全文获取类型
收费全文 | 123篇 |
免费 | 13篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 6篇 |
综合类 | 8篇 |
化学工业 | 20篇 |
金属工艺 | 14篇 |
机械仪表 | 5篇 |
建筑科学 | 7篇 |
矿业工程 | 19篇 |
能源动力 | 3篇 |
轻工业 | 1篇 |
水利工程 | 33篇 |
无线电 | 6篇 |
一般工业技术 | 8篇 |
冶金工业 | 4篇 |
原子能技术 | 2篇 |
自动化技术 | 9篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 3篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 8篇 |
2017年 | 1篇 |
2016年 | 5篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 3篇 |
2012年 | 11篇 |
2011年 | 11篇 |
2010年 | 16篇 |
2009年 | 15篇 |
2008年 | 13篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
排序方式: 共有145条查询结果,搜索用时 31 毫秒
81.
基于生态足迹分析的义乌市生态承载力评价 总被引:1,自引:0,他引:1
传统生态足迹计算方法过于依赖统计年鉴,尤其是两个十分重要的数据:土地利用因子、产量因子均来自普查统计数据,由此产生的误差对生态足迹的计算结果影响较大。随着遥感技术发展的日益成熟,当前基于遥感技术实现土地利用和产量因子的准确监测已成为可能。因此,本研究通过遥感监测获取土地利用和产量因子,然后对义乌市2000年和2007年的生态足迹分别计算,并进行了动态变化分析。结果显示,义乌市生态承载力在急剧下降,并基于以上结果,提出几点关于减缓义乌市生态足迹增长速度、确保城市的可持续发展的建议。 相似文献
82.
83.
84.
The Eu(III) separation in supported dispersion liquid membrane (SDLM),with polyvinylidene fluoride membrane (PVDF) as the support and dispersion solution containing HNO3 solution as the stripping solution and Di(2-ethylhexyl) phosphoric acid (D2EHPA) dis-solved in kerosene as the membrane solution,was studied.The effects of pH value,initial concentration of Eu(III) and different ionic strengths in the feed phase,volume ratio of membrane solution and stripping solution,concentration of HNO3 solution,concentration of carrier,different stripping agents in the dispersion phase on the separation of Eu(III) were also investigated,respectively.As a result,the optimum separation conditions of Eu(III) were obtained as the concentration of HNO3 solution was 4.00 mol/L,concentration of D2EHPA was 0.160 mol/L,and volume ratio of membrane solution to stripping solution was 30:30 in the dispersion phase,and pH value was 5.00 in the feed phase.Ionic strength had no obvious effect on the separation of Eu(III).Under the optimum conditions studied,when initial concentration of Eu(III) was 1.00×10–4 mol/L,the separation rate of Eu(III) was up to 94.2% during the separation period of 35 min.The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry.The results were in good agreement with the literature data. 相似文献
85.
The transport of Dy(III) through a dispersion supported liquid membrane (DSLM) consisting of polyvinylidene fluoride membrane (PVDF) as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and 2-ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester (PC-88A) dissolved in kerosene as the membrane solution, was studied. The effects of pH value, initial concentration of Dy(III) and different ionic strength in the feed phase, volume ratio of membrane solution and stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on transport of Dy(III) were also investigated, respectively. As a result, when the concentration of HCl solution was 4.0 mol/L, concentration of PC-88A was 0.10 mol/L, and volume ratio of membrane solution and stripping solution was 40:20 in the dispersion phase, and pH value was 5.0 in the feed phase, the transport effect of Dy(III) was the best. Ionic strength had no obvious effect on transport of Dy(III). Under the optimum condition studied, when initial concentration of Dy(III) was 0.8 × 10?4 mol/L, the transport rate of Dy(III) was up to 96.2% during the transport time of 95 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The diffusion coefficient of Dy(III) in the membrane and the thickness of diffusion layer between feed phase and membrane phase were obtained and the values were 1.99 × 10?7 m2/s and 15.97 μm, respectively. The results were in good agreement with experimental results. 相似文献
86.
87.
滴灌工程中科学合理的施工和运行管理是保证工程质量和系统正常运行的关键,结合施工和
运行管理经验,在对滴灌工程主要环节的施工方法和运行管理模式进行了分析的基础上,总结了滴灌
工程施工及运行管理中存在的问题,分析这些问题存在的原因,提出相应的处理对策和方法,为该技
术的进一步推广应用提供参考。 相似文献
88.
90.