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41.
A detailed investigation on luminescence properties of gem-grade zirconia (NFC) as a function of Ti doping is presented. The
effect of various parameters such as Ti concentration, environment of heat treatment and temperature was studied in detail
and the optimum conditions for producing zirconia with luminescence properties comparable to standard material determined. 相似文献
42.
S. B. Rane V. Deshapande T. Seth G. J. Phatak D. P. Amalnerkar B. K. Das 《Powder Metallurgy and Metal Ceramics》2004,43(9):437-442
Submicron silver powder was prepared from AgNO3 by a chemical reduction method in the presence of a mixture of caprylic acid and triethanolamine as a surfactant. Hydrazine hydrate (N2H4·H2O) is preferred as a reducing agent. A spherical silver powder with an average particle size of about 150 nm was achieved. Effort was also made to correlate the crystal structure and microstructure evolution of the prepared powders with the resultant thick film characteristics. 相似文献
43.
Foster JL Carter JN Sollenberger LE Blount AR Myer RO Maddox MK Phatak SC Adesogan AT 《Journal of dairy science》2011,94(4):2042-2050
This study determined the nutritive value, ensiling characteristics, and in situ disappearance kinetics of bahiagrass (Paspalum notatum Flügge ‘Tifton 9’), perennial peanut (Arachis glabrata Benth. ‘Florigraze’), annual peanut [Arachis hypogaea (L.) ‘FL MDR 98’], cowpea [Vigna unguiculata (L.) Walp. ‘Iron clay’], and pigeonpea [Cajanus cajan (L.) Millsp. ‘GA-2’]. All forages were harvested at maturity stages that optimized dry matter (DM) yield and nutritive value. After harvest, forages were wilted to 45% DM, and 4 replicate bales of each legume and 8 bales of bahiagrass were wrapped in polyethylene and ensiled for 180 d. After each bale was opened, the forage was thoroughly mixed, and representative subsamples were taken for laboratory analysis and in situ incubation. Wilting and ensiling decreased the rumen-undegradable protein, water-soluble carbohydrate, crude protein (CP), and in vitro true digestibility (IVTD) of bahiagrass, perennial peanut, and cowpea, and increased their neutral detergent fiber (NDF) concentrations. Among haylages, CP concentration was greatest for annual peanut, followed by perennial peanut and cowpea, and least for bahiagrass. In contrast, NDF concentration was greater in bahiagrass than in legumes. Pigeonpea had the greatest NDF concentration among legumes and lowest IVTD of all haylages. All haylages were aerobically stable for at least 84 h, but pH was lower in perennial peanut and cowpea than in pigeonpea. Ammonia-N concentrations tended to be greater in legume haylages than in bahiagrass haylage. Butyrate concentration was greater in annual and perennial peanut than in bahiagrass. Total VFA concentration was greater in annual and perennial peanut and cowpea haylages than in bahiagrass haylage. Undegradable DM fractions were greater and extent of DM degradation was lower in bahiagrass and pigeonpea than in other haylages but lag time and degradation rates did not differ. Annual and perennial peanut and cowpea haylages were as aerobically stable and had greater CP, IVTD, and extent of degradation than did bahiagrass haylage; therefore, they are promising forages for dairy cow diets in the southeastern United States. 相似文献
44.
V. Phatak A. Gupta V.R. Reddy S. Chakravarty H. Schmidt R. Rüffer 《Acta Materialia》2010,58(3):979-988
The effect of nitrogen incorporation on the kinetics of L10 transformation in FePt alloy films was studied. Films with a maximum possible amount of nitrogen were prepared by sputtering a FePt compound target with pure nitrogen. As-prepared films consisting of nano-grains of Pt and Fe0.7N0.3 transformed to face-centered cubic FePt phase with a certain amount of nitrogen incorporated in the grains after annealing at 573 K. It was found that the presence of N results in faster kinetics of L10 transformation compared with pure FePt alloy films, as well as a substantial reduction in grain size. Detailed structural and diffusion measurements were carried out to elucidate the mechanism of enhanced transformation kinetics as well as grain size reduction. The activation energy for volume diffusion of Fe in FePtN films was found to be 0.27 ± 0.14 eV, while that in FePt was 0.50 ± 0.17 eV. Faster atomic diffusion in nitrogen-containing films was the cause of an enhanced rate of L10 transformation. Further studies reveal that, in partially transformed FePtN alloy films, N is incorporated mainly in the grain boundary region, which hinders grain growth and results in a smaller grain size. 相似文献
45.
46.
S L Chaplot B A Dasannacharya R Mukhopadhyay K R Rao P R Vijayaraghavan R M Iyer G M Phatak J V Yakhmi 《Bulletin of Materials Science》1991,14(3):603-605
Coherent inelastic neutron scattering measurements have been carried out on the high temperature superconductors Tl2CaBa2Cu2O8 (Tl-2122,T
c
=107 K) and YBa2Cu3O7 (Y-123,T
c
=92 K), at the Dhruva reactor at Trombay. The density of phonon states in Tl-2122 is enhanced at 6–17 meV and reduced at 40–70meV
compared to that in Y-123. 相似文献
47.
SC Phatak 《Canadian Metallurgical Quarterly》1985,31(5):1832-1840
48.
S. B. Rane T. Seth G. J. Phatak D. P. Amalnerkar M. Ghatpande 《Journal of Materials Science: Materials in Electronics》2004,15(2):103-106
The technology for realizing conductive thick films from metal powders is of considerable importance in the manufacture of various electronic devices, such as hybrid integrated circuits, multilayer ceramic capacitors, three-dimensional circuits for mobile communication, etc. Silver thick films have been extensively used to provide electrical contacts in silicon solar cells, hybrid circuits, and other devices, as they have the lowest resistivity as well as the lowest cost among the noble metals. Metal powders for thick-film pastes are normally obtained through chemical precipitation from an aqueous or organic solution of their corresponding salts. This method is able to provide the desired particle shape and size and also offers a low preparation cost. In this paper, we have reported the effect of inorganic binders on the properties of silver thick films. The thick-film pastes were formulated from specially treated silver powders and using the three different types of inorganic binders such as glass frit, metal oxides, and a mixture of both. The effect of these inorganic binders on the surface structure, adhesion with alumina, solderability, and electrical properties was determined by analyzing the physical and chemical behavior of the inorganic binders in the silver thick films during firing. The films with an addition of glass frit and mixtures of glass frit and metal oxide did not provide good adhesion and solderability simultaneously. However, the silver thick films containing 10 wt % bismuth oxides exhibited excellent characteristics, i.e. high adhesion strength, good solderability, and low sheet resistivity. As expected, the adhesion strength decreased with decrease in the binder content. 相似文献
49.
A.A. Phatak N. Koryabkina S. Rai J.L. Ratts W. Ruettinger R.J. Farrauto G.E. Blau W.N. Delgass F.H. Ribeiro 《Catalysis Today》2007,123(1-4):224-234
We report the kinetic parameters for the water–gas shift (WGS) reaction on Pt catalysts supported on ceria and alumina under fuel reformer conditions for fuel cell applications (6.8% CO, 8.5% CO2, 22% H2O, 37.3% H2, and 25.4% Ar) at a total pressure of 1 atm and in the temperature range of 180–345 °C. When ceria was used as a support, the turnover rate (TOR) for WGS was 30 times that on alumina supported Pt catalysts. The overall WGS reaction rate (r) on Pt/alumina catalysts as a function of the forward rate (rf) was found to be: r = rf(1 − β), where rf = kf[CO]0.1[H2O]1.0[CO2]−0.1[H2]−0.5, kf is the forward rate constant, β = ([CO2][H2])/(Keq[CO][H2O]) is the approach to equilibrium, and Keq is the equilibrium constant for the WGS reaction. The negative apparent reaction orders indicate inhibition of the forward rate by CO2 and H2. The surface is saturated with CO on Pt under reaction conditions as confirmed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The small positive apparent reaction order for CO, in concert with the negative order for H2 and the high CO coverage is explained by a decrease in the heat of adsorption as the CO coverage increases. Kinetic models based on redox-type mechanisms can explain the observed reaction kinetics and can qualitatively predict the changes in CO coverage observed in the DRIFTS study. 相似文献
50.
Rohan Phatak Nimai Pathak Shafeeq Muhammed Amitabh Das Sanjay K. Sali 《Journal of the American Ceramic Society》2020,103(4):2617-2629
Niobates of the formula Ba2LaNbO6 and BaLaM2+NbO6 (M2+ = Mg, Ca) were synthesized by the conventional solid state route. Size dependence of M-cation on the bulk crystal structure of BaLaM2+NbO6 was studied and compared with the Ba2LaNbO6 compound. X-ray diffraction study confirmed that BaLaMgNbO6 compound has the rhombohedral () crystal structure as compared to the monoclinic (I2/m) in BaLaCaNbO6 and Ba2LaNbO6. The change in the local structure of La cation among these compounds was investigated by carrying out Photoluminescence study on 2 atom% Eu3+-doped samples. PL study of BaLaMgNbO6:Eu3+ sample indicates Eu3+ ions occupying the distorted 12-coordinated A-site, while in Ba2LaNbO6: Eu3+, Eu3+ is present at highly symmetric octahedral B-site. Upon excitation, the light emission of these compounds changes from reddish-orange to red to purple in the order Ba2LaNbO6:Eu → BaLaCaNbO6:Eu → BaLaMgNbO6:Eu3+, due to change in Eu3+-ions site occupancy. Lifetime study also confirmed the presence of two different Eu3+ components at two different lattice sites and their respective emission spectra were isolated by time resoled emission spectroscopy. Furthermore, this site selective lattice occupancy of Eu3+ ions also gave various new insights about its radiative and nonradiative properties at different lattice sites. This works presents a complete structural understanding of BaLaMNbO6-based matrices and their versatile phosphor characteristics when doped with Eu3+ ion. 相似文献