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Offshore jack-up platform rack steel must exhibit high strength and toughness as well as excellent welding properties.A high-quality large ingot is a prerequisite for obtaining a high-performance rough part.The electroslag remelting withdrawing(ESRW)technology using a T-shaped mold and bifilar mode was introduced to replace casting technology.Numerical simulation of the ESRW process was performed to determine the distribution of the temperature and velocity fields and to determine the optimum process for producing rack steels.Several A514 Qslab ingots with dimensions of 0.32m×1.40m×4.00 m were produced using ESRW technology in an industrial plant.The industrial test indicated that slab ingots produced by the ESRW method exhibited uniform chemical compositions and compact macrostructures.A 115.4mm thick plate was produced from the rough ingot after 11 rolling passes.Samples were obtained from different positions in the steel plate to test the mechanical performance and examine the microstructure,and the results revealed that the properties of the steel plate satisfied ASTM standards.The ESRW process improved the tensile strength and toughness of the slab ingot,enabling significant improvements in the anisotropy and low temperature toughness,which are critical for the development of rack steel for offshore platforms. 相似文献
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Many processes are used to join reinforcing bar (steel bar), but only afew of them, e.g. overlapping welding, gas pressure welding, thread joining, cold pressure sleeve joining, are able to be used on building sites because the conditions of building sites are very particular. First, the work of joining reinforcing bar is mobile, that is to say, it must be moved from one place to another after having accomplished one joint. So it demands that the welding equipment ( especially the welding head) must be convenient for moving. So it must be small and light. Second, the electricity capacity of the welding equipment can not be too large because the whole electricity capacity of a building site is limited. Third, the welding process ought to be simple because the situationog building sites is very poor and is on the open air. The more complex the process is, the more difficult the work will be. Fourth, the quality of the joint should be reliable and stable because it is impossible to check the quality of every joint, and there is no suitable way to do it even by now. For those reasons, the electros lag pressure butt welding has got great development recent years and is just suitable to be used on building sites to join vertical reinforcing bars. The articl e introduces its basic principle, processing, chief properties, and some testre sults. 相似文献
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电渣熔铸过程中数学模型的分类及数值模拟的简便求解 总被引:6,自引:2,他引:4
在综述国内外电渣熔铸过程中数学模型研究的发展状况的基础上,分析了其中偏微分方程与其定解问题中的边界条件的特点.然后,在常用的铸件轴对称的假设下,对偏微分方程及其边界条件进行变换,得出了各二维方程及边界条件所属的类型.在此基础上提出了简单有效的求解方法,并进行了渣池电位和渣池温度场的模拟计算,结果表明算法是有效的. 相似文献
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《Baosteel Technical Research》2010,(Z1):85
More than 50 years have passed since the ESR commercialization.Main steps of the ESR technology and appropriate equipment,developing until now,will be outlined.The trends in development of ESR technology and equipment will be also discussed.A special attention will be paid to such applications as ESR of slab ingots for soknown "z-steel" manufacturing,hollow ingots and bimetal steel production. 相似文献
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T型结晶器抽锭电渣重熔高速钢90 mm方锭新工艺 总被引:1,自引:0,他引:1
晶界处碳化物严重影响高速工模具钢的红硬性和耐磨性能,电渣重熔工艺能够有效地改善钢锭中碳化物尺寸及分布。传统电渣重熔生产较小钢锭的截面尺寸约为[?]200 mm,减小钢锭截面尺寸和增大冷却速率将会进一步减轻碳化物的偏析程度,但将降低生产效率、提高生产成本。采用双极串联、T型结晶器、抽锭电渣重熔新工艺生产90 mm方锭,并与相同熔化速度传统电渣重熔生产[?]200 mm钢锭进行对比试验。对钢锭成分、低倍、夹杂物、显微组织进行检验分析结果表明,90 mm方钢锭中碳化物尺寸和分布明显优于[?]200 mm钢锭,碳化物在后序锻造或轧制过程中更容易被破碎。新工艺电耗也低于传统电渣重熔工艺。 相似文献
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Deoxidation during electroslag remelting of S136 die steel was experimentally studied. The characteristics of inclusions in the electrode and ESR ingots were determined by image analyzer and SEM‐EDS. The results show that the oxygen content can be reduced from 89 ppm in the electrode to the lowest (12 ppm) in the ingot only when protective Ar gas remelting in combination with specially designed slag deoxidation treatment were employed simultaneously. The proportion of the oxygen combined as oxide inclusions increases with decreasing the total oxygen content in ESR ingot. The original inclusions in the electrode are mainly large (Mn,Cr)S and the large inclusions in the form of Al2O3 core surrounded by an outer sulfide layer, besides a few pure Al2O3 inclusions. After ESR process, while only pure Al2O3 inclusions with the size of about 1 µm were observed in ESR ingots. The large inclusions in the electrode were removed during ESR process. With higher oxygen content in the ingot, the contents of inclusions and large inclusions would be relatively higher. The results from industrial experiments have confirmed the availability of the present oxygen control technique. The mechanisms of oxygen behavior and control as well as inclusion evolution during ESR process were proposed based on experimental results along with thermodynamic analysis. 相似文献