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排序方式: 共有339条查询结果,搜索用时 15 毫秒
1.
D. Sinha G.K. Sarker S. Ghosh A. Kulshreshtha K.K. Dwivedi D. Fink 《Radiation measurements》1998,29(6):599-604
Photon induced modifications in Triafol-TN and Triafol-BN polymers have been studied in the dose range of 101–106 Gy at room temperature using a 60Co source. To monitor the chemical and structural changes induced by gamma rays, UV, IR, and ESR studies were carried out. Thermal studies were also conducted for understanding the effects of gamma irradiations on these polymers. Variation of track etching characteristics and activation energy for bulk etching have been studied at different gamma rays doses. The experimental results are presented and discussed. 相似文献
2.
Thin carbon films were deposited on silicon substrates at room temperature using a 0.355 μm Nd:YAG laser wavelength at low irradiance in the presence of argon gas. Various techniques including scanning electron microscopy, X-ray diffraction and Raman spectroscopy were used to analyze the film quality. The influence of the argon gas pressure on the properties of the films is demonstrated and a correlation with the optical emission data is presented. 相似文献
3.
4.
Parametric excitation of the electron-acoustic wave (EAW) has been analysed using a hydrodynamical model. The plasma has been assumed to consist of multiply charged ions. The ratio (α) of the hotter ion concentration to that of the electrons is a sensitive parameter. The condition for the occurrence of the EAW is well satisfied for the smaller values of α. The growth rate of the instability gets enhanced by increasing α and the charge state of the hotter ions. The values of α can be varied within short range only. 相似文献
5.
V. N. Dwivedi P. L. Mahanta A. Premadas 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(3):575-581
A procedure for the complete chemical analysis of magnesium or sodium diuranate (yellow cake) sample is reported. Uranium is determined gravimetrically after peroxide precipitation. Optimum parameters, such as pH, quantity of hydrogen peroxide, volume of sample, temperature and complexing agent for quantitave precipitation of uranium, and effective separation of other elements were studied. Aluminum, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn were determined by flame atomic absorption spectrometer and B, Mo, SO4, REEs and Y by inductively coupled plasma atomic emission spectrometer in the filtrates of hydroxide and peroxide precipitation separation. The proposed method is accurate and the precision is characterized by an RSD of ~0.2% for U; 2 to 6% for Mg, Na, K, Ca, Fe, SiO2, Al, Cd, Co, Cr, Fe, Mn, Ni, Pb, and Zn and 3 to7% for REEs, Y, Mo and B 相似文献
6.
Amit Sircar Rajesh K. Dwivedi R. K. Thareja 《Applied physics. B, Lasers and optics》1996,63(6):623-627
An experimental investigation of laser-induced breakdown using Nd:YAG laser harmonics for argon, nitrogen and oxygen gases is reported. Pressure dependence as well as wavelength dependence of the breakdown threshold irradianceI
th is investigated. The experimental observations for 1.064 and 0.532 m laser wavelengths are in agreement with theoretical calculations which include the effects of multiphoton ionization and cascade ionization. 相似文献
7.
Summary Xylenol orange reacts very sensitively with gallium(III), indium (III) and thallium(III) to form reddish violet colored chelates having max 560 nm in case of Ga and In and max 590 nm in case of Ti at PH 4.0. The molar ratio for all the chelates is 1 1 (metal reagent). Optimum conditions including the range for adherence to Beer's law, effect of PH on the color intensity, effect of excess reagent, and sensitivity are reported for the photometric determination of these metal ions using Xylenol orange.
Zusammenfassung Xylenolorange reagiert sehr empfindlich mit Gallium(III), Indium(III) und Thallium(III) unter Bildung rötlich-violetter Chelate mit einem Absorptionsmaximum bei 560 nm im Falle von Ga und In bzw. 590 nm für Tl bei pH 4,0. Das Molverhältnis ist in jedem Fall 11. Die besten Arbeitsbedingungen, der Gültigkeitsbereich des Beerschen Gesetzes, der Einfluß des PH auf die Farbintensität und des Reagensüberschusses sowie die Empfindlichkeit werden für die photometrische Bestimmung der genannten Ionen angegeben.相似文献
8.
Clowers BH Dwivedi P Steiner WE Hill HH Bendiak B 《Journal of the American Society for Mass Spectrometry》2005,16(5):660-669
A series of isobaric disaccharide-alditols, four derived from O-linked glycoproteins, and select trisaccharides were rapidly resolved using tandem high resolution atmospheric pressure ion-mobility time-of-flight mass spectrometry. Electrospray ionization was used to create the gas-phase sodium adducts of each carbohydrate. Using this technique it was possible to separate up to three isobaric disaccharide alditols and three trisaccharides in the gas phase. Reduced mobility values and experimentally determined ion-neutral cross sections are reported for each sodium-carbohydrate complex. These studies demonstrated that ion mobility separations at atmospheric pressure can provide a high-resolution dimension for analysis of carbohydrate ions that is complementary to traditional mass spectral (m/z) ion analysis. Combining these independent principles for separation of ions provides a powerful new bioanalytical tool for the identification of isomeric carbohydrates. 相似文献
9.
The Morita-Baylis-Hillman reaction (MBHR) of conjugated nitroalkenes has been successfully carried out for the first time. A variety of aromatic and heteroaromatic nitroalkenes react with formaldehyde at room temperature in the presence of stoichiometric amounts of imidazole and catalytic amounts of anthranilic acid in THF providing moderate to good yields of the multifunctional adducts in most of the cases. 相似文献
10.
ZnO nanoparticles were synthesized by the continuous spray pyrolysis technique (CoSP) and the effect of applied voltage across the spray nozzle and an annular ground electrode during spray has been studied. X-ray diffraction and transmission electron microscopy studies showed that the product has (hexagonal) wurtzite structure with the average particle size decreasing from 18.5?nm to 12.9?nm in the presence of a high DC voltage (1?kV). The higher value of the absorption peak for the nanoparticles synthesized without voltage is supportive of this behavior. The films deposited by spin coating using these nanoparticles can be used for a variety of applications, particularly as photoelectrodes for dye-sensitized solar cells. 相似文献