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161.
Group decision-making for leakage management strategy of water network   总被引:2,自引:0,他引:2  
The problem of leakage is complex and requires actions drawn from different aspects of water network management. Inadequate maintenance has serious consequences, both financial and environmental. This paper proposes a group decision-making model based on PROMETHEE V method to aim a leakage management strategy, which takes into account the points of view of four stakeholders, selecting feasible options, and considering the available budget as constraint. Thus, this strategy is the combination of options that will efficiently meet technical, socio-economic and environmental criteria to achieve sustainable development.  相似文献   
162.
运用相关性分析、因子分析及多元线性回归模型对南通市2020—2021年15个监测井第Ⅲ承压层地下水的监测数据进行分析,研究深层地下水中氨氮的主要影响因素。结果表明,氨氮的主要来源是地下水沉积物中有机质的矿化及一部分工业开采引入的氮污染,地下水的还原性环境是氨氮赋存的主要成因;地下水中As、Fe及总硬度含量的同时增加也能反映氨氮含量的提高;硝态氮(NO-3-N)与NH3-N在深层地下水中是竞争关系,当地下水环境处于还原性时,更易于NH3-N的富集。降低深层地下水中氨氮的主要方法是减少有机污染物输入及还原性废水的入渗。  相似文献   
163.
为探究高压设备在承压过程中法兰连接处螺栓受应力情况,基于力磁耦合效应,结合对螺栓拉伸过程中应力分布的有限元仿真,对螺栓进行了轴向拉伸过程中的应力检测,探究了螺纹连接不同位置的磁信号在拉伸过程的变化。试验结果表明:螺母前几扣处应力较大,后几扣处几乎没有应力集中;对螺栓六角头进行磁信号检测,发现六角头处应力集中不明显;对比42CrMo及35CrMo材料试样在相同拉伸及卸载载荷情况下的磁信号,反映了不同材料应力增大均可促进其磁信号发生变化;通过检测螺母有无铁磁性时螺栓拉伸过程中的磁信号,发现螺母所受压应力对磁信号变化影响较大。结果对工程应用磁信号检测金属法兰密封性具有指导性作用。  相似文献   
164.
梅梁湖水体浮游植物与环境因子的关系   总被引:5,自引:1,他引:5  
根据2008年的4月—11月梅梁湖水域应急监测数据,探讨了梅梁湖水体浮游植物与环境因子的关系。相关性分析结果表明,蓝绿藻含量与TP、pH值和DO呈极显著正相关;与TN、SD和EC呈极显著负相关;与NH3-N呈显著负相关。多元逐步回归分析结果表明,梅梁湖浮游植物生长受多个环境因子的共同影响,但主要为TP、TN、水温和风速。  相似文献   
165.
Larsen syndrome is characterized by multiple congenital joint dislocations and flattened facies. Some cases have been familial, with both autosomal dominant and recessive patterns of inheritance. Reports of a form of Larsen syndrome, lethal in the neonatal period, are reviewed. We present a family in which recurrence of the syndrome was diagnosed prenatally, but a lethal outcome again resulted despite preparation for anticipated perinatal complications. Because of the wide clinical variation and the lack of a known metabolic defect, delineation between the various forms of Larsen syndrome is difficult. While the lethal variant appears to be a combination of the Larsen phenotype and pulmonary hypoplasia, other features noted in the lethal cases, such as abnormal palmar creases and laryngotracheomalacia, are also seen in patients with Larsen syndrome who survive.  相似文献   
166.
Many animals use chemical signals in sexual selection, but it is not clear how these sexual traits might have evolved to signal honestly male condition. It is possible that there is a trade-off between maintaining the immune system and the elaboration of ornaments. We experimentally challenged the immune system of male Iberian wall lizards, Podarcis hispanica, with a bacterial antigen (lipopolysaccharide), without pathogenic effects, to explore whether the immune activation affected chemical ornaments. Immune activation resulted in decreased proportions of a major chemical in femoral secretions (cholesta-5,7-dien-3-ol = provitamin D(3)) known to be selected in scent of males by females and which active form (vitamin D) has a variety of important effects on immune system function. This result suggests the existence of a potential trade-off between physiological regulation of the immune system and the allocation of essential nutrients (vitamins) to sexual chemical ornaments in male lizards.  相似文献   
167.
    
Predicting the logarithm of hexadecane/air partition coefficient (L) for organic compounds is crucial for understanding the environmental behavior and fate of organic compounds and developing prediction models with polyparameter linear free energy relationships. Herein, two quantitative structure activity relationship (QSAR) models were developed with 1272 L values for the organic compounds by using multiple linear regression (MLR) and support vector machine (SVM) algorithms. On the basis of the OECD principles, the goodness of fit, robustness and predictive ability for the developed models were evaluated. The SVM model was first developed, and the predictive capability for the SVM model is slightly better than that for the MLR model. The applicability domain (AD) of these two models has been extended to include more kinds of emerging pollutants, i.e., oraganosilicon compounds. The developed QSAR models can be used for predicting L values of various organic compounds. The van der Waals interactions between the organic compound and the hexadecane have a significant effect on the L value of the compound. These in silico models developed in current study can provide an alternative to experimental method for high-throughput obtaining L values of organic compounds.  相似文献   
168.
    
It is widely acknowledged that a simplified and robust approach to evaluating thecombined effects of chemical mixtures is critical for ecological risk assessment(ERA) of contaminated soil. The earthworm( Eisenia fetida) was used as a model to study the combined effects of polymetallic contamination and the herbicide siduron in field soil using a microcosm experiment. The responses of multiple biomarkers, including the activities of catalase(CAT), superoxide dismutase(SOD), glutathione reductase(...  相似文献   
169.
The designation of marine protected areas (MPAs) may have intense social and economic effects on human communities. Driven by overarching global and European policies and national legislations, current systematic conservation planning in the UK and France requires an ecosystem approach that takes into account not only nature but also the human activities that take place in an area. Here, we identified a set of 64 socioeconomic variables potentially relevant for marine and coastal stakeholders in a European context and a comprehensive set of 20 marine and coastal stakeholder categories. Ninety national organisations in the UK and France belonging to those categories and potentially affected by/interested in the designation of multiple-use MPAs were identified and surveyed. Results show that environmental NGOs, research centres, local councils, managing agencies and statutory nature conservation bodies perceived that they are positively affected by these MPAs, whereas fishers’ organisations, shipping and aggregate industrial organisations and recreational organisations perceived to be chiefly negatively affected by MPAs. On average, the ecological effects of multiple-use MPAs are perceived as ‘largely positive’, though 30% of respondents did not perceive any positive ecological effects from these MPAs. The social, economic and cultural effects of such MPAs are perceived as ‘moderately positive’. Most respondents perceived broad range (>10 km) and permanent ecological, social, economic and cultural effects from multiple-use MPA designation suggesting high societal expectations towards these areas. However, only five variables were perceived to vary in intensity after the designation of multiple-use MPAs: ‘research’, ‘environmental performance by citizens, businesses and towns’, ‘number of green businesses’, ‘tourism’ and ‘economic activities’. The most important ‘social’ variables for stakeholder organisations referred to local populations’ engagement with the MPA, tourism and research. The most important ‘economic’ variables were linked to fishing, shipping and aquaculture activities. These variables highlight relevant topics to be considered in MPA planning, designation and management processes, especially in the UK and France. There were statistically significant differences in the ratings of socioeconomic variables between many organisations belonging to the same intuitive stakeholder categories, suggesting the importance of including as wide a range of stakeholder organisations as feasible in MPA socioeconomic-related processes. Our methods and findings can help to inform and streamline ongoing and future participatory MPA planning, management and monitoring processes in Europe and in other regions with similar socioeconomic characteristics.  相似文献   
170.
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