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991.
A novel and ef?cient synthetic route to α‐aminophosphonates containing benzothiazole moiety via a cascade three‐component reaction from conveniently available starting materials has been developed. The target compounds 3a – 3g , 7 and 8a , 8b were evaluated for their anticancer activities against the cancer cell line HL‐60 in vitro by the MTT method. Compound 3g showed good cancer inhibitory activity against the tested cell line. Further study is necessary to find out the potential antitumor activities.  相似文献   
992.
采用改进的坩埚下降法成功地生长了Tm/Yb共掺氟化钇锂单晶. 该单晶体具有每吸收一个蓝色光子并能发射出2个1000 nm近红外光子的下转换发光效应. 测定了样品的激发光谱、发射光谱和荧光衰减曲线. 在465 nm蓝光激发下观察到由Yb3+2F5/22F7/2能级跃迁所致的960~1050 nm 波段的发射带,此发光带源于Tm3 对Yb3 离子的能量下转换过程. 应用Inokuti-Hirayama模型,研究了晶体的能量转换过程,结果表明Tm3 向Yb3 的能量传递是一个电偶极子相互作用机制过程. 当Tm3 与Yb3 离子的掺杂浓度为0.49mol%与5.99mol%时,单晶的量子剪裁效率达到最大值167.5%.  相似文献   
993.
采用强流金属蒸汽真空弧(MEVVA)离子源注入机,先将Si大束流注入热氧化SiO2/单晶硅,直接形成镶嵌在SiO2中的纳米晶Si,再小束流注入Er。Er离子在掺杂层中的浓度可达10^21cm^-3量级,大大地提高了作为孤立发光中心的Er^3 浓度。在77K和室温下,观察到了Er^3 的1.54цm特征发射。  相似文献   
994.
Teleportation of a three—particle entangled W state   总被引:8,自引:0,他引:8       下载免费PDF全文
We have investigated the problem of teleporting a three-particle entangled W state and we propose a scheme based on entanglement spapping to complete the teleportation.We also put forward a scheme for the teleportation of a general W state by using nonmaximally entangled quantum channels.The probability of success of the latter scheme is obtained.  相似文献   
995.
顾建兵  杨向东  王怀谦  李慧芳 《中国物理 B》2012,21(4):43102-043102
The geometrical structures, relative stabilities, electronic and magnetic properties of small B n Al (2 ≤ n ≤ 9) clusters are systematically investigated by using the first-principles density functional theory. The results show that the Al atom prefers to reside either on the outer-side or above the surface, but not in the centre of the clusters in all of the most stable B n Al (2 ≤ n ≤ 9) isomers and the one excess electron is strong enough to modify the geometries of some specific sizes of the neutral clusters. All the results of the analysis for the fragmentation energies, the second-order difference of energies, and the highest occupied-lowest unoccupied molecular orbital energy gaps show that B 4 Al and B 8 Al clusters each have a higher relative stability. Especially, the B 8 Al cluster has the most enhanced chemical stability. Furthermore, both the local magnetic moments and the total magnetic moments display a pronounced odd-even oscillation with the number of boron atoms, and the magnetic effects arise mainly from the boron atoms except for the B 7 Al and B 9 Al clusters.  相似文献   
996.
讨论了利用三明生铁和马坑生铁制取的马氏体抗磨球墨铸铁的白口倾向、淬裂倾向以及防止淬裂.提高冲击疲劳抗力的措施.  相似文献   
997.
Two decoration techniques, solidification-induced band texture decora tion and focal-conictexture decoration, have been established to exhibit the director field of disclinations in a low-molar-mass methacrylate liquid crystal. The disclinations with strength s = 1/2 and s = ±1 are observed by the two decor ation methods. For the solidification-induced band texture decoration, the molecular orientation is perpendicular to the direction of the band. While for focal- conictexture decoration, it has been proved by the results of IR dichroism that the direction of the director is parallel to the direction of the focal-conic. Therefore, the sketch map of the molecular director filed can be mapped according to the morphological pattern of the solidification-induced band textureor focal-conic texture.  相似文献   
998.
Transition-metal oxides have attracted much attention due to its abundant crystalline phases and intriguing physical properties. However, some of these compounds are difficult to be fabricated directly in film form due to the ease of valence variation of transition-metal elements. In this work, we reveal the reversible structural transition between SrVO\begin{document}$_3$\end{document} and Sr\begin{document}$_2$\end{document}V\begin{document}$_2$\end{document}O\begin{document}$_7$\end{document} films via thermal treatment in oxygen atmosphere or in vacuum. Based on this, Sr\begin{document}$_2$\end{document}V\begin{document}$_2$\end{document}O\begin{document}$_7$\end{document} epitaxial films are successfully synthesized and studied. Property characterizations show that the semitransparent and metallic SrVO\begin{document}$_3$\end{document} could reversibly switch into transparent and insulating Sr\begin{document}$_2$\end{document}V\begin{document}$_2$\end{document}O\begin{document}$_7$\end{document}, implying potential applications in controllable electronic and optical devices.  相似文献   
999.
Mitochondria‐targeting theranostic probes that enable the simultaneously reporting of and triggering of mitochondrial dysfunctions in cancer cells are highly attractive for cancer diagnosis and therapy. Three fluorescent mitochondria‐targeting theranostic probes have been developed by linking a mitochondrial dye, coumarin‐3‐carboximide, with a widely used traditional Chinese medicine, artemisinin, to kill cancer cells. Fluorescence images showed that the designed coumarin–artemisinin conjugates localized mainly in mitochondria, leading to enhanced anticancer activities over artemisinin. High cytotoxicity against cancer cells correlated with the strong ability to accumulate in mitochondria, which could efficiently increase the intracellular reactive oxygen species level and induce cell apoptosis. This study highlights the potential of using mitochondria‐targeting fluorophores to selectively trigger and directly visualize subcellular drug delivery in living cells.  相似文献   
1000.
By changing the ratio of reactants, two mononuclear Dy complexes, [Dy(phen)(acac)(3)] (1) and [Dy(phen)(2)(NO(3))(2)(acac)]·H(2)O (2) have been synthesized and structurally characterized. In 1, a Dy atom bearing square-antiprism coordination geometry exhibits SMM behaviour, while compound 2 with a bicapped-square-antiprism geometry does not show such SMM properties. The different magnetic behaviours seen in 1 and 2 are probably due to a different coordination environment and ligand field around the Dy(III) ions. The results proved the important influence of the structural environment of a SMM on its magnetic behaviour.  相似文献   
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