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排序方式: 共有427条查询结果,搜索用时 15 毫秒
101.
Jing Liqiang Sun Zhihua Yuan Fulong Wang Baiqi Xin Baifu Fu Honggang 《中国科学B辑(英文版)》2006,49(4):345-350
The pure, 1 mol% only La or only Cu doped TiO2 and La and Cu codoped TiO2 were prepared by a sol-gel process. The effects of doping on photoinduced charge properties of nanosized TiO2 were mainly investigated by means of Surface Photovoltage Spectrum (SPS) and Photoluminescence Spectrum (PL), together with
their relationships with photocatalytic activity. The results show that La dopant can inhibit the phase transformation of
TiO2, meanwhile improve the separation rate of photoinduced charge carriers, and enrich the binding surface states. However, Cu
dopant has a reverse effect compared to La dopant. This is responsible for the results that doping La is favorable for the
increase in the photocatalytic activity for degrading the RhB solution, while doping Cu is bad to photocatalyitc reaction.
In addition, codoping La and Cu cannot exhibit an obvious combination effect. 相似文献
102.
Synthesis of a carbon analogue of N-acetylmannosamine via acetolysis on a relatively stable ozonide 总被引:1,自引:0,他引:1
After a 2-methylpropenyl group was added to a carbohydrate framework through regioselective opening of a glucose-derived epoxide, hydrolysis or acetolysis of the methyl glycoside in various derivatives was problematic. Ozonolysis of the olefin followed by brief treatment with dimethyl sulfide gave a mixture of diastereomeric ozonides that proved to be stable for weeks at room temperature. Acetolysis of these ozonides at low temperature allowed selective cleavage of the methyl glycoside in the presence of the 1,2,4-trioxolane as well as selective formation of the alpha-acetate. 相似文献
103.
104.
105.
Preparation of large-pore mesoporous nanocrystalline TiO2 thin films with tailored pore diameters 总被引:1,自引:0,他引:1
A novel and facile synthesis route to large-pore mesoporous nanocrystalline anatase thin films with tunable pore diameters in narrow distribution of sizes ranging from 8.3 to 14 nm is reported, using triblock copolymer as the template and Ti(OBu(n))4 as the inorganic precursor. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption. A reasonable formation mechanism is also presented in this work. 相似文献
106.
Haiqing Sun Duorong Yuan Xianqin Hou Xinqiang Wang Liqiang Liu Dajiang Zhang Ye Han 《Crystal Research and Technology》2007,42(1):65-68
A new second order nonlinear optical coordination complex crystal tris allylthiourea zinc bromide was synthesized and grown from ethanol for the first time. Elemental analyses, X‐ray powder diffraction and infrared spectroscopy confirmed the formation of the new material. The thermal characterization was determined by the differential thermal analysis and thermogravimetric analysis. The transmission spectrum of the crystal shows a wide transparent UV‐Vis‐NIR band. The powder SHG efficiency is higher than that of urea crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
107.
Liqiang Cui Hyun Yong Cho Joong-Won Shin Naresh Hiralal Tarte Seong Ihl Woo 《Macromolecular Symposia》2007,260(1):49-57
Polyethylene(PE)/clay nanocomposites have been successfully prepared by in situ polymerization with an intercalation catalyst titanium-montmorillonite (Ti-MMT) and analyzed by X-ray diffraction analysis (XRD), Fourier transform infrared analysis (FT-IR), Transmission electron microscopy (TEM), differentail scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and tensile testing. XRD and TEM indicate that the clay is exfoliated into nanometer size and disorderedly dispersed in the PE matrix, and the PE crystallinity of PE/clay nanocomposite declines to 15∼30%. Compared with pure PE, PE/clay nanocomposites behave higher thermal, physical and mechanical properties; the layer structure of the clay decreases the polymerization activity and produce polymer with a high molecular weight. For PE/clay nanocomposites, the highest tensile strength of 33.4 MPa and Young's modulus of 477.4 MPa has been achieved when clay content is 7.7 wt %. The maximum thermal decomposition temperature is up to 110 °C higher, but the thermal decomposition temperature of the PE/clay nanocomposites decreases with the increases of the clay contents in the PE matrix. 相似文献
108.
109.
Weigang Du Xuemei Liu Liqiang Tan 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):1173-1179
Attapulgite has been applied in the sorption of metal and radionuclide ions since its discovery. Herein, radionuclide Am(III)
sorption onto attapulgite was carried out at 25 °C in 0.01 mol/L NaNO3 solutions. Effects of contact time, Am(III) initial concentration, pH, humic acid and temperature on Am(III) sorption onto
attapulgite were investigated. The sorption of Am(III) increases with increasing contact time and reaches a maximum value
within 24 h at different Am(III) initial concentration. The fast sorption velocity indicates that strong chemical sorption
or strong surface complexation contributes to the sorption of Am(III) onto attapulgite under the experimental conditions.
The experimental data can be described well by the pseudo-second-order rate model. The sorption of Am(III) onto attapulgite
is strongly dependent on pH values and surface complexation is the main sorption mechanism. The presence of HA enhances the
sorption of Am(III) onto attapulgite at pH < 8.5, whereas, at pH > 8.5, little effect of HA on Am(III) sorption is observed.
The Langmuir, Freundlich and D-R models were used to simulate the sorption data at different pH values and the results indicated
that Langmuir model simulates the experimental data better than Freundlich and D-R models. The thermodynamic parameters indicates
that the sorption of Am(III) onto attapulgite is an endothermic and spontaneous process. The results suggest that the attapulgite
is a suitable material as an adsorbent for preconcentration and immobilization of Am(III) from aqueous solutions. 相似文献
110.
Yi Zuo Yongnan Zheng Yongjun Xu Baoqun Cui Liqiang Li Yingjun Ma Fan Ping Daqing Yuan Shuang Gao Shengyun Zhu 《Hyperfine Interactions》2013,222(1-3):87-93
An Isotope Separator On-Line (ISOL), dedicated to on-line perturbed angular correlation (PAC) and positron annihilation spectroscopy (PAS), has been constructed at CIAE based on the HI-13 tandem accelerator, and a 30 keV radioactive beam of 62Zn with intensity of 2 ×107/s produced by it. Using the 62Zn radioactive beam the investigation of the nano-crystalline soft magnetic Fe73.5Cu1Nb3Si13.5B9 materials has been fulfiled for the first time by the on-line time differential PAC technique. Two quadrupole interaction frequencies ω 01 (?=?440 Mrad/s) and ω 02 (?=?90 Mrad/s) were gained, indicating there are two implantation sites of 62Zn. The frequency ω 02 shows a fluctuation of the crystal lattice constants and proves the characteristic distribution model of nano-crystalline grain boundary. The frequency ω 01 demonstrates that the implanted 62Zn occupies the site of the ordered grain core. The fractions of ω 01 and ω 02 are f01?=?38 % and f02?=?62 %, respectively. 相似文献