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71.
Guanshi Qin Tatsuya Yamashita Yusuke Arai Yasutake Ohishi 《Optics Communications》2007,279(2):298-302
We demonstrate a 22 dB all-fiber amplifier at 546 nm using Er3+-doped fluoride fiber by forward upconversion pumping of a 974 nm laser diode. The gain saturation effects and the power conversion efficiency of this amplifier are investigated in detail based on gain characteristics and numerical simulations. 相似文献
72.
航空公司航线决策的一种系统方法 总被引:5,自引:0,他引:5
本通过对航空公司基于现有运力选择航线这一决策问题的诸多影响因素的综合分析,根据经验和灵敏度分析的结果,提炼出适于决策的关键因素作为这个多目标决策问题的目标属性,给出了确定各属性值和其权的相应技术和方法,并运用适宜本问题的决策分析方法,完成决策过程,这是作提出的一种较为系统的航线决策概念和方法,也是一种可程序化的方法,借助于计算机并建立相应的数据库,能快速,方便地完成这一决策分析,对如何选择最佳的航线网络,也可类此采用本方法。 相似文献
73.
A rapid, sensitive and selective method is described for the determination of traces of fluoride in real samples based on the integration of retention and fluorescence detection (λex = 335 nm, λem 405 nm) of a ternary complex [zirconium(IV)-Calcein Blue-fluoride) using a conventional flow cell packed with an anion-exchange resin. A study of a large number of experimental variables (flow-injection configuration, type of support, eluting carrier, sample pH, etc.) allowed the development of an optimized, highly selective determination of fluoride with an analytical concentration range of 1–40 ng ml?1 (r.s.d. 1%) with a sampling frequency of 30 h?1. A critical comparison with a probe sensor using the same chemical system showed the described flow-through sensor to be clearly superior. 相似文献
74.
M. Yamaga T. Inoue S. Yabashi M. Honda J.-P. R. Wells K. Shimamura 《辐射效应与固体损伤》2013,168(6-12):977-982
Electron paramagnetic resonance (EPR) spectra of Ce 3+ in LiLuF 4 (LLF) and LiSr 0.8 Ca 0.2 AlF 6 (LSCAF) observed at low temperatures (<20 v K) show that the Ce 3+ centers have tetragonal and pseudo-trigonal symmetry with ( g , g )=(2.751, 1.467) and (2.14, 0.80), respectively. The EPR lines of Ce 3+ in LSCAF are inhomogeneously broadened by different Ce 3+ configurations which correspond to the random occupation of the second nearest neighbor cation sites by Ca 2+ and Sr 2+ and/or charge compensators. These EPR results indicate that the Ce 3+ centers in LLF and LSCAF are associated with substitution of Ce 3+ for Lu 3+ with eight-fold coordination and Sr 2+ /Ca 2+ with six-fold coordination, respectively. Fourier transform infrared absorption has been used to measure transitions between the 2 F 5/2 ground state and the 2 F 7/2 multiplet of Ce 3+ in LLF at 10 v K. The optical absorption and luminescence of Ce 3+ :LLF and Ce 3+ :LSCAF in the UV range are strongly polarized. The energy levels and polarization dependence of the optical transitions can be accounted for in terms of the crystal field potential experienced by the Ce 3+ ions under the action of the different point group symmetries. 相似文献
75.
This work is a critical review of the chemical-physical properties of the fluoride salts of interest in the Molten Salt Reactor project. In total five salt compositions are discussed. Two of them are choices for coolant applications (based on LiF-BeF2 and NaF-NaBF4 systems) one is considered as a heat transfer salt (LiF-NaF-KF system) whereas the other two are the main candidates for the fuels in non-moderated breeder and thermal breeder reactors, respectively (LiF-ThF4 and LiF-BeF2-ThF4 systems). For all the systems the phase diagrams are presented with the emphasis on the melting behaviour and the vapour pressure. Heat capacity, density, viscosity and thermal conductivity, as well as the solubility for actinides in case of the fuels are presented also. 相似文献
76.
Yan Ling Lia Hao Fang 《中国化学快报》2008,(5)
As an important intermediate to study cyclin-dependent kinase(CDK)inhibitors,2-aryl-8-(piperidin-4-yl)-5,7-dimethoxy-4H- chromen-4-one derivatives were prepared usingβ-diketone route with low yield.In our study,chalcone route has been investigated and the result suggested that the benzaldehydes substituted with electron-donating group give much better yield thanβ-diketone route.This new method will be an efficient way to start further research on new anticancer flavonoids. 相似文献
77.
Periodic current oscillations during anodic dissolution of monocrystalline p-Si(100) in buffered ammonium fluoride solutions (0.1 mol dm−3 fluoride, pH 4.5) were investigated using a flow cell in order to eliminate mass transport limitations. The flow cell was designed to permit simultaneous in-situ ellipsometry, impedance and potential modulated microwave reflectivity measurements. Analysis of the ellipsometric response showed that the current oscillations are accompanied by a synchronous variation of the overall oxide thickness with an amplitude of 4.5±0.1 nm. Analysis of the relationship between the total oxide thickness and the current during the oscillation cycle shows that to a first approximation the rate of chemical dissolution of anodic oxide remains constant. Oscillations of the electrode admittance and potential modulated microwave reflectivity were also measured. The imaginary component of the admittance is related to the oscillation in thickness of a narrow inner region of ‘dry’ oxide and to changes in the accumulation capacitance. The oscillation in the potential modulated microwave reflectivity is interpreted in terms of the changes in the density of holes accumulated at the p-Si SiO2 interface. 相似文献
78.
This study investigated the variations in human plasma fluoride concentrations ([F]) and sought to determine the causes. Five subjects (27-33 years old) received a low-F diet during the 5 days of the study. Plasma samples and urine were collected every 3 h from 8 a.m. to 8 p.m. F, PTH, Ca and P were analyzed with the electrode, by chemiluminescence, AAS and colorimetry, respectively. A trend for the plasma [F] was found. The peak [F], 0.55 ± 0.11 μmol L−1, occurred at 11 a.m. and the lowest [F], 0.50 ± 0.06 μmol L−1 occurred between 5 and 8 p.m. Plasma [F] were positively correlated with urinary F excretion rates and with serum PTH levels, but not with the Ca or P levels. Serum PTH levels were positively correlated with urinary F excretion rates and negatively correlated with plasma Ca. The results suggest that the renal system seems to control the daily fluctuations in plasma [F]. 相似文献
79.
Novel CdClOH sub‐nanocone crystals were successfully synthesized on a large scale by a facile solution‐based method using polymers as crystal growth modifiers. The crystals showed cone‐like morphology. Some factors affecting the morphology and size of the product, such as reaction temperature, concentrations of polyacrylamide (PAM), and pH value of the solution, were systematically studied. Experiments implied that polymer PAM played a key role in the formation of CdClOH sub‐nanocones. A possible formation mechanism of CdClOH sub‐nanocones was suggested based on nucleation‐etching process‐recrystallization in a mild aqueous solution. Furthermore, the as‐prepared CdClOH sub‐nanocones could be further transformed into CdS hollow sub‐nanocones by an anion‐exchange reaction. 相似文献
80.