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781.
782.
针对高温螺栓的蠕变变形失效,通过组织成分和表面形貌分析查找材料塑性下降、蠕变失效的原因,并从控制元素含量和热处理工艺方面提出了应对措施. 相似文献
783.
Antimony speciation in the environment: Recent advances in understanding the biogeochemical processes and ecological effects 总被引:2,自引:0,他引:2
Mengchang He Ningning Wang Xiaojing Long Chengjun Zhang Congli M Qianyun Zhong Aihua Wang Ying Wang Aneesa Pervaiz Jun Shan 《环境科学学报(英文版)》2019,31(1):14-39
Antimony(Sb) is a toxic metalloid, and its pollution has become a global environmental problem as a result of its extensive use and corresponding Sb-mining activities. The toxicity and mobility of Sb strongly depend on its chemical speciation. In this review, we summarize the current knowledge on the biogeochemical processes(including emission, distribution,speciation, redox, metabolism and toxicity) that trigger the mobilization and transformation of Sb from pollution sources to the surrounding environment. Natural phenomena such as weathering, biological activity and volcanic activity, together with anthropogenic inputs, are responsible for the emission of Sb into the environment. Sb emitted in the environment can adsorb and undergo redox reactions on organic or inorganic environmental media, thus changing its existing form and exerting toxic effects on the ecosystem. This review is based on a careful and systematic collection of the latest papers during 2010–2017 and our research results, and it illustrates the fate and ecological effects of Sb in the environment. 相似文献
784.
在实验室测定了环嗪酮有不同pH条件下的水解、不同土壤中的降解及其在直径为2cm长为30cm的玻璃管中的淋溶移动情况,试验结果表明,环嗪酮在pH为5、7、9三种不同缓冲溶液中的水解半衰期分别为5179.3、2413.9、866.4天;在东北黑土、江苏黄棕壤、浙江黄壤与江西红壤四种不同土壤中的降解半衰期分别为40.3、9.6、77.1和120.3天;在上述四种土壤中的移动速率次序为东北黑土<江苏黄棕<浙江黄壤<江西红壤。田间试验结果表明,环嗪酮在试验区土壤中的淋溶性能极高,施药后半月内即可淋溶到60~120cm深的土层中,淋溶到60cm以下土层中的量占环嗪酮总使用量的14.7%,在试验区内外的观测井中也检测到它的残留。但其在土壤的消失速率也很快,施药2个月后,在试验区各土层与观测井中均已无残留检出,在试验区环境条件下,它的使用将不会导致对地下水的污染。 相似文献
785.
Kai Li Hui Chen Yajuan Wang Zhihua Shan Jeff Yang Patrick Brutto 《Journal of Cleaner Production》2009,17(17):1603-1606
During the last few decades new materials and technologies have being studied and applied in order to reduce the ecological impact of leather production. Severe restrictions imposed by the pollution control authorities on the disposal of chromium, total dissolved solids and chlorides in tannery effluents have forced the tanners and researchers to look for eco-benign pickling and tanning processes. In this study, we would focus on the novel process development of pickling with the presence of oxazolidine based product. Investigations indicated that oxazolidine is a potential material to replace neutral salts in pickling and, realize high chrome exhaustion in the subsequential chrome tanning. 相似文献
786.
介绍了基于VB SQL SERVER电子阅览室登录系统的设计与实现.从数据库设计、操作过程等方面讨论了所遇到的并解决的关键问题:登录功能的实现,语音功能、上机计时收费、打印收费功能以及各种统计查询功能的实现等,形成了一个完整的,功能较为齐全的,安全性和工作效率较高的电子阅览室登录系统. 相似文献
787.
788.
789.
Li H. Shi Shan Zhao Ting Gui Jin Xu Fei Wang 《Journal of environmental science and health. Part. B》2013,48(11):761-769
ABSTRACTThe degradation dynamics and terminal residues of dufulin enantiomers were investigated in two typical corn plants. A convenient and precise chiral method by high-performance liquid chromatography coupled with tandem triple quadrupole mass spectrometry (HPLC/MS/MS) using a Chiralpak IC column was developed and validated for measuring dufulin enantiomers in corn plants and corn. The two enantiomers of dufulin quickly dissipated in the corn plant, and no noticeable stereoselectivity was observed during degradation or in the final residues. After 30% rac-dufulin wettable powder with a 1- to 1.5-fold dose of the recommended value was sprayed two to three times on corn plants, the residue levels of S-(+)-dufulin and R-(-)-dufulin in corn from both sites were lower than or equal to 0.0520 mg kg–1 on days 7, 14 and 21 after the last application. The dietary risk assessment indicated that dufulin did not exhibit obvious dietary health risks in corn samples when good agricultural practices were implemented. The findings from this study may be used to better understand the chiral profiles of dufulin in the environment and the effect of dufulin residues in corn on health. 相似文献
790.
用陶瓷膜做滤材处理含油废水的研究 总被引:6,自引:0,他引:6
本实验是以无机膜之一的陶瓷做滤材,对含油污水处理进行研究.探讨了含油种类与膜的性质、含油浓度和透过速度的关系及反冲洗对透过速度的影响.通过实验证明:轻质油比重油的透过速度大;油水中含油浓度对透过浓度影响不大;反冲洗会使透过速度得到恢复;浊度去除率可达96%以上,陶瓷膜超滤法处理含油废水是可行的. 相似文献