排序方式: 共有33条查询结果,搜索用时 31 毫秒
1.
2.
3.
The relative efficiencies for two dissociative channels in the vacuum UV photolysis of carbonyl sulphide have been determined using the flash photolysis-resonance fluorescence technique to measure initial yields of atomic oxygen and atomic sulphur. At wavelengths above 105 nm, the dissociation of OCS to form atomic sulphur exceeded that for the formation of atomic oxygen to such an extent that only an upper limit could be placed on the minor process, ΦS >/ 50 ΦO. In addition, the flash photo-excitation of carbonyl sulphide produced a long-lived spontaneous emission in the UV and vacuum UV that might be due to molecular fluorescence from OCS. 相似文献
4.
5.
Pseudo‐Isomerism by Different Jahn‐Teller Ordering: Crystal Structures of the Hemihydrate and the Monohydrate of (pyH)[MnF(H2PO4)(HPO4)] With pyridinium counter cations (pyH+) the MnIII fluoride phosphate anion [MnF(H2PO4)(HPO4)]— can be stabilized. It forms a chain structure with Mn3+ ions bridged by a fluoride ion and two bidentate phosphate groups. Under sleightly differing conditions either the hemihydrate (pyH)[MnF(H2PO4)(HPO4)]·0.5H2O ( 1 ) or the monohydrate (pyH)[MnF(H2PO4)(HPO4)]·H2O ( 2 ) is formed. The hemihydrate 1 crystallizes monoclinic in space group P21/n, Z = 8, a = 7.295(1), b = 17.052(2), c = 18.512(3) Å, β = 100.78(1)°, R = 0.033, the monohydrate triclinic in space group P1¯, Z = 2, a = 7.374(1), b = 8.628(1), c = 10.329(1) Å, α = 83.658(8)°, β = 77.833(9)°, γ = 68.544(8)°, R = 0.025. Whereas the topology of the chain anions is identical in both structures, the Jahn‐Teller effect is expressed in different ordering patterns: in 1 antiferrodistortive ordering of [MnF2O4] octahedra is observed, with alternating elongation of an F—Mn—F‐axis or a O—Mn—O‐axis, respectively. This leads to asymmetrical Mn—F—Mn‐bridges. In 2 ferrodistortive ordering is found, with elongation of all octahedra along the F—Mn—F‐axis. Thus, symmetrical bridges are formed with long Mn—F distances. This unusual pseudo‐isomerism is attributed to the differing influence of inter‐chain hydrogen bonds. 相似文献
6.
Josef-Christian Buhl Claudia Taake F. Stief M. Fechtelkord 《Reaction Kinetics and Catalysis Letters》2000,69(1):15-21
Investigations on the formation of nitrate enclathrated cancrinite were performed under low temperature hydrothermal conditions (353 K, autogeneous pressure). The alkaline transformation of kaolinite in the presence of sodium nitrate was selected as the preferred method of synthesis. All experiments were carried out at high alkalinity, using a 16 molar NaOH solution as well as at low NaOH concentrations (2 molar NaOH). Qualitative phase analysis was performed by X-ray-powder diffraction and IR-spectroscopy. Besides cancrinite formation no further intermediate phases were formed. Quantitative data of the educt conversion into cancrinite was determined by 27Al MAS NMR spectroscopy and integration of the resonance signals of four- and six-coordinated aluminium. Whereas full conversion could be found already after 24 h of reaction under highly alkaline conditions, only an insufficient progress of the reaction resulted in the case of low alkalinity. 相似文献
7.
8.
Jahn‐Teller Ordering in pipzH2[Mn2F8], a Fluoromanganate(III) with a New Layer Structure From a solution of (pipzH2)[MnF2(HPO4)(H2O)]·(H2PO4) in concentrated hydrofluoric acid the title compound could be crystallized and was characterized by X‐ray crystallography: monoclinic, space group P21/n, Z = 8, a = 13.275(1), 10.400(1), c = 14.928(1) Å, β = 112.337(8), R = 0.0265. The structure shows a new type of anionic layers [Mn2F8] built of dimers of edge‐sharing [MnF6] octahedra linked via common vertices, alternating with layers of piperazinium(2+) cations. A dense network of hydrogen bonds N–H···F achieves a strong 3D interconnection. Strong elongation of the [MnF6] octahedra is observed due to the Jahn‐Teller effect.The long axes show parallel (ferrodistortive) orientation within the dimers, but the ordering between the dimers is antiferrodistorive. A possible mechanism of formation is discussed on the basis of precursor structures. 相似文献
9.
M. S. Jovanović J. Brborić S. Vladimirov B. Zmbova LJ. Vuksanović D. Živanov-Stakić V. Obradović 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(1):321-324
A new diiodine substituted IDA derivative, 2,4-diiodine-6-methyl IDA (DIIODIDA) was synthesized and labeled with99mTc. It was established that99mTc-DIIODIDA had high radiochemical purity. Biodistribution and influence of bilirubin on99mTc-DIIODIDA biokinetics has been studied in rats and compared to the corresponding results for99mTc-SOLCOIODIDA. Related to99mTc-SOLCOIODIDA,99mTc-DIIODIDA has much better biliary exretion (55.18 versus 43.63%). No change of99mTc-DIIODIDA biokinetics, under influence of bilirubin was noticed. Biliary excretion of99mTc-SOLCOIODIDA has been reduced for about 60%. The protein binding of99mTc-DIIODIDA and99mTc-SOLCOIODIDA were also determined, using in vitro method of precipitation. These results showed that99mTc-DIIODIDA hepatobiliary imaging agent is superior to the presently used99mTc-monoiodine IDA derivatives. 相似文献
10.
本文获得了有各种相互作用的一般n阶特征量泛函,其耦合系数反映了不同特征量泛函之间的耦合强度.依据定量因果原理,导出了一般n阶特征量泛函的变分原理,获得了一般n阶特征量泛函的Euler-Lagrange方程,它的不同系数可拟合不同的物理现实,如从线性到任意n阶非线性物理系统,使复杂难解的任意n阶非线性物理系统变得具体可解.并获得了该对称变换下不变的m个的守恒量,以及它们之间的关系和统一描述.依据定量因果原理导出了相对性原理,证明了绝对加速参考系、牵连参考系和相对参考系的力都有来自加速度和质量变化的贡献.利用定量因果原理自然导出了广义牛顿第一定律和广义牛顿第二定律,而且还导出了一个新定律,即广义牛顿第三定律,亦即平移不变性系统合力为零定理.进而将研究结论应用于对银河系的修正引力势、分子势、夸克禁闭势等,且其结果与物理实验一致. 相似文献