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51.
We report on the fabrication of WO3 nanowires on Si (100) substrate using nickel catalyzed electron beam assisted rapid thermal annealing process. A 7 nm thick W layer deposited on the nickel coated substrate was annealed under high vacuum using electron beam (3 keV) for 30, 60 and 90 s. The nickel activates the growth of tungsten nanowires with a high aspect ratio and subsequently is oxidized due to the high refractory nature of tungsten under exposure to oxygen gas. The resulting changes in surface morphology, oxidization state and elemental composition of WO3 nanowires were investigated systematically. The oxidization of metallic tungsten nanowire was found to depend on the annealing time. 相似文献
52.
Ramaswamy BR Kim JW Isobe T Chang KH Amano A Miller TW Siringan FP Tanabe S 《Journal of hazardous materials》2011,192(3):1739-1745
Ultra high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) determination of four paraben preservatives (methyl, ethyl, propyl and butyl) and two antimicrobial agents (triclosan and triclocarban) belonging to personal care products (PCPs) in 20 species of fish from Manila Bay (Philippines) was performed. Detection of PCPs with greater frequency indicates the ubiquitous contamination of Manila Bay. Concentrations of total paraben were one order of magnitude higher than the antimicrobials in almost all fish, except in Stolephorus indicus and Leiognathus equulus. A positive correlation was observed between parabens concentration and fish length (r = 0.31-0.49; p<0.05 to <0.001) and fish weight (r = 0.28-0.49; p<0.05 to <0.001), but not for the antimicrobials. The estimated dietary exposure values of the four parabens in the Philippines through fish is four orders of magnitude lower than the acceptable daily intake (ADI) of 10mg/kg/day, but the values of antimicrobials are just half of the ADI of TCS. To our knowledge, this is the first report of PCPs contamination in fish from Philippines. 相似文献
53.
Eduardo Patazca Tatiana Koutchma Hosahalli S. Ramaswamy 《Journal of food science》2006,71(3):M110-M116
ABSTRACT: Establishment of a high-pressure sterilization process requires data on pressure and temperature-dependent inactivation kinetics of target pathogenic, spoilage, or surrogate spore-forming bacteria in the food being tested. The objective of this study was to examine the response of Geobacillus stearothermophilus ATCC10149 spores to various temperature, time, and pressure combination treatments (500 to 700 MPa; 92°C to 111°C, 0.01 to 360 s). The pressure inactivation of spores was characterized at elevated temperatures under isobaric and isothermal conditions during the holding time using a laboratory-scale high-pressure unit. The inactivation kinetics was well described by the log-linear regression model. As expected, the rate of spore inactivation increased with increasing pressure and temperature. Decimal reduction times at constant pressure ( D T,P values) varied from 29.4 to 108.8 s at 92°C, 17.4 to 76 s at 100°C, and 6.1 to 51.3 s at 111°C within the pressure range of 500 to 700 MPa. The resistance of spores to temperature and pressure was characterized with zT and zP values and compared with their resistance to conventional steam heating. The conventional thermal resistance of G. stearothermophilus species did not correlate to the thermal resistance at high pressure. The study provides kinetic data on the effects of pressure and temperature on the inactivation of a heat-resistant bacterial spore species under conditions applicable to the commercial processing of low-acid foods. 相似文献
54.
55.
H. S. Ramaswamy 《Drying Technology》1993,11(2):413-414
56.
57.
Quantitative Fourier transform infrared analysis for anisidine value and aldehydes in thermally stressed oils 总被引:5,自引:0,他引:5
J. Dubois F. R. van de Voort J. Sedman A. A. Ismail H. R. Ramaswamy 《Journal of the American Oil Chemists' Society》1996,73(6):787-794
A Fourier transform infrared (FTIR) transmission-based spectroscopic method was investigated for the simultaneous monitoring
of aldehyde formation and the determination of anisidine value (AV) in thermally stressed oils. Synthetic calibration standards
were prepared by adding known amounts of hexanal,t-2-hexenal andt,t-2,4-decadienal to canola oil (these compounds considered representative of aldehydic compounds formed during oxidation) plus
random amounts of other compounds representative of oxidation by-products. The standards were analyzed for their chemical
AV. With the partial least squares (PLS) technique, an FTIR spectrometer was calibrated to predict both the concentrations
of individual aldehyde types and AV, with the individual aldehyde contributions being related to the chemical AV by multiple
linear regression to derive “apparent” AV values. The predictive capability of the PLS calibrations was assessed by analyzing
canola oils that were thermally stressed at 120, 155, and 200°C. The apparent AV, predicted for these samples, matched the
chemical AV values within ±1.65 AV units. A PLS calibration also was derived by using thermally stressed samples as calibration
standards. This approach provided similar predictive accuracy as the use of synthetic calibration standards. As such, quantitative
determination of AV by FTIR spectroscopy was shown to be feasible, and the synthetic calibration approach provided additional
information on the aldehyde types present in a sample and allowed the use of a simple gravimetric approach for calibrating
an FTIR spectrometer. This study provides the basis for the development of a rapid, automated FTIR method for the direct analysis
for AV of thermally stressed fats and oils in their neat form without the use of chemical reagents. The implementation of
such a method as a quality control tool would eliminate the use and disposal of hazardous solvents and reagents, required
by the conventional chemical method, and drastically reduce analysis time (∼2 min/sample). Possible applications include monitoring
of the oxidative state of frying oils or evaluation of oxidative stability of biodegradable lubricants. 相似文献
58.
Some current models for moisture diffusion in paper in the hygroscopic range are analyzed. In general, two types of diffusion models can be recognized. Models of the first type treat paper as a homogeneous medium with moisture flux that is proportional to the gradient in moisture content. Although useful in some instances this approach fails frequently because it homogenizes the internal dynamics and relaxation processes occurring within the paper material. Recent studies have shown that a subtler approach which treats paper as a composite of fibers and void spaces is more successful at describing moisture transport dynamics. A review of these studies along with a generalization of this approach to three dimensions is considered here. The parameters appearing in such models can be identified with the physical processes of diffusion through the void space and through the fiber matrix. Diffusivities in these individual phases are supplemented by a local kinetic coefficient representing moisture flux interchange between the void and fiber phases. When the local moisture exchange coefficient takes on large values, the fibers and the void spaces are at local equilibrium with no net exchange of moisture. Under such conditions, the model reduces to the simpler Fickian diffusion model with nonlinear moisture diffusivity equivalent to earlier models. 相似文献
59.
The authors consider a tapered velocity coupler (TVC) that meets the adiabatic invariance condition with sufficiently strong coupling between the fundamental modes of individual guides in the middle region of the coupler while permitting individual excitation at the input end and sorting of the modes at the output end. This approach helps reduce the device length considerably by permitting much higher taper angle. A TVC consisting of one tapered and another straight, graded index waveguide is modeled using the normal modes of the entire, composite TVC structure. The analytical results are in excellent agreement with experimental results for a TVC fabricated in Ti:LiNbO3. It is shown that the representation of the local normal modes as the superposition of the modes of the uncoupled guides leads to erroneous results 相似文献
60.
S.M. Kostritskii R.F. Tavlykaev R.V. Ramaswamy Yu.N. Korkishko V.A. Fedorov 《Photonics Technology Letters, IEEE》2004,16(10):2260-2262
We have realized broad-band distributed Bragg reflectors with photorefractive gratings recorded at 441.6 nm in channel Ti : Cu : LiNbO/sub 3/ waveguides. Proton-assisted copper exchange is used to enable a high level of copper doping and, thereby, achieve an extremely large modulation of refractive index (/spl ges/ 5/sup */10/sup -4/) within a photorefractive grating. Experimental structures demonstrate reflectivities up to 17% with full-width at half-maximum bandwidths in excess of 1.2 nm at center wavelengths around 1.55 /spl mu/m. 相似文献