全文获取类型
收费全文 | 34599篇 |
免费 | 2234篇 |
国内免费 | 2559篇 |
专业分类
电工技术 | 1063篇 |
综合类 | 2001篇 |
化学工业 | 6583篇 |
金属工艺 | 4113篇 |
机械仪表 | 2321篇 |
建筑科学 | 755篇 |
矿业工程 | 736篇 |
能源动力 | 1459篇 |
轻工业 | 1982篇 |
水利工程 | 183篇 |
石油天然气 | 863篇 |
武器工业 | 152篇 |
无线电 | 5684篇 |
一般工业技术 | 8766篇 |
冶金工业 | 1320篇 |
原子能技术 | 448篇 |
自动化技术 | 963篇 |
出版年
2024年 | 135篇 |
2023年 | 409篇 |
2022年 | 598篇 |
2021年 | 761篇 |
2020年 | 878篇 |
2019年 | 728篇 |
2018年 | 767篇 |
2017年 | 1038篇 |
2016年 | 1009篇 |
2015年 | 1012篇 |
2014年 | 1534篇 |
2013年 | 1923篇 |
2012年 | 2168篇 |
2011年 | 2714篇 |
2010年 | 1951篇 |
2009年 | 2082篇 |
2008年 | 1951篇 |
2007年 | 2398篇 |
2006年 | 2273篇 |
2005年 | 1888篇 |
2004年 | 1701篇 |
2003年 | 1448篇 |
2002年 | 1296篇 |
2001年 | 1156篇 |
2000年 | 1015篇 |
1999年 | 804篇 |
1998年 | 697篇 |
1997年 | 570篇 |
1996年 | 472篇 |
1995年 | 446篇 |
1994年 | 374篇 |
1993年 | 315篇 |
1992年 | 231篇 |
1991年 | 168篇 |
1990年 | 118篇 |
1989年 | 101篇 |
1988年 | 68篇 |
1987年 | 43篇 |
1986年 | 23篇 |
1985年 | 20篇 |
1984年 | 19篇 |
1983年 | 10篇 |
1982年 | 14篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1976年 | 7篇 |
1974年 | 7篇 |
1959年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
51.
Mehdi Qasim Jinan Al‐Dabbagh Naser Mahmoud Ahmed V.G. Chigrinov Gurumurthy Hegde 《Journal of the Society for Information Display》2014,22(4):187-190
Indium tin oxide‐coated thin films (200 nm) are deposited on glass substrates by using R.f. sputtering technique. Here, we investigate the influence of new technique of treatment, which is called as “oil thermal annealing” on the nano‐structured indium tin oxide thin films at fixed temperature (150 °C) which improves adhesion strength, electrical conductivity and optical properties (transmittance) of the films. Oil thermal annealing is used to reduce inherent defects that may be introduced during the prepared thin film and cooling processes. Proposed technique is highly suitable for liquid crystal displays, solar cells and organic light emitting diodes, and many other display‐related applications. 相似文献
52.
ZHENG Nan YANG Ping WANG QiYi YANG ZhongHai & HUANG Nan Key Laboratory of Advanced Technology for Materials of Education Ministry Key Laboratory of Artificial Organ Surface Engineering of Sichuan School of Materials Science Engineering Southwest Jiaotong University Chengdu China 《中国科学:信息科学(英文版)》2010,(1)
Microgrooves were prepared on Si(100) surface by photolithography and wet etching.Subsequently,Si-N-O films were deposited on the microgrooves by unbalanced magnetron sputtering(UBMS) and micro-patterned surfaces of Si-N-O films were obtained.The size of the micropatterns was measured by surface profilometer.The chemical composition of Si-N-O films were characterized by X-ray photoelectron spectrometry(XPS) and the wettability of the micropatterned surfaces was evaluated by contact angle measurement.The beh... 相似文献
53.
YAO Yu & ZHANG JingZhou College of Energy Power Engineering Nanjing University of Aeronautics Astronautics Nanjing China 《中国科学:信息科学(英文版)》2011,(7)
Experimental and numerical researches were conducted to investigate the cooling performance of a single row of consoles (converging slot-hole) on a large-scale flat-plate model. The results show that the coolant flow from a row of consoles shows good lateral uniformity of adiabatic effectiveness, with regions of slightly enhanced cooling occurring between the consoles. For the console cooling geometry, the interaction between coolant jet from inclined console and the mainstream flow results in reasonable vo... 相似文献
54.
采用多弧离子镀设备,在高速钢W18Cr4V上先进行等离子氮化,再沉积TiN薄膜,研究了不同渗氮温度和时间对PN+TiN薄膜组织和性能的影响。结果表明,温度为500℃左右和时间为2h以上条件下对W18Cr4V进行渗氮处理后再沉积TiN薄膜,可以得到最佳的薄膜表面显微硬度(1800~2000HV0.05)和膜/基结合力(50N),涂层耐磨性也得到明显提高。 相似文献
55.
Wei-Mon Yan 《加拿大化工杂志》1993,71(1):54-62
Numerical results are presented for effects of latent heat transport associated with film vaporization on laminar mixed convection heat and mass transfer in a vertical channel with a half channel width b = 0.01 m. The influences of the inlet liquid mass flowrate and wall temperature on the film vaporization and the associated heat and mass transfer characteristics are examined for air-water and air-ethanol systems with gas Reynolds number Reg = 2000. Predicted results obtained by including transport in the liquid film are contrasted with those where liquid film transport is neglected, showing that the assumption of an extremely thin film made in Lin et al. (1988) and Yan and Lin (1989) is only valid for systems having small liquid mass flow rates. Additionally, it is found that the interfacial heat flux is predominantly determined by latent heat transfer connected with film evaporation. 相似文献
56.
The effects of insoluble eutectic Si particles on the growth of anodic oxide films on ZL114A aluminum alloy substrates were in-vestigated by optical microscopy (OM) and scanning electron microscopy (SE... 相似文献
57.
58.
Depositing silver on magnesium alloy by both electroless plating and organic coatings was studied. The organic coating was made by immersing samples in organosilicon heat-resisting varnish. In this method the organic coating acts as interlayer between the substrate and silver film. When the reaction starts, silver deposits directly on the interlayer. X-ray diffraction and SEM analysis were used to determine the composition and morphology of the interlayer and silver film. The potentiodynamic polarization curves for corrosion studies of coated magnesium alloys were performed in a corrosive environment of 3.5% NaCl(mass fraction) at neutral pH (6.9). The results indicate that compared with the substrate, the corrosion resistance of coated magnesium alloys increases greatly. Moreover, the method proposed in this work is environmentally friendly, non-toxic chemicals were used. In addition, it provides a new concept for the corrosion inhibition of magnesium alloys. 相似文献
59.
Nanocrystalline titania films codoped with aluminum and boron were prepared by cathodic vacuum arc deposition. In the process, titanium alloy target was used under an O2/Ar atmosphere, and sensitization of films were carried out by natural dye-sensitized complex in anhydrous ethanol. The structure, surface morphology and UV-vis spectra of titania films codoped were measured by X-ray diffraction analysis, scanning electron microscopy and ultraviolet-visible spectrometer. Theas-deposited films are found to be amorphous. The films annealed were examinedto be of anatase structure with orientation along the (101) planes, the averagecrystal size is in the range between 41 and 45 nm. SEM results show that thereare some pores in the codoped titania films, the optical properties of the dye-sensitized films were also measured which reveals that the spectral responses of films shift to the visible region. Under simulated sunlight illumination, the overall energy conversion efficiency of dye-sensitized nanocrystalline solar cell is 0.9%. 相似文献
60.
Influence of electroplating conditions on magnetic properties of Fe-36wt.% Ni alloy film 总被引:1,自引:0,他引:1
A Fe-Ni soft magnetic film was prepared in sulphate solution by electroplating. The influences of the molar ratio of n [Fe2+ ]/ n [Ni2+ ], current density, bath temperature, pH and L-ascorbic acid concentration on magnetic properties of Fe-Ni alloy film were investigated. The results show that the saturated flux density(BS) of the film increases initially and decreases after it reaches the specific value with the increase of n [Fe2+ ]/ n [Ni2+ ] molar ratio, current density, bath temperature and pH. However, the relationship between L-ascorbic acid concentration and B S keeps linear. It is observed that the coercive force( Hc) is enhanced with the increase of n [Fe2+ ]/ n [Ni2+ ] molar ratio, current density and pH. By comparison, when the bath temperature increases, Hc always decreases. With the increase of L-ascorbic acid concentration, the coercive force increases initially and then decreases. 相似文献