全文获取类型
收费全文 | 49950篇 |
免费 | 6745篇 |
国内免费 | 1574篇 |
专业分类
电工技术 | 2214篇 |
综合类 | 2006篇 |
化学工业 | 14688篇 |
金属工艺 | 2229篇 |
机械仪表 | 1796篇 |
建筑科学 | 4304篇 |
矿业工程 | 1569篇 |
能源动力 | 964篇 |
轻工业 | 6645篇 |
水利工程 | 984篇 |
石油天然气 | 1536篇 |
武器工业 | 227篇 |
无线电 | 4801篇 |
一般工业技术 | 5668篇 |
冶金工业 | 2580篇 |
原子能技术 | 536篇 |
自动化技术 | 5522篇 |
出版年
2024年 | 220篇 |
2023年 | 1033篇 |
2022年 | 3498篇 |
2021年 | 3708篇 |
2020年 | 1655篇 |
2019年 | 1712篇 |
2018年 | 1880篇 |
2017年 | 2441篇 |
2016年 | 3539篇 |
2015年 | 3974篇 |
2014年 | 4081篇 |
2013年 | 3983篇 |
2012年 | 2798篇 |
2011年 | 2122篇 |
2010年 | 1809篇 |
2009年 | 1813篇 |
2008年 | 1700篇 |
2007年 | 2770篇 |
2006年 | 2977篇 |
2005年 | 2493篇 |
2004年 | 1556篇 |
2003年 | 1510篇 |
2002年 | 1093篇 |
2001年 | 698篇 |
2000年 | 637篇 |
1999年 | 360篇 |
1998年 | 205篇 |
1997年 | 182篇 |
1996年 | 194篇 |
1995年 | 158篇 |
1994年 | 168篇 |
1993年 | 109篇 |
1992年 | 94篇 |
1991年 | 96篇 |
1990年 | 119篇 |
1989年 | 90篇 |
1988年 | 58篇 |
1987年 | 57篇 |
1986年 | 55篇 |
1985年 | 56篇 |
1984年 | 67篇 |
1983年 | 40篇 |
1982年 | 35篇 |
1981年 | 35篇 |
1980年 | 45篇 |
1966年 | 25篇 |
1964年 | 34篇 |
1962年 | 64篇 |
1959年 | 21篇 |
1955年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
P. S. Lawson 《Biomass & bioenergy》1992,2(1-6):319-330
In recent years it has been recognised by an increasing number of nations that there is considerable energy potential within MSW. As a result many countries have established R,D& D programmes to examine methods of exploiting this potential. The IEA's MSW Conversion Activity was set up in 1986 to provide an infrastructure for sharing information and co-ordinating work in this area internationally. This Activity was extended in 1989 and currently a total of 9 nations participate in it.
To cope with the wide scope of the area (encompassing both biological and thermal processing of MSW) the Activity was divided into three subgroups or Expert Working Groups (EWGs). Each of these dealt with a distinct area of expertise:
- 1. •Downstream effects of source separation and screening of MSW
- 2. •Sampling and analytical protocols
- 3. •Landfill gas
In addition to these groups a central secretariat based at Harwell (UK) has provided guidance, established and administered databases of contacts and produced a series of national reports.
This paper describes the achievements of the Activity and discusses work proposed for the future. 相似文献
82.
83.
84.
85.
86.
87.
Importance of Solar Drying is increasing worldwide, especially in areas where the use of the abundant, renewable and clean solar energy is essentially advantageous. In the developing countries and in rural areas the traditional open-air drying methods should be substituted by the more effective and more economic solar drying technologies.
R&D needs should be considered in the basic research and experimental fields; in performance measurement; in the modelling-simulation-design and testing. The international co-operation of experts should be improved and more efforts would be needed in the policy and in the public information. 相似文献
R&D needs should be considered in the basic research and experimental fields; in performance measurement; in the modelling-simulation-design and testing. The international co-operation of experts should be improved and more efforts would be needed in the policy and in the public information. 相似文献
88.
It is demonstrated that glassy carbon powder can be thermochemically activated. During activation, a film with open pores is created on the glassy carbon particles. This film has a large internal surface area, which is accessible to liquids and gases. A simple model for the evolution of the internal surface area in glassy carbon powder during thermochemical gas-phase oxidation is also presented and compared with experimental data. Experimental results are in qualitative agreement with the model. We found that a sharp particle size distribution is desirable with regard to potential technical applications. 相似文献
89.
90.