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111.
Stream fish bioassessment methods assume that fish assemblages observed in sample sites reflect responses to local stressors, but fish assemblages are influenced by local factors as well as regional dispersal to and from connected streams. We hypothesized that fish movement to and from refugia and source populations in connected rivers (i.e., riverine dispersal) would weaken or decouple relations between fish community metrics and local environmental conditions. We compared fish-environment relations between streams that flow into large rivers (mainstem tributaries) and streams that lack riverine confluences (headwater tributaries) at multiple spatial grains using data from the USEPA's Environmental Monitoring and Assessment Program in the mid-Atlantic highlands, USA (n = 157 sites). Headwater and mainstem tributaries were not different in local environmental conditions, but showed important differences in fish metric responses to environmental quality gradients. Stream sites flowing into mainstem channels within 10 fluvial km showed consistently weaker relations to local environmental conditions than stream sites that lacked such mainstem connections. Moreover, these patterns diminished at longer distances from riverine confluences, consistent with the hypothesis of riverine dispersal. Our results suggest that (1) the precision of fish bioassessment metrics may be improved by calibrating scoring criteria based on the spatial position of sites within stream networks and (2) the spatial grain of fish bioassessment studies may be manipulated to suit objectives by including or excluding fishes exhibiting riverine dispersal.  相似文献   
112.
We conducted case studies of three successful examples of collaborative, community-based natural resource conservation and development. Our purpose was to: (1) identify the functions served by interactions within the social networks of involved stakeholders; (2) describe key structural properties of these social networks; and (3) determine how these structural properties varied when the networks were serving different functions. The case studies relied on semi-structured, in-depth interviews of 8 to 11 key stakeholders at each site who had played a significant role in the collaborative projects. Interview questions focused on the roles played by key stakeholders and the functions of interactions between them. Interactions allowed the exchange of ideas, provided access to funding, and enabled some stakeholders to influence others. The exchange of ideas involved the largest number of stakeholders, the highest percentage of local stakeholders, and the highest density of interactions. Our findings demonstrated the value of tailoring strategies for involving stakeholders to meet different needs during a collaborative, community-based natural resource management project. Widespread involvement of local stakeholders may be most appropriate when ideas for a project are being developed. During efforts to exert influence to secure project approvals or funding, however, involving specific individuals with political connections or influence on possible sources of funds may be critical. Our findings are consistent with past work that has postulated that social networks may require specific characteristics to meet different needs in community-based environmental management.  相似文献   
113.
During the second half of the 20th century, the Ganga River ecosystem has been continuously altered by several ongoing anthropogenic processes, accommodating multi-dimensional pressure due to increase of nearly four-fold human population. For solution of any environmental issues of the river, the Earth System Science approach is required to have maximum socio-economic benefits to millions of people living in Indian and Bangladesh. A bibliography containing more than 250 references on environmental studies of the Ganga River was prepared to preserve its ecosystem by providing the baseline support in this regard.  相似文献   
114.
In Asia, limited studies have been published on the association between daily mortality and gaseous pollutants of nitrogen dioxide (NO2), ozone (O3), and sulfur dioxide (SO2). Our previous studies in Wuhan, China, demonstrated long-term air pollution effects. However, no study has been conducted to determine mortality effects of air pollution in this region. This study was to determine the acute mortality effects of the gaseous pollutants in Wuhan, a city with 7.5 million permanent residents during the period from 2000 to 2004. There are approximately 4.5 million residents in Wuhan who live in the city's core area of 201 km2, where air pollution levels are highest, and pollution ranges are wider than the majority of the cities in the published literature. We used the generalized additive model to analyze pollution, mortality, and covariate data. We found consistent NO2 effects on mortality with the strongest effects on the same day. Every 10-microg/m3 increase in NO2 daily concentration on the same day was associated with an increase in nonaccidental (1.43%; 95% confidence interval [CI]: 0.87-1.99%), cardiovascular (1.65%; 95% CI: 0.87-2.45%), stroke (1.49%; 95% CI: 0.56-2.43%), cardiac (1.77%; 95% CI: 0.44-3.12%), respiratory (2.23%; 95% CI: 0.52-3.96%), and cardiopulmonary mortality (1.60%; 95% CI: 0.85-2.35%). These effects were stronger among the elderly than among the young. Formal examination of exposure-response curves suggests no-threshold linear relationships between daily mortality and NO2, where the NO2 concentrations ranged from 19.2 to 127.4 microg/m3. SO2 and O3 were not associated with daily mortality. The exposure-response relationships demonstrated heterogeneity, with some curves showing nonlinear relationships for SO2 and O3. We conclude that there is consistent evidence of acute effects of NO2 on mortality and suggest that a no-threshold linear relationship exists between NO2 and mortality.  相似文献   
115.
Numerical models are often used to evaluate the potential impact of human alternation of natural water bodies and to help the design of the alternation to mitigate its impacts. In the past decade, three-dimensional hydrodynamic and reactive transport modeling has matured from a research subject to a practical analysis technology. This paper presents a practical study in which a three-dimensional hydrodynamic and water quality model [hydrodynamic eutrophication model (HEM-3D)] was applied to determine the optimal location for treated wastewater discharged from marine outfall system in the Keelung harbor and the adjacent coastal sea. First, model validation was conducted with respect to surface elevation, current, and water quality variables measured in the Keelung harbor station and its coastal sea. The overall performance of the model was in qualitative agreement with the available field data. The model was then used to evaluate several scenarios of the locations from marine outfall system. Based on model simulation results, a location at the northeast of Ho-Ping Island was recommended for adoption because the environmental impact is smaller than any other alternative.
Wen-Cheng LiuEmail:
  相似文献   
116.
城市生活垃圾生命周期管理   总被引:20,自引:0,他引:20  
生命周期评价是一种全面的环境管理工具,具有潜在的发展前景。0它通过对产品,产品系统,工艺活动整个生命周期的环境影响环境改善的机会进行评价。根据国际环境毒理与化学学会1993年和ISO14000环境管理体系中关于生命周期评价的技术框架,本文应生命周期评价在城市生产垃圾管理系统中的作用及管理系统的清单分析,影响评价和改善评价进行研究。  相似文献   
117.
BACKGROUND, AIM, AND SCOPE: The use of fish embryos is not regulated by current legislations on animal welfare and is therefore considered as a refinement, if not replacement of animal experiments. Fish embryos represent an attractive model for environmental risk assessment of chemicals since they offer the possibility to perform small-scale, high-throughput analyses. MAIN FEATURES: Beyond their application for determining the acute toxicity, fish embryos are also excellent models for studies aimed at the understanding of toxic mechanisms and the indication of possible adverse and long-term effects. Therefore, we have reviewed the scientific literature in order to indicate alternative applications of the fish embryo model with focus on embryos of the zebrafish. RESULTS AND DISCUSSIONS: The analysis of the mode of action is important for the risk assessment of environmental chemicals and can assist in indicating adverse and long-term effects. Toxicogenomics present a promising approach to unravel the potential mechanisms. Therefore, we present examples of the use of zebrafish embryos to study the effect of chemicals on gene and protein patterns, and the potential implications of differential expression for toxicity. The possible application of other methods, such as kinase arrays or metabolomic profiling, is also highlighted. Furthermore, we show examples of toxicokinetic studies (bioconcentration, ABC transporters) and discuss limitations that might be caused by the potential barrier function of the chorion. Finally, we demonstrate that biomarkers of endocrine disruption, immune modulation, genotoxicity or chronic toxicity could be used as indicators or predictors of sub-acute and long-term effects. CONCLUSIONS: The zebrafish embryo represents a model with an impressive range of possible applications in environmental sciences. Particularly, the adaptation of molecular, system-wide approaches from biomedical research is likely to extend its use in ecotoxicology. RECOMMENDATIONS AND PERSPECTIVES: Challenges for future research are (1) the identification of further suitable molecular markers as indicators of the mode of action, (2) the establishment of strong links between (molecular) effects in short-term assays in embryos and long-term (toxic) effects on individuals, (3) the definition of limitations of the model and (4) the development of tests that can be used for regulatory purposes.  相似文献   
118.
随着我国原油罐区规模的逐渐扩大,原油罐区安全管理也在经受着严峻的挑战。以西北某原油罐区为例,建立了基于ARAMIS体系原油罐区风险评估模型,从识别危险设备出发,找出对应设备的关键事件,建立事故树和事故后果蝴蝶结图,从而建立完整的事故场景,并对事故场景进行风险后果严重度分析;然后考虑到欧盟国家与我国国情存在明显的差异,邀请国内相关专家对人员、环境、设施的相对重要性程度重新进行评估,并根据层次分析法计算得到人员、环境、设施脆弱性指标的权重值,构建了适合我国原油罐区特性的系统脆弱性计算方程;最后,基于风险后果严重度和系统脆弱性评估结果,计算得到系统的风险值,并确定原油罐区系统的风险水平。结果表明:相较于欧盟研究中心调查打分法,我国调查打分法对人员脆弱性指标的权重有所提高,导致计算得到的原油罐区系统整体风险值略高,体现我国对原油泄漏严重后果的重视程度更高,也进一步体现了引入层次分析法并据此制定适于我国国情的原油罐区风险评价方法的必要性。该风险评估结果可为原油罐区火灾事故模拟和制定应急预案提供数据支持和决策依据。  相似文献   
119.
根据HJ/T 10.2-1996中的微波远场轴向功率密度计算公式,对所选取典型WCDMA基站的安全防护距离进行了理论预测,并与实测得到的基站电磁辐射强度达标距离对比.结果表明,理论计算的安全防护距离在水平方向上较实测达标距离更为保守,在垂直方向上则较为接近.从发射功率、话务量、监测条件、建筑物干扰和WCDMA基站特点等方面分析了实测结果与理论计算差异的产生原因,并基于基站副瓣和后瓣实测电磁辐射强度远低于理论预测值的实践,认为WCDMA网络基站运行时的电磁辐射强度超标范围应远小于理论计算结果,其所造成的电磁辐射对环境影响较小.  相似文献   
120.
制药废水硝化-反硝化除氮研究   总被引:12,自引:0,他引:12  
孟怡  徐亚同 《化工环保》1999,19(4):204-207
含高浓度氮的制药废水经好氧生化处理后,虽然出水的COD,BOD5均可达到行业排放标准,但TN仍高达约170mg/L。本研究在曝气池中设置填料,利用生物膜外层好氧,内层缺氧厌氧的条件,使硝化-反硝化脱氮在同一构筑物内进行,NH3-N和TN去除率分别可达约90%和70%。在本试验条件范围内,温度越高,负荷越低,硝化和反硝化作用越完全,NH3-N和TN去除率越高。  相似文献   
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