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排序方式: 共有157条查询结果,搜索用时 15 毫秒
1.
Abstract The purpose of this study is to propose an alternative forecasting approach for improving the current water supply outlook in Korea. Using a rainfall-runoff model, the existing technique for the water supply outlook in Korea produces monthly low, average, and high runoff forecasts. The proposed technique is called Ensemble Streamflow Prediction (ESP), and is currently implemented by the National Weather Service in the U.S.A. ESP appears particularly valid in Korea where the historical rainfall record is much more comprehensive than the historical streamflow record. This study applies ESP to runoff forecasting for a river basin in Korea to examine its applicability. An ensemble of one-month ahead runoff forecasts at the Gongju gauging station in the Keum River basin, Korea, was generated for each month. The resulting ESP forecasts were compared with the corresponding observed runoff data as well as the existing forecasts. Although this study is limited to one case study, the following conclusions can be made: (1) the ESP technique dominates the existing forecasting techniques in terms of both systematic and random errors; and (2) ESP is more accurate when high flows occur. 相似文献
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V. V. Chaldyshev E. V. Kundelev A. N. Poddubny A. P. Vasil’ev M. A. Yagovkina Y. Chend N. Maharjan Z. Liu M. L. Nakarmi N. M. Shakya 《Semiconductors》2018,52(4):447-451
Photoluminescence, optical reflectance and electro-reflectance spectroscopies were employed to study an AlGaAs/GaAs multiple-quantum-well based resonant Bragg structure, which was designed to match optical Bragg resonance with the exciton-polariton resonance at the second quantum state in the GaAs quantum wells. The structure with 60 periods of AlGaAs/GaAs quantum wells was grown on a semi-insulating substrate by molecular beam epitaxy. Broad and enhanced optical and electro-reflectance features were observed when the Bragg resonance was tuned to the second quantum state of the GaAs quantum well excitons manifesting an enhancement of the light-matter interaction under double-resonance conditions. By applying an alternating electric field, we revealed electro-reflectance features related to the x(e2-hh2) and x(e2-hh1) excitons. The excitonic transition x(e2-hh1), which is prohibited at zero electric field, was allowed by a DC bias due to brake of symmetry and increased overlap of the electron and hole wave functions caused by electric field. 相似文献
4.
Snehlata Shakya Anupam Saxena Prabhat Munshi 《Research in Nondestructive Evaluation》2018,29(2):78-94
Two adaptive discretization frameworks are tested for computerized tomography (CT) data reconstruction. Removal of inactive pixels is primary motivation. Efficient and user independent entropy optimized masking is employed for spatial filtering purposes. Density of nodes at high gradient of reconstructed physical property is used as adaptation criterion. An alternative option, independent from noisy projection data and nature of the physical properties, is also discussed. Sensitivity analysis between the uniform and nonuniform (evolved via adaptive route) reconstruction grid reveals the utility of nonuniform grids. Iterative and transform based reconstruction techniques are used. Outcomes are tested successfully on three real world projection data from two different compact CT setups and one commercial high-resolution micro-CT scanner. 相似文献
5.
Various criteria of formation of perovskites and K2NiF4-type compounds, which are the end members of homologous Ruddlesden-Popper series of phases, have been discussed. RP-phases
show some general trends in their physical properties. Literature survey of the formation of these phases, their properties,
and effect of oxygen stoichiometry and doping is presented. Some conditions for their synthesis are also described. 相似文献
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The use of tetravalent ceric ions to initiate graft-copolymerization of methyl methacrylate onto natural rubber (NR) has been investigated. The rate of grafting has been determined by varying the concentration of monomer and cerium(IV), the temperature and the solvents. The graft yield increases with increasing monomer concentration up to 1.877 M, with further increase of the monomer, the graft yield decreases. The percentage of grafting increases with increasing cerium(IV) concentration up to 0.035 M, thereafter it decreases. With increasing temperature the graft yield increases. The effect of CuSO4 on the rate of grafting has also been investigated. A plausible mechanism has been suggested and the kinetic rate expressions have been derived. 相似文献
8.
Das Satish K. Nanda Umakanta Biswal Sudhansu M. Pandey Chandan Kumar Giri Lalat Indu 《SILICON》2022,14(6):2965-2973
Silicon - Short channel effects (SCEs) along with mobility degradation has a great impact on CMOS technology below 100 nm. These effects can be overcome by using gate and channel... 相似文献
9.
Anaerobic Degradability: Effect of Particulate COD 总被引:1,自引:0,他引:1
Batch bioassay tests were conducted to evaluate the effect of particulate chemical oxygen demand (COD) (CODP) on anaerobic digestion of wastewater at different ratio of food to microorganism (F/M). Synthetically prepared soluble and complex wastewaters were used. Experiments were conducted in seven sets of serum bottles maintained at F/M ranging from 0.18 to 2.0. Each set contained six bottles having a total COD (CODT) of 500 mg and CODP from 0 to 100%. Methane generation conforms to the first order rate kinetics. At all F/M, k?(day?1) decreased linearly with increase in fraction of CODP?(CODPF = CODP/CODT). Biomethane potential (BMP), and substrate and sludge activities also exhibited declining trend with increasing CODPF. The optimum value of F/M ranged from 0.57 to 0.68. The two variables, CODPF and F/M, were compounded to yield the ratio of CODP to microorganisms [M, measured as volatile suspended solids (VSS)]. On increasing the CODP/VSS from 0 to 0.9, the rate constant for methane generation is reduced by 81%. BMP30, percent sludge activity, and substrate utilization rate are lowered by 52–55%. These correlations could serve as useful guidelines to quantitatively assess the impact of particulate COD on biodegradability parameters. 相似文献
10.
Indu Fransham Clifford Leslie Walters 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1981,172(1):4-8
Summary Haem pigments in thin slices of meat can be differentiated by transmission spectrophotometry. The spectral characteristics of the various forms of haem pigment in this situation have compared well with those exhibited in aqueous solution.[/p]The optimum thickness of slice for the observation of haem pigment is 2.0 mm using a Pye Unicam SP 800 recording spectrophotometer. Detachable cells have been constructed that permit the reconstitution of tissues into slices of this thickness when examining meat products too fragile to section conventionally. In this way, sections representative of areas of superficial discoloration can be assembled for spectrophotometric evaluation of contributing haem pigments.[/p]In many cases, selective changes can be applied to a particular form of haem protein for its evaluation by differential spectrophotometry. Reference systems have also been developed for direct examination of the haem pigments, including those formed during curing. Only small samples of tissue are required, so that localized areas of a meat product(s) can be studied without difficulty.
Gebrauch von Durchlässigkeitsspektrophotometrie für die Wertung von Hämpigmenten in situ in Muskelschnitten
Zusammenfassung Hämpigmente in dünnen Fleischscheiben können durch Durchlässigkeitsspektrophotometrie unterschieden werden, wobei deren spektrale Verteilungscharakteristik der verschiedenen Hämpigmente sich mit denen in wässriger Lösung gut vergleichen lassen.[/p]Die optimale Scheibendicke zur Ablesung von Hämpigmenten ist 2,0 mm bei Benutzung eines Pye Unicam SP 800 registrierenden und integrierenden Spektralphotometers. Es wurden ablösbare Zellen hergestellt, die die Wiederherstellung der Gewebe in Schnitte dieser Dicke bei der Untersuchung von Fleischprodukten, die zu zart zum Schneiden sind, erlauben. Auf diese Weise können repräsentative Schnitte von oberflächlichen Verfärbungsflächen für die spektrophotometrische Wertung der verantwortlichen Hämpigmente gewonnen werden. In vielen Fällen können selektive Änderungen auf eine besondere Form von Hämpigmenten, für deren Wertung durch Differentialspektrophotometrie, angewandt werden. Bezugssysteme für direkte Untersuchung der Hämpigmente, einschließlich deren, die während des Pökelns entstehen, wurden zusätzlich entwickelt. Da nur kleíne Gewebemuster erforderlich sind, können lokalisierte Fleischproduktflächen mühelos studiert werden.相似文献