全文获取类型
收费全文 | 2216篇 |
免费 | 174篇 |
国内免费 | 60篇 |
专业分类
安全科学 | 126篇 |
废物处理 | 17篇 |
环保管理 | 1041篇 |
综合类 | 577篇 |
基础理论 | 365篇 |
环境理论 | 2篇 |
污染及防治 | 43篇 |
评价与监测 | 57篇 |
社会与环境 | 129篇 |
灾害及防治 | 93篇 |
出版年
2023年 | 18篇 |
2022年 | 39篇 |
2021年 | 48篇 |
2020年 | 51篇 |
2019年 | 49篇 |
2018年 | 60篇 |
2017年 | 84篇 |
2016年 | 93篇 |
2015年 | 92篇 |
2014年 | 77篇 |
2013年 | 120篇 |
2012年 | 79篇 |
2011年 | 130篇 |
2010年 | 89篇 |
2009年 | 105篇 |
2008年 | 97篇 |
2007年 | 113篇 |
2006年 | 107篇 |
2005年 | 82篇 |
2004年 | 70篇 |
2003年 | 75篇 |
2002年 | 51篇 |
2001年 | 56篇 |
2000年 | 53篇 |
1999年 | 68篇 |
1998年 | 41篇 |
1997年 | 37篇 |
1996年 | 42篇 |
1995年 | 40篇 |
1994年 | 27篇 |
1993年 | 17篇 |
1992年 | 22篇 |
1991年 | 18篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 21篇 |
1986年 | 22篇 |
1985年 | 24篇 |
1984年 | 22篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1980年 | 15篇 |
1979年 | 17篇 |
1978年 | 20篇 |
1977年 | 14篇 |
1975年 | 10篇 |
1973年 | 16篇 |
1972年 | 14篇 |
1971年 | 16篇 |
排序方式: 共有2450条查询结果,搜索用时 656 毫秒
891.
Fast economic and social changes in recent years in China have brought massive expansion, redevelopment, and restructuring
of cities. These changes offer cities the opportunity to improve environmental quality through urban green spaces (UGSs) and
to address the challenges of meeting community aspirations. This study explored peoples’ minds concerning UGSs in Guangzhou
city in south China in relation to the following: (1) knowledge and perception of 25 ecosystem services and 8 negative impacts;
(2) attitude toward site condition and management; (3) expectation of landscape design; and (4) preference ranking of venues.
A questionnaire was designed to solicit opinions from 340 respondents randomly chosen from residents living in the study area.
The results indicated widespread recognition of ecosystem services and strong support of UGS programs. Negative responses
were weakly expressed. Amelioration of urban microclimate and environmental quality were emphasized. Environmental functions
stressed in publicity programs, together with aggravating environmental problems in the city, tended to focus respondents’
attention on UGS benefits. Wildlife habitat, species conservation and other natural ecosystem services drew limited concerns.
Awareness of economic benefits was very low. Visual-landscape contributions with strong preference for naturalistic design
and recreational benefits were highlighted. Compared with other countries, Guangzhou residents were characterized by visual–scenic–recreation
orientation and pragmatic–utilitarian perception of UGSs, reflecting underlying differences in the understanding of inherent
ecosystem services of green spaces. Relevant UGS policies and practices could adopt the approaches of market survey, citizen
participation, and precision planning in order to meet increasingly mature and refined demands. Citizens’ understanding of
high-order ecosystem services could be enhanced to encourage appreciation of nature and their associated benefits. 相似文献
892.
Linking linear programming and spatial simulation models to predict landscape effects of forest management alternatives 总被引:1,自引:0,他引:1
Forest management planners require analytical tools to assess the effects of alternative strategies on the sometimes disparate benefits from forests such as timber production and wildlife habitat. We assessed the spatial patterns of alternative management strategies by linking two models that were developed for different purposes. We used a linear programming model (Spectrum) to optimize timber harvest schedules, then a simulation model (HARVEST) to project those schedules in a spatially explicit way and produce maps from which the spatial pattern of habitat could be calculated. We demonstrated the power of this approach by evaluating alternative plans developed for a national forest plan revision in Wisconsin, USA. The amount of forest interior habitat was inversely related to the amount of timber cut, and increased under the alternatives compared to the current plan. The amount of edge habitat was positively related to the amount of timber cut, and increased under all alternatives. The amount of mature northern hardwood interior and edge habitat increased for all alternatives, but mature pine habitat area varied. Mature age classes of all forest types increased, and young classes decreased under all alternatives. The average size of patches (defined by age class) generally decreased. These results are consistent with the design goals of each of the alternatives, but reveal that the spatial differences among the alternatives are modest. These complementary models are valuable for quantifying and comparing the spatial effects of alternative management strategies. 相似文献
893.
Understanding effects of flow alteration on stream biota is essential to developing ecologically sustainable water supply
strategies. We evaluated effects of altering flows via surface water withdrawals and instream reservoirs on stream fish assemblages,
and compared effects with other hypothesized drivers of species richness and assemblage composition. We sampled fishes during
three years in 28 streams used for municipal water supply in the Piedmont region of Georgia, U.S.A. Study sites had permitted
average withdrawal rates that ranged from < 0.05 to > 13 times the stream’s seven-day, ten-year recurrence low flow (7Q10),
and were located directly downstream either from a water supply reservoir or from a withdrawal taken from an unimpounded stream.
Ordination analysis of catch data showed a shift in assemblage composition at reservoir sites corresponding to dominance by
habitat generalist species. Richness of fluvial specialists averaged about 3 fewer species downstream from reservoirs, and
also declined as permitted withdrawal rate increased above about 0.5 to one 7Q10-equivalent of water. Reservoir presence and
withdrawal rate, along with drainage area, accounted for 70% of the among-site variance in fluvial specialist richness and
were better predictor variables than percent of the catchment in urban land use or average streambed sediment size. Increasing
withdrawal rate also increased the odds that a site’s Index of Biotic Integrity score fell below a regulatory threshold indicating
biological impairment. Estimates of reservoir and withdrawal effects on stream biota could be used in predictive landscape
models to support adaptive water supply planning intended to meet societal needs while conserving biological resources. 相似文献
894.
国土空间规划对新时期流域水环境保护意义重大。本文结合国土空间规划对流域水环境影响的全过程(污染产生—污染排放—污染入河)机制,构建了国土空间规划视角下流域水环境变化评估指标体系和框架。以长春市第二松花江流域为例,利用系统动力学模型和一维水动力模型QUAL2K量化了国土空间规划对流域水环境的影响。结果表明,到国土空间规划近期目标年(2025年),流域水环境状况良好,体现为流域大部分河段COD和NH3-N达标,水环境容量最小为44.96 kg/d和5.10 kg/d。国土空间规划中的总量目标、环保设施建设和相关布局的实施将会使COD和NH3-N污染产生量降低52.61%和14.16%;污染排放量降低26.45%和59.09%;水环境容量增加10.68%和57.17%。总体而言,国土空间规划对流域水环境改善潜力巨大,同时改善潜力因不同区域、污染源、污染物而异。本研究提出的评估框架为国土空间规划背景下流域水环境保护提供了思路。 相似文献
895.
896.
生态市建设规划是促进可持续发展的有效措施。本文分析了生态市建设规划与早期生态示范区建设规划存在的差异,探讨了编制生态市建设规划的一些基础理论和理性认识。 相似文献
897.
气候因素能够对城市生态规划和生态修复造成较大的影响,通过科学使用气象技术可以对城市生态规划进行改善,同时还能促进生态修复。本文主要对城市生态规划和生态修复中的气象技术进行分析,对气象技术在该领域的应用也做了一定的研究,旨在更好地促进城市生态规划和修复的发展。 相似文献
898.
目前潮州城市城市建设的迅猛发展使得生态环境呈超负荷的状态,而绿道建设和推进能有效推动我囯城市生态环境的良性发展。花园城市新加坡的绿道系统及整体生态环境的发展有许多经验可借鉴和采纳,本文通过总结出新加坡绿道建设的一些优秀案例,提出适用于潮州城市绿道建设的建议,为潮州城市"城市绿道网络系统与慢行系统"的规划与建设作支撑,推进生态环境建设。 相似文献
899.
Wildlife corridors aim to promote species’ persistence by connecting habitat patches across fragmented landscapes. Their implementation is limited by patterns of land ownership and complicated by differences in the jurisdictional and regulatory authorities under which lands are managed. Terrestrial corridor conservation requires coordination across jurisdictions and sectors subject to site-specific overlapping sources of legal authority. Mapping spatial patterns of legal authority concurrent with habitat condition can illustrate opportunities to build or leverage capacity for connectivity conservation. Streamside areas provide pragmatic opportunities to leverage existing policy mechanisms for riverine and terrestrial habitat connectivity across boundaries. Conservation planners and practitioners can make use of these opportunities by harmonizing actions for multiple conservation outcomes. We formulated an integrative, data-driven method for mapping multiple sources of legal authority weighted by capacity for coordinating terrestrial habitat conservation along streams. We generated a map of capacity to coordinate streamside corridor protections across a wildlife habitat gap to demonstrate this approach. We combined values representing coordination capacity and naturalness to generate an integrated legal-ecological resistance map for connectivity modeling. We then computed least-cost corridors across the integrated map, masking the terrestrial landscape to focus on streamside areas. Streamside least-cost corridors in the integrated, local-scale model diverged (∼25 km) from national-scale least-cost corridors based on naturalness. Spatial categories comparing legal- and naturalness-based resistance values by stream reach highlighted potential locations for building or leveraging existing capacity through spatial coordination of policy mechanisms or restoration actions. Agencies or nongovernmental organizations intending to restore or maintain habitat connectivity across fragmented landscapes can use this approach to inform spatial prioritization and build coordination capacity. Article impact statement: Combined mapping of legal authority and habitat condition reveals capacity to coordinate actions along streams for clean water and wildlife. 相似文献
900.
基于RS/GIS的武汉市九峰城市森林保护区景观结构特征及规划对策 总被引:2,自引:0,他引:2
大型的城市森林绿地是城市生态框架的重要组成部分,其景观结构的优化有助于城市生态系统结构与功能稳定。九峰城市森林保护区是武汉近郊最大的森林绿地。应用快鸟遥感影像并结合实地调查,在RS和GIS的支持下对九峰城市森林保护区的景观结构进行了分析,并探讨了森林景观的规划对策。结果表明:九峰城市森林保护区景观分为林地、农耕地、苗圃地、水域、建设用地、墓地、荒地、草地和裸岩9个景观类型,263个斑块,其中林地最多,占总面积的36.56%,占斑块总数的8.75%,为景观基质,但对景观过程的控制作用不强。建设用地和农耕地斑块形状最为复杂,易造成人类活动干扰的扩散。林地成片分布,破碎化程度较低,连通性较高,有利于其资源保护。九峰城市森林保护区表现出整体结构简单,局部结构复杂的特征。针对这些景观结构特征,提出了大幅提高林地比例,压缩建设用地和其他人类活动明显的景观类型面积,构建聚集间有离析的空间优化格局,加强荒地和裸岩的植被恢复,设置“踏脚石”斑块和建立保护性廊道的景观优化对策,以期为九峰城市森林保护区的规划与管理提供依据。 相似文献