钾的方法检出限为0.001 mg/L,定量限为0.01 mg/L,测定结果的相对标准偏差为2.6%~4.3%(n=6),样品加标回收率为97.8%~102.3%。与HG/T 3543-2014中的酸溶制样法相比,该方法能够将催化剂样品中的难溶钾盐溶出,分析结果准确度更高,可用于天然气转化催化剂中氧化钾含量的测定。 相似文献
228.
选用HP-NINOWax毛细管色谱柱及氢火焰离子化检测器(FID),采用程序升温,建立了4种脂肪烷基二甲基叔胺的分析方法。结果表明,4种脂肪烷基二甲基叔胺质量浓度在0.005~1.0 g/L范围内,其峰面积与质量浓度有良好的线性关系,相关系数(R2)在0.9996以上。检出限(LODs,信噪比为3)在0.001~0.002 g/L之间,定量限(LOQs,信噪比为10)在0.003~0.005 g/L之间,回收率在90%~130%之间,相对标准偏差为1.3%~6.9%(n=6)。方法的线性范围宽、回收率高、选择性好,可用于叔胺的产品质量分析及生产过程控制分析。利用该方法对阳离子表面活性剂合成反应中十六烷基二甲基叔胺进行监测,结果很好地符合双分子亲核取代反应。该方法比滴定分析法更快速、精确,与液相色谱法相比,不需要进行柱前衍生或者使用色谱-质谱联用仪器。 相似文献
229.
The studies were devoted to determination of the effect of gas atmosphere and its pressure on the second step of decomposition
of hydrated titanium dioxide (HTD) promoted by sulfate groups.
It has been found that thermal decomposition of HTD at temperatures above 300°C consists of a number of processes such as
dehydroxylation, desulfuration, recrystallization and sintering of solid grains, photochemical processes (if the decomposition
proceeds in the presence of light) and adsorption of gas phase components (in the presence of air or SO2).
Kinetic parameters characterizing this step of decomposition have been determined for processes carried out in vacuum and
in argon or air atmospheres (at a pressure of 13.33hPa). The kinetic curves of decomposition carried out in the presence of
gases capable of being adsorbed on the surface of partly dehydrated HTD are featured by local extrema due to simultaneous
processes of decomposition and adsorption of gas components.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
230.
Donna M. Brestensky Thomas R. Hoye Christopher W. Macosko 《Journal of polymer science. Part A, Polymer chemistry》1995,33(12):1957-1967
Anionic living polymerization methods, using organometallic initiators such as butyllithium reagents, have proven useful for, inter alia, styrene polymerization and are amenable to subsequent functionalization of poly(styryl)lithium in the termination step. In this study, general methods for the selective preparation of small styrene oligomers and termination of the intermediate oligo(styryl)lithium anions were investigated. The crude reaction mixtures were analyzed directly by tandem gas chromatography/mass spectrometry (GC/MS). Of the carbon- and silicon-based electrophiles tested, chloro(chloroalkyl)silanes, Cl-SiR2(CH2)nCl in particular, were shown by GC/MS to be regioselective end-capping reagents, thus allowing subsequent transformation to the primary amine. The combined GC/MS data allow not only an estimate of the degree of functionalization, but also the identification of by-products, thus providing insight into the end-capping process that otherwise might be difficult to access. © 1995 John Wiley & Sons, Inc. 相似文献