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981.
Mai Xuang Trung J. Lipták F. Štěrba P. Cejnar J. Štěrbová 《Czechoslovak Journal of Physics》1992,42(5):499-512
Four resonances in the55Mn(p, )56 Fe reaction at the centre-of-mass proton beam energy E
P
CM
=1320, 1504, 1508 and 1649 keV were studied. Angular distributions for some strong -rays following the radiative decay of the resonances were measured and analysed in terms of the channel-spin formalism. Spin-parity assignmentI
r
=3+, 4+ and 3+ was acquired for the 1320, 1504 and 1649 keV resonances, respectively. No definite assignment was established for the 1508 keV resonance and the resonance is assumed to be a very tight multiplet. Analysis of primary transitions to bound states of the Fe final nucleus permited us to assign these states. The 2+, 2+, 2+, 6+ and 4+ assignments were ascribed to the states at excitation energyE
x
=5705, 5303, 4738, 4692 and 4658 keV, respectively, while for the 5132 keV state ambiguous assignment 3+ or 4+ was found. Multipole mixing ratio was established for some primaries. The coupling of angular momenta of proton and target nucleus in the formation of the 3+ resonances was also roughly discussed.Participated partly in the course of his work on diploma thesis.The authors wish to thank the staff of the Van de Graaff accelerator at Charles University in Prague for the efficient operation of the machine. One of us (M. X. T.) acknowledges the staff of the Dept. of Nuclear Physics of Charles University, Prague, for the excellent working conditions. 相似文献
982.
983.
Dr. Yu Kitazawa Mamoru Watanabe Yui Masumoto Mai Otsuka Dr. Kazunori Miyamoto Dr. Atsuya Muranaka Dr. Daisuke Hashizume Dr. Ryo Takita Prof. Dr. Masanobu Uchiyama 《Angewandte Chemie (International ed. in English)》2018,57(6):1501-1504
We designed, synthesized, and characterized two types of dimeric forms of monocarba‐closo‐dodecaborate, namely, a “dumbbell”‐shaped dianion having a C?C bond and a “clackers”‐shaped monoanion having an iodonium linker. The unique architectures of these anionic molecules were established by X‐ray analysis. Spectroscopic analysis, DFT calculations, and reactivity experiments revealed high anionic and chemical stability of both anions, which are crucial properties for weakly coordinating anions. 相似文献
984.
The chemical constituents identified in the essential oils hydrodistilled from the leaves of Amomum gagnepainii T.L.Wu, K.Larsen and Turland and Amomum repoense Pierre ex Gagnep (Zingiberaceae) of Vietnam origin are reported. The chemical analyses were performed by means of gas chromatography–flame ionisation detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC-MS). The main compounds of A. gagnepainii were farnesyl acetate (18.5%), zerumbone (16.4%) and β-caryophyllene (10.5%). On the other hand, Amomum repoense comprised of monoterpenes dominated by β-pinene (33.5%), (E)-β-ocimene (9.6%), γ-terpinene (9.1%) and α-pinene (8.4%). This is the first report on the essential oils of A. gagnepainii and A. repoense grown in Vietnam or elsewhere. 相似文献
985.
986.
Xin Sui Baohui Wang Haiming Wu 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(2):304-309
The crystallization kinetics and morphology of CaCO3 crystals precipitated from the high salinity oilfield water were studied. The crystallization kinetics measurements show that nucleation and nuclei growth obey the first order reaction kinetics. The induction period of precipitation is extended in the high salinity solutions. Morphological studies show that impurity ions remain mostly in the solution phase instead of filling the CaCO3 crystal lattice. The morphology of CaCO3 precipitates can be changed from a smooth surface (calcite) to rough spheres (vaterite), and spindle rod bundles, or spherical, ellipsoid, flowers, plates and other shapes (aragonite). 相似文献
987.
制备了一种粘附在堇青石蜂窝陶瓷载体上的CeO_2-Y_2O_3(CeY)复合氧化物新涂层.以二氧化铈和柠檬酸钇为前驱体,制备过程中无有害物质产生,对环境友好.CeY涂层和Pd/CeY催化剂通过SEM、EDX、XRF和Raman光谱等表征.结果表明,此涂层的粘结强度高,对活性组分的吸附性能好,适合用来负载钯催化剂.Y_2O_3大部分进入了峰窝陶瓷的孔道内,CeO_2和Pd物种则富集在载体的表面.以CO、甲苯和乙酸乙酯的催化燃烧来评价Pd/CeY催化剂的性能,此催化剂具有较好的催化活性和热稳定性.500℃焙烧的催化剂,CO、甲苯和乙酸乙酯的T_(99)(转化率99%以上所需的最低反应温度)分别为150、220和310℃;1050℃焙烧的催化剂,它们的T_(99)分别为180、250和330℃.高温焙烧的催化剂,活性物种PdO的晶粒增大,这可能导致催化剂的活性下降. 相似文献
988.
989.
Shape-selective synthesis and oxygen storage behavior of ceria nanopolyhedra, nanorods, and nanocubes 总被引:8,自引:0,他引:8
Mai HX Sun LD Zhang YW Si R Feng W Zhang HP Liu HC Yan CH 《The journal of physical chemistry. B》2005,109(51):24380-24385
Single-crystalline and uniform nanopolyhedra, nanorods, and nanocubes of cubic CeO2 were selectively prepared by a hydrothermal method at temperatures in the range of 100-180 degrees C under different NaOH concentrations, using Ce(NO3)3 as the cerium source. According to high-resolution transmission electron microscopy, they have different exposed crystal planes: {111} and {100} for polyhedra, {110} and {100} for rods, and {100} for cubes. During the synthesis, the formation of hexagonal Ce(OH)3 intermediate species and their transformation into CeO2 at elevated temperature, together with the base concentration, have been demonstrated as the key factors responsible for the shape evolution. Oxygen storage capacity (OSC) measurements at 400 degrees C revealed that the oxygen storage takes place both at the surface and in the bulk for the as-obtained CeO2 nanorods and nanocubes, but is restricted at the surface for the nanopolyhedra just like the bulk one, because the {100}/{110}-dominated surface structures are more reactive for CO oxidation than the {111}-dominated one. This result suggests that high OSC materials might be designed and obtained by shape-selective synthetic strategy. 相似文献
990.
Haiming Wang 《Tetrahedron》2006,62(17):3985-3988
A temperature-controlled highly selective dimerization of α-methylstyrene to produce 2,4-diphenyl-4-methyl-1-pentene and 1,1,3-trimethyl-3-phenylindan was catalyzed by Brönsted acidic ionic liquid [Hmim]+BF4−. At 60 °C, 2,4-diphenyl-4-methyl-1-pentene was formed in 93% selectivity with >92% conversion under a solvent-free condition while 1,1,3-trimethyl-3-phenylindan could be obtained in 100% selectivity when the reaction temperature was increased to 170 °C. The ionic liquid [Hmim]+BF4− could be reused with almost no loss of activity. 相似文献