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971.
K. Maz.xl;letka R. Tellgren H. Rundlf W. Szczepaniak L. Rycerz 《Solid State Ionics》1996,90(1-4):67-74
The room and high temperature structures of Li2UI6 have been determined using the neutron powder diffraction. It has been shown that at 300 K, the compound crystallizes in trigonal unit cell with a = B = 7.3927(8), c = 13.826(2) Å with space group P-31c. Above the phase transition occuring at 775 K, the structure transforms into monoclinic C2/m space group with unit cell constants: a = 7.733(5), B = 13.234(7), C = 7.645(4) Å, β = 110.59(3) deg. The measurement of electrical conductivity as a function of temperature has been performed. Based on the crystallographic data, a discussion of the shape of observed conductivity curve has been carried out. 相似文献
972.
Microbial degradation of a tetramethylarsonium salt during incubation at 25°C was investigated under both aerobic and anaerobic conditions. Two media (1/5 ZoBell 2216E and inorganic salt medium), added with the sediments or suspended substances as the sources of the microorganisms, were used. Degradation of the tetramethylarsonium salt occurred only in the ZoBell medium: under anaerobic conditions, trimethylarsine oxide and dimethylarsinic acid were derived with the sediments, and dimethylarsinic acid with the suspended substances, the salt degrading more rapidly with the former than with the latter. Small amounts of two metabolites, trimethylarsine oxide and inorganic arsenic(V), was also derived in the aerobically incubated ZoBell medium added with the suspended substances. This result means that the tetramethylarsonium salt is degraded to inorganic arsenic, which is the starting material for arsenic circulation in marine ecosystems, via trimethylarsine oxide and dimethylarsinic acid. 相似文献
973.
Aqueous solutions of methyl iodide (CH3I) react with metal ores and with metals, causing them to dissolve in water. This dissolution has been investigated in both static extraction and flow systems. Aqueous concentrations of metals are enhanced anywhere from 3- to 242-fold. The proposed mechanism involves electrophilic attack on the solid surface, thereby breaking the linkages binding the metal to the solid lattice and causing dissolution. Because biogenic sources constitute a major component of global CH3I flux, prospects for related polyfunctional algal haloorganics as aqueous ore or metal solubilizers are noted. 相似文献
974.
The effect of pressure on the 2H and 4H polytype of PbI2 has been investigated by Raman and optical absorption spectroscopy, using the diamond anvil cell. The 2H-polytype undergoes
pressure-induced phase transitions at 5 kbar and near 30 kbar. The 4H-polytype exhibits phase transitions near 8 kbar and
above 30 kbar. The Raman modes abruptly change at these pressures. The optical absorption edge shifts red at the rate of 15±1
MeV/kbar in the 2H-PbI2 and at the rate of 7 MeV/kbar in phase II. The latter phase is most likely to possess a 3d-structure and not a layer type.
The possible structures for the high pressure phases are discussed. 相似文献
975.
液氯消毒自来水的最大优点是价格低廉 ,消毒效果优良 ,使用比较方便。但液氯消毒自来水会有潜在危险的有机卤代物形成[1,2 ] 。二氧化氯(ClO2 )是一种比液氯更为有效的消杀剂 ,它在消毒过程中几乎不形成氯仿等有机氯 ,生成的总有机氯比液氯也要少得多 ,并能明显降低异味和色度[3 ,4] 。实践证明ClO2 是理想的饮用水消毒剂之一。ClO2 消毒自来水后 ,水中剩余ClO2 以及可能还有的少量氯的其他氧化态物质 ,统称为有效氯 ,其量的多少直接影响自来水的质量 ,研究剩余有效氯量 (以后均以ClO2 计 )的测定方法 ,对自来水的生产和饮水… 相似文献
976.
J. V. Crivello T. Yoo J. A. Dougherty 《Journal of polymer science. Part A, Polymer chemistry》1995,33(14):2493-2504
A series of cationically polymerizable mono-and difunctional alkoxyallene monomers have been prepared via the straight forward base catalyzed isomerization of the corresponding propargyl ethers. Rate studies conducted using real-time infrared spectroscopy showed that these monomers exhibit high reactivity in photoinitiated cationic polymerization. Monomers bearing a single alkoxyallene group undergo rapid polymerization to yield crosslinked polymers indicating that both double bonds react during polymerization. A mechanism has been proposed that explains this observation. © 1995 John Wiley & Sons, Inc. 相似文献
977.
A. N. Kasatkin A. N. Kulak R. Kh. Biktimirov G. A. Tolstikov O. V. Shitikova V. R. Sultanmuratova 《Russian Chemical Bulletin》1992,41(4):740-747
2-Alkenylidenemalonic ester monoepoxides react with organolithium and organomagnesium compounds to give 1-ethoxycarbonyl-4-alkyl-6-alkenyl(alkyl, aryl, alkynyl)-3-oxabicyclo[3.1.0]hexan-2-ones in high yields. The latter, when an alkenyl fragment is present, undergo rearrangement in the presence of LiI to substituted 1-ethoxycarbonyl-3-oxabicyclo[3.3.0]-6-octen-2-ones or 3-(1,3-butadienyl)-4-butanolides.Institute of Chemistry, Bashkir Science Center, Ural Branch, Russian Academy of Sciences, Ufa 450054. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 946–954, April, 1992. 相似文献
978.
停流流动注射分析同时测定碘离子和亚硝酸根的研究 总被引:10,自引:0,他引:10
基于铁(Ⅲ)-硫氰酸根络合物褪色动力学反应,利用流动注射分析停流技术,建立了流动注射动力学分析法同时测定碘离子和亚硝酸根离子的新方法,方法对碘离子的线性范围为2×10^--1.6×10-4mol/L,对亚硝酸根的线性范围为4×10^-7-1×10mol/L。应用于全成混合液中碘离子和亚硝酸根的测定,结果满意。 相似文献
979.
Ahmed Kamal B. Rajendra Prasad A. Venkata Ramana A. Hari Babu K. Srinivasa Reddy 《Tetrahedron letters》2004,45(17):3507-3509
The tetrahydroquinoline moiety is an important structural component of a number of natural products. The reaction of aryl azides with 3,4-dihydro-2H-pyran in the presence of FeCl3-NaI affords the corresponding tetrahydroquinoline derivatives in an efficient manner. Most of the cyclizations exhibited cis selectivity. 相似文献
980.
本文研究了催化剂的种类和用量对硅烯醚型引发剂引发的基团转移聚合的影响。发现四丁基二苯甲酸氢铵(Bu_4NH(C_6H_5CO_2)_2,TBABB)和HsI_2的催化效果较好。只需引发剂的4%的HgI_2即可使MMA的基团转移聚合达到完全转化。认为有效的氧负离子催化剂应由较稳定的铵正离子和电负性较大的氧负离子所组成。过量的催化剂不利于基团转移聚合的进行。考察了TBABB催化剂对温度的依赖性及其浓度对聚合速率,分子量和分子量分布,转化率的影响。 相似文献