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排序方式: 共有489条查询结果,搜索用时 22 毫秒
1.
《Carbon》2014
The objective of this study was to analyze the influence of the presence of activated carbon on the degradation of the triiodinated contrast medium diatrizoate (DTZ) by the simultaneous use of gamma radiation and activated carbon. Four commercial activated carbons (Ceca, Witco, Sorbo, and Merck) with different textural and chemical characteristics were used for this purpose. The percentage DTZ removal obtained was considerably higher with the gamma radiation/activated carbon (GM/AC) system than with radiolysis in the absence of activated carbon, and it depended on the specific activated carbon employed. First, we optimized the amount of activated carbon required to maximize the amount of DTZ removed by the GM/AC system (0.06 g). The degradation constants were higher with the GM/AC system than with radiolysis alone, evidencing a synergic effect that favors pollutant removal. This synergic effect is independent of the textural but not the chemical characteristics of the activated carbon, observing a higher synergic activity for carbons with a higher surface content of oxygen, specifically quinone groups. We also highlight that the synergic effect of the activated carbon requires adsorbent–adsorbate electrostatic interaction and is absent when this interaction is hindered. 相似文献
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《Carbon》2014
Four commercial activated carbons with different chemical and textural characteristics were modified by gamma irradiation under five different conditions: irradiated in absence of water, in presence of ultrapure water, in ultrapure water at pH = 1.0 and 1000 mg L−1 Cl−, in ultrapure water at pH = 7.5 and 1000 mg L−1 Br−, and in ultrapure water at pH = 12.5 and 1000 mg L−1 NO3−. Changes in surface chemistry were studied by X-ray photoelectron spectroscopy; pH of point of zero charge, total acidic groups and total basic groups, which were determined by assessment with HCl and NaOH; and textural changes were determined by obtaining the corresponding adsorption isotherms of N2 and CO2. Outcomes show that the activated carbon surface chemistry can be modified by gamma irradiation and that the changes depend on the irradiation conditions. Modifications in the sp2 hybridization of the surface carbons suggest that the irradiated carbons undergo graphitization. Measurements of structural parameters indicate that the irradiation treatment does not modify the textural properties of the carbons. Finally, studies of pristine and irradiated activated carbons using diffuse reflectance spectroscopy with the Kubelka–Munk function revealed a reduction in band gap energy in the irradiated carbons associated with an increase in sp2 hybridization of the carbon atoms. 相似文献
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Negotiated settlements have become a frequently used alternative to contested proceedings when setting prices charged by public utilities under the US rate-of-return regulatory model. The behavior of the representatives of consumer advocates and the firms during settlement negotiations determine customer prices. This paper examines this behavior by using data from the Florida Public Service Commission to estimate the payoff functions of both parties. The estimation suggests that the advocate and the firm weight the present rate change more than the consumer's future average price and the firm's future operating revenue in their settlement decisions. It also indicates that the time saved by settlements is not a primary reason for their popularity. 相似文献
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《Carbon》2015
Carbon nanotubes (CNTs) may elicit inflammatory responses following pulmonary exposure. Conversely, enzymatic biodegradation of CNTs by inflammatory cells has also been reported. The aim of this study was to study the degradation of oxidized single-walled CNTs (ox-SWCNTs) by lactoperoxidase (LPO), a secreted peroxidase present in the airways, and whether pulmonary surfactant affects this biodegradation. To this end, ox-SWCNTs were incubated in vitro with recombinant bovine LPO + H2O2 + NaSCN in the presence and absence of porcine lung surfactant (Curosurf®) and biodegradation was monitored using UV–Vis–NIR spectroscopy, Raman spectroscopy, and scanning electron microscopy. The interaction of recombinant LPO with bundles of ox-SWCNTs was confirmed by atomic force microscopy. Cell-free biodegradation of ox-SWCNTs was also observed ex vivo in murine bronchoalveolar lavage fluid in the presence of H2O2 + NaSCN. Our study provides evidence for biodegradation of ox-SWCNTs with a lung surfactant ‘bio-corona’ and expands the repertoire of mammalian peroxidases capable of biodegradation of ox-SWCNTs. These findings are relevant to inhalation exposure to these materials, as LPO serves as an important component of the airway defense system. 相似文献
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An improved Langmuir method is described and applied to produce transparent, conductive and flexible single layer of multiwall carbon nanotubes. This paper presents properties of multiwall carbon nanotubes spread on water subphase and in a form of Langmuir–Schaefer layers on a quartz plate and on flexible polymeric foil. The results show very high homogeneity of the monolayers on a very large area obtained with the use of the proposed modified Langmuir method and indicate their relatively high radiation transmission and electrical conductivity. Laser scanning confocal and scanning electron microscopic images of the layers are presented. The microscopic visualization of the nanolayers is supported by spectroscopic studies (transmittance, photoacoustics) in the range from ultraviolet to mid-infrared. Moreover, electric measurements (current versus voltage characteristics) of the carbon material on the polymeric foil are presented.The obtained results of the investigated multiwall carbon nanotubes are discussed in a view of potential application in optoelectronics. 相似文献
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《Food Control》2015
Tree nut allergies are considered an important health issue in developed countries. To comply with the regulations on food labeling, reliable allergen detection methods are required. In this work we isolated almond-specific recombinant antibody fragments (scFv) from a commercial phage display library bypassing the use of live animals, hence being consistent with the latest policies on animal welfare. To this end an iterative selection procedure employing the Tomlinson I phage display library and a crude almond protein extract was carried out. Two different almond-specific scFv (named PD1F6 and PD2C9) were isolated after two rounds of biopanning, and an indirect phage ELISA was implemented to detect the presence of almond protein in foodstuffs. The isolated scFvs demonstrated to be highly specific and allowed detection of 40 ng mL−1 and 100 ng mL−1 of raw and roasted almond protein, respectively. The practical detection limit of the assay in almond spiked food products was 0.1 mg g−1 (110–120 ppm). The developed indirect phage ELISA was validated by analysis of 92 commercial food products, showing good correlation with the results obtained by a previously developed real-time PCR method for the detection of almond in foodstuffs. The selected phage clones can be affinity maturated to improve their sensitivity and genetically engineered to be employed in different assay formats. 相似文献
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This work presents a combined experimental and numerical approach to the design and analysis of tape-laid thermoplastic composite cryogenic tanks. A detailed material and defect characterisation of automated tape-laid CF/PEEK is undertaken using optical micrography and 3D X-ray CT (computed tomography) as well as cryogenic testing to investigate damage formation. Resulting material data is used as input for a novel XFEM (extended finite element method)–cohesive zone methodology which is used to predict intra- and inter-ply damage in an internally pressurised cryogenic tank. An optimised tank lay-up is presented and analysed using the numerical method to ensure resistance to microcrack formation and fuel leakage through the tank walls under operating loads. 相似文献