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991.
ESCA (electron spectroscopy for chemical analysis) studies of β-C2S in the early stages of hydration have yielded valuable information on the chemical changes on the hydrating surface. These changes are less pronounced than, but very similar to, those noted for C3S. The data indicate that, although β-C2S hydrates more slowly than C3S, the same hydration mechanism applies to both. The studies also suggest surface hydroxylation as a first step in the hydration process. 相似文献
992.
993.
994.
995.
Baik Joon Hyun Yim Sung Dae Nam In-Sik Mok Young Sun Lee Jong-Hwan Cho Byong K. Oh Se H. 《Topics in Catalysis》2004,30(1-4):37-41
Topics in Catalysis - Among the catalysts screened, Cu-ion exchanged ZSM5 zeolite exhibited the highest NO removal activity, particularly at low reaction temperatures below 200 °C,... 相似文献
996.
抗T淋巴母细胞单克隆抗体与柔红霉素的结合物,在体外对T淋巴母细胞CEM显示出选择性杀伤作用,而对K562、Raji、SP2/0等非T淋巴细胞则无杀伤效应。由此证实单抗3Al-柔红霉素免疫结合物具有导向杀伤癌细胞的性能,为临床特异性治疗肿瘤带来了新的希望。 相似文献
997.
998.
由二氧化碳出发合成有机碳酸酯 总被引:4,自引:0,他引:4
对以二氧化碳为原料合成有机碳酸酯的环氧路线、酯交换和直接合成方法作了综合评述 ,认为直接合成是最佳的合成路线。碳酸酯的直接合成可在均相及多相催化体系中进行 ,负载金属、金属甲氧基化合物及碱均可作为催化剂。直接法研究的关键在于高性能催化剂的开发、由二氧化碳对金属 -氧键插入反应导致的催化循环的构筑及耦合反应的应用。 相似文献
999.
The influence of Glu44 and Glu56 of cytochrome b5 on the protein structure and interaction with cytochrome c 总被引:1,自引:0,他引:1
Sun Yu-Long; Xie Yi; Wang Yun-Hua; Xiao Gu-Tian; Huang Zhong-Xian 《Protein engineering, design & selection : PEDS》1996,9(7):555-558
The gene encoding trypsin-solubilized bovine liver microsomalcytochrome b5 (82 residues in length) has been mutated, in whichthe codons of Glu44 and Glu56 were changed to those of Ala.The mutated genes were expressed in Escherichia coli successfullyand three mutant proteins (E44A, E56A and E44/56A) were obtained.The UV-visible, CD and 1H NMR spectra of proteins have beenstudied. The results show that the mutagenesis at surface residuesdoes not alter the secondary and tertiary structures of cytochromeb5 significantly. The interactions between recombinant cytochromeb5 and its mutants with cytochrome c were studied by using opticaldifference spectra. The results demonstrated that both Glu44and Glu56 of cytochrome b5 participate in the formation of acomplex between cytochrome b5 and cytochrome c. 相似文献
1000.
A semi-empirical equation of state for the freely jointed square-well chain fluid is developed. This equation of state is
based on Wertheim’s thermodynamic perturbation theory (TPT) and the statistical associating fluid theory (SAFT). The compressibility
factor and radial distribution function of square-well monomer are obtained from Monte Carlo simulations. These results are
correlated using density expansion. In developing the equation of state the exact analytical expressions are adopted for the
second and third virial coefficients for the compressibility factor and the first two terms of the radial distribution function,
while the higher order coefficients are determined from regression using the simulation data. In the limit of infinite temperature,
the present equation of state and the expression for the radial distribution function are represented by the Carnahan-Starling
equation of state. This semi-empirical equation of state gives at least comparable accuracy with other empirical equation
of state for the square-well monomer fluid. With the new SAFT equation of state from the accurate expressions for the monomer
reference and covalent terms, we compare the prediction of the equation of state to the simulation results for the compressibility
factor and radial distribution function of the square-well monomer and chain fluids. The predicted compressibility factors
for square well chains are found to be in a good agreement with simulation data. The high accuracy of the present equation
of state is ascribed to the fact that rigorous simulation results for the reference fluid are used, especially at low temperatures
and low densities.
This paper was presented at the 8th APCChE (Asia Pacific Confederation of Chemical Engineering) Congress held at Seoul between
August 16 and 19, 1999. 相似文献