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51.
<正> 压铸锌合金性能的老化现象,与所含杂质(如Pb,Sn,Cd)及合金在常温下的相变有关。 曾取三种压铸锌合金〔Zn-4Al-0.05Mg,Zn-4Al-2.7Cu-0.05Mg和Zn-4Al-1Cu-0.05Mg〕,观察不同含Pb量对长期时效后合金性能的影响。 相似文献
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采用两步法和埋入PMN-PT单晶为模板的等离子放电烧结(SPS)技术制备出了致密的单一钙钛矿相的PMN-PNN-PT陶瓷,随后在1200℃下退火100h来诱导晶体的生长。实验结果表明,PMN-PNN-PT单晶〈111〉方向的生长速度明显快于〈001〉方向,而〈111〉方向生长的晶体形状为V字形,这是由钙钛矿结构的生长机理决定的,钙钛矿结构晶体的生长是通过〈001〉方向的层状生长来实现的。 相似文献
54.
XU Yourong ZHANG Henghua CHEN Darning XIE Fuchun XU Mingyu Shanghai University of Science Technology Shanghai ChinaCHEN Lanying SU Baorong QIAN Hongbin Shanghai Optics Fine Mechinery Research Institute Academia Sinica Shanghai China XU Yourong professor Department of Materials Science Engineering Shanghai University of Science Technology Shanghai China 《金属学报(英文版)》1993,6(5):300-303
Effect of laser scanning speed on phase constitution,microstructure,microhardness and wearresistance of laser-cladding hard facing alloy Stellite 12 has been investigated by means of across-flow-type CO_2 laser of 1.5 kW.The laser-cladding layer on the alloy consists of ma-trix phase of suppersaturated solid solution γ(Co,Cr)and complex hexagonal carbideM_7C_3.Under certain condition,at higher laser scanning speed,the suppersaturated solubilityof elements increases in γ(Co,Cr),and the precipitation of the complex carbtde M_7C_3 de-creases,so the microhardness increases and the wear resistance decreases.But at slower laserscanning speed,more complex carbide M_7C_3 may precipitate,and the wear resistance may beimproved.Therefore,it is believed that the principal factor in improving wear resistance is theprecipitation of carbide M_7C_3,while increment of microhardness is the suppersaturated solu-bility of elements in matrix phase γ(Co,Cr). 相似文献
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激光熔覆Stellite硬面合金扫描速度对相组织和耐磨性的影响 总被引:8,自引:0,他引:8
本文报导应用横流式连续CO_2激光器,采用不同激光扫描速度,对熔覆Stellite 12钴基硬面合金的合金层的相组成、微观组织结构对耐磨性和显微硬度影响的研究结果。表明:(1)激光熔覆合金层是由过饱和的γ(Co,Cr)基体相和复杂的六方M_7C_3碳化物相所组成(2)在其他参数不变的情况下,随激光扫描速度的提高,γ(Co,Cr)基体相过饱和度增大,而析出的碳化物含量减少,因而合金层的硬度升高,耐磨性有所下降;而降低激光的扫描速度,碳化物M_7C_3析出增加,有利于提高合金层的耐磨性、因此碳化物M_7C_3析出量是提高耐磨性的主要因素,而增加基体相γ(Co,Cr)的过饱和度则是硬度提高的主要因素 相似文献
56.
DV Beard PL Molina KE Muller KM Denelsbeck BM Hemminger JR Perry MP Braeuning DH Glueck WD Bidgood M Mauro 《Canadian Metallurgical Quarterly》1995,197(3):753-758
PURPOSE: Interpretation time of serial staging chest CT cases, which each contained current and previous examinations, with a simple prototype workstation called filmstack was experimentally compared with interpretation time with a film alternator. MATERIALS AND METHODS: The filmstack displayed a "stack" of sections for each examination; user controls allowed rapid selection of preset attenuation windows and both synchronized and unsynchronized scrolling. Eight radiologists were timed as they used the filmstack and the film alternator to interpret four ergonomically complex serial CT cases. RESULTS: All reports dictated on the basis of findings with filmstack and film were of acceptable clinical accuracy. The time to examine a case with filmstack was significantly faster than the time with film, including the time to load and unload the alternator (99% confidence [P = .01]). There was no statistically significant difference in interpretation time between filmstack and prehung film. CONCLUSION: Use of a low-cost stacked CT workstation with a single 1,024 x 1,024 monitor is an effective means of interpreting cases that require comparison of multiple CT examinations. 相似文献
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Andreas Goralczyk Sofya Savicheva Ramin Montazeri Simona Fine Fadoua Mayoussi Pang Zhu Kay Steffen Frederik Kotz-Helmer Dorothea Helmer Bastian E. Rapp 《Advanced Engineering Materials》2023,25(8):2201314
Superhydrophobic coatings are widely applicable, e.g., as self-cleaning surfaces or water–oil separation membranes, yet their wider usage is impeded due to costs of fabrication, size, or substrate limitation. Spray-coating is a versatile coating procedures and might offer a good solution for the fabrication of these superhydrophobic coatings, due to the fact that coatings can be fabricated on various materials in a simple, fast, and inexpensive manner. Most procedures rely on hybrid coatings of hydrophobized nanoparticles and a polymeric matrix, which have several drawbacks including the easy loss of nanoparticles and difficult waste handling. Here, the fabrication of the superhydrophobic material, called Fluoropor, for the first time, by spray-coating on various substrates including metals, tissues, concrete, and glass is presented. It is fabricated by spray-coating a mixture of a highly fluorinated monomer blended with porogens followed by photopolymerization. The superhydrophobicity of the material relies on the porous structure on the micro-/nanoscale across the bulk material and does not require any nanoparticles. Excellent self-cleaning ability of these coatings, resistance against thermal and abrasive impact, and their application as oil–water separation membranes are shown. This versatile applicability is highly promising for real-world application as self-cleaning coatings or oil–water separating membranes. 相似文献
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Eight subjects spent a single night in the sleep laboratory. Event-related potentials (ERPs) were recorded during the presentation of two auditory "oddball' stimulus conditions in which tonal frequency was manipulated. In the first condition, 1000 Hz "standard' and 2000 Hz "deviant' tones were presented. In the second condition, the deviant tone was reduced to 1050 Hz. In both conditions, deviant probability was 0.2. Stimuli were presented every 600 ms during wakefulness and stages 2, 4, and REM of sleep. A distinctive N1 wave was visible in both stimulus conditions when the subject was awake. The deviant stimuli elicited a "mismatch negativity' (MMN) that inverted in polarity at the mastoid. In REM sleep, an N1 and a MMN were also elicited in both conditions. In the large deviance condition, the MMN had a slightly attenuated amplitude and was shorter in duration while in the small deviant condition, its peak latency was unusually early. Neither the N1 nor the MMN could be recorded in non-REM sleep. 相似文献
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