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国内外锥形双螺杆挤出机发展概况 总被引:6,自引:3,他引:6
本文介绍了国内外锥形双螺杆挤出机的发展概况,同时提出了关于国内锥形双螺杆挤出机发展的建议。 相似文献
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《Journal of the European Ceramic Society》2020,40(4):1592-1601
Porous ceramic diesel particulate filters (DPFs) are extruded products that possess macroscopic anisotropic mechanical and thermal properties. This anisotropy is caused by both morphological features (mostly the orientation of porosity) and crystallographic texture. We systematically studied those two aspects in two aluminum titanate ceramic materials of different porosity using mercury porosimetry, gas adsorption, electron microscopy, X-ray diffraction, and X-ray refraction radiography. We found that a lower porosity content implies a larger isotropy of both the crystal texture and the porosity orientation. We also found that, analogous to cordierite, crystallites do align with their axis of negative thermal expansion along the extrusion direction. However, unlike what found for cordierite, the aluminium titanate crystallite form is such that a more pronounced (0 0 2) texture along the extrusion direction implies porosity aligned perpendicular to it. 相似文献
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The present study evaluated the effects of three galactomannans on the physical and nutritional characteristics, and sensory acceptability of pea–rice based extruded products, targeted as nutritional snacks. A base blend of 70:30 pea and rice fortified with guar gum (GG), locust bean gum (LBG) and fenugreek gum (FG), at 5%, 10%, 15% and 20%, was extruded at pre-determined optimum processing conditions. All three gums resulted in good expanded products. Increasing the inclusion levels of gums, however, had no effect (P > 0.05) on the degree of expansion. Addition of 5% GG and LBG reduced (P < 0.05) the hardness, while the inclusion of GG and LBG at levels higher than 5%, and all inclusion levels of FG, increased (P < 0.05) the hardness of extruded products. Relative to other treatments, FG produced extrudates that were harder and crispier. The mean scores of sensory evaluation indicated that all products containing gums up to 15% were within the acceptable range. Extrusion increased (P < 0.001) the soluble fibre content and decreased the insoluble fraction; the magnitude of these changes were greater in GG and FG. The addition of 15% gums in the pea–rice blend reduced (P < 0.05) the glycaemic index to less than 55. Overall, the data suggest that all three galactomannans could be incorporated up to 15% in a pea–rice blend to develop nutritious, organoleptically acceptable, extruded snack products with low glycaemic index. 相似文献
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The microstructure, mechanical properties and corrosion behavior of Mg–2 Zn–0.6 Zr alloy under the as-cast and asextruded conditions were investigated. Microstructure analysis indicated the remarkable grain refinement by extrusion, as well as notable reductions in volume fraction and size of precipitate phases. As compared with the as-cast alloy, the asextruded alloy exhibited better mechanical performance, especially in yield strength which was promoted from 51 to 194 MPa. Refined grains, dispersive precipitate phases and texture were thought to be the main factors affecting the improved performance in strength. The electrochemical measurement and immersion test revealed the corrosion rate of Mg–2 Zn–0.6 Zr alloy by extrusion decreased from 1.68 to 0.32 mm/year. The reasons for the enhanced corrosion resistance were mainly attributed to the decreased volume fraction and Volta potential of the precipitate phases, the refinement of the grain size, as well as the formation of more protective corrosion film. 相似文献
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Microwave sintering was used to process porous hydroxyapatite scaffolds fabricated by the extrusion deposition technique. The effects of microwave sintering on the microstructure, phase composition, degradation, compressive strength and biological properties of the scaffolds were investigated. After rapid sintering, scaffolds with controlled structure, high densification and fine grains were obtained. A significant increase in mechanical strength was observed relative to conventional sintering. The scaffolds (55–60% porosity) microwave sintered at 1200 °C for 30 min exhibited the highest average compressive strength (45.57 MPa). The degradation was determined by immersing the scaffolds in physiological saline and monitoring the Ca2+concentration. The results indicated that the microwave-sintered scaffolds possessed higher solubility than conventionally sintered scaffolds, as it released more Ca2+ at the same temperature. Furthermore, an in vitro MC3T3-E1 cell culturing study showed significant cell adhesion, distribution, and proliferation in the microwave-sintered scaffolds. These results confirm that microwave sintering has a positive effect on the properties of porous hydroxyapatite scaffolds for bone tissue engineering applications. 相似文献
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采用Tanner方法修正的非线性MaxweⅡ本构方程,对振动力场作用下的聚合物熔体在平行异向双螺杆挤出机螺槽内的行为与响应进行了近似解析研究。分析了不同幂律指数的聚合物熔体在螺槽内的速度分布及其对振动力场的响应。随着幂律指数减小,C型室中上部混合变差,但振动力场使速度场随时间周期性变化,促进了流体界面再取向,进而提高混合效果。 相似文献
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Lanthanum/manganese doped barium titanate (BT) based PTCR functional heater elements/structures were fabricated with desirable electrical properties for the first time using Additive Manufacturing (AM). 3D printed components of varying size and shape and prototype honeycomb lattices with high density were achieved through AM. Aqueous, less organic containing (2.5 wt% additives versus 10–30 wt% added typically), eco-friendly ink formulations were developed with suitable rheological properties for 3D printing. For BT prints, the sintered densities of the 3D ceramic parts were found to be >99% TD, highest reported value so far. The microstructure, electrical properties and heating characteristics of the printed PTCR components were studied in detail and their thermal stability evaluated using infrared imaging and benchmarked against commercial PTCR heating element. The heating behaviour of the solid and porous 3D printed components was demonstrated to be similar, paving the way for light weight (?47% reduction in weight) heaters suitable for automotive/aerospace applications and less materials wastage during device fabrication. 相似文献