全文获取类型
收费全文 | 505篇 |
免费 | 75篇 |
国内免费 | 58篇 |
专业分类
电工技术 | 12篇 |
综合类 | 40篇 |
化学工业 | 36篇 |
金属工艺 | 5篇 |
机械仪表 | 12篇 |
建筑科学 | 76篇 |
矿业工程 | 52篇 |
能源动力 | 68篇 |
轻工业 | 75篇 |
水利工程 | 114篇 |
石油天然气 | 18篇 |
武器工业 | 1篇 |
无线电 | 18篇 |
一般工业技术 | 45篇 |
冶金工业 | 6篇 |
原子能技术 | 3篇 |
自动化技术 | 57篇 |
出版年
2024年 | 5篇 |
2023年 | 25篇 |
2022年 | 29篇 |
2021年 | 31篇 |
2020年 | 40篇 |
2019年 | 31篇 |
2018年 | 28篇 |
2017年 | 29篇 |
2016年 | 32篇 |
2015年 | 30篇 |
2014年 | 39篇 |
2013年 | 56篇 |
2012年 | 45篇 |
2011年 | 57篇 |
2010年 | 48篇 |
2009年 | 22篇 |
2008年 | 26篇 |
2007年 | 21篇 |
2006年 | 9篇 |
2005年 | 11篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1998年 | 4篇 |
1996年 | 1篇 |
1992年 | 1篇 |
1986年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有638条查询结果,搜索用时 250 毫秒
71.
Power generation from renewable energy sources and fossil fuels are integrated into one system. A combination of technologies in the form of a carbon capture utilization (CCU)-combined power station is proposed. The technology is based on energy generation from fossil fuels by a coal power plant with CO2 recovery from exhaust gases, and pyrolysis of natural gas to hydrogen and carbon, completed by reverse water-gas shift for the conversion of CO2 to CO, which will react with hydrogen in a Fischer-Tropsch synthesis for synthetic diesel. The carbon from the pyrolysis can replace other fossil carbon or can be sequestered. This technology offers significant CO2 savings compared to the current state of technology and makes an environmentally friendly use of fossil fuels for electricity and fuel sectors possible. 相似文献
72.
Luisa Barbieri Alessandro Bigi Fernanda Andreola Isabella Lancelotti Grazia Ghermandi Maria Teresa Cotes Palomino Carmen Martínez García 《International Journal of Applied Ceramic Technology》2021,18(2):353-368
Within a circular economy approach, this study investigates the environmental impact of lightweight aggregates (LWAs) produced starting from different mixes of different clays with brewery sludge and cattle bone flour ash (CBA), used as poring and fertilizing agents, respectively. The environmental impact was evaluated by means of release tests, insulation capacity, carbon footprint (CFP), and particulate matter emission during pellet firing. Release tests representative of LWAs realistic application showed very high release of phosphate and satisfactory release of potassium. The thermal insulation of the LWAs was tested by thermal imaging camera and resulted highly variable depending on the composition, with the mix containing CBA performing best. This latter composition leads also to the smallest CO2 equivalent emission, due to the calorific power of CBA, allowing lower consumption of fossil fuels during the LWA production. Finally, total particulate emissions during the thermal treatment resulted similar in terms of mass for all mixes, while differences in terms of particle morphology and composition occurred. Samples containing residue resulted with a quite good release behavior, CFP, and insulation properties, but higher emission of particles, particularly when glass is added. 相似文献
73.
74.
An evolutionary algorithm for the multi‐objective pick‐up and delivery pollution‐routing problem
下载免费PDF全文
![点击此处可从《International Transactions in Operational Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mauricio Bravo Lorena Pradenas Rojas Victor Parada 《International Transactions in Operational Research》2019,26(1):302-317
The design of sustainable logistics solutions poses new challenges for the study of vehicle‐routing problems. The design of efficient systems for transporting products via a heterogeneous fleet of vehicles must consider the minimization of cost, emissions of greenhouse gases, and the ability to serve every customer within an available time slot. This phenomenon gives rise to a multi‐objective problem that considers the emission of greenhouse gases, the total traveling time, and the number of customers served. The proposed model is approached with an ε‐constraint technique that allows small instances to be solved and an evolutionary algorithm is proposed to deal with complex instances. Results for small instances show that all the points that approach the Pareto frontier found by the evolutionary algorithm are nondominated by any solution found by the multi‐objective model. For complex instances, nondominated solutions that serve most of the requests are found with low computational requirements. 相似文献
75.
76.
ABSTRACTWe analyzed the consumptive water reduction of diet shifting along with food waste reductions in the case of the United States. We find that a dietary shift to healthy diet will not always lead to reduced water footprint. Dietary shifts to vegan and vegetarian diets provide larger reduction in the consumptive water footprint. Reducing food loss and waste produced the largest potential water footprint reduction in our analysis of the US food system. Our findings suggest that a combination of measures that include dietary shift, reducing caloric intake, and reducing food waste result in a significant decline in water footprint. 相似文献
77.
坝式小水电在发挥“以电代柴”效益的同时,也对水资源及水生态环境产生了一定的负面影响。开展坝式小水电站生态环境影响评价研究,对于合理开发水资源,协调水电站开发与流域自然、社会、经济之间的关系具有重要意义。根据坝式小水电站的生态环境影响特点,应用层次分析法建立了指标评分体系,结合生态足迹法的思想来赋予各指标权重,构建了基于EF-AHP法的坝式小水电站综合评价模型,选取西北地区某坝式电站进行了案例应用分析,探讨了评价体系的适用性。结果表明,该模型提高了不同电站之间生态环境影响评价结果的可比性、客观性、实用性。该指标体系为客观评价坝式小水电生态环境影响提供了新的科学手段,对掌握小水电生态环境效应具有重要意义。 相似文献
78.
京津冀地区主要农作物生产水足迹研究 总被引:1,自引:0,他引:1
利用京津冀地区(2个直辖市、11个地级市)气象及农业基础数据,采用彭曼公式与CROPWAT软件相结合的计算方法,分析了2014年京津冀地区主要农作物的生产水足迹。结果表明:小麦在整个生长期需水量主要以蓝水足迹为主,玉米在整个生长期主要以绿水足迹为主;2014年京津冀地区主要农作物总的生产水足迹为437.03×108m3,其中绿水足迹为137.71×108m3,蓝水足迹为176.03×108m3,灰水足迹为123.30×108m3;从京津冀地区主要农作物总的生产水足迹空间格局上来看,沧州、保定、邯郸和石家庄地区的主要农作物生产水足迹较大,是水资源调控的主要地区。 相似文献
79.
为缓解我国干旱区经济生态转型的紧迫压力,对干旱区内陆河流域进行可持续发展评价迫在眉睫。采用生态足迹模型以及三项可持续发展能力评价指标,通过测定塔里木河流域1950—2015年承载力和生态足迹,评价其可持续性。结果表明:在历经近70 a的变化环境尤其是人类活动的高强度影响下,65 a间全流域生态足迹增大近87倍,随着时间的推移,在经历不同的发展阶段后,生态负荷逐渐增加,流域处于不可持续的赤字状态;可持续发展能力评价指标变化表明,塔里木河流域正逐渐偏离可持续性。研究成果有针对性的讨论了塔里木河流域的发展模式,并提出走降低经济发展速度但仍保持增长、减缓资源消耗与环境污染、使环境压力趋于回落发展等建议,以促进流域经济可持续发展。 相似文献
80.
为研究山东省水资源生态承载力现状,缓解山东省用水压力,基于生态足迹的理论和方法,构建了水资源二级账户;同时,从城市发展的角度,选取了城市建设和社会经济中的相关指标,利用统计产品与服务解决方案(Statistical Product and Service Solutions,SPSS)软件,分别对山东省水资源生态足迹和生态承载力进行了相关性分析。分析结果表明:山东省水资源生态足迹和生态承载力均呈现出下降的趋势,水资源处于生态赤字状态;山东省水资源生态足迹受农业用水的影响最大,水资源生态承载力受降水的影响最大,城市设施水平对提高水资源生态承载力具有正面效应。因此,为了提高山东省的水资源生态承载力,提出了有针对性的措施,即应要改变农业灌溉方式,调节生产生活方式,并充分利用雨水资源,从而使得雨污资源化。 相似文献