全文获取类型
收费全文 | 22271篇 |
免费 | 1989篇 |
国内免费 | 933篇 |
专业分类
电工技术 | 1201篇 |
综合类 | 1030篇 |
化学工业 | 3744篇 |
金属工艺 | 1463篇 |
机械仪表 | 1642篇 |
建筑科学 | 1269篇 |
矿业工程 | 608篇 |
能源动力 | 816篇 |
轻工业 | 1523篇 |
水利工程 | 313篇 |
石油天然气 | 970篇 |
武器工业 | 115篇 |
无线电 | 2976篇 |
一般工业技术 | 3590篇 |
冶金工业 | 1243篇 |
原子能技术 | 184篇 |
自动化技术 | 2506篇 |
出版年
2024年 | 108篇 |
2023年 | 461篇 |
2022年 | 776篇 |
2021年 | 1111篇 |
2020年 | 826篇 |
2019年 | 678篇 |
2018年 | 820篇 |
2017年 | 776篇 |
2016年 | 803篇 |
2015年 | 914篇 |
2014年 | 1110篇 |
2013年 | 1346篇 |
2012年 | 1446篇 |
2011年 | 1607篇 |
2010年 | 1381篇 |
2009年 | 1356篇 |
2008年 | 1224篇 |
2007年 | 1016篇 |
2006年 | 975篇 |
2005年 | 850篇 |
2004年 | 651篇 |
2003年 | 636篇 |
2002年 | 590篇 |
2001年 | 499篇 |
2000年 | 465篇 |
1999年 | 472篇 |
1998年 | 455篇 |
1997年 | 353篇 |
1996年 | 326篇 |
1995年 | 260篇 |
1994年 | 209篇 |
1993年 | 137篇 |
1992年 | 111篇 |
1991年 | 77篇 |
1990年 | 74篇 |
1989年 | 63篇 |
1988年 | 43篇 |
1987年 | 34篇 |
1986年 | 33篇 |
1985年 | 22篇 |
1984年 | 17篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 15篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
A new excimer laser annealing (ELA) process that uses a floating amorphous-Silicon (a-Si) thin film with a multichannel structure is proposed for high-performance poly-Si thin-film transistors (TFTs). The proposed ELA method produces two-dimensional (2-D) grain growth, which can result in a high-quality grain structure. The dual-gate structure was employed to eliminate the grain boundaries perpendicular to the current flow in the channel. A multichannel structure was adapted in order to arrange the grain boundary to be parallel to the current flow. The proposed poly-Si TFT exhibits high-performance electrical characteristics, which are a high mobility of 504 cm/sup 2//Vsec and a low subthreshold slope of 0.337 V/dec. 相似文献
2.
Injun Lee Taeseong Jung Junggi Kim Suho Ro Chulsu Kim Yeji Lee Youngmi Kim Juhyun Lee Misook Kang 《Journal of Industrial and Engineering Chemistry》2008,14(6):869-873
This study focuses on the relationship between photo-catalytic performance and optical property over Si-incorporated TiO2. The Si-incorporated TiO2 particles exhibited a pure structure of anatase having a particle size of less than 20 nm and surface area of more than 190 m2/g. The absorbance did not shift to a higher wavelength in spite of the incorporation of the Si ions, but the intensity of the photoluminescence (PL) curve was the smallest in the case of the 2.0 mol% Si-TiO2, which was related to the recombination between the excited electrons and holes. Based on these results, the photodecomposition of methyl orange in the liquid reaction was enhanced over the 2.0 mol% Si-incorporated TiO2 compared with that over pure TiO2: Methyl orange at 10.0 ppm was completely decomposed after 100 min when 1.0 g of the 2.0 mol% Si-incorporated TiO2 was used. 相似文献
3.
Y.M. Wong W.P. Kang J.L. Davidson J.H. Huang D.V. Kerns 《Diamond and Related Materials》2008,17(4-5):552-555
A novel integrated vacuum field emission (VFE) differential amplifier (diff-amp) utilizing carbon nanotube (CNT) emitters has been developed. A dual-mask microfabrication process was employed to achieve a VFE diff-amp by integrating identical CNT VFE transistors with built-in split gates and integrated anodes. The identical pair of triode amplifiers was well-matched in their device characteristics. The measured ac small-signal characteristics of the diff-amp showed a common-mode-rejection ratio (CMRR) of ~ 320 (~ 50 dB). The proposed analytical model of the CMRR was verified to be in good agreement with the experimental data. The successful implementation of the CNT diff-amp demonstrates a new way to achieve temperature and radiation tolerant VFE integrated microelectronics. 相似文献
4.
Sun-Jung Kim Pyeong-Seok Cho Jong-Heun Lee Chong-Yun Kang Jin-Sang Kim Seok-Jin Yoon 《Ceramics International》2008,34(4):827-831
Various compositions of gas sensing films were prepared by the combinatorial deposition of SnO2, ZnO, and WO3 sol solutions and their gas sensing behaviors were investigated. The film composition could be manipulated conveniently via the alternate dropping of different oxide sol solutions. From the correlation between film compositions and gas sensitivities, the selective detection of C2H5OH and CH3COCH3 in the presence of CO, C3H8, H2, and NO2 could be attained. In addition, the discrimination between C2H5OH and CH3COCH3, which is a challenging issue due to their similar chemical nature, becomes possible. This research demonstrates the precise design of the sensor-material composition for the selective gas detection via the combinatorial approach. 相似文献
5.
6.
Kang W.P. Wisitsora-at A. Davidson J.L. Kerns D.V. 《Electron Device Letters, IEEE》1998,19(10):379-381
A boron-doped diamond field emitter diode with ultralow turn-on voltage and high emission current is reported. The diamond field emitter diode structure with a built-in cap was fabricated using molds and electrostatic bonding techniques. The emission current versus anode voltage of the capped diamond emitter diode with boron doping, sp2 content, and vacuum thermal electric (VTE) treatment shows a very low turn-on voltage of 2 V. A high emission current of 1 μA at an anode voltage of less than 10 V can be obtained from a single diamond tip. The turn-on voltage is significantly lower than comparable silicon field emitters 相似文献
7.
Since electronic switching systems usually require very strict reliability requirements as well as good performance objectives, we need to jointly analyse the performance and reliability of switching systems. In this paper, we compare conventional time–space–time switches with single space switches with those with multiple separated space switches, from the viewpoints of reliability and performance. We consider time–space–time switching networks which consist of N incoming time switches, i.e. one NxN space switch, two (N/2)x(N/2) space switches, and four (N/4)x(N/4) space switches. We introduce a Markov reliability model to study the effect of failures and analyse the reliability and performance of three different types of switching networks in terms of average blocking probability and the mean time to unreliable operation, as we vary the offered traffic. As a result, T–S–T switching networks with multiple separated space switches exhibit better performance and reliability than those with single space switches. 相似文献
8.
钒冶炼焙烧添加剂选择研究 总被引:1,自引:0,他引:1
对小型钒冶炼厂焙烧工艺所用添加剂进行改进的可能性进行了探讨,研究了几种常用添加剂的焙烧条件,分析比较了其性能,提出用NaCl-Na2CO3作焙烧添加剂替代NaCl可大幅度减少大气污染,提高冶钒转化率;且不改变工艺流程,无需设备投资,具有较好的经济效益和环境效益。 相似文献
9.
The fabrication of functional textiles able to provide thermal regulation and comfort for the body has attracted increasing interest in recent years. This research investigated fabric coatings containing energy absorbing, temperature stabilizing, phase‐change material microcapsules (PCMMcs), and their methods of application. Specifically, a coated fabric was directly prepared by a dual‐type coating method, in which the PCMMcs were dispersed in a polyurethane coating solution with no binder. The thermal performances of the dual‐coated samples were evaluated by differential scanning calorimetry, and their physical characteristics were examined by scanning electron microscopy, thermal vision camera, porosity, water vapor transmission rate (WVTR), and water entry pressure (WEP) analyses. Furthermore, the microclimate characteristics of the thermally enhanced fabrics were investigated under experimental conditions using a human‐clothing‐environment (HCE) simulator system. The study results confirmed the superior performance of the dual‐coated fabrics in terms of thermal regulation and body comfort, compared with those coated by the dry or wet coating method, because of the improved WEP, WVTR, and thermal performance. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
10.