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排序方式: 共有190条查询结果,搜索用时 15 毫秒
1.
2.
In a reaction system consisting of FeCl2,tetrathiometallate and cycloalkylthiolate,two Fe4S4 cubane-like cluster compounds were obtained with the following crystallographic data:(PhCH2NMe32[Fe4S4 (SC5H9)4](Ⅰ),monoclinic space group P21/c,a=1.6327(4),6=1.1229(3),c=2.802 5( 10) nm,β=94.63(2)°,Z=4,and R=0.074; (Et4N)2[Fe4S4(SC6H11)4](Ⅱ),tetragonal space group I42m,a=1.16705(9),b=1.167 06(2),c=2.063 26(5) nm,Z=2,Dabs=1.28 g/cm3,and R=0.078 The participation of cy-cloalkylthiolate ligand does not obviously arouse the change of the Fe4S4 core structure.Meanwhile,the influence of the cation on the structural symmetry of the Fe4S4 cluster dianion is also discussed. 相似文献
3.
Qiutian Liu Chunxi Zhang Changneng Chen Hongping Zhu Yuheng Deng Jinhua Cai 《中国科学B辑(英文版)》1997,40(6):616-623
In a reaction system consisting of FeCl2, tetrathiometallate and cycloalkylthiolate, two Fe4S4 cubanelike cluster compounds were obtained with the following crystallographic data: (PhCH2NMe3)2 [ Fe4S4 (SC5H9)4] (I), monoclinic space groupP21/c,a = 1.632 7(4),b=1.122 9(3),c = 2. 802 5(10) nm, β= 94.63(2)°, Z=4, andR= 0.074; (Et4N)2[F4S4(SC6HlI)4] (II), tetragod space group
,a = l.167 05(9),b = 1.167 06(2),c = 2.063 26(5) nm,Z = 2, Dobs = 1. 28 g/cm3, andR = 0. 078. The participation of cycloalkylthiolate ligand does not obviously arouse the change of the Fe4S4 core structure. Meanwhile, the influence of the cation on the structural symmetry of the Fe4S4 cluster dianion is also discussed.
Project supported by the National Natural Science Foundation of China and the Climbing Program Foundation of China. 相似文献
4.
Xifeng Hou Yanhui Zheng Xiaolong Ma Yuheng Liu Zichuan Ma 《Molecules (Basel, Switzerland)》2021,26(4)
To expand the applications of graphene-based materials to biogas purification, a series of reduced graphene oxide aerogels (rGOAs) were prepared from industrial grade graphene oxide using a simple hydrothermal method. The influences of the hydrothermal preparation temperature on the textural properties, hydrophobicity and physisorption behavior of the rGOAs were investigated using a range of physical and spectroscopic techniques. The results showed that the rGOAs had a macro-porous three-dimensional network structure. Raising the hydrothermal treatment temperature reduced the number of oxygen-containing groups, whereas the specific surface area (SBET), micropore volume (Vmicro) and water contact angle values of the rGOAs all increased. The dynamic adsorption properties of the rGOAs towards hexamethyldisiloxane (L2) increased with increasing hydrothermal treatment temperature and the breakthrough adsorption capacity showed a significant linear association with SBET, Vmicro and contact angle. There was a significant negative association between the breakthrough time and inlet concentration of L2, and the relationship could be reliably predicted with a simple empirical formula. L2 adsorption also increased with decreasing bed temperature. Saturated rGOAs were readily regenerated by a brief heat-treatment at 100 °C. This study has demonstrated the potential of novel rGOA for applications using adsorbents to remove siloxanes from biogas. 相似文献
5.
Kinetic Resolution of Racemic Mandelic Acid Esters by N,N′‐Dioxide–Scandium‐Complex‐Catalyzed Enantiomer‐Selective Acylation
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Yuheng Zhang Prof. Dr. Xiaohua Liu Lin Zhou Wangbin Wu Tianyu Huang Yuting Liao Lili Lin Prof. Dr. Xiaoming Feng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(48):15884-15890
A simple and efficient acylative kinetic resolution of racemic mandelic acid esters was accomplished with a chiral N,N’‐dioxide–scandium(III) complex under mild and base‐free reaction conditions. A variety of mandelic acid esters performed well in the reaction, obtaining both acylated products (up to 49% yield, 97% ee) and recovered substrates (up to 49% yield, 95% ee) in high enantioselectivities with perfect selectivity factors (up to 247). The enantioselective recognition and catalytic models were also proposed for the catalytic KR reaction. 相似文献
6.
7.
Joshua Lee Yuheng Bu Prasanna Sattigeri Rameswar Panda Gregory W. Wornell Leonid Karlinsky Rogerio Schmidt Feris 《Entropy (Basel, Switzerland)》2022,24(4)
As machine learning algorithms grow in popularity and diversify to many industries, ethical and legal concerns regarding their fairness have become increasingly relevant. We explore the problem of algorithmic fairness, taking an information–theoretic view. The maximal correlation framework is introduced for expressing fairness constraints and is shown to be capable of being used to derive regularizers that enforce independence and separation-based fairness criteria, which admit optimization algorithms for both discrete and continuous variables that are more computationally efficient than existing algorithms. We show that these algorithms provide smooth performance–fairness tradeoff curves and perform competitively with state-of-the-art methods on both discrete datasets (COMPAS, Adult) and continuous datasets (Communities and Crimes). 相似文献
8.
Lei Zhang Wei Tong Jiyu Fan Changjin Zhang Renwen Li Yuheng Zhang 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,83(3):325-328
Ferrimagnetic spinel selenide CuCr2Se4 has been investigated by the
electron spin resonance (ESR) spectroscopy. Experimental results reveal that ESR signals
originate from the localized d-shell electrons of Cr3+ ions.
In addition, the ESR linewidth ΔH
PP
increases
linearly with decreasing temperature. It is suggested that the spin-orbit coupling may be
one of the contributions to the broadening of
ΔH
PP
. Our ESR results support the model of
the ferrimagnetic hybridization between localized 3d
3
electrons of Cr3+ with delocalized holes of Se 4p band. 相似文献
9.
Junfeng Wang Di Yin Zhengyou Liu Decheng Tian Yuheng Zhang 《Solid State Communications》2004,132(10):653-656
The thermoelectric power (TEP) of the quasi-one-dimensional charge-density-wave (CDW) conductors rubidium blue bronze Rb0.3MoO3 and its alloy Rb0.15K0.15MoO3 were measured in the temperature range 80-280 K. The result showed a sign change from a small positive value to a great negative value where the Peierls transition temperatures (Tp) are 183 and 180 K for Rb0.3MoO3 and Rb0.15K0.15MoO3, respectively. Above Tp, the TEP for both samples can be described with the empirical relation S=AT+B; while below Tp, the TEP fits well the relation S=AT+B/T based on the experimental data. The Fermi energies εF for Rb0.3MoO3 and Rb0.15K0.15MoO3 are estimated to be 1.55 and 0.53 eV, respectively. 相似文献
10.
The enhancement of phase-conjugnte wave in cerium-doped bismuth germanatecrystal(Ce:BGO) was investigated.The result indicated that the phase congugate mirror(PCM) reflectivity of the doped BGO is one order higher than that of pure BGO and the re-sponse time is also decreased for doped BGO.Their mechanism were discussed. 相似文献