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501.
为研究新一代信息技术产业在鄂湘赣的产业链协同发展,本文运用里昂惕夫投入产出模型,首先对新一代信息技术产业的后向(前向)直接、间接关联产业部门分别进行定量化分析,构建新一代信息技术产业的产业链,并得出新一代信息技术产业链的主要关联部门。通过计算Ghosh逆矩阵和Leontief逆矩阵的平均值矩阵F,测度鄂湘赣地区产业链主要关联部门间的成本推动效应和需求拉动效应。基于此,运用平均波及步数法测度鄂湘赣3省之间新一代信息技术产业链的关联程度,最终得出鄂湘赣3省新一代信息技术产业基于产业链进行协同发展的对策建议。 相似文献
502.
Bashar R. M. Al-Gailani Gillian M. Greenway 《International journal of environmental analytical chemistry》2013,93(9):637-646
A miniaturized flow-injection analysis system constructed from a glass base plate and polydimethylsiloxane (PDMS) top plate was employed for the determination of iron in river water. Two designs were investigated, one utilizing a syringe pump and the other utilizing EOF pumping with a mini-filtration system incorporated. The syringe pump system was used to optimize the analytical method on chip, where the pump was used to deliver both the analyte and the reagents to the reactor chip. The highly sensitive chemiluminescence reaction between alkaline luminol (3-aminophthalhydrazide) and 0.1?M of hydrogen peroxide (H2O2) in the presence of iron(II) was utilized. The bright blue light (λ max?~?440?nm) emitted was detected using a miniaturized photomultiplier tube interfaced directly under the chip. The light intensity signals were recorded, and the corresponding concentration of iron(II) concentration was determined. The calibration for iron(II) standards was linear up to 0.75?µg?mL?1 (y?=?5.7839x?+?0.0378, r2 ?=?0.9939) with a precision value of up to 3.72% RSD, for n?=?3. The limits of detection (blank?+?3s y/x) were found to be 28?ng?mL?1. The system which utilized EOF pumping and incorporated a minifiltration unit provided a linear calibration for 0–5?µg?mL?1 (y?=?3.316x?+?0.1831; correlation coefficient, r 2?=?0.9996) over a working range of 0.0–0.5?µg?mL?1. This system provided lower limits of detection 5.1?ng?mL?1 and better repeatability (%RSD less than 0.5% for n?=?4), but problems occurred with the mini-filtration system at higher iron(II) concentrations. The EOF pumping system provided slightly higher results for the concentration of iron(II) in the Humber estuary (0.058?µg?mL?1), but these results were in line with the results expected by the Environment Agency. 相似文献
503.
Kwang Ho KimSoo Min Lee Donha ChoiIn-Gyu Choi Joon Weon Choi 《Journal of Analytical and Applied Pyrolysis》2011,92(1):2-9
Fast pyrolysis of yellow poplar wood (Liriodendron tulipifera) was performed under different temperature ranges and residence times in a fluidized bed reactor to maximize the yield of biooil. In this study, the pyrolysis temperature ranged from 400 °C to 550 °C, and the residence time of pyrolysis products was controlled between 1.2 and 7.7 s by inert nitrogen gas flow. The results revealed that the distribution of thermal degradation products (biooil, biochar, and gas) from the woody biomass was heavily influenced by pyrolysis temperature, as well as residence time. The highest yield of biooil was approximately 68.5 wt% (wet basis), with pyrolysis conditions of 500 °C and 1.9 s of residence time. Water content of the biooils produced at different temperatures was 25-30 wt%, and their higher heating values were estimated to be between 15 MJ/kg and 17 MJ/kg. Using GC/MS analysis, 30 chemical components were identified from the biooil, which were classified into 5 main groups: organic acids, aldehydes, ketones, alcohols, and phenols. In addition, biochar was produced as a co-product of fast pyrolysis of woody biomass, approximately 10 wt%, at temperatures between 450 °C and 550 °C. The physicochemical features of the biochar, including elemental analysis, higher heating values, and morphological properties by SEM, were also determined. 相似文献
504.
A new design of a membraneless gas-diffusion (MGD) unit coupled to a multisyringe flow injection system is proposed. The spectrophotometric determination of ammonium using an acid-base indicator was chosen to show the feasibility of this approach. Hence, in alkaline medium, ammonium ions are transformed into ammonia (donor channel) which diffuses through the headspace into the acceptor stream (bromothymol blue solution), causing a pH change and subsequently a colour change. The exploitation of the enhanced potentialities of this re-designed MGD device was the main purpose of the present work. Hence, several strategies concerning flow management were studied seeking to characterize and improve the analytical features of the methodology and moreover, untreated environmental samples were analysed without previous filtration. Consequently, stopped flow in acceptor channel with continuous flow in donor channel was chosen for the application to wastewater and spiked river water samples. A linear concentration range between 10.0 and 50.0 mg L−1 of NH4+, a limit of detection of 2.20 mg L−1 and a determination frequency of 11 h−1 were obtained. 相似文献
505.
标准方法(GB 7816-1998)测定黄磷中砷时,采用敞开式消解法预处理样品。实践表明该方法耗时,易引入污染,造成测定误差,而且稍有不慎易使黄磷自燃。作为改进,提出了回流冷凝消解法,即2~3 g试样于硝酸(3+2)溶液60 mL中,在160℃电热板上加热回流消解。消解完成后的试液按Ag-DDTC方法进行砷的测定。结果表明:回流冷凝消解法不仅避免了试样的自燃,而且大大缩短了试样消解时间,所测得砷结果的准确度达到原标准方法的水平。 相似文献
506.
In this paper, we study the long-time behavior of solutions of a reaction–diffusion model in a one-dimensional river network, where the river network has two branches, and the water flow speeds in each branch are the same constant . We show the existence of two critical values and 2 with , and prove that when , the population density in every branch of the river goes to 1 as time goes to infinity; when , then, as time goes to infinity, the population density in every river branch converges to a positive steady state strictly below 1; when , the species will be washed down the stream, and so locally the population density converges to 0. Our result indicates that only if the water-flow speed is suitably small (i.e., ), the species will survive in the long run. 相似文献