全文获取类型
收费全文 | 24653篇 |
免费 | 2438篇 |
国内免费 | 1110篇 |
专业分类
电工技术 | 2522篇 |
技术理论 | 1篇 |
综合类 | 1743篇 |
化学工业 | 5445篇 |
金属工艺 | 811篇 |
机械仪表 | 906篇 |
建筑科学 | 1005篇 |
矿业工程 | 1466篇 |
能源动力 | 5156篇 |
轻工业 | 439篇 |
水利工程 | 148篇 |
石油天然气 | 1067篇 |
武器工业 | 545篇 |
无线电 | 2173篇 |
一般工业技术 | 1636篇 |
冶金工业 | 1430篇 |
原子能技术 | 213篇 |
自动化技术 | 1495篇 |
出版年
2024年 | 85篇 |
2023年 | 390篇 |
2022年 | 652篇 |
2021年 | 794篇 |
2020年 | 884篇 |
2019年 | 670篇 |
2018年 | 643篇 |
2017年 | 729篇 |
2016年 | 751篇 |
2015年 | 780篇 |
2014年 | 1414篇 |
2013年 | 1263篇 |
2012年 | 1660篇 |
2011年 | 1917篇 |
2010年 | 1420篇 |
2009年 | 1493篇 |
2008年 | 1325篇 |
2007年 | 1661篇 |
2006年 | 1469篇 |
2005年 | 1282篇 |
2004年 | 1157篇 |
2003年 | 1047篇 |
2002年 | 876篇 |
2001年 | 747篇 |
2000年 | 615篇 |
1999年 | 473篇 |
1998年 | 344篇 |
1997年 | 313篇 |
1996年 | 279篇 |
1995年 | 228篇 |
1994年 | 179篇 |
1993年 | 123篇 |
1992年 | 134篇 |
1991年 | 67篇 |
1990年 | 69篇 |
1989年 | 49篇 |
1988年 | 38篇 |
1987年 | 32篇 |
1986年 | 13篇 |
1985年 | 39篇 |
1984年 | 26篇 |
1983年 | 12篇 |
1982年 | 21篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Ken Kato Yasuhiro Kasuga Masanori Fujiwara Kazuo Onda 《Electrical Engineering in Japan》1996,116(4):94-108
Laboratory-scale and parametric experiments of SO2 and NOx removal from the simulated combustion gas by pulsed corona discharge have been performed by changing the combustion gas composition and temperature, the electrode configuration of plasma reactor, and the polarity of high-voltage electrode. The following results are obtained: 1) the higher the concentration of H2O and O2, the higher the efficiency of desulfurization and denitrification at the same specific input; 2) the pulsed corona discharge with a voltage pulsewidth as short as 200 ns of negative polarity shows the possibility to attain almost 90 percent deSOx and deNOx efficiency at the specific discharge input of 20 J/g, which is almost the same as the specific input in the electron-beam process; 3) the deNOx characteristics show a little temperature dependence in the range of 70 to 130°C, but the deSOx efficiency increases rapidly in the temperature region below 100°C suggesting the thermochemical dependence of deSOx reaction; 4) when desulfurization and denitrification proceed, the white dendritic powder deposits on the plasma reactor whose composition is identified to be 49 mol% (NH4)2SO4 and 47 mol% of 2NH4NO3 · (NH4)2SO4, and the ratio of SO2, NO and NH3 of the deposit is almost equal to that of supplied gas. 相似文献
102.
Because of its high–temperature chemical stability, SiC ceramic is a promising material for high-temperature device applications such as thermoelectric energy converters. However, the electrical conductivity of SiC ceramic is too low for it to be used as a thermoelectric energy converter at the cold junction. Therefore, we propose a SiC-Si functionally gradient material (FGM) in order to improve the electrical conductivity of the SiC ceramic at the cold junction. An SiC rod was fired in a temperature gradient furnace. One end of the SiC rod was maintained at 2473 K and the other end was maintained at 1973 K for 30 min. After firing, the porous SiC edge fired at 1973 K was dipped into molten Si in order to infiltrate molten Si into the porous SiC. The microstructure of the FGM is classified into three regions: the SiC-Si composite material; the porous SiC ceramic; and the densified SiC ceramic. The electrical conductivity, the Seebeck coefficient and the thermal conductivity for each region of SiC-Si FGM was measured at 300 K; a figure of merit was calculated. The figure of merit of the SiC-Si FGM at the cold junction, at room temperature, was 108 times higher than that of a nongradient SiC ceramic. 相似文献
103.
P. Balle H. Bockhorn B. Geiger N. Jan S. Kureti D. Reichert T. Schrder 《Chemical Engineering and Processing: Process Intensification》2006,45(12):1065-1073
This study deals with the development of a laboratory bench for the practical evaluation of catalysts that are useful for the direct conversion of NOx and soot in the exhaust of diesel engines. The employed model exhaust is generated by using a diffusion burner with additionally dosing some gaseous components to the burner gas to obtain a realistic feed composition. The produced soot is extensively characterized by employing thermogravimetry, transmission electron microscopy, N2 physisorption and temperature programmed techniques. The results of the different characterization methods show that the present soot is suitable for the intended catalytic investigations. The simultaneous conversion of NOx and soot is examined like in practice, i.e. the soot is separated from the tail gas by a diesel particulate filter (DPF) that is coated with the catalyst. The deposited soot is then catalytically converted by NOx and O2 to form N2 and CO2. The conversions of NOx and soot are measured by exclusively applying gas analysers, whereby a special experimental procedure is developed to determine the soot removal. Hence, additional soot related analytics are not required. To show the suitability of the constructed bench a Pt/Fe2O3/β-zeolite sample is taken as test catalyst that is reported to be very active in NOx/soot reaction. The measurements performed with and without catalyst clearly show the effect of the used sample in simultaneous NOx/soot conversion. We therefore consider the constructed laboratory bench to be a useful tool for testing and ranking catalytic materials. 相似文献
104.
105.
简要介绍了国内少有的干气催化部分氧化转化制氢工艺,重点讨论了转化水碳比的控制条件,对降低水碳比操作进行了有益地探讨。 相似文献
106.
107.
108.
洁净型煤技术开发研制 总被引:4,自引:0,他引:4
通过对洁净型煤技术的介绍,并对型煤质量及燃烧测试分析,认为洁净型煤技术是一种煤的高效洁净燃烧、改善环境空气质量及节约能源的有效技术。 相似文献
109.
本文提出了一种基于LonWorks和DSPs的智能节点设计方案,并给出了具体的实现方法。该方案简单、可靠,充分利用了LonWorks强大的网络性、可靠性和DSPs强大的数据处理能力,大大提升了节点的智能化程度。 相似文献
110.
H. -C. Chiao H. -L. Lin X. -T. Li C. -X. Ding 《Journal of Thermal Spray Technology》1992,1(2):111-115
Diamond growth with rates up to 100 to 140 μm/hr was achieved using an oxygen-acetylene combustion spraying technique in an
atmospheric environment. Investigations on the processing indicated that the gas flow ratio, substrate position, substrate
temperature, temperature distribution, and substrate pretreatment were the most important factors affecting the growth of
diamond crystals. Evaluation by means of X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and electron
probe microanalysis showed that the synthesized diamond was nearly perfect in morphology, structure, and purity. 相似文献