全文获取类型
收费全文 | 5336篇 |
免费 | 504篇 |
国内免费 | 870篇 |
专业分类
安全科学 | 797篇 |
废物处理 | 241篇 |
环保管理 | 1421篇 |
综合类 | 2669篇 |
基础理论 | 610篇 |
环境理论 | 3篇 |
污染及防治 | 473篇 |
评价与监测 | 125篇 |
社会与环境 | 221篇 |
灾害及防治 | 150篇 |
出版年
2023年 | 59篇 |
2022年 | 111篇 |
2021年 | 164篇 |
2020年 | 159篇 |
2019年 | 158篇 |
2018年 | 151篇 |
2017年 | 196篇 |
2016年 | 227篇 |
2015年 | 237篇 |
2014年 | 270篇 |
2013年 | 339篇 |
2012年 | 369篇 |
2011年 | 422篇 |
2010年 | 317篇 |
2009年 | 318篇 |
2008年 | 273篇 |
2007年 | 401篇 |
2006年 | 364篇 |
2005年 | 264篇 |
2004年 | 223篇 |
2003年 | 209篇 |
2002年 | 175篇 |
2001年 | 165篇 |
2000年 | 153篇 |
1999年 | 152篇 |
1998年 | 105篇 |
1997年 | 89篇 |
1996年 | 81篇 |
1995年 | 75篇 |
1994年 | 47篇 |
1993年 | 31篇 |
1992年 | 47篇 |
1991年 | 26篇 |
1990年 | 20篇 |
1989年 | 16篇 |
1988年 | 16篇 |
1987年 | 23篇 |
1986年 | 22篇 |
1985年 | 26篇 |
1984年 | 22篇 |
1983年 | 13篇 |
1982年 | 14篇 |
1980年 | 15篇 |
1979年 | 19篇 |
1978年 | 20篇 |
1977年 | 14篇 |
1975年 | 11篇 |
1973年 | 16篇 |
1972年 | 14篇 |
1971年 | 17篇 |
排序方式: 共有6710条查询结果,搜索用时 15 毫秒
1.
Shu-Yii Wu Yong-Fang Liu Ya-Chieh Li Chun-Min Liu 《International Journal of Green Energy》2015,12(10):1025-1030
The CO2 absorption capacities of potassium glycinate, potassium sarcosinate (choline, proline), mono-ethanolamine (MEA), and tri-ethanolamine were evaluated to find the optimal absorbent for separating CO2 from gaseous products by a CO2 purification process. The absorption loading, desorption efficiency, cost, and environmental tolerance were assessed to select the optimal absorbent. MEA was found to be the optimum absorbent for separating the CO2 and H2 mixture in gaseous product. The maximum absorption loading rate was 0.77 mol CO2 per mol MEA at temperature of 20°C and absorbent concentration of 2.5 mol/L, whereas desorption efficiency was 90% by heating for 3 h at 130°C. MEA was found to be an optimal absorbent for the purification process of CO2 during gaseous production. 相似文献
2.
Fishing‐gear restrictions and biomass gains for coral reef fishes in marine protected areas 下载免费PDF全文
Stuart J. Campbell Graham J. Edgar Rick D. Stuart‐Smith German Soler Amanda E. Bates 《Conservation biology》2018,32(2):401-410
Considerable empirical evidence supports recovery of reef fish populations with fishery closures. In countries where full exclusion of people from fishing may be perceived as inequitable, fishing‐gear restrictions on nonselective and destructive gears may offer socially relevant management alternatives to build recovery of fish biomass. Even so, few researchers have statistically compared the responses of tropical reef fisheries to alternative management strategies. We tested for the effects of fishery closures and fishing gear restrictions on tropical reef fish biomass at the community and family level. We conducted 1,396 underwater surveys at 617 unique sites across a spatial hierarchy within 22 global marine ecoregions that represented 5 realms. We compared total biomass across local fish assemblages and among 20 families of reef fishes inside marine protected areas (MPAs) with different fishing restrictions: no‐take, hook‐and‐line fishing only, several fishing gears allowed, and sites open to all fishing gears. We included a further category representing remote sites, where fishing pressure is low. As expected, full fishery closures, (i.e., no‐take zones) most benefited community‐ and family‐level fish biomass in comparison with restrictions on fishing gears and openly fished sites. Although biomass responses to fishery closures were highly variable across families, some fishery targets (e.g., Carcharhinidae and Lutjanidae) responded positively to multiple restrictions on fishing gears (i.e., where gears other than hook and line were not permitted). Remoteness also positively affected the response of community‐level fish biomass and many fish families. Our findings provide strong support for the role of fishing restrictions in building recovery of fish biomass and indicate important interactions among fishing‐gear types that affect biomass of a diverse set of reef fish families. 相似文献
3.
Current demand analysis methods do not formally cover the case of chronic deficits in quantity or quality of water and sanitation
services. These services include drinking water supply (DWS), wastewater and sewage treatment (WST), and municipal solid waste
management (MSW). Formal analysis of this case would, at minimum, define the deficit state and evaluate appropriate options
for reducing it. This paper proposes for a formal analytical model for municipal sanitation systems (MSS) that operate with
deficits in at least one of the constituent services of DWS, WST, or MSW. The model introduces definitions and notation for
describing the deficit state for conducting demand analysis on municipal sanitation systems. This model of demand analysis
for systems with chronic deficits will hereinafter be referred to as deficit analysis. A case study for Bacoor, Philippines is presented as an example. 相似文献
4.
Improvements on Flood Alleviation in Germany: Lessons Learned from the Elbe Flood in August 2002 总被引:1,自引:0,他引:1
The increase in damage due to natural disasters is directly related to the number of people who live and work in hazardous
areas and continuously accumulate assets. Therefore, land use planning authorities have to manage effectively the establishment
and development of settlements in flood-prone areas in order to avoid the further increase of vulnerable assets. Germany faced
major destruction during the flood in August 2002 in the Elbe and Danube catchments, and many changes have been suggested
in the existing German water and planning regulations. This article presents some findings of a “Lessons Learned” study that
was carried out in the aftermath of the flood and discusses the following topics: 1) the establishment of comprehensive hazard
maps and flood protection concepts, 2) the harmonization of regulations of flood protection at the federal level, 3) the communication
of the flood hazard and awareness strategies, and 4) how damage potential can be minimized through measures of area precaution
such as resettlement and risk-adapted land use. Although attempts towards a coordinated and harmonized creation of flood hazard
maps and concepts have been made, there is still no uniform strategy at all planning levels and for all states (Lae
nder) of the Federal Republic of Germany. The development and communication of possible mitigation strategies for “unthinkable
extreme events” beyond the common safety level of a 100-year flood are needed. In order to establish a sustainable and integrated
flood risk management, interdisciplinary and catchment-based approaches are needed. 相似文献
5.
李宏规 《中国人口.资源与环境》1992,(1)
人口是人口、资源与环境巨系统中最根本的因素。人口增长过快,将直接加大对资源与环境的压力,并影响人口素质的提高。所以,长期坚持实行计划生育这一基本国策是实现人口、资源、环境协调发展的重要保证。为此,必须要统一认识,增强控制人口的危机感和责任感;实施人口和计划生育目标管理责任制;扎实稳妥地做好农村计划生育工作;齐抓共管,保证人口计划的完成。 相似文献
6.
Evolution of environmental impact assessment as applied to watershed modification projects in Canada
Herman J. Dirschl Nicholas S. Novakowski M. Husain Sadar 《Environmental management》1993,17(4):545-555
This article reviews the application of environmental impact assessment (EIA) procedures and practices to three watershed
modification projects situaled in western Canada. These ventures were justified for accelerating regional economic development,
and cover the period during which public concerns for protecting the environment rapidly made their way into the national
political agenda. An historical account and analysis of the situation, therefore, seems desirable in order to understand the
development of EIA processes, practices, and methodologies since the start of construction of the first project in 1961. This
study concludes that there has been good progress in predicting and evaluating environmental and related social impacts of
watershed modification proposals. However, a number of obstacles need to be overcome before EIA can firmly establish itself
as an effective planning tool. These difficulties include jurisdictional confusions and conflicts, division of authority and
responsibility in designing and implementing appropriate mitigative and monitoring measures, lack of tested EIA methodologies,
and limited availability of qualified human resources. A number of conclusions and suggestions are offered so that future
watershed modification proposals may be planned and implemented in a more environmentally sustainable fashion. These include:
(1) EIA processes must be completed before irrevocable decisions are made. (2) Any major intrusion into a watershed is likely
to impact on some major components of the ecosystem(s). (3) Mitigation costs must form part of the benefit-cost analysis of
any project proposal. (4) Interjurisdictional cooperation is imperative where watersheds cross political boundaries. (5) The
EIA process is a public process, hence public concerns must be dealt with fairly. (6) The role of science in the EIA process
must be at arms length from project proponents and regulators, and allowed to function in the interest of the protection of
the environment and public health and safety.
The views expressed here are the authors’ own and do not necessarily reflect those of FEARO and/or other government agencies
and officials involved in the review of these projects. 相似文献
7.
可持续旅游是 80年代中期以后提出的关于旅游业发展的新思想。经过十多年的不断拓展深化 ,已经得到世界各国的广泛认同 ,并作为跨世纪旅游业发展的战略指导思想。本文从可持续旅游的由来和对可持续旅游内涵实质的界定角度出发 ,结合可持续旅游实现途径的探讨 ,以井冈山风景名胜区为例 ,对风景区旅游业可持续发展进行了深入的探讨 ,为景区的发展规划提出了战略性构想 ,以期能对井冈山风景名胜区旅游资源的可持续利用和旅游业的可持续发展起到抛砖引玉的作用 相似文献
8.
On-going population growth and resulting domestic demand for water require rapid and effective decision-making as regards groundwater management and control of the various sources of salinization and pollution in Coastal aquifers. Sustainability of water resources for utilization by future generations must therefore be a high priority, not only for the purpose of fulfilling needs for water usage but also for bringing people into harmony with their ambient natural environment.The objective of this paper is to propose an empirical approach for prioritization of the needs involved for sustainable aquifer management. The approach involves a schematic format to:(1) develop a global understanding of an aquifer's hydrological and environmental properties in order to delineate appropriate eco-hydrological scenarios and recommend corresponding operational management activities; and(2) emphasize the importance of educating and increasing the awareness of the population involved as to the need for and viability of socially acceptable measures for sustainable management of groundwater and other resources.The psychologist Abraham Maslow utilized a pyramid to illustrate that until people's most basic needs were fulfilled, higher levels of needs would remain irrelevant. This paper postulates a comparable pyramid prioritizing hydrological needs required for progressing towards sustainable groundwater resources. Two sub-regions of Israel's Coastal aquifer in the Sharon region have been presented as representative areas, each characterized by different stress of exploitation. In assessing these sub-regions situation, specific measures have been recommended for achieving and/or maintaining sustainable groundwater resources in light of the ambient environment, and the level of the population on the pyramidal hierarchy of groundwater needs. 相似文献
9.
日本国土开发利用及对我国的启示 总被引:1,自引:0,他引:1
日本在战后经历了经济高速增长,工业化和城市化快速推进的发展历程,其间土地利用在结构、规模、价格、集约利用等方面发生了巨大变动。本文全面分析了二战之后,日本在经济高速增长、产业结构巨大变动、城市化迅速推进的发展过程中.农业用地、工业用地和城市用地在结构、规模、价格、集约利用程度等方面的特征;日本政府针对经济发展和土地利用的变动和影响。制订的一系列规划调整措施和政策法规体系。通过以上分析,探讨日本在有限的土地资源条件下实现经济高速增长的原因、途径和措施,以及对我国的启示。 相似文献
10.
论环境产业 总被引:1,自引:0,他引:1
曹曼 《中国人口.资源与环境》2008,18(6)
本文在可持续发展视角下,把环境的保护、修复、维护的生产活动及与之直接相关的服务活动称为环境产韭,包括发挥减少、避免污染环境作用的资源再利用鼗和发挥治理污染物与修复、改善环境作用的环境维护业.通过探讨环境产业的内涵、发展历程、运行机制和在产业体系中的位置与作用,指出环境产业是在法规保障下政府强行推动产生和发展起来的,是产业体系中不可缺少的重要组成部分;考虑自然环境对社会行为的影响,改进政府行为构建适台环境产业与传统产业协调发展的经济体制是加快发展环境产业的关键. 相似文献