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71.
根据石化企业环境应急工作面临的任务和国内外发展趋势,对企业的环境应急现状和存在问题进行了分析和评价,论述了开展环境应急工作的必要性和紧迫性,探讨了石化企业开展环境应急工作的指导思想和方法。  相似文献   
72.
ADAM暖体假人(Advanced Thermal Manikin)是当今世界上最先进的热能测试人体舒适度模型。是热能测试人体模型技术上的一个飞跃。ADAM是由美国国家可再生资源实验室和美国西北测试科技公司(MTNW)共同研制的,用来精确检测车辆和航行器内短时间的环境变化。ADAM有126个独立的发汗区,可以高度精确地模拟人在不同环境气候条件下的感觉和舒适度,以及人体的各种反应,如出汗、呼吸等等。  相似文献   
73.
The discovery of cell-free DNA (cfDNA) in maternal plasma has opened up new promises for the development of non-invasive prenatal testing (NIPT). Application of cfDNA in NIPT of fetus diseases and abnormalities is restricted by the low amount of fetal DNA molecules in maternal plasma. Fetus-derived cfDNA in maternal plasma are shorter than maternal DNA, thus leveraging the maternal and fetus-derived cfDNA molecules size difference has become a novel and more accurate method for NIPT. However, multiple biological properties such as size distribution of plasma DNA, proportion of fetal-derived DNA and methylation levels in maternal plasma across different gestational ages still remain largely unknown. Further insights into the size distribution and fragmentation pattern of circulating plasma cfDNA will shed light on the origin and fragmentation mechanisms of cfDNA during physiological and pathological processes in prenatal diseases and enhance our ability to take the advantage of plasma cfDNA as a molecular diagnostic tool. In the review, we start by summarizing the research techniques for the determination of the fragmentation profiles of cfDNA in maternal plasma. We then summarize the main progress and findings in size profiles of maternal plasma cfDNA and cffDNA. Finally, we discuss the potential diagnostic applications of plasma cfDNA size profiling.  相似文献   
74.
A comparative study on the metazooplankton community was conducted in three different eutrophic areas, including Lake Wulihu, Meiliang Bay and the central open water area, in Lake Taihu from Oct. 2003 to Sep. 2004. Forty metazooplankton species were identified in Lake Wulihu, 37 in Meiliang Bay, and 34 in the central open water area. The annual average abundance of metazooplankton was 218 ind. l(-1) in the central open water area, 309 ind. l(-1) in Meiliang Bay, and 384 ind. l(-1) in Lake Wulihu. In Lake Wulihu, rotifers, Brachionus calyciflorus and Brachionus angularis, were the dominant species, which contributed 20.9% and 17.2% to the total metazooplankton abundance. Bosmina coregoni and Ceriodaphnia cornuta were the dominant species, contributing 20.4% and 11.3% of the total in Meiliang Bay, and contributing 21.6% and 16.2% of the total in the central open water area. There was a significant positive relationship between rotifers abundance and Secchi transparency. Cladoceran and copepod abundance were positively correlated with total phosphorus and water temperature. Our results show that structures of metazooplankton community differ between the three lake areas with different eutrophic states in Lake Taihu.  相似文献   
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Uniparental disomy (UPD) is an uncommon chromosome condition, but UPD involving chromosome 21 is rarely reported. We reported here a case who had first trimester screening test for Down syndrome, chorionic villus sampling for fetal karyotyping, quantitative fluorescence polymerase chain reaction (QF-PCR), as well as non-invasive prenatal testing (NIPT) by maternal plasma sequencing. There were discordant results between fetal karyotyping and NIPT due to UPD 21combined with confined placental mosaicism of trisomy 21. This demonstrated that it is possible to detect placental mosaicism by NIPT, but further studies are required to confirm its sensitivity. Therefore, all positive NIPT results must be confirmed by conventional invasive test and karyotyping. QF-PCR has the additional benefit in diagnosing UPD. © 2013 John Wiley & Sons, Ltd.  相似文献   
78.
基于余震序列分布信息的地震极灾区快速判断方法研究   总被引:1,自引:0,他引:1  
利用震级加权标准差椭圆法研究了基于震后短期内(24 h)余震序列判定地震极灾区的方法,研究结果表明:1利用该方法判断宏观震中是一种比较可行的方法,不同震源破裂方式的震例利用该方法判断宏观震中的精度不同,倾滑-近倾滑型破裂方式的震例利用余震序列判定宏观震中的精度最高;2整体上看,利用该方法判断极灾区长轴方向的准确性低于利用距震中最近活动断裂判断的准确性,但对于倾滑-近倾滑型破裂方式的震例,利用该方法的准确性高于利用断层数据判定的准确性。  相似文献   
79.
Excessive nitrogen (N) and phosphorus (P) loading of aquatic ecosystems is a leading cause of eutrophication and harmful algal blooms worldwide, and reducing nutrient levels in water has been a primary management objective. To provide a rational protection strategy and predict future trends of eutrophication in eutrophic lakes, we need to understand the relationships between nutrient ratios and nutrient limitations. We conducted a set of outdoor bioassays at the shore of Lake Taihu. It showed that N only additions induced phytoplankton growth but adding only P did not. Combined N plus P additions promoted higher phytoplankton biomass than N only additions, which suggested that both N and P were deficient for maximum phytoplankton growth in this lake (TN:TP = 18.9). When nutrients are present at less than 7.75-13.95 mg/L TN and 0.41-0.74 mg/L TP, the deficiency of either N or P or both limits the growth of phytoplankton. N limitation then takes place when the TN:TP ratio is less than 21.5-24.7 (TDN:TDP was 34.2-44.3), and P limitation occurs above this. Therefore, according to this ratio, controlling N when N limitation exists and controlling P when P deficiency is present will prevent algal blooms effectively in the short term. But for the long term, a persistent dual nutrient (N and P) management strategy is necessary.  相似文献   
80.
Soybean wastewater was used to generate biomass resource by use of purple non-sulfur bacteria (PNSB). This study investigated the enhancement of PNSB cell accumulation in wastewater by Mg2+ under the light-anaerobic condition. Results showed that with the optimal Mg2+ dosage of 10 mg/L, biomass production was improved by 70% to 3630 mg/L, and biomass yield also was improved by 60%. Chemical Oxygen Demand (COD) removal reached above 86% and hydraulic retention time was shortened from 96 to 72 hr. The mechanism analysis indicated that Mg2+ could promote the content of bacteriochlorophyll in photosynthesis because Mg2+ is the bacteriochlorophyll active center, and thus improved adenosine triphosphate (ATP) production. An increase of ATP production enhanced the conversion of organic matter in wastewater into PNSB cell materials (biomass yield) and COD removal, leading to more biomass production. With 10 mg/L Mg2+, bacteriochlorophyll content and ATP production were improved by 60% and 33% respectively.  相似文献   
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