全文获取类型
收费全文 | 6247篇 |
免费 | 281篇 |
国内免费 | 118篇 |
专业分类
电工技术 | 141篇 |
综合类 | 358篇 |
化学工业 | 1436篇 |
金属工艺 | 82篇 |
机械仪表 | 228篇 |
建筑科学 | 158篇 |
矿业工程 | 1364篇 |
能源动力 | 657篇 |
轻工业 | 20篇 |
水利工程 | 23篇 |
石油天然气 | 298篇 |
武器工业 | 5篇 |
无线电 | 308篇 |
一般工业技术 | 208篇 |
冶金工业 | 152篇 |
原子能技术 | 42篇 |
自动化技术 | 1166篇 |
出版年
2023年 | 49篇 |
2022年 | 104篇 |
2021年 | 175篇 |
2020年 | 244篇 |
2019年 | 149篇 |
2018年 | 164篇 |
2017年 | 132篇 |
2016年 | 179篇 |
2015年 | 169篇 |
2014年 | 360篇 |
2013年 | 344篇 |
2012年 | 331篇 |
2011年 | 520篇 |
2010年 | 390篇 |
2009年 | 328篇 |
2008年 | 322篇 |
2007年 | 374篇 |
2006年 | 356篇 |
2005年 | 340篇 |
2004年 | 283篇 |
2003年 | 277篇 |
2002年 | 190篇 |
2001年 | 129篇 |
2000年 | 112篇 |
1999年 | 116篇 |
1998年 | 97篇 |
1997年 | 91篇 |
1996年 | 55篇 |
1995年 | 51篇 |
1994年 | 58篇 |
1993年 | 24篇 |
1992年 | 21篇 |
1991年 | 12篇 |
1990年 | 14篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有6646条查询结果,搜索用时 0 毫秒
921.
922.
James B. Lee 《Journal of microscopy》1985,137(2):145-154
The application of an image analyser to the rapid measurement of coal reflectance histograms is described. The ability of an image analyser to utilize a two-dimensional image allows the coal only to be represented in the reflectance histogram, with contribution from the resin used in particulate block specimens eliminated. While the accuracy of reflectance measurement with an image analyser is not as great as can be obtained with a spot photometer system, sufficient accuracy is obtainable for rank determination. 相似文献
923.
《矿业科学技术学报(英文版)》2018,28(6):1009-1014
A large amount of energy is consumed in a coal and gas outburst since a mass of coal is pulverized and ejected, accompanying a great quantity of gas emitted, resulting in a major mining hazard in underground coal mining around the world. Understanding how potential energy stored in gassy coal seams dissipates in the process of outbursting may possibly be a key to clarify the mechanisms responsible for coal and gas outburst. The present study was aimed to evaluate energy for crushing coal to various size fractions in coal and gas outbursts through theoretical and experimental investigation into the shape of fine coal particles and their equivalent diameter. Theoretical analysis indicates that the shape of a particle has a significant impact both on its equivalent diameter and hence on its outer surface area.Microscopic observations demonstrate the particle fraction with diameters less than 0.075 mm, produced from crushing coal samples, mostly takes on a spherical or ellipsoidal shape, and experimental data also show this part of particles consists of 30%–50% surface area newly generated from crushing operation,though these fine coal accounts for only less than ten percentages by weight. Further, analysis of experimental data indicates that the total surface area of this particle size fraction varies exponentially with input crushing energy, and the specific area energy is not a constant but probably in association with physical properties and textures of material. 相似文献
924.
Mercury emissions from coal combustion: modeling and comparison of Hg capture in a fabric filter versus an electrostatic precipitator 总被引:2,自引:1,他引:1
Mercury emissions from coal combustion must be reduced, in response to new air quality regulations in the U.S. Although the most mature control technology is adsorption across a dust cake of powdered sorbent in a fabric filter (FF), most particulate control in the U.S. associated with coal combustion takes the form of electrostatic precipitation (ESP). Using recently developed models of mercury adsorption within an ESP and within a growing sorbent bed in a FF, parallel analyses of elemental mercury (Hg(0)) uptake have been conducted. The results show little difference between an ESP and a FF in absolute mercury removal for a low-capacity sorbent, with a high-capacity sorbent achieving better performance in the FF. Comparisons of fractional mercury uptake per-unit-pressure-drop provide a means for incorporating and comparing the impact of the much greater pressure drop of a FF as compared to an ESP. On a per-unit-pressure-drop basis, mercury uptake within an ESP exhibited better performance, particularly for the low-capacity sorbent and high mass loadings of both sorbents. 相似文献
925.
Utilization of coal fly ash in the glass-ceramic production 总被引:2,自引:0,他引:2
Manufacturing the glass-ceramic has been proposed as a useful choice to recycle coal fly ash from power plants. In this work, a glass-ceramic of SiO2-Al2O3-Fe2O3-CaO family was synthesized by mixing 90 wt% of coal fly ash, from a power plant in west of China, with Na2O, and then melted at 1350 degrees C. The ceramization of the obtained glass was carried out at 770 degrees C for 2h. Esseneite and nepheline were found present as major crystal phases. The produced glass-ceramic exhibited good chemical durability as well as good mechanical properties. The toxicity characteristic leaching procedure (TCLP) method found that the glass-ceramic was non-hazardous. 相似文献
926.
归纳、统计了双鸭山矿务局历史上发生的矿井事故率和造成的生产损失,对各类事故率和产生根源进行了分析,提出了安全预防对策。 相似文献
927.
928.
主要阐述煤、半煤岩巷中深孔控制爆破参数和全断面一次起爆,确定出合理的装药结构、起爆时差与顺序,获得良好的爆破效果和经济效益。 相似文献
929.
本文依据18个省(市)、36个矿区,264个大中小煤矿的实地调查资料和27个矿务局的报告材料,对我国的煤炭资源的基本状况及其开采利用中的问题作了概要剖析与总结,并就煤炭工业发展,体制,经济政策,资源保护等六个方面提出了17条对策建议。 相似文献
930.