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Velocity profiles for the inner and outer flow regions of annuli are proposed for the turbulent flow of drag reducing fluids. Theoretical expressions for friction factors are developed. From the shear stress equations and the velocity profiles, estimates for the entrance lengths are given. 相似文献
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Spectral Measurement of the Film-Substrate Index Difference in Proton-Exchanged LiNbO(3) Waveguides 总被引:1,自引:0,他引:1
El Hadi K Rastogi V Shenoy MR Thyagarajan K De Micheli M Ostrowsky DB 《Applied optics》1998,37(27):6463-6467
We report the spectral characterization of proton-exchanged lithium niobate (PE:LiNbO(3)) waveguides in terms of the variation of the refractive-index difference between the waveguiding layer and the substrate. The dispersion of the extraordinary refractive-index increase (deltan(e)) is measured from 405 to 1319 nm with several light sources. Two types of proton-exchanged waveguide, prepared under different conditions, are studied. These measurements should be of use in the optimization of PE:LiNbO(3) waveguides for nonlinear optical applications, particularly in second-harmonic generation in the blue-green wavelength region. 相似文献
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The mathematical formulation for targeting during energy allocation with carbon capture and storage (CCS) is formally developed. For operating-cost optimization with zero excess, it is shown that CCS sources may be regarded as resources with their cost taken as the increment over the non-CCS option. CCS sources along with clean-carbon resources may then be targeted by profile matching with the limiting composite to establish optimal primary cases. The limiting composite curve is itself sacrosanct and obtained by a single computation of the composite table algorithm (CTA) including only non-CCS sources. Carbon emission networks (CENs) are designed by the nearest neighbors algorithm (NNA). A cost criterion is established to determine cost-factor ranges for optimality of the primary cases, and results validated by solving linear programming (LP) and mixed integer linear programming (MILP) formulations. The methodology essentially comprises four distinct stages – targeting, network design, cost analysis, and optimization – with the first two stages not requiring any cost data. 相似文献
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Molecular modeling was carried out using DFT to identify the suitable displacing agent for carrying out Gd isotope separation using displacement chromatography. EDTA was identified as the best eluting agent among EDTA, malic acid and citric acid. Displacement chromatography of Gd adsorption band in cation exchange resin was performed to observe the isotope effects in the Gd ion exchange processes involving complex forming reagent – EDTA. The heavier isotope of 160Gd was found to be enriched at the front boundary of Gd adsorption band, while the lighter isotopes of 155Gd and 157Gd were enriched at the rear boundary. 相似文献
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Viscoelastic properties of borax loaded CMC‐g‐cl‐poly(AAm) hydrogel composites and their boron nutrient release behavior 下载免费PDF全文
Borax (Na2B4O7, 10.5% Boron) loaded CMC‐g‐cl‐poly(AAm) hydrogel composites were prepared by in situ grafting of acrylamide on to sodium carboxymethyl cellulose in the presence of borax by free radical polymerization technique to develop slow boron (B) delivery device. The composition, morphology, and mechanical properties of synthesized composites were studied by X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, texture analyser, and dynamic shear rheometer. Characterization revealed formation of borate ion ( ) from borax during polymerization reaction leading to extensive crosslinking of cellulosic chains and generation of mechanically strong composite hydrogels. Dynamic release of from the synthesized composites hydrogels followed Fickian diffusion mechanism and composites with high mechanical strength resulted in slow release of B. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43969. 相似文献
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Separation of nickel from copper in ammoniacal/ammonium carbonate solution using ACORGA M5640 by selective stripping was carried out. The influence of equilibration time, equilibrium pH and extractant concentration on the extraction of both the metals was studied. It was found that the copper extraction equilibrium was reached in a shorter time than the nickel extraction equilibrium. Nickel extraction decreases above an equilibrium pH of 9.0, while the extraction of copper remains unaffected by the changes in the equilibrium pH range of 7–10. Co-extraction, ammonia scrubbing and the selective stripping of copper and nickel were performed for a solution containing 3 g/l each of copper and nickel and 60 g/l ammonium carbonate. The extraction and the percentage stripping of copper and nickel were almost quantitative. 相似文献
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Integration – supporting multiple application classes with heterogeneous performance requirements – is an emerging trend
in networks, file systems, and operating systems. We evaluate two architectural alternatives – partitioned and integrated
– for designing next-generation file systems. Whereas a partitioned server employs a separate file system for each application
class, an integrated file server multiplexes its resources among all application classes; we evaluate the performance of the
two architectures with respect to sharing of disk bandwidth among the application classes. We show that although the problem
of sharing disk bandwidth in integrated file systems is conceptually similar to that of sharing network link bandwidth in
integrated services networks, the arguments that demonstrate the superiority of integrated services networks over separate
networks are not applicable to file systems. Furthermore, we show that: an integrated server outperforms the partitioned server
in a large operating region and has slightly worse performance in the remaining region; the capacity of an integrated server
is larger than that of the partitioned server; and an integrated server outperforms the partitioned server by a factor of
up to 6 in the presence of bursty workloads. 相似文献