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961.
Additive hazards model with random effects is proposed for modelling the correlated failure time data when focus is on comparing the failure times within clusters and on estimating the correlation between failure times from the same cluster, as well as the marginal regression parameters. Our model features that, when marginalized over the random effect variable, it still enjoys the structure of the additive hazards model. We develop the estimating equations for inferring the regression parameters. The proposed estimators are shown to be consistent and asymptotically normal under appropriate regularity conditions. Furthermore, the estimator of the baseline hazards function is proposed and its asymptotic properties are also established. We propose a class of diagnostic methods to assess the overall fitting adequacy of the additive hazards model with random effects. We conduct simulation studies to evaluate the finite sample behaviors of the proposed estimators in various scenarios. Analysis of the Diabetic Retinopathy Study is provided as an illustration for the proposed method. 相似文献
962.
It is a well-known fact that characters of a finite group can give important information about the group's structure. Also it was proved by the third author of this article that a finite simple group can be uniquely determined by its character table. Here the authors attempt to investigate how to characterize a finite almost simple group by using less information of its character table, and successfully characterize the almost simple K3-groups by their orders and at most three irreducible character degrees of their character tables. 相似文献
963.
We study the structure of arbitrary split Leibniz triple systems with a coherent 0-root space. By developing techniques of connections of roots for this kind of triple systems, under certain conditions, in the case of T being of maximal length, the simplicity of the Leibniz triple systems is characterized. 相似文献
964.
An environmentally benign synthesis of isoxazolines and isoxazoles mediated by potassium chloride in water 总被引:1,自引:0,他引:1
An effective and environmentally benign procedure for the synthesis of isoxazolines and isoxazoles has been developed by a cycloaddition of nitrile oxides with alkenes or alkynes in water. In this approach, potassium chloride is first oxidized into chlorine in water by the environmentally friendly oxidant Oxone®, then aldoximes are oxidized into nitrile oxides by the in situ generated hypochlorous acid, finally a 1,3-dipolar cycloaddition between nitrile oxides and alkenes or alkynes occurs to provide the corresponding isoxazolines and isoxazoles in good yields. 相似文献
965.
Aryl nitriles can be efficiently synthesized through transition-metal-mediated cyanation of aryl halides, arenes, aryl boronic acids, and so on. Among those most commonly used transition-metals, copper catalysts are surely much more inexpensive and easier to handle, compared to any other metal catalysts. Considering the high-efficiency of copper catalysts in the activation of C–X, C–H, and C–B bond as well as in the formation of C–CN bond, this Letter summarizes various copper-mediated cyanations based on the different kinds of cyanide reagents, such as metal cyanides, potassium hexacyanoferrate(II), acetone cyanohydrins, DDQ, AIBN, benzyl cyanide, malononitrile, nitromethane, and DMF. Our group’s recent contributions to this area are also demonstrated. 相似文献
966.
The organocatalytic sulfenylation of α-nitroesters mediated by diaryl-l-prolinols was developed. A range of α-sulfenylated α-nitroesters were obtained in good yields with moderate to good enantioselectivities. 相似文献
967.
Qiu‐Yan Chen Xian Cheng Tao Wang Zi‐Hao Yu Chong Zhang Shu‐Kun Lin Hao‐Hong Li Zhi‐Rong Chen 《无机化学与普通化学杂志》2014,640(2):439-443
A new low‐dimensional benzyl viologen/iodoargentate hybrid, [(BV)2(Ag5I9)]n ( 1 ) (BV2+ = benzyl viologen) was prepared. In 1 , (Ag6I9)n2– chain exhibits a new type of one‐dimensional chain constructed from vertex‐sharing of Ag5I10 units, and its two‐dimensional layer structure was constructed from C–H ··· I hydrogen bonds. Strong luminescence at 404 nm can be detected in 1 . DFT calculation suggests that 1 displays a reduced bandgap, which is led by a more dispersed LUMO band of BV2+ compared with MV2+ in [MV(Ag2I4)]n. 相似文献
968.
Two new silver(I) trans‐cinnamates, namely [Ag(2‐cca)(H2O)]2 ( 1 ) and [Ag(4‐cca)]n ( 2 ) (2‐ccaH = 2‐chlorocinnamic acid and 4‐ccaH = 4‐chlorocinnamic acid), were synthesized and structurally characterized. Single crystal X‐ray studies reveal that each silver(I) atom in 1 is two‐coordinate by a 2‐chlorocinnamate ligand and one water molecule to afford a discrete centrosymmetric dimer with the ligand‐unsupported Ag···Ag interactions (3.218(4) Å), while a pair of symmetry‐related silver(I) atoms in 2 are clamped by two μ2‐η1:η1 4‐chlorocinnamate ligands to yield a binuclear silver(I) moiety incorporating a ligand‐supported Ag···Ag interaction (2.819(5) Å). Both complexes 1 and 2 show potent urease inhibitory activities with the respective IC50 values of 0.66 and 1.10 μM. 相似文献
969.
The TbIII compound [Tb(tci)(H2O)]n · n(DMF) ( 1 ) [H3tci = tri(2‐carboxythyl)isocyanurate, DMF = N,N′‐dimethylformamide] was synthesized by the reaction of terbium oxide, H3tci, and two drops of concentrated nitric acid in the presence of DMF and H2O. Single crystal X‐ray analysis reveals that it features a three‐dimensional (3D) framework based on infinite –Tb–COO–Tb– chains. The tci ligand in 1 links six different TbIII ions with its two carboxylate groups in μ2‐κ1O;κ2O,O′ mode and the third in μ2‐κ1O;κ1O′ mode. Thermal analysis reveals that it remains high thermal stability until 390 °C. Luminescence investigation shows that it emits characteristic green light of TbIII ions. 相似文献
970.
Yan‐Xue Chen Kang‐Kang Tang Xin Wang Bing‐Yi Chen Guo‐Qiang Qin Jin‐Hui Yang 《无机化学与普通化学杂志》2014,640(11):2292-2295
The zinc(II) coordination polymer [Zn3(BPT)2(μ2‐H2O)2(H2O)2]n · n(DMA) ( 1 ) (H3BPT = biphenyl‐3,4′,5‐tricarboxylic acid, DMA = N,N′‐dimethylactamide) was obtained by the solvothermal reaction of H3BPT with Zn(NO3)2 in DMA/H2O mixed solvent. Single crystal X‐ray analysis reveals that compound 1 has a complicated 3D framework containing linear trinuclear [Zn3(COO)4(μ2‐H2O)2] clusters as building subunits, which can be simplified into a (3,6)‐connected rtl topological network with the Schläfli symbol {4.62}2{42.610.83}. The calculated results of total and partial density of states (DOS) indicate that the luminescence of 1 mainly originates from intraligand charge transfer. 相似文献