全文获取类型
收费全文 | 251730篇 |
免费 | 22936篇 |
国内免费 | 11046篇 |
专业分类
电工技术 | 23941篇 |
技术理论 | 32篇 |
综合类 | 24644篇 |
化学工业 | 29827篇 |
金属工艺 | 10955篇 |
机械仪表 | 12366篇 |
建筑科学 | 35318篇 |
矿业工程 | 14297篇 |
能源动力 | 8934篇 |
轻工业 | 17512篇 |
水利工程 | 12222篇 |
石油天然气 | 14056篇 |
武器工业 | 3346篇 |
无线电 | 16342篇 |
一般工业技术 | 17689篇 |
冶金工业 | 12717篇 |
原子能技术 | 1996篇 |
自动化技术 | 29518篇 |
出版年
2024年 | 1124篇 |
2023年 | 3233篇 |
2022年 | 6282篇 |
2021年 | 8182篇 |
2020年 | 7948篇 |
2019年 | 5990篇 |
2018年 | 5588篇 |
2017年 | 7161篇 |
2016年 | 8586篇 |
2015年 | 9373篇 |
2014年 | 17325篇 |
2013年 | 14704篇 |
2012年 | 18199篇 |
2011年 | 20181篇 |
2010年 | 14918篇 |
2009年 | 15228篇 |
2008年 | 13923篇 |
2007年 | 16960篇 |
2006年 | 15488篇 |
2005年 | 13465篇 |
2004年 | 11164篇 |
2003年 | 9879篇 |
2002年 | 8002篇 |
2001年 | 6617篇 |
2000年 | 5671篇 |
1999年 | 4393篇 |
1998年 | 3054篇 |
1997年 | 2644篇 |
1996年 | 2144篇 |
1995年 | 1794篇 |
1994年 | 1473篇 |
1993年 | 1033篇 |
1992年 | 828篇 |
1991年 | 584篇 |
1990年 | 500篇 |
1989年 | 463篇 |
1988年 | 275篇 |
1987年 | 206篇 |
1986年 | 180篇 |
1985年 | 195篇 |
1984年 | 150篇 |
1983年 | 117篇 |
1982年 | 63篇 |
1981年 | 84篇 |
1980年 | 83篇 |
1979年 | 38篇 |
1978年 | 22篇 |
1977年 | 22篇 |
1975年 | 17篇 |
1959年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
This article presents a two-dimensional transient model for gas-solids flow and heat transfer through pipes using the coupled Computational Fluid Dynamics and Discrete Element Method approach. Numerical simulations have been conducted to examine the modification of fluid thermal structure due to the presence of particles in a pneumatic transport pipeline. Modeled results have demonstrated the key role of transversal motion of rebounding particles in the pipe cross section in altering fluid temperature. Further implementation of this modeling technique in air-drying processes is discussed and possible experimental methods for the measurement of in situ particle and fluid motion and temperature profile are cited. 相似文献
53.
J. C. Jones H. Rahmati T. D. H. Do 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,54(4):317-318
Wood shaving samples were heated in both cubic baskets and in a previously described system realising the conditions of the ‘infinite slab’ in thermal ignition. Results from the two sets of experiment were found to be totally consistent with each other. 相似文献
54.
55.
Safe and Economic Operation of Power Plants – Research Results in the Field of Materials, Design and Maintenance Components of power plants which undergo high temperatures are subjected to complex loading situations. The requirements on the used materials result from the special operation conditions of the plants and have to be adjusted to the steadily growing requirements on higher efficiency of the complete power plant as well as to those of safe and economic operation. The expenses for control and downtimes are directly connected with economic efficiency and availability. However, in case of new procedures or components it is not possible to revert to the existing know‐how. Different failure mechanisms than known before can occur. The same goes for the load situation. Therefore the knowledge base has to be extended to in‐advance or even parallely running scientific examinations that life assessment and maintenance strategies can be applied which guarantee the operational reliability and the efficiency of the plant. The main emphasis of these F&E works has to be put on condition monitoring based on actual operational data, the standard materials’ and component’s behaviour (deformation, damage and failure behaviour) in connection with design of components and the related material laws. In the framework of applied AVIF projects, following problems are handled:. – qualification of materials by determinating parameters related to practise. – optimal design of components by making available material laws and numerical tools. – economic manufacturing of components by qualifying processing methods such as welding. – The results can be transferred to concepts for safe and economic operation of power plants, especially for newly introduced materials for which there is no operational experience available. 相似文献
56.
总结了实际工作中防突管理的经验和问题 ,探讨了科学理论与具体实际的有机结合与统一 ,采取针对性强的有效措施 ,确保突出矿井的安全生产 相似文献
57.
58.
全文围绕树立和落实科学发展观这一主题 ,研究和探索如何在新时期、新阶段进一步做好国土资源管理工作的新思路、新途径和新方法。提出要进一步加强国土资源宏观管理 ,更好地为甘肃省经济社会的协调、可持续发展提供保障服务。 相似文献
59.
F Javier Álvarez‐Hornos Carmen Gabaldón Vicente Martínez‐Soria Paula Marzal Josep‐Manuel Penya‐roja 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(5):643-653
BACKGROUND: Two peat biofilters were used for the removal of toluene from air for one year. One biofilter was fed with pure toluene and the other received 1:1 (by weight) ethyl acetate:toluene mixture. RESULTS: The biofilters were operated under continuous loading: the toluene inlet load (IL) at which 80% removal occurred was 116 g m?3 h?1 at 57 s gas residence time. Maximum elimination capacity of 360 g m?3 h?1 was obtained at an IL of 745 g m?3 h?1. The elimination of toluene was inhibited by the presence of ethyl acetate. Intermittent loading, with pollutants supplied for 16 h/day, 5 days/week, did not significantly affect the removal efficiency (RE). Biomass was fully activated in 2 h after night closures, but 6 h were required to recover RE after weekend closures. Live cell density remained relatively constant over the operational period, while the dead cell fraction increased. Finally, a 15 day starvation period was applied and operation then re‐started. Performance was restored with similar re‐acclimatization period to that after weekend closures, and a reduction in dead cell fraction was observed. CONCLUSION: This study demonstrates the capacity of the system to handle intermittent loading conditions that are common in industrial practices, including long‐term starvation. Copyright © 2008 Society of Chemical Industry 相似文献
60.