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The microstructural evolution of casting porosities and creep-induced cavities for a damaged nickel-based superalloy under different hot isostatic pressing(HIP) conditions was investigated in order to understand the effects of HIP parameters on the healing behavior of micropores. A number of small-sized creep cavities formed during long-term service and large-sized porosities formed during the casting process were observed. These microdefects were partially healed after treated at high temperature of 1100 °C combined with 150 MPa pressure for 2 h, together with the formation of the socalled concentrically oriented c0 rafting structure. When HIP temperature was increased to 1150 and 1175 °C, both the amount and the size of the microdefects were decreased. The concentrically oriented c0 rafting around creep cavities became more remarkable, and the primary c0 denuded zone was also formed between the raft structure and the cavity.Energy-dispersive X-ray spectroscopy analysis revealed that the c matrix solute atoms diffused toward the cavity under the concentration gradient, whereas the c0-forming elements diffused in a negative direction. When increasing HIP temperature up to 1200 °C, the micropores were hardly observed, indicating that both casting porosities and creep-induced cavities had almost been healed. Meanwhile, the c0 rafting structure disappeared since HIP temperature was beyond the c0 solvus temperature. It is revealed by the experimental results that the atomic diffusion could mainly dominate the healing process of micropores. 相似文献
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Solid oxide fuel cells (SOFCs) based on the proton conducting BaZr0.1Ce0.7Y0.2O3–δ (BZCY) electrolyte were prepared and tested in 500–700 °C using humidified H2 as fuel (100 cm3 min–1 with 3% H2O) and dry O2 (50 cm3 min–1) as oxidant. Thin NiO‐BZCY anode functional layers (AFL) with 0, 5, 10 and 15 wt.% carbon pore former were inserted between the NiO‐BZCY anode and BZCY electrolyte to enhance the cell performance. The anode/AFL/BZCY half cells were prepared by tape casting and co‐sintering (1,300 °C/8 h), while the Sm0.5Sr0.5CoO3–δ (SSC) cathodes were prepared by thermal spray deposition. Well adhered planar SOFCs were obtained and the test results indicated that the SOFC with an AFL containing 10 wt.% pore former content showed the best performance: area specific resistance as low as 0.39 Ω cm2 and peak power density as high as 0.863 W cm–2 were obtained at 700 °C. High open circuit voltages ranging from 1.00 to 1.12 V in 700–500 °C also indicated negligible leakage of fuel gas through the electrolyte. 相似文献
46.
本文以降低气孔废品率为例,着重介绍了博拉图、流程图、因果图、回归分析、风险分析和控制图等常用质量技术在熔模铸造质量控制与改进中的应用,对质量技术应用起到一定的借鉴作用。 相似文献
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载安礼 《西南石油学院学报》1989,11(2):126-132
本文用系统工程的方法探索原油生产任务分配和资金投入的最优方案问题,给出了油田的能力模型和石油部的规划模型;同时,又考虑了和国民经济发展对原油的需求接口。这样,由规划模型和需求模型分两路前馈,反复协调、优化,最后得出既适合油田能力,又尽力满足国家要求的原油和资金的最优分配方案。从而为石油部在给各大油田分配原油产量和资金作决策时,提供了科学依据。 相似文献
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《Journal of the European Ceramic Society》2014,34(12):3061-3068
In order to reduce the interaction between the Ti alloys and ceramic shell during the casting, materials with high thermal and chemical inertness were used in investment casting. An investigation was undertaken to analyze the influence of the change of binder systems on the slurries, facecoats and the thermo-chemical properties of the facecoat systems using an Y2O3–ZrO2 filler material. The results showed that, using alumina-sol as the binder in the slurry gave the longest life of around three days followed by that using the commercially available zirconia-sol at around 6 h, and the yttria sol based slurry giving a shortest life of around 1.5 h. Meanwhile using the alumina-sol can also enhance the facecoat sintering properties. There was no obvious evidence observed that the change of the binder system influenced the facecoat chemical inertness. 相似文献
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《Journal of the European Ceramic Society》2019,39(16):5213-5235
The rising cost of energy and concerns about the environmental impact of manufacturing processes have necessitated the need for more efficient and sustainable manufacturing. The ceramic industry is an energy intensive industrial sector and consequently the potential to improve energy efficiency is huge, particularly through the introduction of modern sintering technologies. Although several energy efficient sintering processes have been developed, there is no comprehensive techno-economic analysis which compares and contrasts these techniques. This paper presents a critical review and analysis of a number of sintering techniques and compares them with the recently developed cold sintering process (CSP), including mode of operation, sintering mechanism, typical heating rates, duration of sintering, energy consumption profile and energy saving potential, limitations, key challenges for further development and current research efforts. By using a figure of merit, pounds per tonne of CO2 saved (£/tCO2-eq), which links initial capital investment with energy savings, within a framework derived from ranking principles such as marginal abatement cost curves and Pareto optimisation, we have demonstrated that under the scenarios considered for 3 separate functional oxides ZnO, PZT and BaTiO3, CSP is the most economically attractive sintering option, indicating lower capital costs and best return on investment as well as considerable energy and emission savings. Although the current work establishes the viability of CSP as a competitive and sustainable alternative to other sintering techniques, the transition from laboratory to industry of CSP will require hugely different facilities and instrumentation as well as relevant property/performance validation to realise its full potential. 相似文献
50.
简述了电炉短流程工艺的特点,介绍了超高功率电炉、LF精炼炉及连铸中间包各部位用耐火材料的选择与应用。实践表明,超高功率电炉一精炼炉一连铸用耐火材料已完全国产化,国产耐火材料取得了良好的使用效果。 相似文献