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351.
352.
以气相色谱石英毛细管柱分离、FID检测,测定废水和废气中N′,N-二甲基甲酰胺(DMF)。在10mg/L~18810mg/L范围内有良好的线性关系。检测限:废水为05mg/L;废气为08mg/m3。样品测定的相对标准差为4%~8%,回收率在76%~112%之间,精密度和准确度均较好 相似文献
353.
354.
对硝基苯酚在沉积物上的吸附特性1 总被引:3,自引:0,他引:3
研究了沉积物吸附对硝基苯酚的作用机理及影响因素.结果表明,对硝基苯酚在沉积物上的吸附由其中的有机质含量和结构决定,体系的pH值对对硝基苯酚的吸附有较大的影响,其主要原因是体系的pH值控制着沉积物中有机质的溶出量.在实验浓度范围内,分配作用在沉积物吸附对硝基苯酚中占主导地位. 相似文献
355.
356.
根据《江苏统计年鉴 (1 999)》等相关资料 ,对江苏耕地资源利用中存在的一些问题进行了分析与总结 ,在此基础上 ,对实现江苏耕地资源可持续利用的相关对策进行了探讨 相似文献
357.
贵州省煤中挥发性和半挥发性微量元素分布规律的初步研究 总被引:25,自引:0,他引:25
研究了贵州省四大煤田不同层位、不同煤种中Hg,As,Se,Pb,Cd,Tl,Zn,Sb等挥发性和半挥发性微量元素的分布规律。贵州省原煤中Hg,As,Se,Pb,Cd,Sb等元素的含量高于地壳克拉克值;Tl,Zn等的含量低于地壳克拉克值;另外,除了Pb,Zn外,贵州省原煤中Hg,As,Se,Cd的含量远远高于东北和内蒙古东部地区。微量元素聚类分析结果表明,Hg,As,Sb可能主要分布于煤的黄铁矿中;Zn和Se可能主要赋存于闪锌矿中;Cd可能部分存在于硫化物中,部分存在于硅酸盐矿物相中;Pb可能主要存在于硅酸盐矿物相中;而Tl在煤中的赋存形式较复杂。 相似文献
358.
During early development in fish, phospholipase A2 (EC 3.1.1.4) regulates membrane lipid modifications, which relates to changes in environmental conditions and provision of
fatty acids required for metabolic energy substrates and prostaglandin biosynthesis. A method to analyze phospholipase A2 in rat tissues has been modified to measure its activity in embryonic Atlantic halibut (Hippoglossus hippoglossus L.). Egg and embryo samples were collected during the 1994 spawning season. Enzyme activity was undetectable at fertilization
but in 10-d embryos was 230 pmol mg−1 h−1 (at 20 °C) and increased by ∼120% at hatch (17-d). Significant alterations in the fatty acid composition of important phospholipids,
phosphatidylcholine (PC) and phosphatidylethanolamine (PE), were also observed. The content of some critical polyunsaturated
fatty acids, and the ratio of unsaturated/saturated fatty acids, declined significantly over development. Acyl-chain restructuring
mediated through the activity of phospholipase A2, coupled with other observed lipid changes (significant increases in the PC/PE ratio and cholesterol content), would produce
a decreased fluidity of membranes during embryonic development, coinciding with the predicted upward movement of larvae in
the water column. Arachidonic acid (20:4n-6) removed from PE could serve as a precursor for biosynthesis of 2-series prostaglandins, and eicosapentaenoic acid (20:5n-3) from PC is a likely source for other prostaglandin types. Despite removal of polyunsaturated fatty acids, there was an
overall increase in lipid and fatty acid concentration, which can be attributed to amino acid catabolism during early developmental
stages.
Received: 9 September 1996 / Accepted: 8 September 1997 相似文献
359.
1—硝基芘对斜生栅藻的毒性研究 总被引:2,自引:2,他引:0
酿要用评价化学品对藻类毒性的标准实验方法,研究了1-硝基芘对斜生栅藻生长的影响,得到了1-NP抑制斜生栅藻生长的EC50(96h)为0.1824mg.1^-1,实验结果还表明,1-NP对藻生长的抑制作用随时间的延长而增加,抑制物性表现为特久且强度大,抑制机理为不可逆性抑制。 相似文献
360.
Lan Q Cui K Zeng F Zhu F Liu H Chen H Ma Y Wen J Luan T Sun G Zeng Z 《Environmental monitoring and assessment》2012,184(8):4921-4929
Phthalate esters (PAEs) were examined in indoor and outdoor dust samples from the subtropical city of Guangzhou, China. The ∑(16)PAEs concentrations ranged from 121 to 3,223 μg g(-1) dust, with the median concentration of 840 μg g(-1) dust. Significantly higher concentrations of PAEs in dust samples were found in offices where electrical and electronic devices, carpet pads, and office furniture were widely used. Of the 16 PAEs, diisobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP), and di(2-ethylhexyl) phthalate (DEHP) dominated the PAEs in indoor and outdoor dust samples, and accounted for >96.8% and >93.1% of the ∑(16)PAEs concentrations, respectively. The median daily inhalation exposure of ∑(16)PAEs were 3.53 and 0.247 μg kg(-1) body weight day(-1), and at the 95(th) percentile were 7.62 and 0.530 μg kg(-1) body weight day(-1), up on the measured concentrations and estimated dust ingestion rates, respectively, for toddles and adults. The ubiquitous distribution of PAEs as noted in this study suggests the need for detailed assessment of PAEs concentrations using more sites and to further investigate the factors influencing PAEs exposure in China. 相似文献