首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   624篇
  免费   28篇
  国内免费   31篇
安全科学   17篇
废物处理   4篇
环保管理   133篇
综合类   244篇
基础理论   153篇
环境理论   1篇
污染及防治   16篇
评价与监测   16篇
社会与环境   88篇
灾害及防治   11篇
  2023年   7篇
  2022年   12篇
  2021年   22篇
  2020年   16篇
  2019年   14篇
  2018年   12篇
  2017年   19篇
  2016年   16篇
  2015年   9篇
  2014年   22篇
  2013年   41篇
  2012年   38篇
  2011年   45篇
  2010年   34篇
  2009年   42篇
  2008年   22篇
  2007年   37篇
  2006年   36篇
  2005年   31篇
  2004年   33篇
  2003年   25篇
  2002年   17篇
  2001年   14篇
  2000年   24篇
  1999年   15篇
  1998年   10篇
  1997年   9篇
  1996年   12篇
  1995年   12篇
  1994年   12篇
  1993年   8篇
  1992年   3篇
  1991年   3篇
  1990年   2篇
  1989年   3篇
  1988年   3篇
  1984年   2篇
  1979年   1篇
排序方式: 共有683条查询结果,搜索用时 31 毫秒
101.
为了更好地利用青岛崂山区地下空间资源,在全面分析该区地形、地质、水文等条件的基础上,结合岩土工程勘察原始数据和现场水样调查分析报告,根据模糊数学理论和专家经验,遴选出地形地貌、地质构造、工程地质、水文地质、洪水淹没、人口密集程度为评价因子并确定各因子的权重,研究构建了该区地下空间利用评价模型。将评价模型与GIS相结合,利用ArcGIS强大的空间分析功能,采用定量分析的方法得到地下空间利用适宜性分区。研究表明青岛崂山区地下空间建设适宜区面积为106.1km^2,占评价区域面积的73.8%;一般区域面积为26.5km^2,占评价区域面积的18.4%;不适宜区域面积为11.14km^2,占评价区域面积的7.8%。  相似文献   
102.
Abstract:  To anticipate the rapidly changing world resulting from global climate change, the projections of climate models must be incorporated into conservation. This requires that the scales of conservation be aligned with the scales of climate-change projections. We considered how conservation has incorporated spatial scale into protecting biodiversity, how the projections of climate-change models vary with scale, and how the two do or do not align. Conservation planners use information about past and current ecological conditions at multiple scales to identify conservation targets and threats and guide conservation actions. Projections of climate change are also made at multiple scales, from global and regional circulation models to projections downscaled to local scales. These downscaled projections carry with them the uncertainties associated with the broad-scale models from which they are derived; thus, their high resolution may be more apparent than real. Conservation at regional or global scales is about establishing priorities and influencing policy. At these scales, the coarseness and uncertainties of global and regional climate models may be less important than what they reveal about possible futures. At the ecoregional scale, the uncertainties associated with downscaling climate models become more critical because the distributions of conservation targets on which plans are founded may shift under future climates. At a local scale, variations in topography and land cover influence local climate, often overriding the projections of broad-scale climate models and increasing uncertainty. Despite the uncertainties, ecologists and conservationists must work with climate-change modelers to focus on the most likely projections. The future will be different from the past and full of surprises; judicious use of model projections at appropriate scales may help us prepare.  相似文献   
103.
基于辽宁省56个气象站的气象资料,利用Kira的温暖指数(WI)、寒冷指数(CI)和徐文铎的湿度指数(HI)分析辽宁省近40年(1967-2006年)气候-植被指标的时空变异。结果表明,就辽宁省区域平均值而言,WI指数呈升高趋势,每10年增加幅度为2.47℃·月,CI指数呈下降趋势,每10年下降幅度为2.31℃·月,HI总体呈下降趋势,波动较WI和CI明显,从气候—植被指数变化趋势看,对红松Pinus koraiensis Sieboldet Zuccarini、长白落叶松Larixolgensis等不利,而对油松Pinu stabulaeformis Carr、栓皮栎Quercus vari abilis Blume等树种有利。空间变化特征表现为,温暖指数界限呈向西北移动的趋势,表明暖温带落叶阔叶疏林带的适宜面积增加,而温带针阔叶混交林带的适宜面积减小;HI指数减小并且向东移,表明随着指数带的北移和东移缩小限制了原有针叶树种的生长,而对栎树Phytophthora ramorum等阔叶树种有利。  相似文献   
104.
This study identified the changing preferences of country park visitors in Hong Kong and the potential for such changes to have further negative impacts on the ecologically sensitive areas of country parks. A questionnaire was used to collect feedback from 644 country park visitors to understand their preferences and visitation patterns. To investigate visitors’ preferences and behaviours and to develop better visitor management strategies, the survey data were compared with studies conducted 20 years ago. The results showed that the most popular nature‐based activities of 20 years ago, namely, picnicking and barbecuing, have significantly declined in popularity, while other activities, namely, nature studies and nature photography, have surged in popularity in recent years. These changes in visitor preferences have directly increased the negative impacts of visitors on country parks as they dispersed away from the high intensity recreation zones to the ecological sensitive areas. This emerging group of country park visitors has not been fully considered in the existing approach to visitor management and may irreversibly impact the ecological value of country parks. In this study, visitor management in Hong Kong's country parks was reviewed based on these research findings, and potential improvements were suggested.  相似文献   
105.
ABSTRACT

Sustainable development is rhetorically framed as exhibiting natural processes, reflected both symbolically and materially. Taking the Frick Environmental Center of Pittsburgh, Pennsylvania as a rhetorical artifact, I argue that spaces where sustainable human-made structures and human-cultivated landscapes meet, reflect blurred borderlands of a culturally constructed urban/nature divide. Considering the Frick Environmental Center as an experiential landscape, my mixed methodology of textual analysis and rhetorical field work identifies how naturalized framing of sustainability bridges the urban/nature divide, inviting restoration, preservation, and construction efforts that are more environmentally engaged.  相似文献   
106.
The combined influence on the environment of all projects occurring in a single area is evaluated through cumulative impact assessments (CIA), which consider the consequences of multiple projects, each insignificant on its own, yet important when evaluated collectively. Traditionally, future human activities are included in CIA using an analytical platform, commonly based on complex models that supply precise predictions but with reduced accuracy. To compensate for the lack of accuracy in current CIA approaches, we propose a shift in the paradigm governing CIA. The paradigm shift involves a change in the focus of CIA investigations from the detailed analysis of one unlikely future to the identification of the patterns describing multiple potential future changes in the environment. To illustrate the approach, a set of 144 possible and equally likely futures were developed that aimed to identify the potential impacts of forest harvesting and petroleum drilling on the habitat suitability of moose and marten in northeast British Columbia, Canada. The evolution of two measures of habitat suitability (average habitat suitability index and surface of the stands with habitat suitability index >0.5) revealed that the human activities could induce cycles in the habitat dynamics of moose and marten. The planning period of 100 years was separated into three distinct periods following a sinusoidal pattern (i.e., increase - constant - decrease in the habitat suitability measures). The attributes that could induce significant changes in the assessment of environment are the choice of harvesting age and species.  相似文献   
107.
介绍了气力输送系统在电厂660MW机组除灰中的应用,并对飞灰特性,以及除灰系统设计、关键技术运用、运行情况、设备维护和故障处理等问题进行了分析论述。  相似文献   
108.
High quality habitat suitability maps are indispensable for the management and planning of wildlife reserves. This is particularly important for megadiverse developing countries where shortages in skilled manpower and funding may preclude the use of mathematically complex modeling techniques and resource-intensive field surveys. In this study, we propose a simulation based k-fold partitioning and re-substitution approach to refine and update logistic regression models that are widely used for habitat suitability assessment and modeling. We test the modeling strategy using data from a rapid field survey conducted for habitat suitability assessment for muntjak (Muntiacus muntjak) and goral (Naemorrhaedus goral) in the central Himalayas, India. Results obtained from simulations match expectations in terms of model behavior and in terms of published habitat associations of the investigated species. Qualitative comparisons with predictions from the GARP, MaxEnt and Bioclimatic Envelopes modeling systems also show broad agreement with predictions obtained from the proposed technique. The proposed technique is suggested as a rapid-assessment precursor to detailed habitat studies such as patch occupancy modeling in situations where funds or trained manpower are not available.  相似文献   
109.
王晓俊 《生态环境》2011,20(3):589-594
分析了路段与景观两个尺度上的道路生态环境影响,结合当今景观生态学、道路生态学的研究成果,系统论述了与道路交通规划建设相关的生态策略:(1)在区域尺度上,依据生态敏感度规划路网密度、保持大型自然空间的生态完整性、提倡非生态敏感地段的交通集中、增加路网的区域水平渗透性;(2)在路段规模上,自然空间的生境避让、保持重要地段的自然连续性、打破交通生态瓶颈、减少道路交通的环境影响、补偿道路建设的生态影响等。这些策略旨在为可持续道路交通提供基于生态合理性的规划原则与方法。  相似文献   
110.
基于“三生”适宜性的县域土地利用冲突识别与分析   总被引:1,自引:0,他引:1  
精准识别潜在土地利用冲突有利于预警权衡和协调冲突用地,有利于科学进行国土空间规划。以“三调”修正数据为基础,基于生产、生活、生态视角,构建高植被覆盖率县域生产、生活、生态即“三生”适宜性评价模型与土地利用冲突识别矩阵,并选取横峰县进行实证分析。结果表明:(1)横峰县“三生”适宜性用地的空间分布与面积构成差异显著,且存在明显的空间叠加特征,暗示着研究区土地利用存在冲突;(2)从潜在冲突识别的结果来看,土地利用适宜区、冲突激烈区、冲突中度区、冲突一般区及冲突微弱区面积占比分别为64.02%、9.66%、17.19%、1.66%、7.48%;(3)各个冲突类型区空间分布、表现形式的差异性决定了冲突和解的对策也需因地制宜。研究结果可为相关及类似县域的国土空间规划提供理论参考。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号