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991.
For 2-convex n-person cooperative TU games, the nucleolus is determined as some type of constrained equal award rule. Its proof is based on Maschler, Peleg, and Shapley’s geometrical characterization for the intersection of the prekernel with the core. Pairwise bargaining ranges within the core are required to be in equilibrium. This system of non-linear equations is solved and its unique solution agrees with the nucleolus. 相似文献
992.
Facile synthesis of complicated 9,9-diarylfluorenes based on BF3.Et2O-mediated Friedel-Crafts reaction 总被引:1,自引:0,他引:1
[reaction: see text] BF3.OEt2-mediated Friedel-Crafts reaction of 9-phenyl-fluoren-9-ol with electron-rich aromatic substrates to prepare a new family of complicated 9,9-diarylfluorenes is described. The 9,9-diarylfluorenes tethered with various functional substituents, e.g., bulky spiro units, hole-transporting moieties, and fluorescent dyes, will be promising building blocks for the construction of optoelectronic materials. 相似文献
993.
In this article, we investigate Programming Evaluation and Review Technique networks with independently and generally distributed activity durations. For any path in this network, we select all the activities related to this path such that the completion time of the sub-network (only consisting of all the related activities) is equal to the completion time of this path. We use the elapsed time as the supplementary variables and model this sub-network as a Markov skeleton process, the state space is related to the sub-network structure. Then use the backward equation to compute the distribution of the sub-network's completion time, which is an important rule in project management and scheduling. 相似文献
994.
995.
This paper covers the dynamic behaviors for a class of Nicholson’s blowflies models with a nonlinear density-dependent mortality term. By using inequality analyze technique and coincidence degree theory, some sufficient conditions are determined that guarantee the permanence of the model and the existence of positive periodic solutions. Moreover, we give an example to illustrate our main results. 相似文献
996.
Lack of information during the growth of carbon nanotubes has hindered efforts to understand the growth mechanism of these unique nanoscale structures. Here, we report that Multi‐walled carbon nanotubes with bamboo‐shaped structure may be synthesized by solvothermal method at 300°C using benzene as carbon source and Zn as catalyst. We have obtained direct experimental information on the growth under Transmission electron microscopy. It has been shown that all the compartments of bamboo‐like tube successively joined leading to the formation of regularly segmented nanobamboos. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
997.
Wanchao Hou Senlin Li Sainan Li Dongfang Shi Chunming Liu 《Journal of separation science》2019,42(6):1133-1143
Nonsteroidal anti‐inflammatory drugs reportedly reduce the risk of developing cancer. One mechanism by which they reduce carcinogenesis involves the inhibition of the activity of cyclooxygenase‐2, an enzyme that is overexpressed in various cancer tissues. Its overexpression increases cell proliferation and inhibits apoptosis. However, selected cyclooxygenase‐2 inhibitors can also act through cyclooxygenase‐independent mechanisms. In this study, using ultrafiltration, enzyme‐immobilized magnetic beads, high‐performance liquid chromatography, and electrospray‐ionization mass spectrometry, several isoflavonoids in Trifolium pratense L. extracts were screened and identified. Semi‐preparative high‐performance liquid chromatography and high‐speed counter‐current chromatography were then applied to separate the active constituents. Using these methods, seven major compounds were identified in Trifolium pratense L. As cyclooxygenase‐2 inhibitors: rothindin, ononin, daidzein, trifoside, pseudobaptigenin, formononetin, and biochanin A, which were then isolated with >92% purity. This is the first report of the presence of potent cyclooxygenase‐2 inhibitors in Trifolium pratense L. extracts. The results of this study demonstrate that the systematic isolation of bioactive components from Trifolium pratense L., by using ultrafiltration, enzyme‐immobilized magnetic beads, semi‐preparative high‐performance liquid chromatography, and high‐speed counter‐current chromatography, represents a feasible and efficient technique that could be extended for the identification and isolation of other enzyme inhibitors. 相似文献
998.
High-resolution photorefractive gratings in nematic liquid crystals sandwiched with photoconductive polymer film 总被引:1,自引:1,他引:0
F. Yao Y. Pei Yu Zhang J. Zhang C. Hou X. Sun 《Applied physics. B, Lasers and optics》2008,92(4):573-576
Photorefractive gratings with high grating resolution were observed in the 20 μm thick low-molar-mass nematic liquid crystal
(NLC) cell with a separate photoconductive (PC) poly(N-vinylcarbazole) layer. An orientational grating with a grating spacing of 1.9 μm was produced. It is believed that a space–charge
field with small fringe spacing forms in the PC layer and its evanescent component penetrates into the NLC layer. The penetrated
evanescent field drives the NLC to reorient, and consequently the orientational grating forms. The model indicates that the
modulated field exists in several hundred nanometers near the surface, and thus the orientational grating is not full of the
NLC film, which is consistent with the observed phenomena of the multiple diffractions. Besides, asymmetric two-beam coupling
of 11.2% was achieved for the grating with a grating spacing of 1.9 μm, and a net gain coefficient of larger than 62 cm−1 was obtained. 相似文献
999.
P. Hou Y. Chen J. Shi Q. Kong L. Ge Q. Wang 《Applied Physics A: Materials Science & Processing》2008,91(1):41-46
Using the transfer matrix method, we investigate the transmission property of a one-dimensional photonic crystal doped with
a linear subwavelength layer and a Kerr-type nonlinear layer. We find that a thin film of subwavelength layer can significantly
modify the characteristic of optical bistability. We also find that the sequence of the thin film and the nonlinear layer
has a major impact on the hysteretic behavior. With the investigations to the linear defect mode and the electric field distribution
in the nonlinear material, we explain these phenomena.
PACS 42.65.Pc; 42.25.Bs; 42.70.Qs; 42.65.-k; 78.66.-w 相似文献
1000.
Sheet resistance of laser-irradiated Ge2Sb2Te5 thin films prepared by magnetron sputtering was measured by the four-point probe method. With increasing laser power the sheet resistance undergoes an abrupt drop from 107 to 103 Ω/□ at about 580 mW. The abrupt drop in resistance is due to the structural change from amorphous to crystalline state as revealed by X-ray diffraction (XRD) study of the samples around the abrupt change point. Crystallized dots were also formed in the amorphous Ge2Sb2Te5 films by focused short pulse laser-irradiated, the resistivities at the crystallized dots and the non-crystallized area are 3.375 × 10?3 and 2.725 Ω m, sheet resistance is 3.37 × 104 and 2.725 × 107 Ω/□ respectively, deduced from the I–V curves that is obtained by conductive atomic force microscope (C-AFM). 相似文献