地下水中NO3-对环境保护的影响

NO3-的含量是衡量地下水是否受污染的重要标志之一,地下水污染是影响环境保护的重要因素.受污染的地下水中的NO3-是微生物氧化作用的产物.长期在水、土壤、食物中积累的硝酸盐在细菌的还原酶作用下,经过了一系列的水化学反应生成亚硝酸盐,引起水环境恶化,严重影响着人们的健康状况.     

Functional MRI activation in children with and without dyslexia during pseudoword aural repeat and visual decode: Before and after treatment.

Children without dyslexia (n=10) received nonphonological treatment, and those with dyslexia received phonological (n=11) or nonphonological (n=9) treatment. Before and after treatment they performed aural repeat, visual decode, and aural match pseudoword tasks during functional MRI scanning that separated stimulus input from response production. Group map analysis indicated that children with dyslexia overactivated compared with good readers during the aural-repeat/aural-match contrast in bilateral frontal (Brodmann's area [BA] 3, 4, 5, 6, 9), left parietal (BA 2, 3), left temporal (BA 38), and right temporal (BA 20, 21, 37) regions (stimulus input) and underactivated in right frontal (BA 24, 32) and right insula (BA 48) regions (response production); they underactivated in BA 19/V5 during the visual-decode/aural-match contrast (response production). Individual brain analysis for children with dyslexia revealed that during the aural-repeat/aural-match contrast (stimulus input), phonological treatment decreased and normalized activation in left supramarginal gyrus and postcentral gyrus. Nonphonological treatment increased and normalized activation during the visual-decode/aural-match contrast (response production) in BA19/V5 and changed activation in the same direction as good readers during aural-repeat/aural-match contrast (stimulus input) in left postcentral gyrus. The significance of the findings for competing theories of dyslexia is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

天铁新建15 000 Nm3/h制氧工程给排水设计

文章分别从设计参数、给排水系统、给排水构筑物及给排水设施主要设备几个方面对天铁15000Nm^3/h制氧工程给排水设计作了具体地介绍。该工程的给排水设施投入使用后运行良好。     

不同加氧处理方式对超级稻产量的影响

通过田间试验研究了不同加氧处理方式下超级稻产量因素的相关因素分析。加氧处理下超级稻单株产量与常规处理比较有显著性差异,采用SPSS统计软件对不同加氧处理下构成超级稻产量因素的每穗实粒数、稻穗数、千粒重进行相关性分析,得出超级稻单株产量与每株穗数相关系数高。不同加氧处理方式下的白天机械加氧、夜间机械加氧、化学加氧的每株穗数高于不加氧处理分别是17.5%、19.27%、12.8%。不同加氧处理组之间的稻穗数进行多重比较未有显著差异,加氧处理与对照常规处理存在显著差异。加氧处理促进了水稻有效分蘖使稻穗数增加,进而提高水稻产量。     

均苯三甲酸合成工艺条件的研究

通过考察反应时间、反应温度等因素,得到均三甲苯液相空气氧化法制备均苯三甲酸的较佳工艺条件为：均三甲苯：冰醋酸：催化剂：二溴乙烷（摩尔比）为1：5：1：0．05、空气流速为0．5m^3／h、反应温度为210℃、反应时间为4h、均苯三甲酸的收率可达85％（摩尔收率）,酸值为796．23mgKOH／g．     

填料式氧合器填料传质与溶血特性的研究

本文在直径5.2 cm的有机玻璃填料式氧合器中,分别填充几种自制小填料(6mm不锈钢O网环,6 mm PVC拉西环,以及7 mm PTFE拉西环等填料),进行血液-O_2的物理吸收实验。以体积传质系数k_Lα和溶血程度作为填料的性能指标,对所用填料进行综合评价与筛选。实验结果表明:在所选填料中,以7 mm PTFE拉西环的性能为最佳。     

组氨酸钴(Ⅱ)氧合过程的理论研究

构筑了组氨酸钴配合物及其氧合构型、双核氧合构型的模型,通过Guassian 03对上述结构进行构型优化并进行频率计算。利用计算结果对各构型的能量、几何构型及电子构型进行讨论,分析了组氨酸钴的氧合过程及老化机理。根据分析,组氨酸钴氧合主要历程是高自旋的未氧合构型氧合形成单核氧合构型,进一步氧合形成过氧桥桥联的双核氧合产物。双核氧合产物的HOMO轨道主要集中在双氧分子上,反应活性较高,易老化;而单核氧合构型中双氧上未配位的氧原子与氨基上的氢形成氢键,双氧自身能量下降,活性低,构型更稳定,表现出很好的氧合可逆性。     

Toward mapping spatiotemporal characteristics of muscle oxygenation in different motor modalities by multichannel near‐infrared spectroscopy

Commonly, the near‐infrared spectroscopy (NIRS) devices are used to measure muscle oxygenated hemoglobin (HBO) concentration and total hemoglobin (HBT) concentration with a single channel, which can obtain the temporal HBO and HBT signals. Lacking of the spatial information of muscle oxygenation will limit the exploration of the heterogeneity of muscle activities. In this study, a multichannel NIRS recording system was used to measure the muscle oxygenation with an attempt to simultaneously provide the temporal and spatial HBO and HBT concentration. In the experiment, the influences of four motor tasks, including active, passive, imaginary movement, and the control task (no movement), on muscle oxygenation were investigated in eight normal subjects. Our results showed that both amplitude and spatial heterogeneity associated with variation in muscle oxygenation during active and passive motor tasks were significantly different between the motor time and rest time (P < 0.05). Furthermore, the region where HBO concentration decreased during the active motor task was in accordance with the anatomical position of contracted muscle, which cannot be observed from the results of the passive task. Considering the imaginary and control tasks in which the muscle was in a fixed/stationary state, the amplitude and spatial heterogeneity associated with variations in muscle oxygenation only exhibited slight changes (P > 0.05). This pilot study suggested that the spatiotemporal information obtained from multichannel NIRS devices might be potential for accurate measurement of the variation in muscle oxygenation during motor tasks, which would be useful for different clinical applications.     

Statistical analysis of the arc behavior in dry hyperbaric GMA welding from 1 to 250 bar

In this paper, mathematical approaches were developed for predicting the hyperbaric GMAW process arc behavior and stability. The variation of stochastic parameters is related to the electrical stability that can be resolved into a number of varying parameters. The results show that most of the arc instability can be traced to the frequency domain of the voltage or current waveform. Uncorrelated current and voltage wave frequencies at higher pressures are found to have a great influence on process stability.