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排序方式: 共有164条查询结果,搜索用时 15 毫秒
61.
新型冠状病毒肺炎疫情(以下简称"新冠肺炎疫情")是一次具有较大环境风险的复合性危机事件,评估总结应对疫情的环境应急管理政策实践进展,识别我国在面对重大疫情时环境应急管理存在的短板具有重要意义。本文通过对新冠肺炎疫情产生的环境影响以及应急措施的进展分析,总结了重大疫情下环境应急管理的经验与不足,建议要健全针对重大疫情的环境应急响应机制,加强环境应急基础能力建设,加快完善支撑保障体系。  相似文献   
62.
The association between gestational infection with human parvovirus (B19) and fetal loss has increased interest in this virus and demand for diagnostic testing. However, serological assays for B19 are not yet widely available. Maternal serum alpha-fetoprotein (MSAFP) testing is commonly used during the second trimester to screen for various fetal defects. We attempted to determine whether an elevated level of MSAFP would be an appropriate indication for B19-specific tests. Over a 26-month period, MSAFP tests were performed at Michigan State University for 21 392 women. Sera remaining after that testing were stored frozen. Of these, 22 case samples—from women with MSAFP levels greater than 3·0 multiples of the median (MOM) and pregnancies that ended in fetal loss—and 44 matched control samples—from women with MSAFP levels greater than 0·4 and less than 2·2 MOM and live births at term—were tested for B19 antibodies. None of the 66 samples was IgM positive, while 33 (50 per cent) were IgG positive. The presence of IgG was not significantly associated with case or control status (matched odds ratio=0·77, 95 per cent confidence interval 0·28–2·11). These findings are consistent with other studies indicating prior infection in approximately half of adults and suggest that elevated screening MSAFP levels, in the absence of other evidence of B19 infection, should not prompt B19-specific testing.  相似文献   
63.
A ring chromosome 19 was found in 14 of 20 metaphases (67 per cent) derived from amniotic fluid cell cultures following amniocentesis because of increased maternal age. Elective termination of the pregnancy revealed a hypotrophic female fetus with mild dysmorphic signs, but no congenital malformations. The case is discussed in relation to three reports in the literature of ring chromosome 19 mosaicism in a phenotypically normal girl, a mentally retarded man, and a boy with normal psychomotor development and minor dysmorphic features.  相似文献   
64.
The coronavirus disease 2019 (COVID-19) pandemic is an unprecedented worldwide health crisis. Many previous research studies have found and investigated its links with one or some natural or human environmental factors. However, a review on the relationship between COVID-19 incidence and both the natural and human environment is still lacking. This review summarizes the inter-correlation between COVID-19 incidence and environmental factors. Based on keyword searching, we reviewed 100 relevant peer-reviewed articles and other research literature published since January 2020. This review is focused on three main findings. One, we found that individual environmental factors have impacts on COVID-19 incidence, but with spatial heterogeneity and uncertainty. Two, environmental factors exert interactive effects on COVID-19 incidence. In particular, the interactions of natural factors can affect COVID-19 transmission in micro- and macro- ways by impacting SARS-CoV-2 survival, as well as human mobility and behaviors. Three, the impact of COVID-19 incidence on the environment lies in the fact that COVID-19-induced lockdowns caused air quality improvement, wildlife shifts and socio-economic depression. The additional value of this review is that we recommend future research perspectives and adaptation strategies regarding the interactions of the environment and COVID-19. Future research should be extended to cover both the effects of the environment on the COVID-19 pandemic and COVID-19-induced impacts on the environment. Future adaptation strategies should focus on sustainable environmental and public policy responses.  相似文献   
65.
Introduction: COVID-19 has disrupted daily life and societal flow globally since December 2019; it introduced measures such as lockdown and suspension of all non-essential movements. As a result, driving activity was also significantly affected. Still, to-date, a quantitative assessment of the effect of COVID-19 on driving behavior during the lockdown is yet to be provided. This gap forms the motivation for this paper, which aims at comparing observed values concerning three indicators (average speed, speeding, and harsh braking), with forecasts based on their corresponding observations before the lockdown in Greece. Method: Time series of the three indicators were extracted using a specially developed smartphone application and transmitted to a back-end platform between 01/01/2020 and 09/05/2020, a time period containing normal operations, COVID-19 spreading, and the full lockdown period in Greece. Based on the collected data, XGBoost was employed to identify the most influential COVID-19 indicators, and Seasonal AutoRegressive Integrated Moving Average (SARIMA) models were developed for obtaining forecasts on driving behavior. Results: Results revealed the intensity of the impact of COVID-19 on driving, especially on average speed, speeding, and harsh braking per 100 km. More specifically, speeds were found to increase by 2.27 km/h on average compared to the forecasted evolution, while harsh braking/100 km increased to almost 1.51 on average. On the bright side, road crashes in Greece were reduced by 49% during the months of COVID-19 compared to the non-COVID-19 period.  相似文献   
66.
吴超 《安全》2020,(2):65-72
为提升安全创新能力和水平及公正评价安全成果,本文从表达安全创新的新概念创设开始,以科学学思想为指导,以元概念演绎法和双向思维法,创设了正负“元事物”“元创事物”“颠覆性元创事物”等系列新概念,将表达安全创新的“负元事物”“负元创事物”和“负颠覆性元创事物”等概念与商业和科技等颠覆性创新对等起来,并推论出正负两类“颠覆性元创事物”所涉及的重要科学问题。之后,通过正负两类“颠覆性元创事物”的比较,并以近期发生的新冠肺炎为典型案例,得到一些发展和鉴别“负颠覆性元创事物”的方法与途径。研究结果对安全科技创新发展和评价等具有重要的理论意义。  相似文献   
67.
68.
为了揭示新冠肺炎疫情下武汉典型饮用水水源中消毒副产物(DBPs)的污染特征与风险水平,选取武汉典型饮用水源地26个采样点位,采用N,N-二乙基-1,4-苯二胺分光光度法和气相色谱仪-微池电子捕获检测器(GC-μECD)法分别对水体中残余氯消毒剂和DBPs进行了检测,并开展健康与生态风险评估.结果表明,26个点位中有16个检出了游离氯或总余氯,检出最大浓度为0.04 mg·L-1,部分点位游离氯超过了国家地表水标准,靠近城市污水厂排水口的点位浓度相对较高.对10个代表性点位进行了34种DBPs的检测,有24种物质被检出,检出率为10.00%~100.00%;ρ(总DBPs)浓度范围为0.11~104.73μg·L-1,平均值为7.26μg·L-1.三氯甲烷检出浓度最高,浓度范围为9.98~11.15μg·L-1,平均值为10.47μg·L-1;一溴一碘乙酰胺检出浓度最低,浓度范围为ND~0.11μg·L-1,平均值为0.01μg·L-1...  相似文献   
69.
The COVID-19 pandemic has highlighted weaknesses in global food systems, as well as opening windows of opportunity for innovation and transformation. While the nature and extent of this crisis is rare, extreme climatic events will increase in magnitude and frequency, threatening similar societal impacts. It is therefore critical to identify mechanisms for developing food systems that are resilient to such impacts. We examine impacts of the crisis on UK food systems and how these further entrenched social inequalities. We present data on the experiences and actions of producers, consumers, and community organisers. The data were collected by adapting ongoing research to include surveys, interviews and online workshops focused on the pandemic. Actors’ responses to the pandemic foreshadow how enduring change to food systems can be achieved. We identify support required to enable these transformations and argue that it is vital that these opportunities are embedded in food justice principles which promote people-centred approaches to avoid exacerbating injustices prevalent pre-crisis. Learning from these experiences therefore provides insights for how to make food systems elsewhere more resilient and just.  相似文献   
70.
2020年初新冠肺炎疫情(COVID-19)暴发后,中国多地实施了严格的管控措施,导致污染物排放量明显下降.但在减排实施的情况下,京津冀PM2.5等污染物浓度较过去5 a同期却明显增长,出现了两次PM2.5重度污染事件.利用欧洲中心ERA5再分析资料分析发现,相对于过去5 a, COVID-19管控期间京津冀地区的气象场表现为偏高的相对湿度、偏低的边界层高度和边界层内异常的辐合上升运动,有利于颗粒物的吸湿增长和二次转化,不利于污染物垂直方向上的扩散.此外,利用WRF-Chem模式开展敏感性试验发现,在京津冀中部地区气象场的变化导致2020年管控期间ρ(PM2.5)升高了20~55μg·m-3,升高比例高达60%~170%.进一步利用过程诊断分析法得出,增强的气溶胶化学过程和不利的湍流扩散条件是2020年COVID-19管控期间PM2.5浓度升高的主要原因.在当今减排的大背景下,边界层高度和相对湿度的变化可能成为预报预测京津冀地区PM2.5污染事件的重要指标...  相似文献   
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