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201.
在四氢呋喃溶液中,用Sm/TiCl4体系还原亚胺合成了咪唑烷衍生物.发现当没有促进剂1,2-二溴乙烷时,咪唑烷衍生物的产率小于20%,加入1,2-二溴乙烷后,产率大大提高.产物的结构通过IR,1HNMR和MS光谱确证.根据实验结果提出了一个可能的反应机理. 相似文献
202.
203.
Hae‐Jeong Lee Christopher L. Soles Da‐Wei Liu Barry J. Bauer Wen‐Li Wu 《Journal of Polymer Science.Polymer Physics》2002,40(19):2170-2177
X‐ray reflectivity has been used to determine the mass uptake of probe molecules in porous thin films supported on thick silicon wafers. The adsorption occurs by capillary condensation when the films are exposed to probe vapor at controlled partial vapor pressures. The probe solvent partial pressure was varied by mixing saturated air and dry air at constant temperature or by changing sample temperature at a constant vapor concentration. Pore size distribution in the films can be calculated from the probe uptake with typical porosimetric approaches such as the application of the Kelvin equation to convert partial pressure into pore size. For illustration, the pore size distribution of three different nanoporous thin films, the primary candidate of ultra‐low‐k interlevel dielectrics in the next generation of integrated circuit chips, was determined with this technique. These samples represent different generations of low‐k dielectrics developed by industry. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2170–2177, 2002 相似文献
204.
以纤维素材料为基质的降解塑料的研究进展 总被引:5,自引:0,他引:5
本文详述了以天然高分子纤维素材料为基质的降解塑料的发展。纤维素材料由于其来源丰富,有良好的反应性,优异的生物降解性,无毒性等,因而可用来制备降解塑料.其开发和应用是解决目前世界范围内的“白色污染”的一条理想途径. 相似文献
205.
同步荧光法同时测定苯甲酸和水杨酸的研究 总被引:6,自引:0,他引:6
根据苯甲酸与水杨酸在酸性条件下荧光光谱出现的差异,用同步荧光法同时测定其混合物中二组份。苯甲酸及水杨酸的检测限分别为0.24μg/mL和0.25μg/mL相对标准偏差分别为1.3%和1.2%。方法用于商品杀菌腐剂中苯甲酸与水杨酸的同时测定,结果满意。 相似文献
206.
Jeong Gwi-Taek Park Don-Hee Hwang Baik Park Kyungmoon Kim Si-Wouk Woo Je-Chang 《Applied biochemistry and biotechnology》2002,98(1-9):1115-1127
The growth properties of Panax ginseng hairy roots transformed by Agrobacterium rhizogenes were compared between flask and aerated column or stirred bioreactor. In flask cultures, sucrose, initially 30 g/L, was nearly
exhausted after 45 d of culture. The pH of the medium dropped from 5.5 to 4.96 after 10 d, but afterward it gradually increased
to 6.4. After 45 d, hairy roots grew about 16-folds. The growth rate of hairy roots in air-bubble column or stirred bioreactor
cultures was 1.13 (1.11) to 1.23 (1.20) g fresh wt (dry wt)/(g of cells·d), respectively. For both bioreactors, growth was
about three times as high as in the flask cultivation. 相似文献
207.
气相色谱法测定饮料中乙醇含量 总被引:12,自引:0,他引:12
采用样品用注射器吸附后直接经C18柱后进样,用气相色谱法测定,该方法适合多样饮料中的乙醇测定,平均回收率为98.6%,检出限为7.7mg/L。 相似文献
208.
J. A. Azizi D. Dollimore P. J. Dollimore G. R. Heal P. Manley W. A. Kneller W. Jin Yong 《Journal of Thermal Analysis and Calorimetry》1993,40(2):831-847
In this study a relationship between the surface and textural properties of carbon blacks and the gasification process induced thermally in air is noted. A temperature jump method was used to follow the gasification in air and to establish the relevant Arrhenius parameters. This can be associated with the activity of ‘basal’ plane carbon atoms as well as ‘edge’ carbon atoms at the surface. This is based on a model of carbon black structure consisting of the irregular packing of small graphite carbon structures. The carbon black surface was measured using a single measurement of adsorption based essentially on the BET volumetric method. The carbon black surface had a rate of oxidation per unit are which clearly indicated that the lower area carbon blacks had a predominately active area of ‘edge’ atoms at the surface while the surface of the higher area carbon blacks had a predominate amount of ‘basal’ plane graphite carbon atoms. 相似文献
209.
Tae Oan Ahn Jung Ho Kim Jong Chan Lee Han Mo Jeong Jong-Yoon Park 《Journal of polymer science. Part A, Polymer chemistry》1993,31(2):435-441
A macro-azoinitiator containing polyarylate segment and azo group was prepared by the solution polycondensation of azobiscyanopentanoyl chloride and hydroxy-terminated polyarylates having viscosity-average molecular weights of 6200, 8100, and 12 400. These macro-azoinitiators were used in the radical polymerization of styrene to synthesize polyarylate-polystyrene block copolymers. Thermal properties measured by the differential scanning calorimetry indicated the phase separated morphology of the block copolymers except at low molecular weight of the block constituents. © 1993 John Wiley & Sons, Inc. 相似文献
210.