首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   76篇
  免费   1篇
化学工业   25篇
金属工艺   1篇
建筑科学   2篇
能源动力   3篇
轻工业   13篇
水利工程   1篇
无线电   3篇
一般工业技术   16篇
冶金工业   4篇
原子能技术   1篇
自动化技术   8篇
  2020年   2篇
  2019年   3篇
  2017年   3篇
  2016年   2篇
  2015年   1篇
  2014年   1篇
  2013年   5篇
  2012年   1篇
  2011年   4篇
  2010年   2篇
  2009年   6篇
  2008年   7篇
  2007年   1篇
  2006年   4篇
  2005年   3篇
  2004年   1篇
  2003年   3篇
  2002年   4篇
  2001年   3篇
  1997年   5篇
  1996年   1篇
  1995年   3篇
  1994年   1篇
  1993年   1篇
  1992年   3篇
  1991年   1篇
  1988年   2篇
  1985年   1篇
  1983年   1篇
  1982年   1篇
  1976年   1篇
排序方式: 共有77条查询结果,搜索用时 15 毫秒
71.
The range of future climate-induced sea-level rise remains highly uncertain with continued concern that large increases in the twenty-first century cannot be ruled out. The biggest source of uncertainty is the response of the large ice sheets of Greenland and west Antarctica. Based on our analysis, a pragmatic estimate of sea-level rise by 2100, for a temperature rise of 4°C or more over the same time frame, is between 0.5 m and 2 m--the probability of rises at the high end is judged to be very low, but of unquantifiable probability. However, if realized, an indicative analysis shows that the impact potential is severe, with the real risk of the forced displacement of up to 187 million people over the century (up to 2.4% of global population). This is potentially avoidable by widespread upgrade of protection, albeit rather costly with up to 0.02 per cent of global domestic product needed, and much higher in certain nations. The likelihood of protection being successfully implemented varies between regions, and is lowest in small islands, Africa and parts of Asia, and hence these regions are the most likely to see coastal abandonment. To respond to these challenges, a multi-track approach is required, which would also be appropriate if a temperature rise of less than 4°C was expected. Firstly, we should monitor sea level to detect any significant accelerations in the rate of rise in a timely manner. Secondly, we need to improve our understanding of the climate-induced processes that could contribute to rapid sea-level rise, especially the role of the two major ice sheets, to produce better models that quantify the likely future rise more precisely. Finally, responses need to be carefully considered via a combination of climate mitigation to reduce the rise and adaptation for the residual rise in sea level. In particular, long-term strategic adaptation plans for the full range of possible sea-level rise (and other change) need to be widely developed.  相似文献   
72.
Thin film transformer and its analysis by integral equation method   总被引:3,自引:0,他引:3  
We propose a thin film transformer for small electronic devices, and apply the integral equation method to analyze this transformer. Both the primary and secondary coils of the film transformer are arranged coaxially on the layer and multiply laminated. The operation principal of the transformer is based on the skin effect and the mutual effect between the coils at high frequency. Because of the coaxially arranged coils, the magnetic field of the transformer can be modeled with an axisymmetric assumption. Using the model, we evaluate the electromagnetic field and calculate the lumped circuit parameters, i.e., inductance and resistance, which are compared with experimental values  相似文献   
73.
The high-speed growth of China’s biotechnology industry during the past 20 years presents an excellent opportunity to examine its overall evaluation and governance from the perspective of science and technology policies. Although China’s biotechnology industry has achieved tremendous extension both in scale and structure, the strengths it has gained from achievements in research and development activities have been significantly weakened in relation to processes of commercialization. After examining the definition of China’s biotechnology industry as well as its evolution, the authors of this paper employ Actor-Networks Theory as a basic theoretical framework to reveal how China’s biotechnology industry develops in the form of evolving networks within the country’s social context and to identify what kinds of relationships exist among the relevant factors. Our hope is to provide guiding insights for improving the governance of China’s biotechnology industry both in policy and in management practices.  相似文献   
74.
The forest biomass is an abundant renewable resource from which biofuels can be derived. In the Kraft process, the cellulose is extracted from the wood to form the paper pulp while the other organic components, primarily hemicelluloses and lignin, are burnt to produce steam. It is possible to divert part of the hemicelluloses or lignin to produce fuels on site, a mode of operation referred to as the integrated forest biorefinery. Hemicelluloses can be hydrolysed into sugars which in turn are converted into ethanol or butanol, while lignin can be extracted from a residual process stream, the black liquor, by acid precipitation, de-ionized, dried and directly used as a fuel or further processed into value added chemicals. Biorefinery processes have been proposed and analysed by simulation on Aspen Plus. Intensive integration of thermal energy, water and material systems is of paramount importance to the sustainability of the global site; the increased energy load on the utility systems could cause rising dependency of the global site on fossil fuels. To avoid this consequence, a new original energy efficiency analysis and enhancement methodology has been developed and validated on actual Canadian Kraft mills before being applied to the integrated biorefinery and, has produced remarkable results far superior to the current engineering practice. This has led to the concept of the GIFBR (green integrated forest biorefinery), i.e., an industrial site with zero fossil fuel consumption and reduced GHG (greenhouse gases) emissions vs. the Kraft process and biorefinery plant alone. The GIFBR incorporates a woody biomass gasifier producing syngas as a fuel for the integrated biorefinery and for steam production or sale. It can also include a CHP (combined heat and power) unit driven by steam made available by liberated production capacity from the installed power plant.  相似文献   
75.
76.
This paper provides recent examples of geothermal energy application in high profile public buildings within urban settings. It outlines the application of a low temperature geothermal resource as a source of heating for the Challenge Stadium in Perth, Western Australia and the use of ambient temperature groundwater in UK for cooling at the Royal Festival Hall and the Tate Modern Gallery in Central London. Key benefits from the Challenge Stadium project completed in 2004 include reduced consumption of fossil based fuel, cost savings, water supply and water infrastructure development for a local school, enhanced sustainability profile for the sports and recreation facility. The groundwater cooling system at the Royal Festival Hall was commissioned in 2004 and fully operational in 2008 whilst the system at the Tate Modern Gallery is at an advanced stage of development. Sustainable development, specifically economic, planning, architectural and environmental factors, were the key reasons for groundwater being used as a low temperature geothermal sink for the latter projects. For cities situated on geothermal resources or productive aquifer systems, one of the greatest potential benefits from low temperature geothermal applications is the demonstration of sustainability principles, especially reduction of CO2 emissions due to displaced usage of fossil fuels. Projects such as Challenge Geothermal, Royal Festival Hall and Tate Modern Gallery can be legitimately recognised as sustainable as they are ecologically friendly and support locally appropriate technological solutions whilst benefitting the community and economy of the city.  相似文献   
77.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号