全文获取类型
收费全文 | 1492篇 |
免费 | 146篇 |
国内免费 | 294篇 |
专业分类
1932篇 |
出版年
2024年 | 11篇 |
2023年 | 37篇 |
2022年 | 46篇 |
2021年 | 56篇 |
2020年 | 78篇 |
2019年 | 90篇 |
2018年 | 77篇 |
2017年 | 127篇 |
2016年 | 130篇 |
2015年 | 101篇 |
2014年 | 92篇 |
2013年 | 103篇 |
2012年 | 50篇 |
2011年 | 66篇 |
2010年 | 54篇 |
2009年 | 118篇 |
2008年 | 104篇 |
2007年 | 79篇 |
2006年 | 79篇 |
2005年 | 73篇 |
2004年 | 64篇 |
2003年 | 47篇 |
2002年 | 35篇 |
2001年 | 29篇 |
2000年 | 28篇 |
1999年 | 29篇 |
1998年 | 20篇 |
1997年 | 14篇 |
1996年 | 12篇 |
1995年 | 13篇 |
1994年 | 14篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 3篇 |
排序方式: 共有1932条查询结果,搜索用时 0 毫秒
51.
全球气候变化和城市化背景下城市生态环境问题越发凸显,面对日趋紧张的土地资源现状,垂直绿化建设成为重要的城市绿地补充手段,对改善城市环境具有重要意义。垂直绿化具有多种生态效益,且其效益发挥受到多因素共同影响。如何统筹协调生态效益和影响因素之间的复杂关系,以使其综合生态效益最大化,是当前垂直绿化建设亟待解决的科学问题之一。基于文献综述法归纳了不同生态效益的机制及其关键影响因素,并对多效益和多影响因素进行了综合分析。结果表明,垂直绿化具有缓解城市热岛、建筑节能减排、固碳、净化空气、降噪、截留雨水和支持生物多样性等七种主要生态效益,并受到植被特征、设施结构特征、气象条件、空间格局等多方面因素的共同影响。基于对效益和影响因素的综合分析,进一步提出了两点规划思路:首先,关注环境需求和效益供给的耦合关系能够更加科学合理地指导区域垂直绿化建设布局。其次,关注生态效益间的关系,以区域关键生态环境问题为导向进行效益权衡并结合考虑其影响因素的重要性程度能为规划设计提供有效建议。 相似文献
52.
在雨涝灾害威胁日益凸显的背景下,基于生态系统水文调节服务供需匹配分析的规划防涝优先干预区识别,为高效降低城市雨涝风险、利用规划措施防涝提供了新的研究思路与科学支撑。运用数据叠置、水文模拟及公式计算法,将城市原生雨涝供给能力与雨涝需求水平统一至同一评估体系中。结合降雨量、下垫面类型,运用径流曲线模型对街区地表径流调节率进行计算,生成供给能力评估结果;以GIS水文模拟结果计算得出的危险性、暴露性和脆弱性指数生成需求水平评估结果。根据石家庄中心四区3a一遇、50a一遇情景供需匹配结果,划定城市街区尺度的规划干预等级,并分类提出相应规划策略。研究结果表明:石家庄市中心四区低供给高需求街区在3a一遇降雨情景下以点状聚集分布;50a一遇降雨情景下,在京广铁路线沿线呈现纵向聚集形态。同时,在两种降雨情景下,规划干预高等级街区均集中出现于桥西区苑东街道、彭后街道、东华街道,长安区长丰街道、建北街道,裕华区裕翔街道、建华南街道。根据规划干预等级、供需相对关系及供需失衡原因,分别提出3a一遇、50a一遇降雨情景下的九类规划干预策略,为城市雨涝灾害的规划应对提供优化思路。 相似文献
53.
生态系统服务与人类福祉的和谐关系是区域规划的基石。现有的区域规划较少同时考虑生态系统服务的供需和流域居民的福祉差异。以城市化流域——官厅水库流域为例,应用改进后的CASA模型、IPCC清单法、SolVES模型和问卷调查量化食物供给、碳固持和文化服务以及人类福祉,再结合服务的供需关系及人类福祉水平开展聚类分区,并针对各区情况提出规划建议。结果显示,官厅水库流域内食物供给和文化服务供大于求,而碳固持服务供不应求。流域福祉位于中等水平,分值为3.44(满分5分)。其中,居民的基本物质需求分值最高(3.64),收入分值(3.00)明显低于流域整体水平。除此之外,居民认为供水、医疗条件和收入这些福祉要素仍有待改善。流域可分为城市发展区、城郊休闲区、生态涵养区和文化建设区。在各区需采用因地制宜的方式,通过增大植被覆盖面、开展文旅产业和推动冰雪项目等形式,提高居民生活质量和维持区域可持续性。 相似文献
54.
上海外高桥保税区可持续发展的生态环境规划研究 总被引:4,自引:0,他引:4
以可持续发展理论和生态规划理论为指导,应用环境监测、遥感分析和GIS等方法评价了上海外高桥保税区大气、水体、土壤、噪声、绿化等生态环境质量现状和发展趋势,从生态环境建设的指标体系、环境保护规划和管理、绿地系统规划等方面提出了对策措施。 相似文献
55.
湿地资源保护是全球生态保护的核心问题之一。在分析湿地资源保护的经济属性的基础上,以北京市野鸭湖湿地为案例,运用经济学的理论和方法以及清晰的图表重点分析了野鸭湖湿地资源保护过程中的外部性以及资源利用中成本与收益两个问题。研究结果表明:(1)从正外部性分析,个人收益小于社会收益,个人保护的湿地资源小于社会最优量,会造成湿地资源保护的不足;从负外部性分析,个人成本小于社会成本,个人对湿地资源的利用水平大于社会最优利用水平,造成湿地资源的过度利用;(2)根据湿地资源利用的成本收益分析结果,"搭便车"行为会造成湿地资源的退化甚至恶化;(3)明晰产权有利于湿地资源配置效率的提高。研究结果可以为中国湿地保护过程中出现的资源利用矛盾提供有益的借鉴,特别是为保护北京野鸭湖湿地提供理论支撑和政策建议。 相似文献
56.
Ya-Zhou Zhang Li-Shen Qian Xu-Fang Chen Lu Sun Hang Sun Jian-Guo Chen 《Plant Diversity》2022,44(3):231
The Qinghai-Tibet Plateau (QTP) is an important cushion plant hotspot. However, the distribution of cushion plants on the QTP is unknown, as are the factors that drive cushion plant distribution, limiting our understanding of the evolution of cushion species in the region. In this study, we assessed spatial patterns of total cushion plant diversity (including taxonomic and phylogenetic) over the entire QTP and compared patterns of diversity of cushion plants with different typologies (i.e., compact vs. loose). We also examined how these patterns were related to climatic features. Our results indicate that the southern QTP hosts the highest total cushion plant richness, especially in the south-central Hengduan Mountains subregion. The total number of cushion species declines from south to north and from southeast to northwest. Compact cushion plants exhibit similar patterns as the total cushion plant richness, whereas loose cushion plants show random distribution. Cushion plant phylogenetic diversity showed a similar pattern as that of the total cushion plant richness. In addition, cushion plant phylogenetic community structure was clustered in the eastern and southwestern QTP, whereas random or overdispersed in other areas. Climatic features represented by annual energy and water trends, seasonality and extreme environmental factors, had significant effects on cushion plant diversity patterns but limited effects on the phylogenetic community structure, suggesting that climatic features indeed promote the formation of cushion plants. Because cushion plants play vital roles in alpine ecosystems, our findings not only promote our understanding of the evolution and formation of alpine cushion plant diversity but also provide an indispensable foundation for future studies on cushion plant functions and thus alpine ecosystem sustainability in the entire QTP region. 相似文献
57.
Urban and periurban forests, which are integrated within the concept of Green Infrastructure, provide important Ecosystem Services, including air purification. In this study, we quantified the Ecosystem Service of particulate matter (PM10) and Ozone (O3) removal from urban and periurban forests in ten metropolitan cities in Italy, and its total monetary value. In order to gain a better understanding of how Ecosystem Services can be regulated on a wider scale, the vegetation ecosystem types were grouped into Physiognomic-Structural Categories of Vegetation according to morphofunctional criteria. The pollution removal was mapped using a remote sensing and GIS approach, by applying a deposition model and a stomatal flux model. We estimated, for the ten metropolitan cities, an overall pollution abatement of 7150 Mg of PM10 and 30,014 Mg of O3 in the year 2003, which was an extremely hot year. Our findings indicate that structural characteristics (i.e. Leaf Area Index) and functional diversity, linked to stomatal conductance, exert a marked influence on the provision of the regulating Ecosystem Services, whose total monetary value was estimated to be equal to 47 and 297 million USD for PM10 and O3 removal, respectively. This study represent the first national-scale assessment of the Ecosystem Services of air pollution removal in Europe, thus providing information that may be useful to stakeholders to manage Green Infrastructure more efficiently. 相似文献
58.
59.
Using species traits to assess human impacts on near shore benthic ecosystems in the Canadian Arctic
Human activities have the potential to alter the diversity and composition of biological communities in natural environments, which can cause changes in ecosystem functioning. This has led to the development of environmental assessment techniques that take into account species identity, as species can contribute differently to various ecosystem processes. Biological Traits Analysis (BTA) is used to compare the abundances of specific biological traits in samples to produce information about how ecosystem functioning may change across a specific terrestrial or aquatic system. In the present study, BTA was used to assess the influence of municipal wastewater effluent on benthic marine communities in near shore soft sediments in four locations across the Canadian Arctic Territory of Nunavut, Canada. Shifts in trait composition were assessed relative to indicators of sediment enrichment (sediment chlorophyll, organic content, degree of anoxia), and natural variation in habitat characteristics (water depth, porosity, average grain size) at a site receiving wastewater and a reference site in each sampling location. The results indicated a mild enrichment effect of wastewater, as evidenced by changes in trait composition at three of the four sites that received wastewater inputs. However, the amount of variance in trait composition explained by metrics of wastewater enrichment in these locations were generally equal to or lower than the amount of variance explained by sediment characteristics related to natural processes. These results provide greater insight into the underlying causes and consequences of human activities than more traditional methods for environmental impact assessment, and can be directly applied in a management context. 相似文献
60.
An index of naturalness 总被引:2,自引:0,他引:2
Antonio Machado 《Journal for Nature Conservation》2004,12(2):95-110