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641.
对石化企业在事故应急预案中安全防护距离的确定给出了各种可以参考的计算方法及参考数据,为企业在事故应急中合理确定安全防护距离提供了决策参考。 相似文献
642.
煤矿作业人员防护服装的设计研究 总被引:1,自引:0,他引:1
煤矿井下作业人员的防护服装对生产的安全、高效有一定的保障作用.本文在调查和分析了井下作业的环境条件、主要工作内容和动作的基础上,对煤矿井下作业人员的防护服装面料的性能要求和设计要点进行了系统的分析.提出了具体的设计方案.本研究的结果可以为此类功能服装的设计与生产提供参考和借鉴. 相似文献
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644.
警用头盔的人机工程学分析 总被引:2,自引:0,他引:2
警用头盔是武警部队使用最为频繁的单兵防护用具,本文基于人机工程学的理论,用人机工程学的观点对武警部队现装备的警用头盔进行分析和探讨,提出解决途径的设想,展望警用头盔的发展前景。 相似文献
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647.
交际法已经发展成为一种世界规模的外语教学理论和教学方法,成为当今世界各国外语教学界普遍承认和接受的基本原则.通过对交际教学法的进一步研究分析,叙述了什么是交际教学法,阐述了运用交际教学法组织大学英语教学的模式和交际教学法在大学英语教学中的运用,指出教师应充分运用交际教学法的基本原理更好地来提高中国英语教学水平. 相似文献
648.
The cellular distributions of Pb and As in the leaves of co-hyperaccumulator Viola principis H. de Boiss. were inspected by synchrotron X-ray fluorescence spectroscopy (SRXRF). The results revealed that Pb and As had similar compartmentalization patterns in the leaves. Both elements were enriched in the bundle sheath and the palisade mesophyll. In comparison with the sheath and the mesophyll, the vascular bundle and the epidermis contained lower levels of Pb and As. The palisade enrichment of Pb and As indicated that V. principis H. de Boiss. may have a special mechanism on detoxification of toxic metals within the mesophyll cells. Relative concentrations of both Pb and As in trichome bases were higher than those in trichome rays. The results of hierarchical cluster analysis and correlation analysis confirmed that the distribution of Pb was similar to that of As in the leaves, and their distribution patterns were different from the nutrient elements, such as K, Ca, Mn, Fe, Ni, Cu and Zn. In vivo cellular localization of Pb and As in the leaves provides insight into the physiological mechanisms of metal tolerance and hyperaccumulation in the hyperaccumulators. 相似文献
649.
Degradation of methyl orange under gamma-irradiation was investigated. The reactions followed pseudo first-order kinetics. Apparent degradation rate constant, estimated through linear regression analysis, increased with an increase of dose rate and a decrease of initial methyl orange concentration. Degradation of methyl orange was significantly accelerated under oxidative condition, but was slightly enhanced under reductive condition. However, the result of decoloration was better under reductive condition than oxidative one. An analysis on the intermediates using Fourier transform infrared and gas chromatography/mass spectrometry demonstrates that the radiolytic degradation of methyl orange was processed with different C-N cleavages under oxidative and reductive conditions. 相似文献
650.
Enhancement of heavy metal accumulation by tissue specific co-expression of iaaM and ACC deaminase genes in plants 总被引:1,自引:0,他引:1
The aerobic riboflavin (Rf)-sensitized photodegradation of the endocrine disruptor 4,4'-isopropylidenebisphenol (bisphenol A, BPA), and of the related compounds 4,4'-isopropylidenebis(2,6-dibromophenol) and 4,4'-isopropylidenebis(2,6-dimethylphenol) has been studied in water and water-methanol mixtures through visible-light continuous photolysis, polarographic detection of oxygen uptake, stationary and time-resolved fluorescence spectroscopy, time-resolved near-IR phosphorescence detection and laser flash photolysis techniques. Bisphenols (BPs) quench excited singlet and triplet states of Rf, with rate constants close to the diffusion limit. BPs and dissolved molecular oxygen, employed in similar concentrations, competitively quench triplet excited Rf. As a consequence, superoxide radical anion and singlet molecular oxygen (O(2)((1)Delta(g))) are produced by electron- and energy-transfer processes, respectively, as demonstrated by auxiliary experiments employing selective quenchers of both oxidative species and the exclusive O(2)((1)Delta(g)) generator Rose Bengal. As a global result, the photodegradation of Rf is retarded, whereas BPs are degraded, mainly by an O(2)((1)Delta(g))-mediated mechanism, which constitutes a relatively efficient process in the case of BPA. Oxidation, dimerization and fragmentation products have been identified in the photooxidation of BPA. Results indicate that BPs in natural waters can undergo spontaneous photodegradation under environmental conditions in the presence of adequate photosensitizers. 相似文献