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排序方式: 共有310条查询结果,搜索用时 62 毫秒
81.
Muhammad K. Majeed Guangyao Ma Yanxiu Cao Hongzhi Mao Dr. Xiaojian Ma Dr. Wenzhe Ma 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(51):11991-11997
Silicon (Si)-based anode materials with suitable engineered nanostructures generally have improved lithium storage capabilities, which provide great promise for the electrochemical performance in lithium-ion batteries (LIBs). Herein, a metal–organic framework (MOF)-derived unique core–shell Si/SiOx@NC structure has been synthesized by a facile magnesio-thermic reduction, in which the Si and SiOx matrix were encapsulated by nitrogen (N)-doped carbon. Importantly, the well-designed nanostructure has enough space to accommodate the volume change during the lithiation/delithiation process. The conductive porous N-doped carbon was optimized through direct carbonization and reduction of SiO2 into Si/SiOx simultaneously. Benefiting from the core–shell structure, the synthesized product exhibited enhanced electrochemical performance as an anode material in LIBs. Particularly, the Si/SiOx@NC-650 anode showed the best reversible capacities up to 724 and 702 mAh g−1 even after 100 cycles. The excellent cycling stability of Si/SiOx@NC-650 may be attributed to the core–shell structure as well as the synergistic effect between the Si/SiOx and MOF-derived N-doped carbon. 相似文献
82.
Inside Cover: A Pyrimidopyrimidine Janus‐AT Nucleoside with Improved Base‐Pairing Properties to both A and T within a DNA Duplex: The Stabilizing Effect of a Second Endocyclic Ring Nitrogen (Chem. Eur. J. 6/2014)
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Zhu Diao M. Abid P. Upadhyaya M. Venkatesan J.M.D. Coey 《Journal of magnetism and magnetic materials》2010,322(9-12):1304-1306
The magnetization curves of arrays of near-spherical soft ferromagnetic particles are compared with those of quasi-two-dimensional dots with similar radius prepared by a rapid e-beam lithographic technique. Curves for the three-dimensional particles are anhysteretic and fit a M(H)/Ms=tanh(cμ0H) law, whereas the two-dimensional arrays show irreversible segments in the first and third quadrants where the planar vortex state transforms to a collinear state by discontinuous rotation of magnetization about an axis perpendicular to the vortex axis. The additional symmetry of the spherical particle allows this rotation to occur continuously, without energy barriers due to the demagnetizing field. 相似文献
85.
Obaid-ur-Rahman Abid Muhammad Farooq Ibad Asad Ali Nasim Hasan Rama Peter Langer 《Tetrahedron letters》2010,51(12):1541-721
The palladium(0)-catalyzed Suzuki cross-coupling reaction of the bis(triflates) of phenyl 1,4-dihydroxy-2-naphthoate afforded various 1,4-diaryl-2-naphthoates. The reactions proceeded with very good site-selectivity. Due to electronic reasons, the first attack occurred at the sterically more hindered position C-1. 相似文献
86.
Ahmad VU Zubair M Abbasi MA Kousar F Rashid MA Rasool N Tareen RB 《Natural product research》2006,20(1):69-74
Phytochemical investigation of Platytaenia multicaule resulted in the isolation of two new ceramides, N-triacontylpentadecanamide and 1,3,4-trihydroxy-2,dodecanoylamino-(24E)-unacotenene, along with two known compounds, beta-sitosterol and beta-sitosterol glycoside. The structure elucidation of the isolated compounds was based primarily on 1D and 2D NMR analyses, including COSY, NOESY, HMQC, and HMBC correlations. 相似文献
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Ahmed M Seayad AM Jackstell R Beller M 《Journal of the American Chemical Society》2003,125(34):10311-10318
A highly chemo- and regioselective hydroaminomethylation of simple as well as functionalized alpha-olefins using a cationic rhodium precatalyst together with Xantphos as ligand is reported. Studies of the influence of ligands and reaction conditions led to an unprecedented selective hydroaminomethylation procedure. The novel procedure constitutes an economically attractive and environmentally favorable synthesis of secondary and tertiary aliphatic amines. 相似文献
89.
Sattar R. Majeed Mina A. Amin Fawzy A. Attaby Marta E. Alberto Ahmed A. Soliman 《Molecules (Basel, Switzerland)》2022,27(3)
Three new palladium complexes ([Pd(DABA)Cl2], [Pd(CPDA)Cl2], and [Pd(HZPY)Cl2]) bearing dinitrogen ligands (DABA: 3,4-diaminobenzoic acid; CPDA: 4-chloro–o-phenylenediamine; HZPY: 2-hydraziniopyridine) were synthesized, characterized, and tested against breast cancer (MCF-7), prostate carcinoma cell line (PC3) and liver carcinoma cell line (HEPG2). [Pd(DABA)Cl2] complex exhibited the highest inhibition percentage, lying between 68–71%. The hydrolysis mechanism of each palladium complex, the key step preceding the binding to the biological target, as well as their photophysical properties were explored by means of DFT and TDDFT computations. Results indicate a faster hydrolysis process for the Pd(DABA)Cl2 complex. The computed activation energies for the first and second hydrolysis processes suggest that all the compounds could reach DNA in their monohydrated form. 相似文献
90.