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   1104篇
  免费   50篇
  国内免费   171篇
安全科学   17篇
废物处理   1篇
环保管理   191篇
综合类   595篇
基础理论   315篇
污染及防治   26篇
评价与监测   49篇
社会与环境   118篇
灾害及防治   13篇
  2024年   6篇
  2023年   12篇
  2022年   24篇
  2021年   29篇
  2020年   26篇
  2019年   28篇
  2018年   25篇
  2017年   44篇
  2016年   48篇
  2015年   57篇
  2014年   34篇
  2013年   61篇
  2012年   83篇
  2011年   88篇
  2010年   70篇
  2009年   70篇
  2008年   60篇
  2007年   72篇
  2006年   71篇
  2005年   79篇
  2004年   49篇
  2003年   63篇
  2002年   37篇
  2001年   46篇
  2000年   32篇
  1999年   36篇
  1998年   10篇
  1997年   10篇
  1996年   19篇
  1995年   8篇
  1994年   9篇
  1993年   4篇
  1992年   4篇
  1990年   2篇
  1987年   1篇
  1986年   1篇
  1984年   4篇
  1981年   1篇
  1980年   2篇
排序方式: 共有1325条查询结果,搜索用时 390 毫秒
71.
Abstract:  Conservation easements are one of the primary tools for conserving biodiversity on private land. Despite their increasing use, little quantitative data are available on what species and habitats conservation easements aim to protect, how much structural development they allow, or what types of land use they commonly permit. To address these knowledge gaps, we surveyed staff responsible for 119 conservation easements established by the largest nonprofit easement holder, The Nature Conservancy, between 1985 and 2004. Most easements (80%) aimed to provide core habitat to protect species or communities on-site, and nearly all were designed to reduce development. Conservation easements also allowed for a wide range of private uses, which may result in additional fragmentation and habitat disturbance. Some residential or commercial use, new structures, or subdivision of the property were permitted on 85% of sampled conservation easements. Over half (56%) allowed some additional buildings, of which 60% restricted structure size or building area. Working landscape easements with ranching, forestry, or farming made up nearly half (46%) of the easement properties sampled and were more likely than easements without these uses to be designated as buffers to enhance biodiversity in the surrounding area. Our results demonstrate the need for clear restrictions on building and subdivision in easements, research on the compatibility of private uses on easement land, and greater public understanding of the trade-offs implicit in the use of conservation easements for biodiversity conservation.  相似文献   
72.
The nexus between human rights and the environment is a key issue for climate policymakers and Indigenous peoples around the world. We combine national spatial, social and biological datasets from Australia to describe where Indigenous carbon projects are happening, why Indigenous people are participating, and how effective these schemes might be at marrying Indigenous co-benefit, biodiversity and carbon emission mitigation goals. Our study shows that many Indigenous people engage in carbon offset schemes as part of their broader cultural responsibility for landscapes, and that they seek to grow the relationship between social and ecological benefits. It also highlights the challenges associated with designing carbon offset schemes that address the impacts of climate change and respond to Indigenous peoples’ world views about what is required to sustain cultural-social-ecological systems.  相似文献   
73.
Abstract: The effectiveness of rare plant conservation will increase when life history, demographic, and genetic data are considered simultaneously. Inbreeding depression is a widely recognized genetic concern in rare plant conservation, and the mixing of genetically diverse populations in restoration efforts is a common remedy. Nevertheless, if populations with unrecognized intraspecific chromosome variation are crossed, progeny fitness losses will range from partial to complete sterility, and reintroductions and population augmentation of rare plants may fail. To assess the current state of cytological knowledge of threatened and endangered plants in the continental United States, we searched available resources for chromosome counts. We also reviewed recovery plans to discern whether recovery criteria potentially place listed species at risk by requiring reintroductions or population augmentation in the absence of cytological information. Over half the plants lacked a chromosome count, and when a taxon did have a count it generally originated from a sampling intensity too limited to detect intraspecific chromosome variation. Despite limited past cytological sampling, we found 11 plants with documented intraspecific cytological variation, while 8 others were ambiguous for intraspecific chromosome variation. Nevertheless, only one recovery plan addressed the chromosome differences. Inadequate within‐species cytological characterization, incomplete sampling among listed taxa, and the prevalence of interspecific and intraspecific chromosome variation in listed genera, suggests that other rare plants are likely to have intraspecific chromosome variation. Nearly 90% of all recovery plans called for reintroductions or population augmentation as part of recovery criteria despite the dearth of cytological knowledge. We recommend screening rare plants for intraspecific chromosome variation before reintroductions or population augmentation projects are undertaken to safeguard against inadvertent mixtures of incompatible cytotypes.  相似文献   
74.
The application of ecological concepts to the industrial setting has been touched upon by literature across several disciplines. Two emerging ecological planning approaches, landscape ecology and industrial ecology, are applied here to look at alternative ways of planning industrial parks. As an emerging field, landscape ecology provides different viewpoints from the traditional approach of natural conservation, which mainly focuses on the protection of nature. The approach of landscape ecology regards the environment as a land mosaic, a mixture of natural and urban environment, which concerns a manageable human-scale environment across one or two human generations. Industrial ecology, on the other hand, goes beyond the traditional “end of pipe” idea of pollution control and learns from the ecosystem concept. The current paper is an attempt to reconcile these two fields as an integrated approach to the planning of industrial areas. Using a case study of Singapore’s Jurong Island industrial park, two fundamental issues behind the idea of landscape ecology and industrial ecology are raised. If raw materials, energy and by-products are more easily replaced or reused by technology and management, then research on industrial ecology and related knowledge will be crucial for developing natural resource substitution by innovative technology and new ways of environmental management. Where it is difficult to substitute natural resources, the skills of planning and managing natural resources will take priority over other strategies. In this situation, the knowledge of landscape ecology needs to be applied to the prediction, design and evaluation of ecologically optimum resource uses, patterns and processes in the mixture of natural, urban and industrial environment. A new concept, “nurtured landscape”, is proposed for mediating between the natural ecosystem and the urban/industrial environment. The nurtured landscape provides a basis for the development of new ecological technology using landscape to ameliorate the polluting effects of the urban/industrial neighbourhood. The planning of Singapore’s Jurong Island industrial park provides a test of applying the principles of landscape ecology and industrial ecology to the possible transformation of an industrial area.  相似文献   
75.
采用《环境影响评价技术导则非污染生态影响》(HJ/T 19-1997)推荐的景观生态学评价方法,应用景观生态学的基本原理,通过对景观多样性指数、景观优势度和人工干扰指数等3类景观格局指数的计算及对比,从景观空间结构、异质性、恢复能力等方面,预测建设项目实施对生态环境的影响程度,并提出工程项目建设应注意的问题和采取的措施.  相似文献   
76.
针对利用水资源环境创建城市生态湿地景观的研究,介绍了南京湿地目前存在的问题,主要包括有湿地水质需要改善、湿地生物多样性受到威胁和湿地科研有待加强,探讨了新济洲国家湿地公园的建设,包括新济洲国家湿地公园定位体现地域特色、新济洲湿地建设思路,介绍了新济洲水资源协调利用,主要包括,建立水资源可持续利用机制、合理控制湿地污水排放、开展湿地治理,提升湿地水质,提出了新济洲国家湿地公园建设内容,并进行了对新济洲国家湿地公园建设效益分析.  相似文献   
77.
山地农村居民点系统因受自然因素及人类活动等多重扰动而处于深刻转型中,探索山区农村居民点时空格局特征及其优化策略,对于优化山区国土空间格局、推进山区国土空间综合治理与乡村振兴具有重要意义。基于构建理论框架,集成运用景观格局指数法、栅格权重叠加评价法、改进蚁群算法(ACO)等,以重庆澄江镇为例,探索山区农村居民点时空格局演变特征及优化过程,提出优化调控策略。结果表明:(1)研究区农村居民点空间格局演变特征呈现集中、靠拢的演化发展趋势,总体呈现匀质、线状、向心、院落四种分布形态;同时高程、坡度、水域、城镇、道路、基础设施等自然—经济社会因素均对山区农村居民点时空格局演化产生重要影响。(2)改进蚁群算法优化后,研究区农村居民点斑块面积(CA)减少10.07%,居民点斑块数量(NP)和密度(PD)分别减少83.12%和81.16%,平均斑块面积(MPS)增加了4.3倍,平均最近邻体距离(MENN)增加了42.82%。优化后69.1%的农村居民点斑块都集中在适宜区和较适宜区内,且重点向交通便利、公共设施完善、生产便利和中心村庄集中。优化后的农村居民点空间格局更加紧凑有序,土地集约节约效率更高。(3)基于仿真优化结果,综合考虑村庄振兴“产业—人口—土地”互动耦合机制,提出城郊融合、产业集聚、景村融合、搬迁撤并四类农村居民点格局优化方案,助推山区乡村振兴。(4)优化结果同时表明改进的蚁群算法非常适用于复杂环境条件下的较小尺度要素空间布局优化,能够为山区国土空间规划编制提供技术支撑。  相似文献   
78.
遗产区域:一种大尺度文化景观保护的新方法   总被引:2,自引:0,他引:2  
遗产区域是美国国内针对大尺度文化景观保护的一种较新的方法。该方法重视人与土地之间的互动关系。强调通过对地方历史文化、自然和游憩资源的综合保护与利用。实现遗产保护、经济发展、重建区域身份、提供游憩机会等多重目标。从美国历史保护运动的发展背景出发。回顾了遗产区域的发展历程,从定义、特征与分类三个方面评述了其概念内涵,并对遗产区域保护中的几个关键问题进行了讨论。最后针对遗产区域保护方法在中国的发展与应用提出了相关建议。  相似文献   
79.
在遥感图像基础上,利用GIS技术从景观指数方面定量分析了唐家河自然保护区主要植被类型在东西、南北和西北至东南3个方向上的梯度变化。结果表明:次生落叶阔叶林、常绿落叶阔叶混交林、针阔叶混交林与针叶林的梯度变化明显,并且在各方向上具有不同的变化特征。其中,常绿落叶阔叶混交林从西北至东南方向的梯度变化最为复杂, 斑块数量与面积分别呈“升—降—升—降”与“升—降—升”的波动变化趋势,而边界密度与平均最近距离呈先升后降的变化趋势,两端破碎度高但连接性好,中部相反。针叶林从北至南的梯度变化最为简单,斑块面积减少,破碎度与复杂度降低,南北两端分布较多,中部较少。唐家河自然保护区植被景观格局在不同方向上的梯度变化研究为地震后该地区的植被保护与管理提供重要指导意义。  相似文献   
80.
为了科学合理施用磷肥,减小对设施农业环境带来的污染风险,以北京市大兴区设施农业集中区为研究对象,通过对不同种植年限设施农业剖面土壤(0~100 cm)磷素含量的测定分析,探究磷素累积与迁移转化特征.结果表明,设施农业表层土壤全磷和有效磷含量变化范围大,显著高于周边粮田土壤,主要跟不同种植年限农户的施磷量相关,随着土层深度的增加,全磷和有效磷含量逐渐减小,呈现表聚特征,其中土壤ω(全磷)范围在0.38~2.58 g·kg-1,ω(有效磷)范围在1.60~256.00 mg·kg-1.随着种植年限的增加,土壤全磷和有效磷含量呈现先增加后减小的趋势,在15 a左右达到峰值,随后逐渐减少,趋于稳定,总体处于较高水平.无机磷主要集中在设施农业表层土壤,其中Ca-P占无机磷的比例最大,达到了98.38%,Ca10-P是最主要的Ca-P形态,含量占Ca-P的78.70%,Ca2-P占比最小,仅占9.50%.不同形态无机磷含量呈现表层土壤富集,向下减少的垂直分布特征;不同土层深度,不同形态无机磷占全磷比例变化存在差...  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