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21.
S. V. Tsukerman V. D. Orlov Lam Ngoc Thiem V. F. Lavrushin 《Chemistry of Heterocyclic Compounds》1972,5(6):726-729
The dipole moments of 24 selenophene analogs of the chalcones have been measured and have been compared with the data calculated by a vectorial additive scheme and also with their chemical structures. Considerations are expressed on the conformational state of the molecules of the compounds investigated. The existence of a correlation between the dipole moments the intramolecular distances, and the Hammett's -parameters has been shown. The applicability of Higashi's equation to the calculation of for , -unsaturated ketones is pointed out. 相似文献
22.
Le Ngoc Xuyen Hoang Dang Lanh Ho Si Thoang J. V?lter 《Reaction Kinetics and Catalysis Letters》1989,39(2):293-298
Pt–Ni/-Al2O3 catalysts have been prepared and studied in n-hexane dehydrocyclization. The selectivity for benzene and toluene, a chain lengthening product formation was improved by Ni and correlated with its content.
Pt–Ni/-Al2O3 -. Ni . Ni , .相似文献
23.
Nguyen Van Do Tran Duc Thiep Truong Thi An Tran Minh Duc Han Ngoc Cuong 《Journal of Radioanalytical and Nuclear Chemistry》1986,107(1):29-37
Photon activation analysis has been success-fully applied to the fast and non-destructive analysis of tin in cassiterite ores
based on the 159.7 keV gamma line of123mSn produced in the124Sn/γ, n/123mSn reaction. In order to improve the accuracy of analytical results, corrections for self-absorption and pile-up effects were
performed. Under typical conditions /15 μA electron beam current, 15 MeV bremsstrahlung energy, 5 min irradiation time and
10 min measurement/ the sensitivity of the analysis is 10 ppm. The proposed method can be used for routine analysis of tin
in geological samples. 相似文献
24.
Mobilities of H+ and H? in He and in H2, and of H+2 and H+3 in He, are calculated from ion-neutral potentials derived from theory and ion-beam scattering. Agreement with experiment is reasonable except for H? in H2 and H+2 in He, which present unexplained puzzles. 相似文献
25.
Correction for pile-up losses in the amplifier is possible by the dead-time fraction indicator of the ADC in case of long-lived radionuclides. If the dead-time meter has been calibrated, an accuracy of 1.5% is feasible up to a dead-time fraction of 25%. The precision decreases from 1.5% at 10% dead-time fraction to 3% at a deadtime fraction of 30%. 相似文献
26.
Dang Vu Giang 《Analysis Mathematica》1991,17(2):133-140
, . . [1] - . . 相似文献
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A general, practical and efficient one-pot synthesis of cyclic enecarbamates is described. The protocol proceeds via reduction of lactam carbamate with Super-Hydride®, followed by in situ dehydration with trifluoroacetic anhydride (TFAA) and diisopropylethylamine (DIPEA). 相似文献
30.
α-n-amylcinnamaldehyde (jasminaldehyde) was obtained with 82 % yield by solid-liquid phase transfer catalysis without solvent within 3 days at room temperature. By use of domestic microwave irradiation, the same yield was obtained within 1 minute at a power of 600 W. 相似文献