全文获取类型
收费全文 | 1253篇 |
免费 | 94篇 |
国内免费 | 233篇 |
专业分类
安全科学 | 62篇 |
废物处理 | 4篇 |
环保管理 | 183篇 |
综合类 | 765篇 |
基础理论 | 177篇 |
环境理论 | 1篇 |
污染及防治 | 25篇 |
评价与监测 | 91篇 |
社会与环境 | 185篇 |
灾害及防治 | 87篇 |
出版年
2024年 | 7篇 |
2023年 | 21篇 |
2022年 | 45篇 |
2021年 | 49篇 |
2020年 | 40篇 |
2019年 | 52篇 |
2018年 | 52篇 |
2017年 | 49篇 |
2016年 | 43篇 |
2015年 | 62篇 |
2014年 | 51篇 |
2013年 | 71篇 |
2012年 | 79篇 |
2011年 | 84篇 |
2010年 | 82篇 |
2009年 | 71篇 |
2008年 | 60篇 |
2007年 | 71篇 |
2006年 | 75篇 |
2005年 | 50篇 |
2004年 | 65篇 |
2003年 | 70篇 |
2002年 | 51篇 |
2001年 | 40篇 |
2000年 | 38篇 |
1999年 | 19篇 |
1998年 | 25篇 |
1997年 | 28篇 |
1996年 | 37篇 |
1995年 | 9篇 |
1994年 | 15篇 |
1993年 | 19篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1977年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有1580条查询结果,搜索用时 125 毫秒
991.
Vries I. de Smaal A. C. Nienhuis P. H. Joordens J. C. A. 《Journal of Coastal Conservation》1996,2(1):139-148
The Dutch Delta Region (S-W Netherlands) originally consisted of interconnected estuaries, interfacing the rivers Rhine, Meuse
and Schelde with the North Sea. The ecosystems were immature, with physical rather than biological control of population dynamics.
Main functions were shipping and shellfisheries. An emergent function of the interconnected estuaries was the buffering and
upgrading of river-borne substances before they entered the sea.
Execution of the Delta Project in the period 1960–1986 resulted in isolation of several water systems disconnected from rivers
and sea, and loss of gradients within these systems. Population dynamics were now controlled by chemical and biological rather
than physical factors. Vulnerability to external perturbation increased. These changes also affected the buffering capacity,
i.e. reduced the utility of the area as stabiliser of the geosystem. Recreational use and appreciation of natural values increased,
potentially conflicting with shipping and shellfisheries.
Retrospective analysis of the environmental policy and management revealed three consecutive strategies in the Delta Project.
1. Reactive one-issue management, focusing on safety against flooding only. This strategy aimed at complete closure of the
estuaries thus transforming them into fresh water lakes. It has destroyed feed-backs and buffering between coastal and inland
waters. This strategy has not promoted sustainable development and has increased the vulnerability of the area to future catastrophes.
2. Protective bio-ecological management focused on the preservation of existing values of landscape and environment, and resulted
in the maintenance of saline conditions and preservation of marshes by shore protection measures. The drawback of this passive
orientation to existing values ?where they are now? is the necessity of continuous intensive care because the natural adaptive
ability is not being restored. 3. Constructive geo-ecological management is based on understanding functional properties within
and between ecosystems as integrated elements of the landscape structure. This strategy aims at environmental protection,
restoration and development of values ?where they must be?. Re-establishment of gradients by e.g. re-introducing tidal influence
and by restoring salt marshes should contribute to sustainable development. 相似文献
992.
河西地区生态环境脆弱性评价与生态环境建设对策研究 总被引:4,自引:0,他引:4
本文在对河西地区生态环境进行脆弱度评价的基础上 ,提出河西地区生态环境建设应走生态经济相结合的道路 ,要从建立水资源持续利用机制、科学实施荒漠化防治工程、加强祁连山水源涵养林的保护以及培育特色产业等方面入手 ,进行生态环境建设等 相似文献
993.
Wang Xiaoxiao 《中国人口.资源与环境(英文版)》2007,5(4):57-63
It is a fact that in U.S. the immigration between rural areas and city areas is free, but in China this type of immigration is restricted by HUKOU system (Hukou, namely the household registration system, was designed to control rural-urban in China). All of those national policies in city areas are much better than those in rural areas, so those corresponding differences bring about great discrepancy of the economic status (mainly including GDP per person and income per resident) between rural and city areas in the same urban region, especially in different urban re- gions because the percentage of urban residents in those urban regions is in-equable. The present paper mainly researches the topic of relationship between the percentage of urban residents and the economic status in an urban region in China, including the relationship between the economic and the political functions of a settlement in China during the process of urbanization. 相似文献
994.
Shlyakhtin G. V. Tabachishin V. G. Khrustov A. V. Zav'yalov E. V. 《Russian Journal of Ecology》2004,35(4):247-253
Based on the concept of an ecological niche, the processes of segregation in the Lower Volga populations of great and little bustards (Otis tarda L. and Tetrax tetrax L). have been studied in the evolutionary and adaptive aspects. The results have shown that segregation of the ecological niches of the two species occurs mainly on a trophic basis, when bird specialization in the use of food resources provides the possibility of changing the nesting biotopes. Some trophic adaptations are temporary and do not modify a species-specific stereotype, whereas other adaptations lead to the development of new forms of behavior and their evolutionary stabilization. Spatial characteristics (biotopic preference, nest location, etc.) complement the identified hierarchical series of parameters characterizing the ecological niches of the species studied. In the Transvolga region of Saratov oblast, the total sizes of great and little bustard populations in the breeding season reach approximately 4100 and 5900 birds, respectively. 相似文献
995.
从实践和理论两个方面探讨了生态示范区的内涵、建设思路、典型模型及生态示范区建设面临的问题与对策建议。 相似文献
996.
论资源开发区域的环境保护:以内蒙古呼伦贝尔为例 总被引:1,自引:0,他引:1
周民良 《中国人口.资源与环境》1994,4(2):39-43
本文以我国一个重要的资源开发区域——内蒙古呼伦贝尔为案例,分析了该区域在资源开发中造成的种种环境问题和引发这些问题的背景因素,据此提出了加强环境保护的措施。作者认为呼伦贝尔出现的环境问题在我国资源开发区域带有一定的典型性,这种状况提醒我们,就发展中大国来说,在资源开发过程中绝不能忽视而只能加强环境保护工作,对我国中西部生态环境脆弱的资源开发区域尤应如此。 相似文献
997.
癌症及其发生的水土环境 总被引:1,自引:0,他引:1
本文从环境学角度分析了癌症高发区的水土环境。表明癌症高发区除水土严重污染,许多常量成份出现异常外,一些微量元素还明显缺少或严重超量。 相似文献
998.
应台湾环保协会邀请,浙江省再生资源回收利用协会赴台湾进行参访考察。通过听取介绍、实地察看、座谈交流等多种方式,学习、借鉴台湾地区在再生资源回收利用体系建设方面的做法与经验,并就我国再生资源回收与利用行业的发展提出建议。 相似文献
999.
建筑施工区域风险研究 总被引:2,自引:2,他引:0
根据国内建筑施工过程现状和作业特点,以及国内外学者对建筑施工过程中风险的研究,考虑到建筑施工区域不但面临单体建筑施工的各种风险,还必须克服单体施工过程中时空上相互干扰而带来的风险,构建了单体建筑风险分析模型、确定单体建筑风险的影响梯度、提出建筑施工区域总风险计算方法。示例分析表明,该风险分析模型和计算方法,可以全面系统地预测区域内风险的分布及其变动情况,有助于实施有针对性的风险预防和控制措施,有益于提高建筑施工区域全过程的安全管理水平。 相似文献
1000.
Land-use change in oases of arid zones play a significant role in the sustainable development and stability of oases. This paper presents a typical case of successful efforts to mitigate land-use change, its drivers and effects on the oasis eco-environment at Keriya Oasis in the western arid zone of China using remotely-sensed data, official statistics, and data collected by field investigation. Mathematical models were developed to quantify important elements related to land-use change, including net change and total change. The results indicate that: (1) approximately 17% of land-use types of Keriya Oasis changed between 1991 and 2002; (2) socioeconomic development, climate change, and economic polices contributed to land-use change in the oasis; (3) inappropriate human activities were the main cause of land-use change and eco-environmental degradation in the oasis; and (4) the stability of the oasis is threatened by land-use change and unexpected eco-environmental changes in the oasis and oasis–desert ecotone. The study suggests irrational human activity in arid zones, and that caution should be exercised to maintain stability and sustainable development of oases. 相似文献