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61.
鸡蛋壳制备乙酸钙冰雪融化剂的研究 总被引:5,自引:1,他引:4
以鸡蛋壳为原料,对高温煅烧分解蛋壳、中和法制备乙酸钙(CA)的最佳反应条件进行了研究,试验结果表明:在所选参数下,其产量最大.即反应温度为50℃,配料摩尔比为CaO:HAc=1:2.8,乙酸浓度为15 mol/L,石灰乳浓度(以氧化钙计)为1.3 mol/L.产品融冰试验表明:CA在环境温度为-10℃以上使用时,其融冰效果较好. 相似文献
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Spectral slope (S), describing the exponential decrease of the absorption spectrum over a given wavelength range, is an important parameter in the study of of chromophoric dissolved organic matter (CDOM) dynamics, and also an essential input parameter in remote sensing models. Furthermore, S is often used as a proxy for CDOM composition, including the ratio of fulvic to humic acids and molecular weight. The relative broad range in S values reported in the literature can be explained by the different spectral ranges and fitting methods used. A single exponential model is used to fit the S values for 17 investigations involving 458 samples in Lake Taihu from January to October in 2004. The average S value was 15.18 ± 1.39 μm−1 for the range of 280–500 nm, which fell within the range reported in the literature. The frequency distribution of S value basically obeyed a normal distribution. Significant differences in S values between summer and other seasons showed that phytoplankton degradation was one of the important sources of CDOM in summer, whereas CDOM mainly came from the river input in other seasons. Furthermore, the estimated S value decreased with increasing wavelength range used in regression. The maximum and minimum values derived from the regression were 17.89 ± 1.25 μm−1 and 13.62 ± 2.11 μm−1 for the wavelength ranges of 280–380 nm and 400–500 nm, respectively, a decrease of 23.9%. S values significantly decreased with the increase of CDOM absorption coefficients. CDOM absorption coefficients could be more appropriately estimated from exponential model introducing the variation of S with absorption coefficients, making them useful for a remote sensing bio-optical model of Lake Taihu. DOC-specific absorption coefficient a*(λ) and the parameter M describing molecular size of the humic molecules could also be used as a proxy for the sources and types of CDOM. A general relationship was found between S and a*(λ), and M values. S increased with the decrease of DOC-specific absorption coefficient and the increase of M corresponding to the decrease of molecular weight. 相似文献
64.
Exchanges of total N and C between a river and its floodplain forest have been enhanced by sedimentation processes during flood pulses at a 5‐ha bottomland hardwood forest located at the Olentangy River Wetland Research Park in central Ohio. In the spring of 2000, the forest was hydrologically restored by notching an artificial levee that had separated the Olentangy River and its floodplain forest for 100 years. One‐hundred flat sediment traps (30 cm × 30 cm) were used to collect sediment samples during spring/summer flooding events from 2003 to 2005. Results showed that sediment deposition is determined by the landscape variability during flooding events, Net sediment deposit in the wettest area averaged 134 ± 12 g‐dry wt m?2 in 2003, 127 ± 17 g‐dry wt m?2 in 2004 and 149 ± 23 g‐dry wt m?2 in 2005. Total N and C sedimentation ranged from 0.49 to 0.92 g‐N m?2 and 5.2 to 19.9 g‐C m?2. Fe dominates the sediment chemistry and results show the elemental abundance in the order of Al > Fe > Ca > K > Mg > S > P > Na > Mn > Zn > B > Cu > Mo. A hydrologic pulsing index (HPI) could be used as an indicator for mass changes of energies with hydrologic pulsing events. Restoration of seasonally flooded bottomland forests could stimulate potentially large nutrient and Fe releases, which would eventually lead to an enhanced forest productivity and biodiversity. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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为保证土石坝稳定安全,病险水库除险加固设计中,通常对病险土石坝坝体内外坡进行培厚施工处理。文章详细介绍了病险土石坝培厚施工的测量控制中,平面控制网和高程控制网的确定以及填筑放样测量方法及控制。 相似文献
67.
无形会计数据信度即度量结果的重复性程度,是反映会计数据的客观性指标。效度是判断度量结果即研究对象结果的有效性程度。会计数据的信度与效度的探讨有助于会计信息质量的改善与质量标准的制定,对于进一步展开会计科学的研究也具有一定的意义。本文通过分析会计数据信度与效度的特征性,探讨与验证会计数据信度与效度路径研究方法。 相似文献
68.
精馏过程的节能,对于减少能源消耗,降低生产成本和保护环境具有十分重要的意义.在精馏过程中可以采用最适宜回流比操作和最佳进料状态,使用中间冷凝器和中间再沸器,高效精馏、热泵精馏.合理安排多组分物料分离流程,直接利用过程热量及开发应用高效换热器等措施.本文从最佳回流比R的选择、进料温度及进料状态的确定等方面,详细的分析了在精馏塔的设计过程中,如何实现设计的优化问题,以实现节能降耗. 相似文献
69.
永远流淌的大瀑布——欧茨小说《大瀑布》的生态解读 总被引:1,自引:0,他引:1
张生茂 《福建商业高等专科学校学报》2008,(3):109-113
全球变暖,生态危机是当下最热点话题,因为生态危机已经威胁到了人类的生命安全.跟许多有识之士一样,欧茨也关注生态问题,虽然她不是生态主义者,更不是生态女性主义者.近作<大瀑布>探讨了人与人、人与社会、人与自然的关系,尤其是人与自然关系的思考给读者以启示:人类只不过是生物圈的一份子而已,任何生命体都有其内在价值. 相似文献
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