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991.
The life cycle analysis of a product enables one to assess its environmental quality. A simple, transparent method taking into account the processes of recycling in the life cycle is developed here. It permits dealing with all types of open loops of all sectors. The principles on which the proposed method is grounded are discussed.  相似文献   
992.
A male genital defect was reported in a Nucella lapillus (L.) population at Dumpton Gap (England). This defect was termed Dumpton syndrome (DS) and appears to be a genetic feature. Its main characteristic is the absence of penis (aphally) in males and in females. In 1992, such a phenomenon was discovered in populations in the vicinity of Brest (Brittany, France). DS-affected females exhibit fewer tributyltin-induced imposex characteristics than expected in normal individuals. The percentage of female sterilization is thus lower, favouring population survival. In consequence, the DS is considered to be a pollution-resistance feature. Comparison with the Dumpton population revealed similarities and differences in the DS characteristics. It is thus hypothesized that the DS observed at the two locations is due to two different biological mechanisms. Indeed, aphallic males with a split prostate were observed but no underdevelopment of their vas deferens and testis was noted in the present study. In this gonochoristic gastropod species, the most DS-affected males in Brest possess an ovotestis and it is thus hypothesized that feminity is remnant in N. lapillus. Incidence of abnormality is ten times higher in females than in males. This suggested that a sex-difference operates in the Brest phenomenon.  相似文献   
993.
电解强化人工湿地处理低碳氮比污水的效能及机制   总被引:1,自引:0,他引:1  
钟乐  夏磊  丁杰 《环境科学学报》2020,40(10):3590-3597
针对人工湿地对低碳氮污水处理效果差这一问题,本研究构建了电解强化潮汐流人工湿地系统,通过对比电解强化前后湿地系统脱氮除磷的效果,从微生物群落结构及污染物电化学去除机制等角度揭示电解潮汐流人工湿地强化脱氮脱磷的机制.研究结果表明:电解潮汐流人工湿地对废水中NH4+-N、TN和TP的去除率(分别为88.30%、82.10%和87.74%)均高于未强化的湿地系统.纯电解过程对氨氮的去除没有影响,但是对硝态氮具有还原作用.相比于未强化的湿地系统,电解潮汐流人工湿地阳极附近基质中含有更多的铁氧键、磷氧键、羟基聚合铁等含磷沉淀物,细菌群落结构更为丰富多样,异养反硝化细菌和基于氢气的自养反硝化细菌(Rhodoblastus)丰度都较高,从而实现氮磷的高效同步去除.  相似文献   
994.
探讨了慢性氟暴露致小鼠海马损伤及L-型钙通道拮抗剂的干预作用.将140只初断乳ICR雄性小鼠随机分为7组:对照组(C组)、高氟组(HF组,饮用30 mg·L-1 NaF溶液)、低氟组(LF组,饮用5 mg·L-1 NaF溶液)、高/低氟+L-型钙通道激动剂组(FPL64176)(HF/LF+FPL)、高/低氟+L-型钙通道拮抗剂组(Nifedipine)(HF/LF+NIF).染氟6个月,染氟结束前1周,HF/LF+FPL和HF/LF+NIF组分别每天腹腔注射激动剂或拮抗剂(5 mg·kg-1·d-1).用TUNEL法检测小鼠海马CA1区细胞凋亡水平,用Western Blot法检测细胞膜L-型钙通道Cav1.2、Ca2+信号通路分子和下游凋亡调节相关分子蛋白表达水平等.结果表明,与对照组比,HF/LF组小鼠海马组织抗氧化能力显著降低(p<0.05或p<0.01),细胞凋亡水平极显著上升(p<0.01),Cav1.2与Bcl-2蛋白表达水平显著下降(p<0.05或p<0.01),Ca2+信号转导通路CaM、CaMKII和促凋亡Bax、Bax/Bcl-2蛋白表达水平显著上升(p<0.05或p<0.01).注射FPL64176的小鼠海马细胞和上述分子指标的损伤加剧,而注射NIF对海马细胞和上述分子蛋白表达有一定的逆转作用.提示L-型钙离子通道介导了氟暴露致小鼠海马损伤,氟暴露致海马细胞膜L-型钙离子通道Cav1.2蛋白、细胞内Ca2+信号转导通路分子和下游凋亡调节相关蛋白表达异常是其分子机制之一,而L-型钙通道拮抗剂NIF可能是一种新型有效的抗氟药物.  相似文献   
995.
长江经济带生态环境保护的若干战略问题   总被引:1,自引:0,他引:1       下载免费PDF全文
长江经济带发展是国家区域协调发展的重大战略之一,要保护长江生态环境,走生态优先、绿色发展之路.当前,长江经济带经济增速放缓,产业结构持续优化,城镇化处于快速发展阶段后期;主要污染物排放强度下降,水环境质量改善,但水生态状况堪忧,生态环境质量持续稳定改善进入攻坚期.通过对社会经济和生态环境形势的研判,阐述了长江经济带生态环境保护的战略需求和目标,并提出了四项战略.结果表明:①长江经济带生态环境保护的战略需求从单一要素、单一指标、部分区域转向水生态环境的系统保护和综合修复.②生态环境保护的战略目标由水环境质量改善转向水生态环境安全提升,未来将逐步转向生态环境健康改善.③空间管控战略需要整合多项区域规划,研究构建流域与区域协同、水陆统筹、山海一体的统一的长江经济带生态环境空间单元划分体系.④产业绿色发展战略的核心是在影响水生态环境安全的相关产业领域加强防控.⑤科技创新战略要突出科技平台的作用,推进数据、人才、技术、成果的汇集和创新,实现生态环境保护由投资驱动向科技创新驱动转型.⑥现代治理能力提升战略要求长江经济带建成生态文明先行示范带,率先完善生态文明制度体系,构建生态环境治理体系和提升生态环境治理能力.研究显示,把握长江经济带生态环境保护的战略需求和目标,推行空间管控、产业绿色发展、科技创新和现代治理能力提升战略,能更加有效地支撑长江经济带和长江三角洲一体化的发展.   相似文献   
996.
将压电陶瓷生产过程中不同生产阶段产生的废品应用于氯化丁基橡胶阻尼减振材料,并比较了它们对阻尼减振性能的影响.  相似文献   
997.
周庄旅游者的结构特征及利益追求   总被引:1,自引:0,他引:1  
旅游客源市场由不同结构特征的旅游者组成,其利益追求各不相同,对此加以分析,可以制定正确的营销策略,提供科学依据.以周庄为案例,采用随机抽样问卷调查法,分别对周庄旅游者的性别结构、年龄结构、文化结构、家庭收入水平结构和职业结构进行了分析.结果显示,周庄旅游者以男性游客为主体,25~44岁的中青年游客占大多数;文化程度以大专及以上层次为主,职业构成比较分散,企事业管理人员居多;家庭月收入水平高于全国平均水平.对旅游者的利益追求进行了初步的探讨,并结合游客结构特征和利益追求的分析结果,提出了周庄未来旅游产品的营销策略.  相似文献   
998.
ABSTRACT

Time-series and machine-learning methods are being strongly exploited to improve the accuracy of short-term load forecasting (STLF) results. In developing countries, power consumption behaviors could be suddenly changed by different customers, e.g. industrial customers, residential customers, so the load-demand dataset is often unstable. Therefore, reliability assessment of the load-demand dataset is obviously necessary for STLF models. Hence, this paper proposes a novel and unified statistical data-filtering method with the best confidence interval to eliminate unexpected noises/outliers of the input dataset before performing various short-term load forecasting models. This proposed novel data-filtering method, so-called the data pre-processing method, is also compared to other existing data-filtering methods (e.g. Kalman filter, Density-Based Spatial Clustering of Applications with Noise, Wavelet transform, and Singular Spectrum Analysis). By using an SCADA system?-based database of a typical 22kV distribution network in Vietnam, NYISO database, and PJM-RTO database, case studies of short-term load forecasting have been conducted with a conventional ARIMA model, an ANN forecasting model, an LSTM-RNN model, an LSTM-CNN combined model, a deep auto-encoder (DAE) network, a Wavenet-based model, a Wavenet and LSTM hybrid model, and a Wavelet Neural Network (WNN) model, which are to validate the novel and unified statistical data-filtering method proposed. The achieved numerical results demonstrate which the accuracy of the aforementioned STLF models can be significantly improved due to the proposed statistical data-filtering method with the best confidence interval of the input load dataset. The proposed statistical data-filtering method can considerably outperform the existing data-filtering methods.  相似文献   
999.
The dominating source of particles in urban air is road traffic. In terms of number concentration, its main contribution is within the range of ultrafine particles (Dp < 100 nm). The dispersion conditions, i.e. transport and dilution, of the submicrometer particles are expected to be like for gases and therefore the particle concentrations in a street canyon can be calculated using gaseous pollutants dispersion models. Such processes, like coagulation or condensation, are less important due to the short residence time within the street canyon environment.Two extensive measuring campaigns were conducted in the street Jagtvej in Copenhagen, Denmark. The particle size distributions were measured by a Differential Mobility Analyser (DMA) coupled to a particle counter, providing high time resolution data (1/2 hourly) on a continuous basis. Measurements of NOx, CO and meteorological parameters were also available. The measured particle number concentrations, especially below 100 nm, reveal very similar dependence on the meteorological conditions as the NOx concentrations. This underpins the conclusion that dilution properties are similar for particles and NOx. For particle sizes over 100 nm, somewhat different behaviour is observed. This points toward existence of additional particle sources, not related to traffic emissions within the street canyon. A significant contribution is believed here to be attributed to long-range transport. The total particle emission from traffic, including daily variation and size distribution, has been calculated using the OSPM dispersion model. Results are in accordance with a previous analysis based on statistical modelling.  相似文献   
1000.

The South American country Brazil is one of the richest countries in terms of natural resources, representing 14 percent of the world’s total biocapacity. However, the biocapacity (biosphere’s ability to generate resources and sequester waste) per capita in Brazil has shown a massive decline over the last five decades, while economic growth and urbanization have rapidly increased for the same period. Brazil is one of the largest creditors of biocapacity to the world, and biocapacity loss in Brazil can lead to devastating environmental consequences. Therefore, this work empirically investigates the influence of urbanization, economic growth, and industrialization on biocapacity controlling human capital from 1961 to 2016 in Brazil. The Bayer and Hack cointegration test, the Autoregressive Distributed Lag (ARDL) technique, and Hacker and Hatemi-J (J Econ Stud 39:144–160, 2012) causality tests are employed. The findings unfolded a U-shaped relationship between economic growth and biocapacity, evidencing that economic growth reduces biocapacity, but after achieving a threshold level, it promotes biocapacity. Urbanization has a negative relationship with biocapacity per capita, indicating that urbanization is a significant driver of the biocapacity loss in Brazil. Further, urbanization and economic growth Granger cause biocapacity. Lastly, relevant policy implications are proposed to overcome the reduction in biocapacity.

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