全文获取类型
收费全文 | 1379篇 |
免费 | 65篇 |
国内免费 | 69篇 |
专业分类
安全科学 | 60篇 |
废物处理 | 5篇 |
环保管理 | 601篇 |
综合类 | 489篇 |
基础理论 | 106篇 |
污染及防治 | 23篇 |
评价与监测 | 17篇 |
社会与环境 | 187篇 |
灾害及防治 | 25篇 |
出版年
2024年 | 5篇 |
2023年 | 23篇 |
2022年 | 39篇 |
2021年 | 68篇 |
2020年 | 42篇 |
2019年 | 22篇 |
2018年 | 30篇 |
2017年 | 34篇 |
2016年 | 51篇 |
2015年 | 30篇 |
2014年 | 55篇 |
2013年 | 78篇 |
2012年 | 125篇 |
2011年 | 114篇 |
2010年 | 87篇 |
2009年 | 62篇 |
2008年 | 59篇 |
2007年 | 128篇 |
2006年 | 77篇 |
2005年 | 65篇 |
2004年 | 77篇 |
2003年 | 80篇 |
2002年 | 33篇 |
2001年 | 21篇 |
2000年 | 33篇 |
1999年 | 23篇 |
1998年 | 15篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1982年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1513条查询结果,搜索用时 15 毫秒
991.
Stefan Gössling 《Environment, Development and Sustainability》2003,5(3-4):383-400
Neoclassic economic theory suggests global market integration as a strategy to reduce poverty. In line with this paradigm, an increasing number of developing countries have focused on tourism to generate foreign exchange earnings and to meet rising workforce pressure. Coastlines in particular, have been at the forefront of tourist infrastructure development. The article describes tourism development in the village of Kiwengwa on the east coast of Unguja Island (Zanzibar), Tanzania. It is shown that changes caused by tourism are far more complex than economic theory suggests. Economically, tourism has substantially increased local income, but it has also led to a focus on individual benefit and dissolving kinship relationships, encouraged the abandonment of traditional resource-use strategies, contributed to the commoditization of local natural resources, and spread the idea that these resources can be replaced with imports. Overall, tourism has fundamentally disrupted the local socio-economic system and led to a self-reinforcing cycle of ecosystem degradation. Tourism development is nevertheless perceived as positive and sustainable, because (i) changes are complex and damage becomes perceptible only in the medium- or long-term future, (ii) the tourist industry tends to shift its impacts to remote areas, i.e. a supplying periphery, (iii) the village has become a center of resource allocation itself, with imports compensating for the losses in local ecosystem capacity. As a development option imposed by the transnational tourist industry, tourism leads to the creation of new centers (i.e. the former periphery) while simultaneously creating new peripheries. In a finite world with a limited hinterland for such a continuous expansion, this cannot be sustainable. 相似文献
992.
干热河谷区生态系统退化及恢复与重建途径:以云南金沙江典型区为例 总被引:34,自引:4,他引:34
钟祥浩 《长江流域资源与环境》2000,9(3):376-383
云南金沙江干热河谷典型区具有北热带温度条件和长达半年以上的干季时间,植被生态系统具有破坏容易难的特点。在人为干扰下,以硬叶阔叶栎类为主的原始植被类型已基本消失,而出现大面积以禾草草类为主的退化生态系统类型。植被生态系统的退化引起严重的环境问题,表现为:(1)河谷区干旱化程度加剧,土壤凋萎湿度(PWP)长达7~8个月,使许多植物无法生长;(2)河流泌沙量呈明显增加的趋势,如元谋龙海上江中游不文站60 相似文献
993.
武汉东湖风景区是国家级风景名胜区 ,近年来 ,由于游客量大增 ,旅游环境受到污染与破坏 ,严重影响旅游环境气氛与质量。运用有关旅游环境容量的理论与方法 ,分析了东湖风景区旅游环境与旅游环境容量问题的出现与原因 ,并以土地与景区构成为基础 ,计算得出其旅游环境容量为每年2 350万人次 ,每天为 64393人次 ,同时最大游客在园量为 160 58人。经比较 ,东湖风景区目前每年和每天的实际游客量远小于其环境容量 ,但由于游客时空分布不均 ,淡季冷清 ,旺季拥挤 ,特别是旺季中午前后的同时游客在园量可达 2 50 0 0人 ,远大于其容量 ,且集中分布于建筑园林区。研究表明 ,东湖风景区的旅游环境容量现状是 :建筑园林区处于饱和、过饱和状态 ,自然风景公园与水上公园远未饱和。因此 ,大力开发林地、水面 ,改善旅游环境 ,搞好淡季促销 ,是东湖风景区调整旅游环境容量 ,实施可持续发展战略的基本措施。 相似文献
994.
城市旅游地景观格局是城市旅游与景观生态共同的研究热点。研究以南京为例,利用Arc GIS技术,以累积耗费距离及旅游地景观演化模型为分析手段,探讨了研究区自1991年以来的景观格局演变与优化问题。结果表明:(1)1991~2003年,旅游景观比重减少而非旅游景观增加;2003~2014年,旅游景观比重增加而非旅游景观递减。景观演化表现为先后台化再旅游化的特征。(2)河湖水面、公园与绿地、建设用地景观形状日趋规则化,林地、交通用地景观形状复杂度不断提升,景观破碎化程度加剧且多样性先上升后下降,表现出快速、高度城市化过程。(3)根据景观生态系统服务功能价值和空间作用,构建生态源地、生态廊道和生态节点等景观组分来加强生态网络的空间联系,提出格局优化方案。(4)非旅游型城市景观应进一步转变为典型旅游景观,以保持景观旅游化及旅游地景观演化的可持续性。 相似文献
995.
Jurkka Kuusipalo 《Journal of Polymers and the Environment》2000,8(2):49-57
Extrusion coating experiments were carried out in the pilot line at Tampere University of Technology (Institute of Paper Converting). Commercially produced 3-hydroxybutyrate/3-hydroxyvalerate copolymer, commercial Finnish paper, and paperboard qualities were utilized as substrates. Functional properties, such as heat-sealing and hot-tack properties, pinhole density, and water vapor transmission rate were determined. PHB/V coatings exhibited approximately four–six times higher water vapor transmission rates (WVTR) than the corresponding LDPE coatings. The incorporation of wax or tall oil rosin into PHB/V improved its water vapor barrier. Curling of PHB/V was reduced by the addition of wax or tall oil rosin into the base polymer. PHB/V provided good heat-sealing characteristics at rather high sealing temperatures. Pinhole density was substantially reduced by using higher molecular weight PHB/V and by incorporating plasticizer into PHB/V. 相似文献
996.
Hiking Trails and Tourism Impact Assessment In Protected Area: Jiuzhaigou Biosphere Reserve,China 总被引:4,自引:0,他引:4
More and more visitors are attracted to protected areas nowadays, which not only bring about economic increase but also seriously adverse impacts on the ecological environment. In protected areas, trails are linkage between visitors and natural ecosystem, so they concentrate most of the adverse impacts caused by visitors. The trampling problems on the trails have been received attentions in the tremendous researches. However, few of them have correlated the environmental impacts to trail spatial patterns. In this project, the trails were selected as assessment objective, the trampling problems trail widening, multiple trail, and root exposure were taken as assessment indicators to assess ecological impacts in the case study area Jiuzhaigou Biosphere Reserve, and two spatial index, connectivity and circularity, were taken to indicate the trail network spatial patterns. The research results showed that the appearing frequency of the trampling problems had inverse correlation with the circularity and connectivity of the trail network, while the problem extent had no correlation with the spatial pattern. Comparing with the pristine trails, the artificial maintenance for the trails such as wooden trails and flagstone trails could prohibit vegetation root from exposure effectively. The research finds will be useful for the future trail design and tourism management. 相似文献
997.
Paul Scholte Olivier Pays Saleh Adam Bertrand Chardonnet Hervé Fritz Jean-Baptiste Mamang Herbert H. T. Prins Pierre-Cyril Renaud Patrick Tadjo Mark Moritz 《Conservation biology》2022,36(2):e13860
When in 2010 the world's governments pledged to increase protected area coverage to 17% of the world's land surface, several Central African countries had already set aside 25% of their northern savannas for conservation. To evaluate the effectiveness of this commitment, we analyzed the results of 68 multispecies surveys conducted in the seven main savanna national parks in Central Africa (1960–2017). We also assembled information on potential drivers of large herbivore population trends (rainfall and number of rangers) and on tourist numbers and revenues. In six out of the seven parks, wild large herbivore populations declined dramatically over time, livestock numbers increased severalfold, and tourism, the pillar under a once thriving local wildlife industry, collapsed. Zakouma National Park (Chad) stood out because its large herbivore populations increased, an increase that was positively correlated with rainfall and number of rangers (a proxy for management inputs). With increasing insecurity and declining revenues, governments find themselves confronted with too few resources to protect vast areas. To deal with this conversation overstretch, we propose to extend the repeatedly promoted solutions––scaled up funding, enhanced management––with a strategic retreat, focusing scarce resources on smaller areas to save wildlife in the Central African savannas. 相似文献
998.
999.
可控制性旅游灾害的影响分析及防治策略探究 总被引:1,自引:0,他引:1
本文在旅游灾害定义研究的基础之上,根据旅游灾害产生的原因和旅游灾害的性质,将旅游灾害分为可控制性旅游灾害和不可控制性旅游灾害.可控性旅游灾害主要是人为原因(包括旅游者和管理者方面)或伴随旅游发展而产生的,这类旅游灾害在现实中已产生了较大影响,对旅游业的发展极为不利.因此探讨可控制性旅游灾害的影响和防治策略,不仅能引起人们对这种人为性旅游灾害的重视,而且还可以推动旅游业健康、稳定的发展. 相似文献
1000.
增权是社区参与旅游研究的重要领域。增权对应的概念是去权,对社区去权的研究能够为增权探索提供扎实的理论基础和路径借鉴。运用文献分析、深度访谈和田野调查等方法,以安徽省太平湖为例,借助社区增权分析框架,探索湖泊型旅游地社区参与的去权过程。研究发现:(1)太平湖渔民群体在政治、经济、心理和社会四个维度上都显现出权利被削弱甚至处于无权的状态。(2)经济利益分配不公是社区居民“权能感”丧失最直接的因素,为改变利益主体之间的权力关系,对政治权益的要求常成为经济诉求的辅助手段;经济、政治和社会三方面去权共同导致了社区心理无权感。(3)太平湖社区参与的去权呈现了螺旋下降的过程。(4)相对区位条件、参与旅游程度、个人能力等因素导致对“权能感”感知明显不同,社区内部出现分化。最后,从制度、政府和社区层面探讨了湖泊型旅游地社区去权的根源。 相似文献