全文获取类型
收费全文 | 126212篇 |
免费 | 11211篇 |
国内免费 | 8039篇 |
专业分类
电工技术 | 4051篇 |
技术理论 | 2篇 |
综合类 | 7453篇 |
化学工业 | 38307篇 |
金属工艺 | 15503篇 |
机械仪表 | 3704篇 |
建筑科学 | 2826篇 |
矿业工程 | 2141篇 |
能源动力 | 4729篇 |
轻工业 | 10593篇 |
水利工程 | 864篇 |
石油天然气 | 4762篇 |
武器工业 | 883篇 |
无线电 | 10985篇 |
一般工业技术 | 18055篇 |
冶金工业 | 7157篇 |
原子能技术 | 1547篇 |
自动化技术 | 11900篇 |
出版年
2024年 | 470篇 |
2023年 | 2294篇 |
2022年 | 4338篇 |
2021年 | 4807篇 |
2020年 | 3953篇 |
2019年 | 3547篇 |
2018年 | 3282篇 |
2017年 | 4007篇 |
2016年 | 4314篇 |
2015年 | 4287篇 |
2014年 | 6146篇 |
2013年 | 7126篇 |
2012年 | 8255篇 |
2011年 | 10214篇 |
2010年 | 7760篇 |
2009年 | 8834篇 |
2008年 | 7563篇 |
2007年 | 8964篇 |
2006年 | 8152篇 |
2005年 | 6398篇 |
2004年 | 5432篇 |
2003年 | 4641篇 |
2002年 | 3810篇 |
2001年 | 3040篇 |
2000年 | 2653篇 |
1999年 | 2001篇 |
1998年 | 1596篇 |
1997年 | 1236篇 |
1996年 | 1152篇 |
1995年 | 968篇 |
1994年 | 892篇 |
1993年 | 681篇 |
1992年 | 540篇 |
1991年 | 437篇 |
1990年 | 380篇 |
1989年 | 304篇 |
1988年 | 186篇 |
1987年 | 124篇 |
1986年 | 118篇 |
1985年 | 95篇 |
1984年 | 73篇 |
1983年 | 44篇 |
1982年 | 65篇 |
1981年 | 65篇 |
1980年 | 48篇 |
1979年 | 38篇 |
1977年 | 23篇 |
1976年 | 16篇 |
1975年 | 22篇 |
1951年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
SUNZhencui CAOWentian WEIQinqin WANGShuyun XUEChengshan SUNHaibo 《稀有金属(英文版)》2005,24(2):194-199
Hexagonal GaN films were prepared by nitriding Ga2O3 films with flowing ammonia. Ga2O3 films were deposited on Ga-diffused Si (111) substrates by radio frequency (r.f.) magnetron sputtering. This paper have investigated the change of structural properties of GaN films nitrided in NH3 atmosphere at the temperatures of 850, 900, and 950℃ for 15 min and nitrided at the temperature of 900℃ for 10, 15, and 20 rain, respectively. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were used to analyze the structure, surface morphology and composition of synthesized samples. The results reveal that the as-grown films are polycrystalline GaN with hexagonal wurtzite structure and GaN films with the highest crystal quality can be obtained when nitrided at 900℃ for 15 min. 相似文献
942.
943.
反应溅射制备AlN薄膜中沉积速率的研究 总被引:14,自引:2,他引:14
通过对浅射过程中辉光放电现象及薄膜沉积速率的研究,发现随着氮浓度的增大,靶面上形成一层不稳定的AlN层,由于AlN的溅射速率远小于Al,从而使薄膜的沉积速率显著下降。同时还研究了其它溅射参数对薄膜沉积速率的影响。结果表明:随靶基距的增大靶功率的减小,不同程度引起沉积速率的下降;随着溅射气压的增大,最初沉积速率不断增大,当溅射气压增大到一定程度时,沉积速率达到最大值,之后随溅射气 压的增大,又不断减小。 相似文献
944.
945.
A novel multilayered coating was developed for applications associated with friction reduction and wear resistance improvement. The nano-engineered coating integrates a soft lubricating layer, consisting of MoS2-PTFE, onto hard load-supporting layers, with controlled surface morphology (roughness and patterning) of cBN-TiN. The coating was synthesized by sequential procedures including electrostatic spray deposition of cBN particles with different average particle sizes, chemical vapor deposition of TiN, deposition of nano- and micro-sized MoS2 dispersed in PTFE, and curing. The effect of cBN particle size (with different combinations of particle size) and deposition parameters (specifically electrical voltage) on the cBN-TiN surface morphology were studied experimentally and optimized. SEM characterization of the as-synthesized cBN-TiN coating shows surface features similar to that of colocasia esculenta, with alternating nano- and micro-sized domes and “pockets”; the MoS2-PTFE top layer has MoS2 particles retained in the pockets by a basket structure formed during PTFE curing. Tribological and scratch tests were carried out for the as-prepared cBN-TiN and cBN-TiN/MoS2-PTFE multilayered coatings. Sliding test results demonstrate significantly lower friction coefficient for the multilayered coating, showing that the unique integration of soft lubricating layer and biomimetically structured hard layer can effectively improve tribological performance. It is suggested that lubrication at the frictional contacts was realized by continuous release of the lubricants, MoS2 and PTFE, from the pockets. 相似文献
946.
947.
1Cr20Co6Ni2WMoV钢热变形行为研究 总被引:1,自引:0,他引:1
文章采用Gleeble-2000热模拟试验机对1Cr20Co6Ni2WMoV热强钢的热变形行为进行研究。变形温度为950℃,1000℃,1050℃,1100℃,1160℃,变形速率为0.01s~(-1),0.1s~(-1),1s~(-1),10s~(-1)。结果表明.1Cr20Co6Ni2WMoV钢在低应变速率热压缩变形过程中发生明显的动态再结晶;当应变速率大于10s~(-1)时,只发生动态回复。动态再结晶晶粒随变形温度降低,应变速率升高而减小。随应变速率的提高,峰值应力和峰值应变均升高。 相似文献
948.
949.
950.
JIANG Guang WU Yinshun LI Jiuqing LIU Haiping University of Science Technology Beijing Beijing China Department of Surface Sciences Corrosion Engineering University of Science Technology Beijing Beijing China 《金属学报(英文版)》1993,6(8):102-107
Observation was carried out of the structure of sulphuric,oxalic or phosphoricfilm on Al after treatment of reanodizing and electrolytic depositing lubricant in(NH_4)_2MoS_4 solution,as well as of the deposited products by means of EMPA,TEMand energy spectro-scopic analysis.The deposited products are mixture of compounds ofS and Mo rather than single MoS_2 and most of them dcposited near the surface layerof the film.Some regular long pores without barrier layer occurred in the film,but theregular fine channels without relation to the structural element parameters of originalanodized film were found in the thickened barrier layer of phosphoric film.Sulphur maybe remained as Mo sulphide in the film during heating under Ar protective environment. 相似文献