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111.
LU Anhuai GAO Xiang QIN Shan & WANG ChangqiuDepartment of Geology Peking University Beijing . China Correspondence should be addressed to Lu Anhuai 《科学通报(英文版)》2003,48(9):920-923
The Xiangtan manganese deposit (XTM) used to be considered a supergene oxide manganese ore in South China. We reported a new identification of the naturally outcropping cryptomelane by examining the physical, chemical and structural features of the XTM supergene oxide manganese ore. The MnO2 content was over 90%, K2O more than 3%, and water from 2.2%-3.1% which is similar to one in zeolite. The cell parameters of the cryptomelane were given as a0 = 0.9974 nm, b0 = 0.2863 nm, c0 = 0.9693 nm and β= 91.47°. There was a larger pseduotetragonal tunnel in the natural cryptomelane that was formed by [MnO6] octahedral double chains with aperture of 0.462×0.466 nm2, filled with K cations resulting in some Mn3+ substituting for Mn4+ to balance the negative charges of structure. The finding is important not only for prospecting manganese resources in South China, but also in application of octahedral molecular sieve of natural cryptomelane as that developed in the tetragonal molecular sieve of natural zeolite o 相似文献
112.
Seven novel solid complexes of the first-row transitional metal with L-α-histidine were synthesized, and their compositions were determined. The constant-volume combustion energies of the complexes were measured by a precision rotation bomb calorimeter. The standard molar enthalpies of combustion and the standard molar enthalpies of formation were calculated. The results indicated that the plots of the standard enthalpies of formation against the atomic number of the metal show a regularity of zigzag. 相似文献
113.
WANG Yi CHU Wuyang SU Yanjing GAO Kewei & QIAO Lijie Department of Materials Physics University of Science & Technology Beijing Beijing China 《科学通报(英文版)》2003,48(12):1203-1206
It is known that some types of ceramics, like Al2O3 and ZrO2, undergo stress corrosion cracking (SCC) or static fatigue fracture under static loading, ever in a rela-tively mild environment, such as moist atmosphere or water at room temperature, which leads to a time-dependent fracture[1—4]. For a transmission electron microscopy specimen of YBa2Cu3O7-x ceramics superconductor, SCC induced by residual stress can occur in an atmosphere with low moisture content[5]. For a lead zirconate ti… 相似文献
114.
Climatic significance of stable carbon isotope in tree rings of Abies spectabibis in southeastern Tibet 总被引:3,自引:0,他引:3
LIU Xiaohong Qin Dahe SHAO Xuemei CHEN Tuo & REN Jiawen . Cold Arid Regions Environment Engineering Research Insti-tute Chinese Academy of Sciences Lanzhou China . Institute of Geographic Sciences Nature Resources Research Chinese Academy of Sciences Beijing China Correspondence should be addressed to Liu Xiaohong 《科学通报(英文版)》2003,48(18):2000-2004
The annually cross-dated stable carbon isotope of tree-ring a-cellulose of Abies spectabibis collected from the southeastern Tibetan Plateau is used to examine its rela-tionship with climatic parameters. The residual D13C series in treerings is constructed after removing the effects of age trend and rising CO2. We found a close relationship between D13C in tree rings and the relative humidity of September—November of the previous year measured at the nearby Ny-ingchi Meteorological Station, albeit a strong 搇agged effect? Thus we developed a transfer function to reconstruct the autumn relative humidity for the Nyingchi region, which explained 37.9% of the total variance (p < 0.001). Our results suggest a high frequency and moderate amplitude variance of the relative humidity before 1800, and the variance re-versed afterwards. 相似文献
115.
本探讨了用磷钼酸作催化剂,以乳酸和正丁醇为原料合成乳酸正丁醋,通过对各种酸醇比,催化剂用量,不同反应时间的正交试验,确定了最佳反应条件。 相似文献
116.
MAYewei ZHOUXiaoshan QIANXinlai ZHAOQingzheng YANGJun GAOXin LIYanchun LIUYuying WANGZheng 《科学通报(英文版)》2003,48(7):687-691
Adenovirus 5 type E1A as a tumor suppressor gene can inhibit tumor growth and enhance the censitivity of chemotherapy and radiotherapy.E1A have the ability to integrate into the host genome,resulting in long-time expres-sion that induces Rb gene inactivation and animal cells im-mortalization.This prompted us to select the E1A protein for treatment of cancer in order to overcome the limitations of E1A gene therapy.Thus,we firstly comstructed E1A eu-caryotic expression vector (pPIC9/E1A),transformated the pichia pastoris yeast cells(GS115) and screened the high-expressing recombinant strains.The positive yeast strains were cultured in the shake flask,and induced for 3d.The crude E1A protein was purified using two steps of col-umu chromatography on HiTrap Q and HiTrap SP.The pu-rified E1A protein was identified by SDS-PAGE and Western blot.E1A protein was mostly located at cellular unclear when Cheriot delivered E1A protein into cells.The analysis in vitro indicated that the E1A protein arrested LN686 cell cycle at G2/M phase,and significantly inhibited the growth of LN686 tumor cells.The current studies firstly provided an experimental basis to further develop E1A protein for tumor treatment. 相似文献
117.
高忠 《太原师范学院学报(自然科学版)》2003,2(4):74-76
房屋增层是近年我国各城市为提高房屋利用所采用的一种行之有效的方法,并且已取得了很好的经济效益,文章中列举了国内的一些房屋增层所出现的事故,并对其作出分析,最后又提出了预防事故发生的措施。 相似文献
118.
研究了具有周期外力的非线性系统的解产生不同的次谐波分枝的参数范围,并且指出了无穷多次谐波分枝是如何与smale马蹄型混沌解共存的. 相似文献
119.
含苯并三氮唑的三脚架化合物及其配合物研究 总被引:5,自引:0,他引:5
合成了两个新的三脚架结构化合物;1,1,1-三(1-苯并三氮唑基甲氧甲)丙烷(A)和三[2,1-苯并三氮唑基甲氧基)乙基]胺(B),获得了它们和一些过渡金属离子形成的配合物,并用元素分析,红外光谱,摩尔电导和热分析等手段对其进行了表征。 相似文献
120.