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611.
特种设备作为危险性较大的工业、民用设备,其发生事故所造成的影响,远远大于一般设施。保险作为消化风险、分化补偿的重要方式,尚未与特种设备建立起完善的事故责任保险制度。本文通过国内外相关制度的比较,探讨建立该制度的必要性及社会的迫切需求。  相似文献   
612.
借助箱模式对汞的干沉降过程进行敏感性分析,并利用区域大气环境模式系统Reg AEMS计算中国地区汞干沉降速度的时空分布特征。结果表明,森林下垫面下三类汞(气态零价汞、活性气态汞和颗粒态汞)的干沉降速度较大(0.13、4.5和0.45 cm·s-1),水体表面上的相对较小(0.0012,0.5和0.11 cm·s-1)。敏感性分析发现,三类汞的干沉降速度随着近地层风速增加;降水或者地表湿度降低会导致零价汞和活性气态汞干沉降速度增加;雪盖厚度会减小气态零价汞的干沉降速度而增加活性气态汞的干沉降速度。三类汞的干沉降速度在区域上分布类似,东北以及南部地区最高,华东地区最小。季节变化上,气态零价汞、活性气态汞的干沉降速度在多数下垫面都夏季最大,冬季最小;颗粒态汞季节变化不明显。  相似文献   
613.
614.
为探索高危岗位矿工风险感知的影响因素,在文献研究和复杂适应系统理论分析基础上,从个体角度构建矿工风险感知影响因素的系统动力学模型。运用Vensim 软件模拟仿真各工作时间段中,矿工风险感知水平及各因素对其影响的动态演化过程。研究表明:工作初期,情绪稳定性水平对风险感知水平促进效果显著,工作倦怠的抑制作用较突出;在工作后期,自我效能感对风险感知水平的削弱影响显著,风险规避态度则发挥较大的促进作用;风险知识经验超出一定范围会对风险感知水平起到反作用;安全教育培训与安全监管对风险感知水平的促进作用相对稳定持久。因此,煤矿企业应根据各因素在工作时间段的不同作用,采取相应措施以提高矿工风险感知水平。  相似文献   
615.
为了掌握突发事件下,乘客疏散行为反应;基于某地铁站突发事件区间隧道乘客紧急疏散事故案例,采用观察分析研究乘客在列车车厢内疏散行为特征、疏散路线规律、车厢内惊慌情绪分布及规律。结果表明:乘客疏散行为呈现波浪规律特征扩散传递;乘客惊慌逃散时呈现同年龄段同性别相互聚集现象;乘客惊慌逃散时呈现羊群效应;乘客惊慌逃散路线呈现圆弧现象;乘客惊慌情绪随着距离事故点的距离增加而减弱,呈负相关。为地铁设计人员、地铁安全评估、仿真模型、疏散应急预案提供数值参考,并对地铁站区间隧道存在的安全疏散问题提出优化建议。  相似文献   
616.
The crop models in the Decision Support System for Agrotechnology Transfer (DSSAT) have served worldwide as a research tool for improving predictions of relationships between soil and plant nitrogen (N) and crop yield. However, without a phosphorus (P) simulation option, the applicability of the DSSAT crop models in P-deficient environments is limited. In this study, a soil-plant P model integrated to DSSAT was described, and results showing the ability of the model to mimic wide differences in maize responses to P in Ghana are presented as preliminary attempts to testing the model on highly weathered soils. The model simulates P transformations between soil inorganic labile, active and stable pools and soil organic microbial and stable pools. Plant growth is limited by P between two concentration thresholds that are species-specific optimum and minimum concentrations of P defined at different stages of plant growth. Phosphorus stress factors are computed to reduce photosynthesis, dry matter accumulation and dry matter partitioning. Testing on two highly weathered soils from Ghana over a wide range of N and P fertilizer application rates indicated that the P model achieved good predictability skill at one site (Kpeve) with a final grain yield root mean squared error (RMSE) of 535 kg ha−1and a final biomass RMSE of 507 kg ha−1. At the other site (Wa), the RMSE was 474 kg ha−1 for final grain yield and 1675 kg ha−1 for final biomass. A local sensitivity analysis indicated that under P-limiting conditions and no P fertilizer application, crop biomass, grain yield, and P uptake could be increased by over 0.10% due to organic P mineralization resulting from a 1% increase in organic carbon. It was also shown that the modeling philosophy that makes P in a root-free zone unavailable to plants resulted in a better agreement of simulated crop biomass and grain yield with field measurements. Because the complex soil P chemistry makes the availability of P to plants extremely variable, testing under a wider range of agro-ecological conditions is needed to complement the initial evaluation presented here, and extend the use of the DSSAT-P model to other P-deficient environments.  相似文献   
617.
Wildlife tourism attractions are characterized as having intricately coupled human-wildlife interactions. Accordingly, the ability to mitigate negative impacts of tourism on wildlife necessitates research into the ecology of the system and of the human dimensions, since plans aimed at optimizing wildlife fitness must also be acceptable to tourists. We developed an integrated systems dynamics model for the management of tourist-stingray interactions at ‘Stingray City Sandbar’ (SCS), Cayman Islands. The model predicts the state of the tourism attraction over time in relation to stingray population size, stingray life expectancy, and tourist visitation under various management scenarios. Stingray population data in the model comprised growth rates and survival estimates (from mark-and-recapture data) and mortality estimates. Inputted changes in their respective rates under different management scenarios were informed by previous research. Original research on the demand of heterogeneous tourist segments for management regulations via a stated choice model was used to calculate changes in the tourist population growth rate from data supplied by the Caymanian government. The management attributes to which tourists were responsive also have anticipated effects on stingray ecology (migration and mortality), and vice versa, thus linking the two components. We found that the model's predictions over a 25-year time span were sensitive to the stingray population growth rate and alternate management options. Under certain management scenarios, it was possible to maximize both the tourist segment in favor of no management and stingray numbers while reducing stingray health. However, the most effective relative strategy included a reduction in visitor density, restricted stingray interactions, and an imposition of a small fee. Over time, although fewer stingrays were predicted to remain at SCS, they would live longer and experience fewer stochastic disease events, and the desirable tourist segment was predicted to predominate. By understanding how management will affect tourist activities and their subsequent impacts on both wildlife health and visitor satisfaction, one can explore the management alternatives that would optimize both.  相似文献   
618.
李超  侯成林  吴为中  朱擎 《生态环境》2010,19(12):2960-2965
以滇池流域受污染的大清河为研究对象,开展了人工快速渗滤系统(CRI)示范工程研究,根据气候条件、进水水质和运行工艺分为6个工况,以探索污染负荷和工艺参数对CRI运行性能的影响。实验结果表明:水力负荷2 m.d-1、湿干比1:1是该示范工程运行的最优工艺条件。CRI系统对有机物(COD)的平均去除率范围17.42%~63.75%;对氨氮去除效果受进水水质影响,高、低污染负荷下NH3-N去除率分别为56.71%、85.48%;CRI示范工程硝化作用较强,反硝化能力较弱,对TN的平均去除率范围为10.69%~28.29%;CRI示范工程对TP的平均去除率为27.62%,最佳工艺条件下为50.23%。CRI系统可通过对填料进行优化组合、适当增大饱水带高度,强化除磷脱氮能力。  相似文献   
619.
During the past few decades, construction and demolition (C&D) waste has received increasing attention from construction practitioners and researchers worldwide. A plethora of research regarding C&D waste management has been published in various academic journals. However, it has been determined that existing studies with respect to C&D waste reduction are mainly carried out from a static perspective, without considering the dynamic and interdependent nature of the whole waste reduction system. This might lead to misunderstanding about the actual effect of implementing any waste reduction strategies. Therefore, this research proposes a model that can serve as a decision support tool for projecting C&D waste reduction in line with the waste management situation of a given construction project, and more importantly, as a platform for simulating effects of various management strategies on C&D waste reduction. The research is conducted using system dynamics methodology, which is a systematic approach that deals with the complexity - interrelationships and dynamics - of any social, economic and managerial system. The dynamic model integrates major variables that affect C&D waste reduction. In this paper, seven causal loop diagrams that can deepen understanding about the feedback relationships underlying C&D waste reduction system are firstly presented. Then a stock-flow diagram is formulated by using software for system dynamics modeling. Finally, a case study is used to illustrate the validation and application of the proposed model. Results of the case study not only built confidence in the model so that it can be used for quantitative analysis, but also assessed and compared the effect of three designed policy scenarios on C&D waste reduction. One major contribution of this study is the development of a dynamic model for evaluating C&D waste reduction strategies under various scenarios, so that best management strategies could be identified before being implemented in practice.  相似文献   
620.
浅谈环境监测质量管理工作   总被引:4,自引:0,他引:4  
简述了进一步提升环境监测质量管理水平的形势与政策需求,剖析了影响质量管理工作质量的5方面因素,提出应增强质量管理工作的计划性,提高质量管理人员的业务水平,提高全员的质量意识,有效利用质量管理信息平台进行管理,加强部门问的沟通和交流,充分发挥质量体系的作用。  相似文献   
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