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41.
The current aqueous cleaning step in the surface preparation of aluminum nitride (AlN) prior to metallization causes performance and reliability issues for the substrates used for microelectronic packaging due to surface reactions. These issues limit the use of AlN and its replacing of BeO, an environmentally hazardous material currently used. The aim of this investigation was to determine the effects of different solutions on the surface of AlN substrates under varying conditions at times up to 2419.2 ks (28 days). Concentration of the solutions, temperature, and immersion time were varied for the AlN samples in the solutions. Both elevated temperatures (50°C and 90°C) and low temperatures (5°C) were investigated.
Four general types of behavior were observed: minor changes in average surface roughness and microstructure, linear change in average surface roughness and pitted grains, nonlinear change in average surface roughness and product formation on AlN surface, and miscellaneous change in average surface roughness with surface product formation.
The surface roughening kinetics were very complex due to changes in both the reaction product morphology and reaction mechanism with temperature, solvent, and pH for a specific solvent. Minor changes in average surface roughness and microstructure were observed for HCl pH = 5, H2 SO4 pH = 5, NaOH pH = 8, NaOH pH = 10, NaOH pH = 12, deionized water and Alfred tap water at 5°C, HCl pH = 3 and oleic acid at 50°C and citric acid and oleic acid at 90°C. Linear changes in average surface roughness and pitted grains were observed for HCl pH = 2 and H2SO4 pH = 3 at 50°C and HCl pH = 2, H2SO4 pH = 3, and deionized water at 90°C. Non-linear change in average surface roughness and product formation on AlN surface was observed for HCl pH = 5, NaOH pH = 8 and Alfred tap water at 50°C and HCl pH = 5 and H2SO4 pH = 2 at 90°C. Miscellaneous changes in average surface roughness with surface product formation were observed for H2SO4 pH = 2, H2SO4 pH = 5, NaOH pH = 10, NaOH pH = 12, citric acid, Micro-90 and deionized water at 50°C and HCl pH = 3, H2SO4 pH = 5, NaOH pH = 8, NaOH pH = 10, NaOH pH = 12, Micro-90 and Alfred tap water at 90°C. 相似文献
Four general types of behavior were observed: minor changes in average surface roughness and microstructure, linear change in average surface roughness and pitted grains, nonlinear change in average surface roughness and product formation on AlN surface, and miscellaneous change in average surface roughness with surface product formation.
The surface roughening kinetics were very complex due to changes in both the reaction product morphology and reaction mechanism with temperature, solvent, and pH for a specific solvent. Minor changes in average surface roughness and microstructure were observed for HCl pH = 5, H2 SO4 pH = 5, NaOH pH = 8, NaOH pH = 10, NaOH pH = 12, deionized water and Alfred tap water at 5°C, HCl pH = 3 and oleic acid at 50°C and citric acid and oleic acid at 90°C. Linear changes in average surface roughness and pitted grains were observed for HCl pH = 2 and H2SO4 pH = 3 at 50°C and HCl pH = 2, H2SO4 pH = 3, and deionized water at 90°C. Non-linear change in average surface roughness and product formation on AlN surface was observed for HCl pH = 5, NaOH pH = 8 and Alfred tap water at 50°C and HCl pH = 5 and H2SO4 pH = 2 at 90°C. Miscellaneous changes in average surface roughness with surface product formation were observed for H2SO4 pH = 2, H2SO4 pH = 5, NaOH pH = 10, NaOH pH = 12, citric acid, Micro-90 and deionized water at 50°C and HCl pH = 3, H2SO4 pH = 5, NaOH pH = 8, NaOH pH = 10, NaOH pH = 12, Micro-90 and Alfred tap water at 90°C. 相似文献
42.
Sayaka Yanagida Yoshikazu Kameshima Toshiya Watanabe 《Materials Research Bulletin》2005,40(8):1335-1344
TiO2 (anatase) coating was prepared on stainless mesh by electrophoretic (EPD) process utilizing an isopropyl alcohol (IPA)-based suspension with submicron TiO2 powder. When the deposition time was 30 s, a smooth thin coating was obtained. It remained crack-free even after sintering. Coating surface morphology was roughened by UV pre-illumination of the suspension. Photocatalytic decomposition of IPA to acetone and resultant electrochemical reaction at cathode during EPD provides heterogeneous deposition. 相似文献
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Phase evolution, densification, and dielectric properties of MgTi2O5 dielectric ceramic, sintered with lithium borosilicate (LBS) glass, were studied. Reaction between LBS glass and MgTi2O5 was significant in forming secondary phases such as TiO2 and (Mg,Ti)2(BO3)O. The glass addition was not necessarily deleterious to the dielectric properties due to the formation of TiO2: permittivity increased and temperature coefficient of resonance frequency could be tuned to zero with the addition of LBS glass, although the inevitable glass-induced decrease of quality factor was not retarded by the formation of TiO2. The sintered specimen with 10 wt% LBS fired at 950 °C for 2 h showed permittivity of 19.3, quality factor of 6800 GHz, and τf of −16 ppm/°C. 相似文献
45.
Ru-Bing Zhang 《Materials Research Bulletin》2005,40(9):1584-1590
Fe-doped titania films are prepared by RF magnetron sputtering on Si wafers with specifically designed TiO2 targets containing different amounts of Fe2O3 powder as a dopant source. The physical properties of the films are investigated in terms of the preparation conditions, such as Fe2O3 content in the target, RF power, substrate temperature and working pressure. The films show the typical crystallographic orientation. The growth rate increases with increasing RF power, but decreases with working pressure. Films with 40 nm and the transmittance over 90% at the visible region are prepared by using Fe-doped titania target. 相似文献
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We describe a liquid helium cryostat, developed to cool SQUID-based receivers in low field MRI systems. The cryostat has a 4 L liquid helium capacity, a hold time of over 3 days and accommodates 10 cm diameter receiver coils. New vacuum insulation methods reduce the noise level by at least an order of magnitude compared to existing commercial designs. The minimum detectable field at 425 kHz, with a 5 cm diameter circular coil, was estimated to be 0.018 fT/Hz1/2 from Q-factor measurements and 0.035 fT/Hz1/2 by direct measurement with a SQUID amplifier. Further measurements indicated that most of this field noise probably originates with dielectric losses in the cryostat’s fibreglass shells. 相似文献
50.
陶瓷微球增强铝基复合材料 总被引:2,自引:0,他引:2
陈友萱 《上海工程技术大学学报》1997,11(3):57-62
介绍一种以铝土矿陶瓷微球增强的铝基复合材料,具有价格低、增强物与基体合金润湿性好、界面反应几乎不存在等优点。又因其增强物为微球,有利于减小应力集中,延缓裂纹萌生与扩展,同时也提高了铸造流动性和塑性成形能力。讨论了其制造工艺、有关特性和问题。 相似文献