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181.
The vanadium trapping effect of Mg and La containing additives in cracking catalyst contaminated with 2300 ppm Ni and 4700 ppm V has been analyzed by microactivity test (MAT) and imaging secondary ion mass spectrometry (SIMS). The results of SIMS imaging are consistent with cracking activity data and show that the La/spinel is a superior vanadium trap for the fluid catalytic cracking of hydrocarbons (FCC) operation. La/spinel serves as a dual function additive for both vanadium trap and SOx removal. The optimum amount of La/spinel added to the cracking catalyst is about 15% by weight. This results in an increased catalytic activity, an increase in gasoline yield, and a decrease in coke and gas factors. The MgAl2O4 phase of Mg/Al2O3 additive is found capable of trapping vanadium while its MgO of Mg/Al2O3 phase can migrate to zeolite particles (the active component of the FCC catalyst) that, in turn, causes a decline in the activity of that catalyst. 相似文献
182.
A novel pyridinium salt photoelectrocyclization-nucleophilic bicyclic aziridine ring opening reaction sequence has been investigated in order to determine its preparative potential. N-Alkylpyridinium perchlorates were found to undergo photoinduced electrocyclization upon irradiation in nucleophilic solvents, such as H(2)O and MeOH, to efficiently produce 6-alkyl-6-azabicyclo[3.1.0]hex-2-en-4-yl alcohols and ethers. The bicyclic aziridine photoproducts react with a number of different nucleophiles (e.g., H(2)O, MeOH, AcOH, AcSH) under acid-catalyzed conditions to produce 5-(nucleophile-substituted)-4-(alkylamino)cyclopenten-3-yl alcohols and ethers. The aziridine ring opening processes are both regioselective and stereoselective, yielding trans,trans-trisubstituted cyclopentenes exclusively, apparently as a consequence of the operation of an SN(2) mechanism. The effects of C-alkyl substitution on the regiochemistry of the pyridinium cation photocyclization reaction were briefly probed, and a method was developed to produce trans,cis-trisubstituted cyclopentenes by use of this tandem preparative sequence. 相似文献
183.
184.
Xing Hai Li Xin Ling Yang Xiao Mei Liang Zhen Peng Kai Yun Ling Fu Heng Chen Dao Quan Wang 《中国化学快报》2007,18(12):1476-1478
α-Chlorocycloalkanones(Ⅳ) were synthesized from cycloalkanones via potassiumα-oxocycloalkylsulfonates(Ⅱ).A two-step mechanism was proposed to explain the formation ofⅣfromⅡ. 相似文献
185.
2,4,6-三硝基苯酚改性锆铝复合氧化物固定相分离富勒烯的色谱性能研究 总被引:1,自引:0,他引:1
制备了用于分离C60和C70的2,4,6-三硝基苯酚改性锆铝复合氧化物高效液相色谱固定相,考察了流动相中甲苯的含量、柱温及流速对C60和C70分离的影响,同时比较了酸腐蚀前后锆铝复合氧化物基质对分离的影响,结果表明,2,4,6-三硝基苯酚改性酸腐蚀后锆铝复合氧化物填料对富勒烯表现出较强的分离能力,具有作为富勒烯制备分离的潜力。 相似文献
186.
Summary P-glycoprotein (P-gp), an ATP-binding cassette (ABC) transporter, functions as a biological barrier by extruding cytotoxic agents out of cells, resulting in an obstacle in chemotherapeutic treatment of cancer. In order to aid in the development of potential P-gp inhibitors, we constructed a quantitative structure–activity relationship (QSAR) model of flavonoids as P-gp inhibitors based on Bayesian-regularized neural network (BRNN). A dataset of 57 flavonoids collected from a literature binding to the C-terminal nucleotide-binding domain of mouse P-gp was compiled. The predictive ability of the model was assessed using a test set that was independent of the training set, which showed a standard error of prediction of 0.146 ± 0.006 (data scaled from 0 to 1). Meanwhile, two other mathematical tools, back-propagation neural network (BPNN) and partial least squares (PLS) were also attempted to build QSAR models. The BRNN provided slightly better results for the test set compared to BPNN, but the difference was not significant according to F-statistic at p = 0.05. The PLS failed to build a reliable model in the present study. Our study indicates that the BRNN-based in silico model has good potential in facilitating the prediction of P-gp flavonoid inhibitors and might be applied in further drug design. 相似文献
187.
Laser-ablated Au atoms have been co-deposited with CO molecules in solid argon to produce gold carbonyls. In addition to the previously reported Au(CO)n (n = 1, 2) and Au2(CO)2 molecules, small gold cluster monocarbonyls Au(n)CO (n = 2-5) are formed on sample annealing and characterized using infrared spectroscopy on the basis of the results of the isotopic substitution and CO concentration change and comparison with theoretical predictions. Of particular interest is that the mononuclear gold carbonyls, Au(CO)n (n = 1, 2), are favored under the experimental conditions of higher CO concentration and lower laser energy, whereas the yields of the gold cluster carbonyls, Au(n)CO (n = 2-5) and Au2(CO)2, remarkably increase with lower CO concentration and higher laser power. Density functional theory (DFT) calculations have been performed on these molecules and the corresponding small naked gold clusters. The identities of these gold carbonyls Au(n)CO (n = 1-5) and Au(n)(CO)2 (n = 1, 2) are confirmed by the good agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts. 相似文献
188.
Rong Zhang Qiao Bai Ling Xu Yan Hui Wang Department of Life Science Technology Beijing University of Chemical Technology Beijing China Institute of Materia Medica Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China 《中国化学快报》2007,18(6):656-658
2-Substituted-2,3-dihydro-4(1H)-quinazolinones were obtained in high yields by condensation of anthranilamide with aryl, alkyl or heteroaryl aldehydes or ketones in the refluxing 2,2,2-trifluoroethanol without any catalyst. 相似文献
189.
190.
A novel assay of γ-globulin (γ-IgG) with a sensitivity at the nanogram level is proposed based on the measurement of enhanced resonance light-scattering (RLS) signals resulting from the interaction of functionalized nano-HgS with γ-globulin. At pH 5.03, the RLS signals of functionalized nano-HgS were greatly enhanced by γ-globulin in the region of 200-700 nm characterized by the peak around 362 nm. Linear relationship can be established between the enhanced RLS intensity and γ-globulin concentration in the range of 10-140 ng ml−1. The limit of detection is 2.71 ng ml−1. Based on this, a new direct quantitative determination method for γ-globulin in blood serum samples without separation of human serum albumin (HSA) is established. The contents of γ-IgG in blood serum samples were determined with recovery of 95.7-102.5% and R.S.D. of 1.6-2.4%. This method is proved to be very sensitive, rapid, simple and tolerance of most interfering substances. 相似文献