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991.
992.
Peng Jiang Sishen Xie Jiannian Yao Shengtai He Haoxu Zhang Dongxia Shi Shijin Pang Hongjun Gao 《科学通报(英文版)》2001,46(12):996-998
A two-dimensional (2D) ordered hexagonal close-packed structure, formed by 1-nonanethiol-capped gold nanoparticles, is reported. The structure was constructed only by dipping the gold nanoparticle colloidal solution on flat substrate. The gold nanoparticles were synthesized as follows: First, AuCl4-1 was transferred from aqueous solution to toluene by the phase-transfer reagent of tetraoctylammonium bromide. Then it was reduced with aqueous sodium borohydride in the presence of a given amount of 1-nonanethiol molecules which was used to control the nucleation and growth of the gold nanoparticles for the desired size. The experimental techniques, such as UV-Vis, FT-IR, and X-ray photoelectron spectroscopy (XPS), were employed to characterize the obtained product. Transmission electron microscopy (TEM) measurement demonstrated the size of the gold nanoparticle and the formation of two-dimensional ordered hexagonal close-packed gold nanoparticle structure. 相似文献
993.
Diagenetic-metallogenic ages of pyritic cherts and their implications in Mojiang nickel-gold deposit in Yunnan Province, China 总被引:3,自引:0,他引:3
Diagenetic-metallogenic ages of pyritic cherts formed by the syn-sedimentation of hydrothermal vent and ages of the Jinchang
Rock Formation in the Mojiang large nickel-gold deposit in the Ailaoshan gold metallogenic belt have been discussed on the
basis of chronology of isotopic geochemistry. Nickel-gold-bearing pyritic cherts in the mining were formed by syn-sedimentation
of hydrothermal vent in the Late Devonian, i.e. age by Sm-Nd isochronal method (t) = (358±8.6) (2σ) Ma and age by Rb-Sr isochronal method (t) = (354.7±0.72) (2σ) Ma. On the other hand, deep-water cherts from the Jinchang Rock Formation of the Upper Devonian in the
area were initiated at the same time; that is, age by Sm-Nd isochronal method (t) = (359±21) (2σ) Ma and age by Rb-Sr isochronal method (t) = (358.02±0.30) (2σ) Ma. 相似文献
994.
Li Yuhua Chen Hui Guo Kunyuan Xie Yongmei Wang Feng Xie Kuangcheng Huang Jiangsheng Ren Daming 《科学通报(英文版)》2001,46(13):1107-1111
A live attenuated AraA- autotrophic mutant ofSalmonella typhimurium (SL3261) was used as carrier for eukaryotic expression vectors EGFPN1, pCMVmIL-12, pCMVhIL-12, pCMVmGM-CSF and pCMVhGM-CSF
and was administered orally to BALB/c and C57BL/6 mice. After 6 weeks, these mice were challenged with 4T1 and Lewis tumor
cells respectively. GFP expression and gene integration could be detected in mice’s livers, spleens, intestines, kidneys and
tumors. The serum level of cytokines increased significantly in treated mice, so did the ratio of CD
8
+
/CD
4
+
, which resulted in the tumor regression and prolongation of the survival time of those mice. These researches laid an experimental
foundation for the tumor gene therapy using live attenuated salmonella. 相似文献
995.
Lianzhi Li Aixin Song Yi Xie Zhongxian Huang Ellen de Waal Kolczak Urszula Gerard W. Canters 《科学通报(英文版)》2001,46(19):1608-1611
The key subunit Ⅱ of cytochrome c oxidase (CcO) contains a soluble binuclear copper center (CuA) domain. The CuA domain of Paracoccus versutus was cloned, expressed, purified and characterized. The gene encoding the CuA domain in pET11d vector was expressed in E. coli BL21 (DE3). The results showed that the CuA domain was expressed mostly in inclusion bodies and the CuA domain protein synthesized in E. coli cells represents approximately 10 percent of the total cellular proteins. Dissolved in urea, dialyzed and recombined with Cu+/Cu2+ and purified by the Q-sepharose fast flow anion-exchange column and Sephadex G-75 gel filtration column, the soluble purple-colored protein, which shows a single band in electrophoresis, was obtained. The UV-visible absorption spectrum of CuA domain showed that there are intense band at 478 nm and a shoulder peak at 530 nm, and two weak bands at 360 and 806 nm respectively, which can be assigned to the charge transfer and the interactions of obitals of Cu—S and Cu——Cu in the mixed-valence binuclear metal center (Cu2S2R2). The far-UV CD spectrum indicated that this domain is predominantly in β-sheet structure. The fluorescence spectra showed that its maximal excitation wavelength and maximal emission wavelength are at 280 and 345 nm, respectively. 相似文献
996.
The occurrence of the dominant C23 n-alkane derived from bryophyte was demonstrated to be related to the cold climate, based on the GC and GC/MS analyses on a 40-cm long peat core, in which this compound exponentially varies in abundance with the depth corresponding to the well-known second Little Ice Age. Both the variation of the chemical components of modern bryophyte resulted from climatic change and the ecological data about the biological growth influenced by climate shed light on the point that the variation of this compound in the peat was related to the cold climate. This was also evidenced by the previously-reported lacustrine data. In addition, the variations of the ratios of ketones/esters and C24 n-alkene/n-alkane (C24︰1/C24︰0) display the trend identical with that of organisms, implicating the replacement between bryophyte and monocotyledon occurring in the peat core. 相似文献
997.
Elastic wave velocity in rocks from Dabieshan and its constraints for lithospheric composition and crust-mantle recycling 总被引:1,自引:0,他引:1
ZHAO Zhidan ZHAO Zhidan Nicolas I.CHRISTENSEN ZHOU Wenge XIE Hongsen ZHANG Zeming 《自然科学进展(英文版)》2001,11(2):115-122
P-and S-wave velocities in eclogites and granulites from the Dabie ultrahigh pressures (UHP) meta morphic belt, China, were measured at room temperature under the hydrostatic pressures up to 1.0 GPa. The ultrahigh pressure eclogites had the highest densities (3.3 ~ 3.6 g.cm-3) , high velocities and the lowest anisotropy (1.4%c ~ 2.6 % ) . The lowest densities (2.8 ~ 3.1 g. cm-3 ) and the highest Poisson' s ratios (0.28 ~ 0.29) were found in gran ulites, whereas the strongest anisotropies (6. 1 % ~8.4% ) were found in the high-pressure (HP) eclogites. Compari son of the velocities in rocks with that observed in the deep seismic sounding profile crossing Dabieshan suggests that e clogites might exist in the lower crust of Dabieshan, but the quantity might be small. The upper mantle has very similar velocities as the UHP eclogites and serpentinizated/water-bearing dunite. The formation of eclogite represents the crust mantle recycling processes. Crustal material is delaminated and sinks into the mantle by way of eclogite, whereas only a small part of the eclogite could return to the crust. 相似文献
998.
999.
1000.
谢秉川 《山东师范大学学报(自然科学版)》2001,16(2):142-145
研究了由超导体及正常导体构成的无规网络,在d维修下的临越行为,采用(i)有效介质伫似(EMA),(ii )多重分形近似两种方法,来确定渗流系统的临界指数M(β)和N(β)。 相似文献