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141.
分析了传统空管裂解生产四氟乙烯工艺存在的污染问题 ,介绍了水蒸汽稀释裂解生产四氟乙烯工艺的污染控制情况。 相似文献
142.
Mary C. Phelan Ph.D. Robert A. Saul Thompson A. Gailey Jr Steven A. Skinner 《黑龙江环境通报》1995,15(3):274-277
Mosaicism for the Wolf-Hirschhorn syndrome, del(4)(p16), is extremely rare and has not been reported in association with a numerical chromosome abnormality. We report the prenatal diagnosis of mosaic del(4)(p16) and non-mosaic trisomy 21 in a 16-week female fetus. The pregnancy ended in spontaneous abortion at 34 weeks secondary to fetal demise. The fetus had features of both 4p – and trisomy 21. 相似文献
143.
Forty-two open neural tube defects (NTDs) were identified in our series of 7440 amniocenteses tested between 11 and 15 weeks of gestation. Using a cut-off of ≥2.0 MOM, the detection rate for open NTDs was 95 per cent; 100 per cent each for anencephaly and spina bifida; and 78 per cent for encephalocele. Two encephaloceles had AFP levels less than 2.0 MOM and negative AChEs. Thirty-four (81 per cent) of these NTDs were tested between 13 and 15 weeks and 8 (19 per cent) before 13 weeks. There were 0.6 per cent false positives by AFP (excluding serious abnormalities and fetal death) and 0.1 per cent after AChE. The likelihood of an open NTD after an elevated AFP (≥2.0 MOM) was 24 and 77 per cent for any serious abnormality. These results, when combined with an earlier study, indicate that amniotic fluid AFP appears to be as sensitive a test for open NTDs between 13 and 15 weeks as between 16 and 20 weeks. Additional experience is necessary to determine this before 13 weeks. 相似文献
144.
The curve of ion exchange ratio(%)-pH of the interactionbetween suspended particles with Cd(II) in the Yellow River wasstudied. The effects of lysine on this curve have been alsoinvestigated. The results showed that (1) Cadmium in Cd(OH)+ formin the suspended particles exchanges with the cations.The exchangeratio of Cd2+ is nearly at its greatest value in the range of pH(8.0-8.5) in natural aquatic system; (2) Ion exchange ratiodecreases as the concentration of Cd2+ raises from 8.9×10-6 mol/L to 2x8.9 x 10-6mol/L; (3) At the lysine concentration of 6.8x10-6 mol/L, it can promote the ion exchange ratio; (4) Adsorption of thesuspended particles to cadmium is weaker in seawater and Jin ShaRiver than in the Yellow River. 相似文献
145.
146.
粤西震旦系Z~b组和Z~c组是重要的含金建造。原岩为一套陆源碎屑岩,其中夹有少量中酸性凝灰岩。建造中的金丰度高于克拉克值2-4倍,金的丰度及其分布主要受变质岩的基性程度,硫化物及有机质数量控制。 相似文献
147.
148.
为探讨中国臭氧短期暴露与死亡率之间的关系,更新适用于中国本地化的暴露-反应系数,本研究全面检索了1990年1月1日-2020年1月1日在Web of Science数据库、PubMed、中国期刊全文数据库(CNKI)、万方医学数据库和维普数据库上发表的文献,以"O3/臭氧(ozone)"、"空气污染(air pollution)"、"死亡率(mortality)"、"时间序列(time-series)","病例交叉(case-crossover)"、"中国(China)"为关键词,对符合纳入标准的文献进行质量评价后提取相关数据,通过Meta分析方法合并估计值.结果显示,大气中臭氧浓度每增加10 μg·m-3,人群总死亡率、心血管系统疾病和呼吸系统疾病死亡率分别增加0.40%(95% CI:0.28%~0.52%)、0.67%(95% CI:0.46%~0.88%)、0.23%(95% CI:-0.20%~0.66%).亚组分析结果表明,除季节外,温度、年龄、性别均不存在显著的修饰作用.本文结论可为开展城市大气污染健康风险精细化评估提供依据. 相似文献
149.
HydrolyticdynamicsofpesticideN'-(2,4-dimethylphenyl)-N-methylformamidineinaquaticsolution¥MoHanhong;YangKewu;AnFengchun;LiuYe... 相似文献
150.
Gong Peiyu Li Xiuzhen Wu Kunjun Shu Jianmin Cao Hongfa Institute of Zookogy Academia Sinica Beijing ChinaInstitute of Zookogy Chinese Research Academy of Environmental Science Beijing China 《环境科学学报(英文版)》1990,(4)
This paper deals with effects of airborne fluorine on the army worm, Mythimna separata (Walker), by rearing the larvae on the wheat foliage exposed to HF or fumigating the larvae on the artificial diet with the pollutant. Larval relative growth rate (GR) and index of population trend of the insect reduced by 5% and 11%, respectively, when the larvae were reared on the foliage taken from the wheat plants exposed to 0.87 g·dm-2·day-1 of fluorine compared with those of the control. An extra instar appeared in a majority of the larvae treated. Survival rate and GR of the larvae on the wheat plant being exposure to the same concentration of fluorine in field open-top fumigation device were 40% and 15% lower than that of the control, respectively. Similar experiment with the insect on the artificial diet also showed that direct impact of the pollutant on the army worm was greater than its indirect effect via their host plant. 相似文献