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981.
982.
983.
GC/MS法建立烟用香精指纹图谱研究 总被引:4,自引:1,他引:4
采用超声辅助液液萃取法(ULLE)对8个不同批次的烟用HMT香精成分进行提取,用GC/MS对其进行定性定量分析,建立了该香精的GC/MS指纹图谱的研究方法,目的在于为烟用香精质量控制提供一种方便、快捷、可靠的分析手段。结果表明:ULLE方法具有操作简便、快速、节能、萃取效率高、重现性好等特点,适合于烟用香精成分的提取。8个批次的HMT香精的指纹图谱稳定性好,相似度高,具有很强的特征性和唯一性。通过该香精指纹图谱的建立,对日后进厂的HMT香精进行质量控制提供了依据。 相似文献
984.
报道了以磷钨钼杂多酸掺杂聚苯胺为催化剂,通过丁醛和乙二醇反应合成了丁醛乙二醇缩醛。系统考察了醛醇物质的量比、催化剂用量以及反应时间诸因素对产品收率的影响。确定适宜的工艺条件为n(丁醛)∶n(乙二醇)=1∶1.5,催化剂的质量为反应物料总质量的0.8%,反应时间1.0 h。在此反应条件下,丁醛乙二醇缩醛的收率可达71.1%。 相似文献
985.
Borgna A. Le Normand F. Garetto T. Apesteguia C. R. Moraweck B. 《Catalysis Letters》1992,13(3):175-188
The effect of an oxidative atmosphere (300 °C) is studied on fresh and sintered unchlorinated naphtha reforming catalysts containing 0.6–1% Pt. The TPR profiles show that only one species is formed using our experimental conditions, regardless of the mean crystallite size of the metal particles. The structural information supplied by EXAFS compared with cuboctahedral particle modeling, implies that such species is a surface platinum oxide, the structure of which is close to that of PtO2, but largely distorted. This is true whether the catalyst is sintered or not. 相似文献
986.
W. D. Branch T. Nakayama M. S. Chinnan 《Journal of the American Oil Chemists' Society》1990,67(9):591-593
Fatty acid composition was determined among seven U.S. runner-type peanut (Arachis hypogaea L.) cultivars: Florunner, Sunrunner, GK-7, Southern Runner, Sunbelt Runner, Okrun, and Langley. Significant year and cultivar
differences were found within these fatty acid profiles. Southern Runner had the best oleic to linoleic ratio and iodine values;
whereas Florunner, Sunrunner, and Langley were the highest in unsaturated and lowest in saturated and long-chain fatty acids.
For the future, breeding programs need to continue developing peanut cultivars with improved oil quality. 相似文献
987.
A digital imaging approach was applied to investigate mortar morphology in thin sections; in particular, the binder/aggregate ratio and the grading curve of five mortar bars were attained by digital image processing (DIP), using the Image Pro Plus 4.1 software package. The imaging procedure employed image segmentation, to extract mortar aggregate, and image filtering, to fix grain boundaries. The results show that digital image processing may be considered as an alternative method to mechanical sieving for the characterisation of mortar morphology, as it appears to be quicker and more accurate than the traditional method. However, digital image processing exhibits limits, which are discussed in the text. 相似文献
988.
Paresh Chandra Dutta 《Journal of the American Oil Chemists' Society》1997,74(6):659-666
Hydrogenated rapeseed oil/palm oil blend, sunflower oil and high-oleic sunflower oil, and French fries fried in these oils
were assessed for contents of sterol oxidation products. Different oxidation products of phytosterols (7α- and 7β-hydroxy-sito-and
campesterol, 7-ketosito- and 7-ketocampesterol, 5α,6α-epoxy-sito- and campesterol, 5β,6β-epoxy-sito-and campesterol, dihydroxysitosterol
and dihydroxycampesterol) were identified and quantiated by gas chromatography (GC) and GC-mass spectroscopy. Rapeseed oil/palm
oil blend contained 41 ppm total sterol oxides before frying operations. After two days of frying, this level was increased
to 60 ppm. Sunflower oil and high-oleic sunflower oil had 40 and 46 ppm sterol oxides, respectively, before frying operations.
After two days of frying operations, these levels increased to 57 and 56 ppm, respectively. In addition to campesterol and
sitosterol oxidation products, small amounts of 7α- and 7β-hydroxystigmasterol were detected in the oil samples. Total sterol
oxides in the lipids of French fries fried at 200°C in rapeseed oil/palm oil blend, sunflower oil, and high-oleic sunflower
oil were 32, 37, and 54 ppm, respectively. The levels of total oxidized sterols, calculated per g sample, ranged from 2.4
to 4.0 ppm. In addition to the content of phytosterol oxides, full scan mass spectra of several oxidation products of stigmasterol
are reported for the first time.
Part of these results were presented at the 86th Annual Meeting of the AOCS, May 7–11, 1995, San Antonio, TX. 相似文献
989.
Synthesis of silver/polymer colloidal composites from surface-functional porous polymer microspheres
This study presents a different colloidal silver (Ag)/polymer system where Ag nanoparticles are deposited uniformly onto surface-functional porous poly(ethylene glycol dimethacrylate-co-acrylonitrile) (poly(EGDMA-co-AN)) microspheres. The formation and morphology of the composite microspheres were characterized from electron microscopy and X-ray diffraction analyses. The significance of the present report is that owing to the high affinity between Ag and nitrile group (CN) on the large surface of the microspheres, the Ag nanoparticles having a face-centered cubic phase were incorporated evenly into the deep pores of the microspheres with fine size and size distribution. In the preservation test, the Ag/poly(EGDMA-co-AN) composite microspheres obtained showed an excellent anti-bacterial performance, elucidating a high applicability for a new preservative. 相似文献
990.