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排序方式: 共有211条查询结果,搜索用时 31 毫秒
201.
Pan D Wan J Xu G Lv L Wu Y Min H Liu J Wang G 《Journal of the American Chemical Society》2006,128(39):12608-12609
We present a novel route for manipulation of the ferromagnetic order in Co-doped TiO2 using UV laser irradiation. The ferromagnetic order of the nanocrystal films decays with aging in air at room temperature, which can be reactivated and enhanced by UV irradiation, whereas the coercive force reduces with irradiation time. Photoinduced trapped electrons were suggested to induce the ferromagnetic order. We believe that light manipulation is a general method for tuning the magnetic properties of oxide-based diluted magnetic semiconductors, which can find practical applications in future integrated magneto-optical nanoelectronics. 相似文献
202.
Jiujiang Zhao Chunying Chen Peiqun Zhang Zhifang Chai Liya Qu Mei Li 《Journal of Radioanalytical and Nuclear Chemistry》2004,259(3):459-463
Selenium and mercury distribution in porcine tissues and their subcellular fractions from a mercury-polluted area of Guizhou
Province and from a not mercury-exposed area of Beijing in China have been studied with neutron activation analysis and hydride
generation-atomic fluorescence spectrometry. Both the selenium and mercury levels are higher in Guizhou porcine tissues and
their subcellular fractions than those in Beijing. These two elements are highly enriched in kidney and liver of Guizhou pig,
while selenium is only enriched in the kidney of Beijing pig. Exposure of mercury may result in redistribution of Se and Hg
in vivo. The Hg/Se molar ratio of the subcellular fractions is very low in the case of relatively low mercury level and gradually
reaches to a high constant value with increasing level of mercury, which implies that selenium and mercury may form some special
complexes in the organisms.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
203.
Silver nanoparticle synthesized from chemical reduction has been successfully utilized as a matrix in matrix-assisted laser
desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) of peptides. Acting as a substrate to adsorb analytes,
as well as a transmission medium for UV laser, silver nanoparticle was found to assist in the desorption/ionization of peptides
with little or no induced fragmentation. The size of the nanoparticle was typically in the range of 160 ± 20 nm. One of the
key advantages of silver nanoparticle for peptides analysis is its simple step for on-probe sample preparation. In addition,
it also minimizes the interferences of sodium dodecyl sulfate (SDS) surfactant background signal, resulting in cleaner mass
spectra and more sensitive signal, when compared to α–cyano-4-hydroxycinnamic acid (CCA) matrix. 相似文献
204.
Arun K. Kota Gaurav Anand Suresh Ramakrishnan Liya L. Regel William R. Wilcox 《Journal of Crystal Growth》2006,290(2):319-333
Sessile drop experiments were performed on molten indium antimonide on clean quartz (fused silica) surfaces. A cell was constructed through which argon, helium, oxygen, hydrogen or a mixture of these was flowed at 600 °C. Some of the InSb was doped with 0.1% Ga. The surface tension σ of oxide-free molten InSb was smaller in Ar than in He, may have increased with increasing O2 in the gas, and was not influenced by Ga or H2. The contact angle θ on silica was higher in the presence of Ar, was lowered by O2, and was not influenced by H2 or Ga. The work of adhesion W and the surface energy σsv of the silica were higher in He than in Ar. The surface remained free of solid oxide only in flowing gas containing 0.8 ppm O2. This behavior is attributed to reaction of O2 at the surface of the melt to form In2O gas. When solid oxide formed on Ga-doped material, it was strongly enriched in Ga, with the Ga/In ratio increasing with the concentration of O2 in the gas.
Examination of published sessile-drop results for liquid metals and semiconductors on silica revealed that W and σsv were highest for reactive melts, in which SiO2 dissolves. For non-reactive melts, W and σsv were lower and θ higher in a gas than in a vacuum, regardless of whether the experiments had been carried out in sealed ampoules, a flowing gas, or dynamic vacuum. The implication is that the surface of silica was different in a vacuum than in a gas at 1 bar. 相似文献
205.
Two metal–organic frameworks of 4,6-bis(imidazol-1-yl)isophthalic acid (H2biip), of general formula, {[M2(biip)2(H2O)]·EtOH2}n (M?=?Co (1), Mn (2)), have been synthesized under solvothermal conditions. Complexes 1 and 2 are isomorphic and exhibit three-dimensional metal–organic frameworks with a 2-nodal (4,8)-connected topological network, Point Symbol {416.612}{44.62}2. The magnetic properties of the complexes were examined, indicating antiferromagnetic interactions between the metal centers in the temperature range from 2 to 300 K. 相似文献
206.
Yang Aina Wang Tong Li Zhihui Xu Yuanyuan Gao Liya Zhang Dongsheng Wang Shufang Zhao Xinqiang Wang Yanji 《Research on Chemical Intermediates》2018,44(1):339-354
Research on Chemical Intermediates - In this study,we investigated a one-step process for synthesis of cyclohexylamine from benzene, hydroxylamine and hydrogen under mild conditions. A... 相似文献
207.
Wang Y Mo Y Zhou L 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1311-1315
A novel method has been developed for the synthesis of thioglycolic acid (TGA)-capped CdSe quantum dots (QDs) in an aqueous medium when selenium dioxide worked as a selenium source and sodium borohydride acted as a reductant. The interaction between CdSe QDs and pepsin was investigated by fluorescence spectroscopy. It was proved that the fluorescence quenching of pepsin by CdSe QDs was mainly a result of the formation of CdSe-pepsin complex. Based on the fluorescence quenching results, the Stern-Volmer quenching constant (Ksv), binding constant (KA) and binding sites (n) were calculated. According to the Foster's non-radiative energy transfer theory, the binding distance (r) between pepsin and CdSe QDs was obtained. The influence of CdSe QDs on the conformation of pepsin has been analyzed by synchronous fluorescence spectra, which provided that the secondary structure of pepsin has been changed by the interaction of CdSe QDs with pepsin. 相似文献
208.
209.
Junli Huang Liya Zhou Yuwei Lan Fuzhong Gong Qunliang Li Jianhua Sun 《Central European Journal of Physics》2011,9(4):975-979
Eu3+-doped CaZrO3 phosphor with perovskite-type structure was synthesized by the high temperature solid-state method. The samples were characterized
by X-ray diffraction, scanning electron microscopy, fluorescence spectrophotometer and UV-vis spectrophotometer, respectively.
XRD analysis showed that the formation of CaZrO3 was at the calcinations temperature of 1400°C. The average diameter of CaZrO3 with 4 mol% doped-Eu3+ was 2μm. The PL spectra demonstrated that CaZrO3:Eu3+ phosphor could be excited effectively in the near ultraviolet light region (397 nm) and emitted strong red-emission lines
at 616 nm corresponding to the forced electric dipole 5
D
0 → 7
F
2 transitions of Eu3+. Meanwhile, the light-emitting diode was fabricated with the Ca0.96ZrO3:Eu0.043+ phosphor, which can efficiently absorb ∼ 400 nm irradiation and emit red light. Therefore Ca0.96ZrO3:Eu0.043+ may have applications for a near ultraviolet InGaN chip-based white light-emitting diode. 相似文献
210.
NaEu0.96Sm0.04(MoO4)2 was prepared by the Pechini method (P phosphor) and as a comparison, also by solid-state reaction technique (S phosphor). The photo-luminescent properties, the morphology and the grain size were investigated. The phosphors show broadened excitation band around 400 nm, high intensity of Eu3+5D0→7F2 emission upon excitation around 400 nm, and appropriate CIE chromaticity coordinates. Intensive red light-emitting diodes (LEDs) were fabricated by combining the phosphor and a 400 nm InGaN chip for the first time, which confirm that the phosphor is a good candidate for near UV LED. The luminescent intensity of P phosphor prepared at 700 °C is near that of S phosphor prepared at 800 °C. In addition, P phosphor shows advantages of lower calcining temperature, shorter heating time, and smaller grain size. Considering all these factors, the suitable method for preparing the promising near UV LED phosphor NaEu0.96Sm0.04(MoO4)2 is recommended to be the Pechini process at 700 °C. 相似文献