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821.
人员疏散是高层建筑火灾应急管理中重要问题之一。仅依靠楼梯无法在火灾初期安全快速地大批量疏散人群,必须引入其他疏散途径,才能达到安全疏散的要求,而引入电梯,实现楼梯电梯耦合疏散,成为未来高层建筑火灾垂直疏散的新趋势之一。运用BuildingEXODUS从不同建筑高度、不同人群密度、不同人员类型3个方面,运用楼梯模式、A型Shuttle Floor模式、B型Shuttle Floor模式、Sky Lobby模式4种模式进行模拟,提出每种情况的最优疏散策略。研究结果表明:任何层数的高层建筑都存在1个或数个最佳分离楼层使楼梯电梯耦合疏散的效率最高;在运用楼梯以及耦合方案2时,疏散时间与建筑高度呈线性关系,且随着楼层的增高耦合方案2所用疏散时间越来越接近楼梯疏散时间的二分之一;不同人群密度与最佳分离楼层无关;当人员平均疏散能力较高时,最佳分离楼层会上移反之则会下降。  相似文献   
822.
为给研究建筑领域节能减碳提供参考,简要介绍了碳排放核算的一般性方法,重点阐述了微观单体建筑碳排放和宏观层面建筑物化和运行碳排放核算模型方法的特点以及研究现状,分析了3类主要模型方法(IPAT系列模型、指数分解分析方法和结构分解分析方法)的优缺点及应用情况,并聚焦于建筑领域,综述了建筑碳排放影响因素研究的几个关键问题,即研究范围、研究方法和关键影响因素。最后,从建筑碳排放的核算范围、核算方法、影响因素等方面进行了展望,指出现有研究的不足和未来研究的方向。  相似文献   
823.
The importance of solving the employment problems by nongovernmental economy in China has aroused the concern of many scholars widely. However, few literatures could be found to deal with the impacts on nonagricultural employment growth in China by nongovernmental economy from several levels such as the whole nation, urban and rural. Based on the research accessed on the relationships between nongovernmental economy and employment, the impacts of the development of nongovernmental economy on non-agricultural employment growth in China are emphasized in this paper. Taking time series data of non-agricultural employment in China's different economy types in 1992-2005 as study objects, by establishing econometric regression models, some meaningful points are found as follows, the impacts of nongovernmental economy on the nonagricultural employment in either national or urban-rural level are rather significant although their impacts' degrees are different. Based on the research findings above, some countermeasures are proposed to accelerate the nongovernmental economic development and improve its ability to absorb nonagricultural employment.  相似文献   
824.
Understanding global sea levels: past, present and future   总被引:4,自引:0,他引:4  
The coastal zone has changed profoundly during the 20th century and, as a result, society is becoming increasingly vulnerable to the impact of sea-level rise and variability. This demands improved understanding to facilitate appropriate planning to minimise potential losses. With this in mind, the World Climate Research Programme organised a workshop (held in June 2006) to document current understanding and to identify research and observations required to reduce current uncertainties associated with sea-level rise and variability. While sea levels have varied by over 120 m during glacial/interglacial cycles, there has been little net rise over the past several millennia until the 19th century and early 20th century, when geological and tide-gauge data indicate an increase in the rate of sea-level rise. Recent satellite-altimeter data and tide-gauge data have indicated that sea levels are now rising at over 3 mm year−1. The major contributions to 20th and 21st century sea-level rise are thought to be a result of ocean thermal expansion and the melting of glaciers and ice caps. Ice sheets are thought to have been a minor contributor to 20th century sea-level rise, but are potentially the largest contributor in the longer term. Sea levels are currently rising at the upper limit of the projections of the Third Assessment Report of the Intergovernmental Panel on Climate Change (TAR IPCC), and there is increasing concern of potentially large ice-sheet contributions during the 21st century and beyond, particularly if greenhouse gas emissions continue unabated. A suite of ongoing satellite and in situ observational activities need to be sustained and new activities supported. To the extent that we are able to sustain these observations, research programmes utilising the resulting data should be able to significantly improve our understanding and narrow projections of future sea-level rise and variability.  相似文献   
825.
Abstract

Ground level ozone pollution has become a significant air pollution problem in Beijing. Because of the complex way in which ozone is formed, it is difficult for policy makers to identify optimal control options on a cost-effective basis. This paper identifies and assesses a range of options for addressing this problem. We apply the Ambient Least Cost Model and compare the economic costs of control options, then recommend the most effective sequence to realize pollution control at the lowest cost. The study finds that installing of Stage II gasoline vapor recovery system at Beijing’s 1446 gasoline stations would be the most cost-effective option. Overall, options to reduce ozone pollution by cutting vehicular emissions are much more cost-effective than options to “clean up” coal-fired power plants.  相似文献   
826.
There are many uncertain factors,such as stochastic,fuzzy and gray information in the risk analysis on natural hazard.The set pair analysis(SPA)deals effectively with the various uncertain factors contributing to evaluation of the risk level of natural disasters.The evaluation indicators and standards of natural disasters risk are analyzed by identity-discrepancycontrary(IDC).The result,the connection numbers,still has uncertainty information.Thus,yielding the risk evaluation model of natural disasters based on connection function,which construct a set pair relation between the indicators of connection numbers and comprehensive evaluation standards,and describe uncertainty of the connection numbers by using connection function.The study showed that the proposed model takes into account only the uncertainty of risk evaluation indicator identification on natural disasters,also the uncertainty of result connection numbers.This approach gives full consideration to the uncertainty of systematic evaluation process along with the actual meaning of comprehensive evaluation functions.Therefore,this means it is able to reduce the uncertainty of final evaluation results and improve the accuracy and reasonability of evaluation results.This model is capable of reflecting actual situation of the risk evaluation on natural disaster affected by various uncertain factors and has a promotional value in the natural disaster risk assessment.  相似文献   
827.
基于MODIS的鄱阳湖湿地植被变化及其对水位的响应研究   总被引:6,自引:0,他引:6  
针对鄱阳湖水情变化如何影响湖区湿地植被生长过程的问题,在鄱阳湖国家级自然保护区内的蚌湖-吴城生态断面上,选取3个梯度分布MODIS像元样点,基于2001~2010年MODIS 增强型植被指数(EVI)时间序列,分析了近10 a来退水期植被生长动态变化过程;结合星子站水位资料,探讨了鄱阳湖退水期水位变化对湿地植被生长的影响。结果表明:各样点EVI年内均值表现为先上升后下降的单峰特征,多年平均值在10月份最大,高程越高的样点其EVI达到年最大值的时间越早;不同水位持续长短及其起讫时期影响植被的生长变化,EVI均值与生长期的拟合优度(075)高于最大值与生长期的拟合优度(049);样点每提前出露10 d,EVI均值约升高002,[JP3]二者相关性R2达到055。研究结果对湖区植被资源管理以及湖泊水位调控效应研究等具有积极的参考意义  相似文献   
828.
针对海洋平台安全仪表系统安全可靠性要求的提高,分析海洋平台安全仪表系统SIL评估及HAZOP分析方法,对SIL评估的必要性、目的和内容、方法与流程进行论述,对SIL等级选择的HAZOP和LOPA分析方法进行介绍,对SIL评估过程中的重要数据问题进行阐述,对SIL等级验证中各参数和失效数据的选取进行说明。通过案例进一步论述SIL评估及HAZOP分析技术的要点和实施步骤,针对该案例提出了提高SIL等级的建议和措施,为海洋平台安全仪表系统的SIL评估提供重要的参考和依据。  相似文献   
829.
Many authors have suggested that Indigenous communities are especially vulnerable to the direct and indirect impacts of climate change, yet there remains a paucity of fine-grained geographic data on the particular impacts of climate change on specific places and on local communities, especially Australian Indigenous communities. While there are some recent studies being undertaken with Australia's Torres Strait Island people, our research takes up the issues of vulnerability and resilience with two Indigenous communities from different environments on the mainland in North Queensland. They are the Aboriginal peoples of the rainforest and reef environments of the Wet Tropics and the Aboriginal people of the discontiguous rainforest, grasslands, dry forests and marine environments of Cape York. The results demonstrate variability in their understandings of climate change and in their capacities to anticipate and manage its impacts, while at the same time illustrating some common held themes about environmental and cultural values, observed environmental change, attributions of cause and effect, and of climate in general.  相似文献   
830.
针对金属密闭容器内液体液位测量问题,设计1种基于超声透射特性的非接触式液位测量装置。测量装置根据被测容器内液体介质与气体介质透射系数不同的原理,通过超声接收探头回波情况判断容器内液体位置,利用软件与硬件结合,调整超声发射探头与接收探头的放大倍数,实现对不同材料、厚度容器内液位的测量。测量装置可以将所测液位、容器倾斜程度等数据通过上位机、阿里云平台等多方位显示。研究结果表明:该测量装置可测量不同材料、厚度密闭容器内承装液体的液位,所测数据较为稳定,测量误差范围不大于3 mm。  相似文献   
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