全文获取类型
收费全文 | 23614篇 |
免费 | 1339篇 |
国内免费 | 1291篇 |
专业分类
电工技术 | 3899篇 |
综合类 | 1412篇 |
化学工业 | 2689篇 |
金属工艺 | 2832篇 |
机械仪表 | 4212篇 |
建筑科学 | 609篇 |
矿业工程 | 628篇 |
能源动力 | 1051篇 |
轻工业 | 457篇 |
水利工程 | 1385篇 |
石油天然气 | 319篇 |
武器工业 | 155篇 |
无线电 | 1380篇 |
一般工业技术 | 2975篇 |
冶金工业 | 657篇 |
原子能技术 | 640篇 |
自动化技术 | 944篇 |
出版年
2024年 | 61篇 |
2023年 | 235篇 |
2022年 | 529篇 |
2021年 | 580篇 |
2020年 | 652篇 |
2019年 | 528篇 |
2018年 | 539篇 |
2017年 | 794篇 |
2016年 | 809篇 |
2015年 | 973篇 |
2014年 | 1357篇 |
2013年 | 1392篇 |
2012年 | 1590篇 |
2011年 | 1939篇 |
2010年 | 1270篇 |
2009年 | 1359篇 |
2008年 | 1412篇 |
2007年 | 1573篇 |
2006年 | 1440篇 |
2005年 | 1221篇 |
2004年 | 1039篇 |
2003年 | 975篇 |
2002年 | 753篇 |
2001年 | 617篇 |
2000年 | 504篇 |
1999年 | 428篇 |
1998年 | 329篇 |
1997年 | 303篇 |
1996年 | 196篇 |
1995年 | 198篇 |
1994年 | 133篇 |
1993年 | 102篇 |
1992年 | 80篇 |
1991年 | 76篇 |
1990年 | 53篇 |
1989年 | 39篇 |
1988年 | 26篇 |
1987年 | 25篇 |
1986年 | 20篇 |
1985年 | 15篇 |
1984年 | 11篇 |
1983年 | 16篇 |
1982年 | 22篇 |
1981年 | 9篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Taro Shimonosono Yoshihiro Hirata Mubin Changgan Syohei Kamei Rina Tokaiya Soichiro Sameshima Toshifumi Yoshidome Katsuhiko Yamaji 《Ceramics International》2018,44(8):8904-8912
This paper reports the performance of porous Gd-doped ceria (GDC) electrochemical cells with Co metal in both electrodes (cell No. 1) and with Ni metal in the cathode and Co metal in the anode (cell No. 2) for CO2 decomposition, CH4 decomposition, and the dry reforming reaction of a biogas with CO2 gas (CH4 + CO2 → 2H2 + 2CO) or with O2 gas in air (3CH4 +?1.875CO2 +?1.314O2 → 6H2 +?4.875CO +?0.7515O2). GDC cell No. 1 produced H2 gas at formation rates of 0.055 and 0.33?mL-H2/(min?m2-electrode) per 1?mL-supplied gas/(min?m2-electrode) at 600?°C and 800?°C, respectively, by the reforming of the biogas with CO2 gas. Similarly, cell No. 2 produced H2 gas at formation rates of 0.40?mL-H2/(min?m2) per 1?mL-supplied gas/(min?m2) at 800?°C from a mixture of biogas and CO2 gas. The dry reforming of a real biogas with CO2 or O2 gas at 800?°C proceeded thermodynamically over the Co or Ni metal catalyst in the cathode of the porous GDC cell. Faraday's law controlled the dry reforming rate of the biogas at 600?°C in cell No. 2. This paper also clarifies the influence of carbon deposition, which originates from CH4 pyrolysis (CH4 → C + 2H2) and disproportionation of CO gas (2CO → C + CO2), on the cell performance during dry reforming. The dry reforming of a biogas with O2 molecules from air exhibits high durability because of the oxidation of the deposited carbon by supplied air. 相似文献
32.
Hajime Tomita 《Electrical Engineering in Japan》2015,190(3):1-8
In this investigation, the nature of the electrostatic discharge (ESD) that occurs when a charged object moves toward a stationary grounded object is experimentally clarified. The spark lengths, discharge currents, and induced voltages in a magnetic probe were measured when a charged metallic spherical electrode connected to a 422 pF capacitor approached a stationary grounded object, which was the current target, for different moving speeds of the charged metallic spherical electrode in a range of 1 mm/s to 100 mm/s. The charge voltages of the capacitor were +6.5 kV and +10 kV. Based on the results, the average gap length shortened with the speed of the spherical electrode. The average peak values of the discharge current and the induced voltage were likely to increase with the speed of the spherical electrode. The average rise times of the discharge current and the induced voltage were likely to drop with the speed of the spherical electrode. The relation between the spark length and the discharge current due to the ESD can be explained qualitatively by using an equation derived from the spark resistance formula proposed by Rompe and Weizel. 相似文献
33.
采油污水处理工艺探讨 总被引:3,自引:0,他引:3
针对采油污水的水质特点,以及其中有机污染物的组成,结合现有处理工艺,确定了以生化法降解有机污染物为核心的处理工艺,实现了达标排放,并对处理工艺适用性进行了分析。 相似文献
34.
本文讨论了磁电雾化电晕放电低温等离子体技术的基本原理,以及它在静电除尘、烟气脱硫等环保生物工程等领域中的应用前景. 相似文献
35.
36.
In this article, a subtractive clustering-based fuzzy identification method and a Sugeno-type fuzzy inference system are used for modeling in metal cutting. This approach is considered with its application on the experimental study of Boring and Trepanning Association (BTA) deep-hole drilling. The model for the surface roughness is identified by using the cutting speed and feed as input data and roughness as the output data. Using subtractive clustering in both input and output spaces performs the model-building process. Minimum error model is obtained through enumerative search of clustering parameters. The fuzzy model obtained is capable of predicting the surface roughness for a given set of inputs (speed and feed). Therefore, the operator can predict the quality of the surface for a given set of working parameters and will then be able to set the machining parameters to achieve a certain surface quality. The fuzzy model is verified experimentally by further experimentation using different sets of inputs. The tool life is also investigated using the same approach. The fuzzy inference system obtained is capable of predicting the tool life for a given set of cutting parameters. Therefore, the operator will be able to predict how many minutes the cutting tool is going to last and will set the time for the next tool change. 相似文献
37.
38.
高功率脉冲水中放电的应用及其发展 总被引:7,自引:0,他引:7
首先介绍了高功率脉冲水下放电的机理,然后综合论述了其应用和研究的状况,从较为成熟的脉冲水处理技术到医疗领域的ESWL应用技术,以及在脉冲电场食品杀菌和水下目标探测方面的最新发展和研究,最后指出了高功率脉冲电技术应用前景以及进行更系统和深入研究的必要性。 相似文献
39.
Investigation into polishing process of CVD diamond films 总被引:1,自引:0,他引:1
A new technique used for polishing chemical vapor deposition (CVD) diamond films has been investigated, by which rough polishing of the CVD diamond films can be achieved efficiently. A CVD diamond film is coated with a thin layer of electrically conductive material in advance, and then electro-discharge machining (EDM) is used to machine the coated surface. As a result, peaks on the surface of the diamond film are removed rapidly. During machining, graphitization of diamond enables the EDM process to continue. The single pulse discharge shows that the material of the coated layer evidently affects removal behavior of the CVD diamond films. Compared with the machining of ordinary metal materials, the process of EDM CVD diamond films possesses a quite different characteristic. The removal mechanism of the CVD diamond films is discussed. 相似文献
40.