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991.
A new approach to the evaluation of two-electron repulsion integrals over contracted Gaussian basis functions is developed. The new scheme encompasses 20 distinct, but interrelated, paths from simple shell-quartet parameters to the target integrals, and, for any given integral class, the path requiring the fewest floating-point operations (FLOPS ) is that used. Both theoretical (FLOP counting) and practical (CPU timing) measures indicate that the method represents a substantial improvement over the HGP algorithm. 相似文献
992.
H. Kawaguchi S. Kataiwa T. Mita Y. Ohtsuka T. Takeuchi S. Kobayashi 《Colloid and polymer science》1990,268(12):1167-1173
Dichlorophene was used as a model drug. Drug-carrying latex particles were prepared by soap-free emulsion copolymerization of dichlorophene acrylate with some hydrophilic methacrylate comonomers. The comonomers used affected not only the structure and colloidal stability of particles, but also the drug-activity of particles. Preliminary study of the drug activity revealed that highly hydrophilic latex particles were very stable and too inactive to be engulfed by amoebae and kill them. On the contrary, less hydrophilic particles carrying a large amount of drug can be an effective device to release drugs at a moderate rate to fight against extracelluar targets such as parasites. 相似文献
993.
T. Kimura H. Gotoh Y. Kobayashi J. Akatsu 《Journal of Radioanalytical and Nuclear Chemistry》1988,125(1):29-40
A non-destructive method for determining the amount of actinoids has been developed. The method is based on thermal neutron coincidence counting and employs a selective detection of neutrons resulting from the spontaneous fission of actinoids. The detection system is described in detail and the measurement results of244Cm as an example are presented. The results show that the measured fission rate of244Cm is consistent with the fission rate calculated from ENDF/B-V data and that the amount of244Cm can be determined within about 5% accuracy even in the presence of a large amount of actinoids, for example, up to 2.6·106, 3.6·104, or 1.6·103 times in the mass ratio of239Pu,241Am, or240Pu to244Cm, respectively. 相似文献
994.
995.
P. Etienne J. Denape J. Y. Paris J. Phalippou R. Sempere 《Journal of Sol-Gel Science and Technology》1996,6(3):287-297
Transparent plastics are not scratch resistant. The damage leads to a loss of optical properties. Coatings prepared using either tetraethoxysilane or colloidal silica particles embedded in glymo is a way to avoid these disadvantages. Tribological experiments are carried out to better understand the surface modification due to a sliding friction. It is shown that the wear track is not directly related to usual mechanical properties such as Young's modulus and the hardness of the coating. The different stages leading to material loss are discussed in term of particle removal and debris circulation (accumulation or elimination) through the friction track. The mechanical properties of the film combined with the film to substrate adhesion are expected to play an important role as it can be deduced from results obtained as a function of the coating composition. 相似文献
996.
Wei L Yang B Yang R Huang C Wang J Shan X Sheng L Zhang Y Qi F Lam CS Li WK 《The journal of physical chemistry. A》2005,109(19):4231-4241
The photoionization and dissociative photoionization of acetone have been studied at the photon energy range of 8-20 eV. Photoionization efficiency spectra for ions CH3COCH3+, CH3+, C2H3+, C3H3+, C3H5+, CH(2-)CO+, CH3CO+, C3H4O+, and CH3COCH2+ have been measured. In addition, the energetics of the dissociative photoionization has been examined by ab initio Gaussian-3 (G3) calculations. The computational results are useful in establishing the dissociation channels near the ionization thresholds. With the help of G3 results, the dissociation channels for the formation of the fragment ions CH3CO+, CH2CO+, CH3+, C3H3+, and CH3COCH2+ have been established. The G3 results are in fair to excellent agreement with the experimental data. 相似文献
997.
Microemulsion electrokinetic chromatography (MEEKC) was evaluated as a screening tool for the indirect measurement of octanol–water partition coefficients (log Po/w) of pesticide compounds. Over 80 pesticide compounds representing a variety of structural characteristics were studied, and good correlation of log Po/w with the logarithm of the retention factor was found. The microemulsion system studied allowed the separation of compounds in the log Po/w range of −1 to 7. In addition, a smaller set of simple organic molecules that vary in structural features was evaluated and compared to the pesticide log Po/w calibration. The pesticide and simple organic molecule log Po/w calibration lines were statistically similar. This suggests that a universal set of standard compounds may be employed for the log Po/w calibration to provide measurements for a variety of compounds with good accuracy. 相似文献
998.
Katritzky AR Zhang S Hussein AH Fang Y Steel PJ 《The Journal of organic chemistry》2001,66(16):5606-5612
Carboxylic acids are converted into the corresponding homologated acids or esters, using easily available 1-(trimethylsilylmethyl)benzotriazole (1) as a one-carbon synthon. The effectiveness of the reaction has been investigated on six aryl and seven alkyl carboxylic acids. 相似文献
999.
1000.
Tanaka M Nakamura M Ikeda T Ikeda K Ando H Shibutani Y Yajima S Kimura K 《The Journal of organic chemistry》2001,66(21):7008-7012
Synthetic procedures for monoazathiacrown ethers were explored, and monoazatrithia-12-crown-4, monoazatetrathia-15-crown-5, and monoazapentathia-18-crown-6 were obtained in moderate yields by the reaction of bis(2-chloroethyl)amine with the appropriate dithiols in the presence of lithium hydroxide in THF. To evaluate metal-ion binding properties of the monoazathiacrown ethers by solvent extraction, lipophilic dodecyl and dodecanoyl groups were incorporated onto the monoazathiacrown ethers. The solvent extraction experiments suggested that monoazathiacrown ethers have Ag(+) and Hg(2+) selectivities and that the relative selectivity between Ag(+) and Hg(2+) depends on their nitrogen atom properties and numbers of sulfur atoms reflecting the respective affinities of nitrogen and sulfur atoms to Hg(2+) and Ag(+). An interesting ability to bind Mg(2+) was observed in the case of N-dodecyl monoazatrithia-12-crown-4. 相似文献