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排序方式: 共有4132条查询结果,搜索用时 15 毫秒
991.
采用预合金粉末热等静压(hot isostatic pressing ,HIP)近净成形工艺制备了一种新型高强韧钛合金,研究了钛合金与低碳钢包套的界面反应。结果表明,钛合金与低碳钢包套之间存在波浪状的界面反应层,其厚度为8μm,钛合金中的合金元素Al、Mo和V向低碳钢中发生了一定程度的扩散,而两种材料的基体元素Ti和Fe发生扩散的程度要明显低于前者;通过选择性化学洗可以将包套去除,并将反应层厚度减少2.5μm,但微观上仍存在波浪状反应层;通过后续的喷砂处理可以进一步减小反应层厚度,并且使界面反应层平直。 相似文献
992.
Jun Wang Hongchao Li Haoxue Yang Yu Zhang William Yi Wang Jinshan Li 《金属学报(英文版)》2021,34(11):1527-1536
The influence of simple thermomechanical processing such as hot deformation and heat treatment on the microstructure and hardness of an Al0.3CoCrFeNi high-entropy alloy has been investigated.Results show that the relatively high deformation temperature can induce discontinuous dynamic recrystallization with fine grains initially nucleating at the elongated grain boundaries.The transition from partial recrystallization to fully recrystallization,as well as the precipitation behavior after annealing,has been described in detail.Both bcc precipitation and completely recrystallized grains can be observed after annealing at 1000 ℃.Based on detailed microstructure analysis,the decrease in hardness value is shown to be related to both dynamic recrystallization and dynamic recovery which lead to softening. 相似文献
993.
The coal poly-generation system for the production of alcohol and ether fuels as well as power is one of advanced coal utilization techniques. The team leaded by Professor Xie Kechang is carrying out the research on the poly-generation system to produce the syngas from the combination of gasified and pyrolyzed coal gas (dual gas resources) for the alcohol ether synthesis. Gas desulfurization is one of the key technologies for this system. The desulfurization matching with dual gas resources based poly-generation system for the production of alcohol and ether fuels as well as power is presented according to gas components, sulfur content, sulfur species and desulfurization accuracy in this technology. This matching desulfurization is classified into hot gas desulfurization, normal gas desulfurization, warm gas desulfurization and organic sulfur catalytic conversion. The preparation of H2S removal sorbents, organic sulfur hydrolysis catalyst and the evaluation of their activities involved in the system were investigated. The H2S removal efficiencies of the crude and fine desulfurization sorbents prepared for hot gas desulfurization are 90% and 99% at 500 °C in simulating coal gas, and their sulfur capacities are 21.85 wt.% and 24.91 wt.%, respectively. The organic sulfur catalyst shows the high hydrolysis activity, and the hydrolysis conversion of COS is more than that of CS2 on the same catalyst. The research will provide necessary information for the matching desulfurization technology in the demonstration project on dual gas resources coal poly-generation system. 相似文献
994.
Yusmady Mohamed Arifin 《Fuel》2010,89(5):934-942
The aim of this study is to investigate fuel deposits by using the hot surface deposition test (HSDT). In this test, diesel fuel droplets were repeatedly impinged to the hot surface and deposits were developed on it. The hot surface temperature affected the deposit formation. Different hot surface temperature showed different droplet-surface interaction, evaporation lifetime and wet/dry condition where various deposit development features resulted. The hot surface temperatures that located near MEP (maximum evaporation rate point) temperature have potential to reduce the deposit formation on the hot surface. The deposition within nucleate heat transfer boiling regime (lower than the MEP temperature) caused greater deposit accumulation on the hot surface compared to the deposition within transition heat transfer boiling regime (near the MEP temperature). Less total amount of deposit that was described as slow deposit development, resulted under non-overlapping impingement and dry deposit condition. Under the overlapping impingement and wet deposit condition, it caused the accumulation of greater total amount of deposit compared to the non-overlapping and dry deposit condition. 相似文献
995.
The benefit of TiO2, ZrO2 and SO4-ZrO2 on the reactions of C5-sugar (xylose), C6-sugar (glucose), cellulose, and lignocellulose was studied in hot compressed water (HCW) at 473-673 K with an aim to produce furfural and 5-hydroxymethylfurfural (HMF). TiO2 and SO4-ZrO2 were found to active for hydrolysis and dehydration reactions producing high furfural and HMF yields with less by-products (i.e. glucose, fructose, xylose, and 1,6-anhydroglucose (AHG)) formation, whereas ZrO2 was highly active for isomerization reaction; thus significant amount of fructose was observed in the liquid product.Importantly, it was also found that the starting salt precursor, the sulfur-doping content (for SO4-ZrO2) and the calcination temperature strongly affected the catalyst reactivity. Catalysts prepared from the chloride-based precursors (i.e. ZrOCl2 and TiCl4) gained higher reactivity compared to those prepared from nitrate-based precursors (i.e. ZrO(NO3)2 and TiO(NO3)2) due to their greater acidity, according to the NH3- and CO2-TPD studies. For SO4-ZrO2, among the catalyst with sulfur contents of 0.75%, 1.8% and 2.5%, SO4-ZrO2 with 1.8% sulfur content presented the highest acidity and reactivity toward hydrolysis and dehydration reactions. It is noted that the suitable calcination temperature for all catalysts was at 773 K; the XRD patterns revealed that different portions of phase formation was observed over catalysts with different calcination temperatures i.e. anatase/rutile for TiO2 and monoclinic/tetragonal for ZrO2 and SO4-ZrO2; the portion of these phase formations obviously affected the acidity-basicity of catalyst and thus the catalyst reactivity. 相似文献
996.
997.
998.
The friction in the bearing channel of hot aluminium extrusion was studied by using a novel simulative friction test: double action extrusion (DAE). FEM simulations of DAEs were carried out to evaluate two commonly used friction models. It was found that full-sticking friction represents the experimental results the best. For a further understanding of the DAE, a theoretical model was developed, and a good agreement between the modeling results and experiments was obtained. The theoretical modeling results revealed that the length difference of the extrudates was caused by the combined effects of friction and material rate dependence at elevated temperatures. 相似文献
999.
Investigation on the determination of flow direction using two parallel cylindrical hot film sensors
Measurement of instantaneous air flow velocity with high frequency can be carried out by using a hot wire anemometer (HWA). HWA works on the basis of heat transfer rate from hot wire to the fluid flow, therefore directional identification of the air flow using hot wire anemometer is a difficult task. By using two parallel cylindrical hot film sensors a probe was built. By considering the wake and heat effect of the upstream sensor on the downstream sensor, direction of the air flow can be identified. In this work, the wake and heat effect resulting from the upstream sensor to the velocity measurement, by the downstream sensor was studied. This measured velocity is dependent of the following factors namely; air velocity, upstream sensor overheat ratio, distance between the two sensors and turbulence intensity of the flow. As a result it was found that the manufactured probe with sensor distance of 1 mm apart is capable of measuring reverse flow measurements of up to 20 m/s for a moderate turbulent flow. 相似文献
1000.
Seong-ho Ahn 《Tribology International》2010,43(4):779-784
A transient finite element simulation is used to solve the two-dimensional contact problem involving thermo-elastoplastic instability (TEPI) in frictional sliding system. The existence of plastic deformation below the critical speed for thermoelastic instability is independent of the size of initial perturbation. For the simulation of the first/second partial contact, the amount of initial perturbation affects only the time interval of the first partial contact and the second partial contact is reached earlier, regardless of the initial perturbation. In addition, it shows that the locations of hot spots after cooling are changed. 相似文献