全文获取类型
收费全文 | 975篇 |
免费 | 17篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 41篇 |
化学工业 | 149篇 |
金属工艺 | 22篇 |
机械仪表 | 22篇 |
建筑科学 | 15篇 |
能源动力 | 29篇 |
轻工业 | 45篇 |
水利工程 | 5篇 |
无线电 | 145篇 |
一般工业技术 | 121篇 |
冶金工业 | 309篇 |
原子能技术 | 28篇 |
自动化技术 | 62篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 6篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 14篇 |
2015年 | 13篇 |
2014年 | 11篇 |
2013年 | 51篇 |
2012年 | 23篇 |
2011年 | 41篇 |
2010年 | 22篇 |
2009年 | 29篇 |
2008年 | 27篇 |
2007年 | 39篇 |
2006年 | 32篇 |
2005年 | 22篇 |
2004年 | 33篇 |
2003年 | 28篇 |
2002年 | 13篇 |
2001年 | 16篇 |
2000年 | 19篇 |
1999年 | 21篇 |
1998年 | 117篇 |
1997年 | 61篇 |
1996年 | 46篇 |
1995年 | 31篇 |
1994年 | 29篇 |
1993年 | 31篇 |
1992年 | 22篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1974年 | 4篇 |
1971年 | 4篇 |
1970年 | 4篇 |
排序方式: 共有993条查询结果,搜索用时 31 毫秒
961.
962.
T. Ido H. Sano S. Tanaka H. Inoue 《Photonics Technology Letters, IEEE》1995,7(12):1421-1423
Frequency-domain measurement of carrier escape times in reverse-biased multiple-quantum wells (MQW's) is proposed and demonstrated. Measurement and analysis of opto-to-electrical (OE) frequency response give the escape times of both electrons and holes with excellent time resolution. Using this technique, we measured escape times in an InGaAs-InAlAs MQW electro-absorption modulator and estimated the carrier density in the wells during optical input. This measurement can clarify the optical saturation effect in optical devices such as MQW electro-absorption modulators. 相似文献
963.
964.
Kinoshita H. Ishida T. Akiyama M. Inomata H. Sano Y. Nishi S. Kaminishi K. 《Electronics letters》1985,21(23):1062-1064
Inverted-structure high electron mobility transistors with insulated-gate structure, i.e. AlGaAs/GaAs/n-AlGaAs, have been successfully applied to E/D-type DCFL ring oscillators. High transconductance of 280 mS/mm was obtained at 77 K in an enhancement-mode FET with 0.8 ?m gate length. Gate leakage current was small enough even at a gate voltage of +1.4 V both at 300 K and 77 K, and a high logic swing of more than 1 V was achieved using a DCFL inverter. A 21-stage ring oscillator showed a minimum gate delay as small as 18.0 ps with power dissipation of 520 ?W/gate at 77 K. 相似文献
965.
Akihisa Kubota Yohsuke Shinbayashi Hidekazu Mimura Yasuhisa Sano Kouji Inagaki Yuzo Mori Kazuto Yamauchi 《Journal of Electronic Materials》2007,36(1):92-97
Elastic emission machining (EEM) is a precise surface preparation technique, which uses chemical reactions between the surfaces
of the workpiece and fine powder particles. The purpose of this study is to clarify the surface removal process of silicon
carbide (SiC) in EEM. A SiC sample with a periodic step-bunched structure was prepared as the initial surface and was flattened
by EEM. Optical interferometer and atomic force microscopy (AFM) observations show that the topmost areas on the periodic
step-bunched structure in contact with the powder particles are preferentially removed and surface protrusion is gradually
reduced as removal depth increases. Moreover, power spectral density analyses reveal that the surface is smoothed in the spatial
wavelength range from 0.07 μm to 10 μm. 相似文献
966.
Hideyuki Hara Yasuhisa Sano Keita Yagi Akihisa Kubota Kazuto Yamauchi 《Science and Technology of Advanced Materials》2007,8(3):162-165
A Si wafer and polysilicon deposited on a Si wafer were planarized using catalyst-referred etching (CARE). Two apparatuses were produced for local etching and for planarization. The local etching apparatus was used to planarize polysilicon and the planarization apparatus was used to planarize Si wafers. Platinum and hydrofluoric acid were used as the catalytic plate and the source of reactive species, respectively. The processed surfaces were observed by optical interferometry, atomic force microscopy (AFM) and scanning electron microscopy (SEM). The results indicate that the CARE-processed surface is flat and undamaged. 相似文献
967.
Using backscattered electron (BSE) imaging and scanning electron microscopy, subsequent to a combined treatment of sodium hypochlorite (NaOCl) and ethylenediamine tetra-acetic acid (EDTA) or only with EDTA etching, we observed some structures of non-collagenous calcified matrixes with the aim of revealing the correlation of deposition between calcification degree and organic amount. In human tooth enamel, the NaOCl-EDTA method eroded more intensively the hypocalcified prisms of enamel tufts containing a relatively large amount of EDTA-insoluble organic matter than the hypercalcified normal prismatic enamel containing a small amount of the organic matter. Afibrillar cementum, one of the non-collagenous calcified tissues similar to the enamel, has been reported to consist of organic-rich and poor incremental lamellae. The BSE imaging showed an alternation pattern of hypocalcification and hypercalcification. The hypocalcified lamellae were retained by EDTA etching, while the hypercalcified lamellae showed a resistance against the NaOCl-EDTA method. In the non-collagenous calcareous concretions of human pineal body, organic-rich and poor, and hyper- and hypocalcified incremental lamellae have been reported. The deposition pattern of calcification degree and organic amount was similar to that in afibrillar cementum, and the hypercalcified lamellae showed a resistance against the NaOCl-EDTA method. In conclusion, the high and the lower calcified regions of non-collagenous calcified matrixes contained smaller and larger amounts of EDTA-insoluble organic matter respectively. Moreover, scanning electron microscopy subsequent to the NaOCl-EDTA method corresponding to the BSE imaging clearly showed fine calcified structures compared with the BSE imaging. 相似文献
968.
Suzuki A Ivandini TA Yoshimi K Fujishima A Oyama G Nakazato T Hattori N Kitazawa S Einaga Y 《Analytical chemistry》2007,79(22):8608-8615
Highly boron-doped diamond (BDD) was deposited on chemically etched micrometer-sized tungsten wires using microwave plasma assisted chemical vapor deposition (MPCVD), and these were used to fabricate BDD microelectrodes. BDD microelectrodes with very small diameter (about 5 microm) and 250 microm in length could be made successfully. In addition to the unique properties of BDD electrodes, such as a very low background current, high stability, and selective oxidation of dopamine (DA) in the presence of ascorbic acid (AA), other superior properties of the microelectrodes, including a constant current response, an increase in the mass transport, and the ability for use in high resistance media were also shown. An application study was conducted for in vivo detection of DA in mouse brain, where the BDD microelectrode was inserted into the corpus striatum of the mouse brain. A clear signal current response following medial forebrain bundle (MFB) stimulation could be obtained with high sensitivity. Excellent stability was achieved, indicating that the BDD microelectrodes are very promising for future in vivo electroanalysis. 相似文献
969.
A carbon nanotube–enhanced SiC (CNT–SiC) coating was deposited on C/C composites to improve the oxidation resistance of C/C. The CNT–SiC coating was prepared by direct growth of CNTs on C/C surface at 700 °C followed by deposition of SiC using chemical vapor deposition at 1150 °C for 1 h. SiC was deposited on the CNTs as well as the interface between CNTs and C/C, making CNTs strongly rooted on C/C surface. The final CNT–SiC coating consisted of two layers: the CNT–SiC layer and SiC layer. In comparison to the SiC coating, the CNT–SiC coating showed fewer cracks and a better oxidation resistance because the CNTs reduce the stress in the coating caused by the mismatch of the coefficient of thermal expansion between C/C and SiC. 相似文献
970.
Okamoto T Sano Y Tachibana K Arima K Hattori AN Yagi K Murata J Sadakuni S Yamauchi K 《Journal of nanoscience and nanotechnology》2011,11(4):2928-2930
Catalyst-referred etching (CARE) is a novel abrasive-free planarization method. CARE-processed 4H-SiC(0001) surfaces are extremely flat and undamaged over the whole wafer. They consist of single-bilayer-height atomic steps and atomically flat terraces. This suggests that the etching properties depend principally on the atomic-step density of the substrate surface. We used on-axis and 8 degrees off-axis substrates to investigate the processing characteristics that affect the atomic-step density of these substrates. We found a strong correlation between the removal rate and the atomic-step density of the two substrates. For the on-axis substrate, the removal rate increased with increasing surface roughness, which increases with an increasing atomic-step density. The removal rate ratio is approximately the same as the atomic-step density ratio of the two substrates. 相似文献