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131.
During prenatal diagnosis for advanced maternal age, a pericentric inversion of a chromosome 19 was detected in a male fetus. The inversion was familial, transmitted to the fetus by the phenotypically normal mother. The pregnancy resulted in a term birth of a phenotypically normal male infant. Inversion 19 appears to be a rare abnormality with only seven families reported thus far including ours. Infants with duplication deficiencies for chromosome 19 have not been reported in these families. This may suggest an apparent suppression of crossing over and recombination within the inverted segment of chromosome 19 during meiosis.  相似文献   
132.
研究了天然水中19种金属元素间的干扰,可测μg/L级金属元素.回收率91-103%.  相似文献   
133.
To control the spread of COVID-19, rigorous restrictions have been implemented in China, resulting in a great reduction in pollutant emissions. In this study, we evaluated the air quality in the Yangtze River Delta during the COVID-19 lockdown period using satellite and ground-based data, including particle matter (PM), trace gases, water-soluble ions (WSIs) and black carbon (BC). We found that the impacts of lockdown policy on air quality cannot be accurately assessed using MODIS aerosol optical depth (AOD) data, whereas the tropospheric nitrogen dioxide (NO2) vertical column density can well reflect the influences of these restrictions on human activities. Compared to the pre-COVID period, the PM2.5, PM10, NO2, carbon monoxide (CO), BC and WSIs during the lockdown in Suzhou were observed to decrease by 37.2%, 38.3%, 64.5%, 26.1%, 53.3% and 58.6%, respectively, while the sulfur dioxide (SO2) and ozone (O3) increased by 1.5% and 104.7%. The WSIs ranked in the order of NO3? > NH4+ > SO42- > Cl? > Ca2+ > K+ > Mg2+ > Na+ during the lockdown period. By comparisons with the ion concentrations during the pre-COVID period, we found that the ions NO3?, NH4+, SO42?, Cl?, Ca2+, K+ and Na+ decreased by 66.3%, 48.8%, 52.9%, 56.9%, 57.9% and 76.3%, respectively, during the lockdown, in contrast to Mg2+, which increased by 30.2%. The lockdown policy was found to have great impacts on the diurnal variations of Cl?, SO42?, Na+ and Ca2+.  相似文献   
134.
With a unique and large size of testing results of 1,842 samples collected from 12 wastewater treatment plants (WWTP) for 14 months through from low to high prevalence of COVID-19, the sensitivity of RT-qPCR detection of SARS-CoV-2 RNA in wastewater that correspond to the communities was computed by using Probit analysis. This study determined the number of new COVID-19 cases per 100,000 population required to detect SARS-CoV-2 RNA in wastewater at defined probabilities and provided an evidence-based framework of wastewater-based epidemiology surveillance (WBE). Input data were positive and negative test results of SARS-CoV-2 RNA in wastewater samples and the corresponding new COVID-19 case rates per 100,000 population served by each WWTP. The analyses determined that RT-qPCR-based SARS-CoV-2 RNA detection threshold at 50%, 80% and 99% probability required a median of 8 (range: 4-19), 18 (9-43), and 38 (17-97) of new COVID-19 cases /100,000, respectively. Namely, the positive detection rate at 50%, 80% and 99% probability were 0.01%, 0.02%, and 0.04% averagely for new cases in the population. This study improves understanding of the performance of WBE SARS-CoV-2 RNA detection using the large datasets and prolonged study period. Estimated COVID-19 burden at a community level that would result in a positive detection of SARS-CoV-2 in wastewater is critical to support WBE application as a supplementary warning/monitoring system for COVID-19 prevention and control.  相似文献   
135.
杭州COVID-19期间大气VOCs体积分数变化特征   总被引:3,自引:1,他引:3  
2019年12月1日至2020年3月31日新型冠状病毒肺炎(COVID-19)期间,采用Syntech Spectras GC955在线气相色谱仪对杭州市大气环境中挥发性有机物(VOCs)进行了在线连续监测,分析了 VOCs的组成特征、日变化规律和大气化学反应活性.结果表明,不同站点疫情前φ(总VOCs)均最高,一级响...  相似文献   
136.
利用挥发性有机物(VOCs)在线监测数据对新冠肺炎疫情(COVID-19)期间(2019年12月25日~2020年2月24日)雄安地区环境空气中VOCs进行监测,探讨了疫情防控前、后VOCs的变化特征、臭氧生成潜势及来源解析.结果表明,疫情防控后φ(TVOCs)平均值为45.1×10-9,约为疫情防控前φ(TVOCs)...  相似文献   
137.
Reduction in air pollution level was prime observation during COVID-19 lockdown globally. Here, the study was conducted to assess the impact of lockdown on the elemental profile of PM10 in ambient aerosol to quantify the elemental variation. To quantify the variation, phase-wise sampling of air pollutants was carried out using the gravimetric method for PM10, while NO2 and SO2 were estimated through the chemiluminescence and fluorescent spectrometric method respectively. The elemental constituents of PM10 were carried out using an Inductively Coupled Plasma Optical Emission Spectrometer and their source apportionment was carried out using the Positive Matrix Factorization model. The results showed that PM10, NO2 and SO2 reduced by 86.97%, 83.38%, and 88.60% respectively during the lockdown sampling phase. The highest mean elemental concentration reduction was found in Mn (97.47%) during the lockdown. The inter-correlation among the pollutants exhibited a significant association indicating that they originate from the same source. The metals like Mn and Cu were found at a higher concentration during the lockdown phase corresponding to vehicular emissions. The comparative analysis of the elemental profile of PM10 concluded that the lockdown effectuated in reduction of the majority of elements present in an aerosol enveloping metropolitan like Kolkata.  相似文献   
138.
近年来,中国经济发达地区以细颗粒物(PM2.5)和臭氧(O3)共同引发的区域性复合型大气污染事件频发,大气氧化性(AOC)在其中发挥着重要作用.基于WRF-CMAQ模型,以2020年疫情管控期为案例探究人为源减排对AOC的影响,选取中国东部3个典型城市(石家庄、南京和广州)进行深入分析,量化排放变化及气象变化对氧化剂和AOC变化的贡献,探讨AOC变化对二次污染物生成的影响.结果表明,与2019年同期相比,2020年石家庄、南京和广州的城市平均AOC分别增加了60%、48.7%和12.6%;氧化剂臭氧、羟基自由基和硝酸根自由基的浓度均有不同程度的增加(1.6%~26.4%、14.8%~73.3%和37.9%~180%).排放变化使3个城市AOC分别增加了0.06×10-4、0.12×10-4和0.33×10-4 min-1,气象变化导致石家庄和南京AOC增加(分别为20%和17.9%),但在广州却相反(-9.3%).增强的AOC导致氮氧化速率和挥发性有机物氧化速率升高,即促进了一次污染物向二次污染物的转化,并抵消了部分一次减排的影响,造成了管控期间二次污染物相对排放的非线性变化.  相似文献   
139.
Although often overlooked, pets and other animals intersect with organizations in interesting, important ways. We seek to define how various animals intersect with organizations, highlight opportunities for theory development, and illustrate important areas for future research. We also explore how pandemics such as COVID-19 might affect the animals we highlight.  相似文献   
140.
新冠肺炎疫情管控期间为探究空气质量变化机制提供了良好的控制环境。基于监测站点数据,运用数理统计和空间分析法探讨污染物时空变化特征及相关性,利用聚类分析、潜在源贡献、浓度权重轨迹分析乌鲁木齐市三次管控期首要污染物(PM2.5)的潜在来源。结果表明:(1)整体来看,三次管控期PM2.5、PM10、CO、NO2、SO2浓度平均分别下降15.02 μg∙m−3、36.83 μg∙m−3、0.26 mg∙m−3、19.83 μg∙m−3、1.18 μg∙m−3,O3浓度平均上升9.15 μg·m−3。日内变化上,PM2.5、PM10、CO、NO2浓度呈现“W”型,SO2、O3呈现“几”字型,各污染物浓度季节差异明显。高值区集中在新市区、天山区、水磨沟区、沙依巴克区及头屯河区的东南部,低值区集中在城郊。(2)温度对PM2.5、O3影响较为显著,相对湿度对CO、NO2影响较为显著;整体上,夏季气象因子与污染物之间相关性较差。(3)乌鲁木齐管控期主要气团沿天山山脉的走向流动,受到西风的长距离气流和盆地内部的短距离气流双重影响。乌鲁木齐市空气质量变化受多种气象条件及气团相互运动影响,研究结果可为今后城市大气污染控制提供参考。  相似文献   
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