全文获取类型
收费全文 | 820篇 |
免费 | 97篇 |
国内免费 | 35篇 |
专业分类
电工技术 | 11篇 |
综合类 | 14篇 |
化学工业 | 194篇 |
金属工艺 | 52篇 |
机械仪表 | 18篇 |
建筑科学 | 10篇 |
矿业工程 | 4篇 |
能源动力 | 29篇 |
轻工业 | 68篇 |
水利工程 | 5篇 |
石油天然气 | 2篇 |
无线电 | 259篇 |
一般工业技术 | 237篇 |
冶金工业 | 16篇 |
原子能技术 | 3篇 |
自动化技术 | 30篇 |
出版年
2024年 | 4篇 |
2023年 | 12篇 |
2022年 | 16篇 |
2021年 | 22篇 |
2020年 | 21篇 |
2019年 | 25篇 |
2018年 | 11篇 |
2017年 | 37篇 |
2016年 | 35篇 |
2015年 | 40篇 |
2014年 | 37篇 |
2013年 | 48篇 |
2012年 | 55篇 |
2011年 | 57篇 |
2010年 | 35篇 |
2009年 | 45篇 |
2008年 | 39篇 |
2007年 | 39篇 |
2006年 | 51篇 |
2005年 | 42篇 |
2004年 | 30篇 |
2003年 | 28篇 |
2002年 | 30篇 |
2001年 | 32篇 |
2000年 | 28篇 |
1999年 | 16篇 |
1998年 | 12篇 |
1997年 | 17篇 |
1996年 | 12篇 |
1995年 | 13篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有952条查询结果,搜索用时 31 毫秒
51.
近年来,农产品药物残留超标引发了一系列食品安全问题,为了保障国家食品安全、保护消费者健康,需要对农产品中的药物残留进行定性定量检测。表面增强拉曼散射技术 (Surface-enhanced Raman scattering , SERS) 是一种极具吸引力的工具,可用于高效检测农药残留。本文介绍了表面增强拉曼光谱检测技术的概况,简介了拉曼增强基底,分析了表面增强拉曼光谱技术在药物标准溶液、农产品(肉类、水产品、果蔬和其他部分农产品等)药物残留检测领域中的研究现状,并针对当前农产品药物残留检测的发展趋势进行前景展望。 相似文献
52.
为了探讨在不同承印物上UV喷墨油墨印刷适性的差异,提高UV喷墨油墨在不同承印物上的印刷质量,选用铜版纸、玻璃卡标签纸、PVC塑料薄膜3种承印材料,分别用相同的UV喷墨油墨进行喷墨印刷,测试样张中线条的密度、模糊度、粗糙度、线宽、对比度等印刷质量指标;测量喷墨油墨在各承印材料上的接触角,结合其润湿情况,分析UV喷墨油墨在不同承印材料上的印刷质量。实验共制备10种不同表面张力与黏度的油墨进行喷墨印刷并测试印刷质量,采用综合分析评价方法评价其印刷质量。结果表明:在不同承印物上印刷时,UV喷墨油墨的印刷质量存在较大差异,实际生产中应根据所采用的承印物匹配相应印刷适性的UV喷墨油墨,以得到最佳印刷效果。 相似文献
53.
54.
M. Romand F. Gaillard M. Charbonnier N. S. Prakash L. Deshayes I. Linossier 《The Journal of Adhesion》1995,55(1):1-16
A number of surface modification methods using mechanical, chemical, electrochemical or physical processes have commonly been employed to treat adherend surfaces and improve adhesion in various bi- or multi-layered systems which play a key role in many advanced technologies. Results reported in this review paper deal more particularly with components of polymer-metal systems and provide typical examples of surface analysis obtained by x-ray photoelectron spectrometry (XPS), ion scattering spectrometry (ISS), low-energy electron induced x-ray spectrometry (LEEIXS), optically stimulated electron emission (OSEE) and Fourier transform infra-red spectrometry (FTIR). These examples concern, on the one hand, metallic adherends (aluminum, stainless steel, zinc-coated steel, gold) the surfaces of which were modified by cleaning, etching, oxidation, conversion or chemical grafting and, on the other hand, bonded joints (polyester-steel and epoxy-aluminum systems) which were delaminated using a peel test and a three-point flexure test, respectively. 相似文献
55.
Two types of silicon (Si) substrates (40 n-type with uniform base doping and 40 n/n+ epitaxial wafers) from the silicon industry rejects were chosen as the starting material for low-cost concentrator solar cells. They were divided into four groups, each consisting of 20 substrates: 10 are n/n+ and 10 are n substrates, and the solar cells were prepared for different diffusion times (45, 60, 75 and 90 min). The fabricated solar cells on n/n+ substrates (prepared with a diffusion time of 75 min) showed better parameters. In order to improve their performances, particularly the fill factor, 20 new solar cells on n/n+ substrates were fabricated using the same procedure (the diffusion time was 75 min)—but with four new front contact patterns. Investigation of current–voltage (I–V) characteristics under AM 1.5 showed that the parameters of these 20 new solar cells have improved in comparison to previous solar cells' parameters, and were as follows: open-circuit voltage (VOC=0.57 V); short circuit current (ISC=910 mA), and efficiency (η=9.1%). Their fill factor has increased about 33%. The I–V characteristics of these solar cells were also investigated under different concentration ratios (X), and they exhibited the following parameters (under X=100 suns): VOC=0.62 V and ISC=36 A. 相似文献
56.
Robert T. Foister 《The Journal of Adhesion》1987,24(2):279-313
Galvanized substrate morphology, oxide layer chemistry, bond failure modes, failure loci, and bondline corrosion have been investigated for adhesive bonds to galvanized steel. Significant differences in surface morphology were observed between the relatively smooth surfaces of “hot-dipped” substrates and the considerably rougher texture of “electroplated” substrates. The hot-dipped substrates were also chemically heterogeneous, with significant amounts of Al, Mg, Ca, and Pb, in addition to Zn, constituting the surface layer. For electroplated substrates, on the other hand, Zn was the major constituent. It was concluded that, for a given adhesive, low strengths and poor bond durability generally correlated with the minimum surface roughness and maximum chemical heterogeneity of the hot-dipped substrates. Higher strengths, and better durability, on the other hand, were observed for electroplated substrates, which showed the greater roughness, as well as chemically the more uniform surface.
Significantly, ESCA spectroscopy of fracture surfaces of unaged samples established that failure loci for both one and two-part epoxy adhesives included the oxide layer of the substrate. This was true for both hot-dipped, as well as electroplated substrates. For aged samples, scanning electron microscopy and X-ray diffraction analysis of failure surface identified zinc-based corrosion products present in the original bond area. 相似文献
Significantly, ESCA spectroscopy of fracture surfaces of unaged samples established that failure loci for both one and two-part epoxy adhesives included the oxide layer of the substrate. This was true for both hot-dipped, as well as electroplated substrates. For aged samples, scanning electron microscopy and X-ray diffraction analysis of failure surface identified zinc-based corrosion products present in the original bond area. 相似文献
57.
This paper examines the optimization of the process parameters of GZO films deposited on polyethylene terephthalate substrates by R.F. magnetron sputtering using the Taguchi method, aiming to obtain highly transparent and conductive films. The influences of the various sputtering factors (R.F. power, sputtering pressure, deposition time, substrate temperature and post-annealing temperature) on electrical resistivity and structural, morphological and optical transmittance of GZO films are analyzed. The electrical resistivity and the optical transmittance of GZO films were improved by post-annealing the substrate during the deposition process. Experimental results indicate the optimal process parameters in GZO films deposited on polyethylene terephthalate substrates can be determined effectively. The electrical resistivity of GZO films is decreased from 1.194 × 10−3 Ω cm to 8.627 × 10−4 Ω cm and the optical transmittance is increased from 86.148% to 90%, leading to multiple performance characteristics in deposition qualities through the Grey–Taguchi method. 相似文献
58.
59.
微晶玻璃是一种在计算机硬盘基板应用方面很有潜力的新型材料,对某厂研制的Li2O·2SiO系硬盘基板用微晶玻璃的力学性能进行了测试,对结果的分布状况进行了统计分析。结果表明:与传统的铝合金材料相比,该材料具有较高的抗弯强度、弯曲弹性模量和维氏硬度;其结果均符合Weibull分布,Weibull模数的最小二乘估计值较高,表明该材料强度分布的离散性小,使用安全可靠性高。 相似文献
60.
Ignacio Contardi Laura Cornaglia Ana M. Tarditi 《International Journal of Hydrogen Energy》2017,42(12):7986-7996
The effect of the support shape on the deposition of ZrO2 by the vacuum-assisted dip-coating method was studied. Disc-shaped and tubular porous stainless steel substrates were used to obtain ZrO2 coated supports for the synthesis of PdAu alloy composite membranes. The microstructure of the ZrO2 modified supports was evaluated by scanning electron microscopy and confocal laser microscopy. Besides, a qualitative assessment of the porosity and roughness of the porous substrates was performed by confocal laser microscopy. Dense and continuous palladium-alloy films were deposited on top of the modified tubes after thirteen ZrO2 deposition-calcination cycles. Cross-section EDS mapping and XRD diffraction analysis showed that a complete PdAu alloy formation was obtained even after annealing at 723 K in hydrogen stream during 5 days. 相似文献