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   548篇
  免费   43篇
  国内免费   30篇
安全科学   17篇
废物处理   5篇
环保管理   310篇
综合类   122篇
基础理论   72篇
污染及防治   24篇
评价与监测   27篇
社会与环境   37篇
灾害及防治   7篇
  2023年   4篇
  2022年   2篇
  2021年   9篇
  2020年   12篇
  2019年   14篇
  2018年   16篇
  2017年   18篇
  2016年   20篇
  2015年   24篇
  2014年   25篇
  2013年   36篇
  2012年   27篇
  2011年   29篇
  2010年   24篇
  2009年   35篇
  2008年   31篇
  2007年   35篇
  2006年   26篇
  2005年   20篇
  2004年   21篇
  2003年   21篇
  2002年   16篇
  2001年   18篇
  2000年   20篇
  1999年   11篇
  1998年   13篇
  1997年   15篇
  1996年   8篇
  1995年   5篇
  1994年   4篇
  1993年   4篇
  1992年   7篇
  1991年   2篇
  1990年   3篇
  1989年   3篇
  1988年   8篇
  1987年   2篇
  1986年   5篇
  1984年   4篇
  1983年   3篇
  1982年   4篇
  1980年   3篇
  1979年   7篇
  1978年   1篇
  1977年   2篇
  1974年   2篇
  1972年   1篇
  1971年   1篇
排序方式: 共有621条查询结果,搜索用时 62 毫秒
521.
中国大城市郊区化对城市可持续发展的影响分析   总被引:1,自引:1,他引:0  
进入20世纪80年代以来,中国经济在改革开放的促进下飞速发展,城市化水平大大提高。随着城市的发展和人民生活水平的提高。以及城市产业结构的调整,我国一些大城市一部分工业尤其是污染扰民工业开始从中心区向郊区搬迁,大城市工业进入郊区化发展阶段。随着住房制度的改革,大城市中许多工薪阶层开始住进郊区的单位分房或自购房。人口郊区化及随之而来的商业郊区化也开始显现。我国大城市郊区化是中国城市发展过程中的一种重要现象。城市郊区化对城市发展产生了深远影响。本文以北京、上海、广州、杭州、苏州、沈阳、大连等大城市为例,概括了当前我国大城市郊区化的现状特点,指出了郊区化对城市可持续发展的影响,提出了相应的管理对策,为城市管理部门提供参考。  相似文献   
522.
We conducted a diagnosis of the environmental management system of the Brazilian auto parts industry, using the LIFE certification methodology (lasting initiative for earth) as a diagnostic tool. This certification recognizes enterprises that develop conservation actions for biodiversity for the purpose of minimizing and/or mitigating their own negative impact on the environment. Through this method, it was possible to quantify and qualify the environmental impact and investigate the existence of conservation actions, as well as evaluate them quantitatively and qualitatively. Therefore, we used this methodology to demonstrate its potential as an economic instrument of environmental management through its application within an EMS certified to the ISO 14001 series. It was shown that there are many benefits of using sustainable environmental resources (possibility to return to ISE-Corporate Sustainability Index-Bovespa) and for the final disposal of waste from production. The main results indicated that the LIFE methodology allows companies to incorporate actions to biodiversity conservation transversally into their EMSs, which can increase the efficiency of enterprise management. We believe that the use of this management model by other companies will enable the intensification of conservation actions in protected areas in their regions.  相似文献   
523.
凤凰城旅游景区转让后的效应评价   总被引:7,自引:0,他引:7  
在我国经济市场化改革的大背景下,转让景区经营权、实行企业化运作成为一些风景名胜区经营管理改革过程中的一种制度创新模式。地处西部大开发战略图中的湘西凤凰县由于在旅游开发中受到了资金缺口和管理瓶颈的双重制约,于2001年底将其辖域内的八大景区(点)的50年经营权转让给了湖南黄龙洞投资股份有限公司。景区经营权转让是一个十分复杂而敏感的话题。本文避开关于景区经营权转让的各种是非争论,基于对旅游地社区各利益主体以及旅游者的实地调查和访谈记录分析,对凤凰景区企业化运作三年来的绩效与影响作了较为客观的评估,并就如何完善景区企业化运作模式、规避经营管理风险和负面影响等提出了相关理论思考和政策建议。  相似文献   
524.
ABSTRACT: Controlling agricultural nonpoint source pollution from livestock grazing is a necessary step to improving the water quality of the nation's streams. The goal of enhanced stream water quality will most likely result from the implementation of an integrated system of best management practices (BMPs) linked with stream hydraulic and geomorphic characteristics. However, a grazing BMP system is often developed with the concept that BMPs will function independently from interactions among controls, climatic regions, and the multifaceted functions exhibited by streams. This paper examines the peer reviewed literature pertaining to grazing BMPs commonly implemented in the southern humid region of the United States to ascertain effects of BMPs on stream water quality. Results indicate that the most extensive BMP research efforts occurred in the western and midwestern U.S. While numerous studies documented the negative impacts of grazing on stream health, few actually examined the success of BMPs for mitigating these effects. Even fewer studies provided the necessary information to enable the reader to determine the efficacy of a comprehensive systems approach integrating multiple BMPs with pre‐BMP and post‐BMP geomorphic conditions. Perhaps grazing BMP research should begin incorporating geomorphic information about the streams with the goal of achieving sustainable stream water quality.  相似文献   
525.
Carbon sequestration in terrestrialecosystems and geologic formations providesa significant opportunity for California toaddress global climate change. The physicalsize of its resources (e.g., forests,agriculture, soils, rangeland, and geologicformations) and the expertise in Californiaprovides a substantial foundation fordeveloping carbon sequestration activities.Furthermore, the co-benefits of carbonsequestration – such as improved soil andwater quality, restoration of degradedecosystems, increased plant and cropproductivity, and enhanced oil recovery – are significant. In fact, carbonsequestration often represents a `noregrets' strategy – implementing carbonsequestration provides multiple benefits,even without the advent of global climatechange.Nevertheless, researchers need to addressseveral issues to determine more accuratelythe potential, benefits, and costs ofsequestering carbon in California'sterrestrial ecosystems and geologicformations, as well as to identify the mostpromising sequestration methods and theiroptimal implementation. One key issue isthe type of regulatory constraints facingdevelopers of carbon sequestrationprojects: what permits are needed fordeveloping these projects? The permittingprocess may impede the penetration ofsequestration technologies into the marketif the costs (including transaction costs)of obtaining the permits are too burdensomeand costly. For example, at least ninefederal regulations and seven stateregulations will potentially influencecarbon sequestration projects inCalifornia. This paper also provides anexample of the types of permits needed fordeveloping a carbon sequestration project,using California as an example. It ispossible that a carbon sequestrationproject may have to obtain a total of 15permits (3 federal, 6 state, 6 local),before it even starts to operate. In theconcluding section, we offer some suggestedareas for research and activities forpolicy makers.  相似文献   
526.
This paper explores the complex heterogeneous experiences of flood impacts based on a bio-psychosocial model of socio-economic, demographic, behavioural and environmental factors. Using ordinary least squares regression on a cross-sectional survey of 1003 individuals, flood impacts in three contiguous coastal neighbourhoods in Lagos, Nigeria, were modelled. The results show that approximately 52% of the variability in flood impact was accounted for by education, age, family structure, ethnicity, personal health concern and income. While involvement in coping was not a significant predictor of flood impacts, relocation emerged as a strong predictor. The inclusion of behavioural factors did not change the magnitude and significance of the relationship between demographic factors and flood impacts. However, the effects of age, education and personal health concern disappeared when environmental factors were controlled. The overall importance of the predictors for determining flood impact in decreasing order is as follows: income > coping strategies > ethnicity = participation in community development > family structure > personal health concerns > housing quality > reasons for living in residential locality > neighbourhood vulnerability to flood > housing vulnerability to flood.  相似文献   
527.
A mass‐balance solute‐transport modeling approach was used to investigate the effects of dense nonaqueous phase liquid (DNAPL) volume, composition, and generation of daughter products on simulated and measured long‐term trends of chlorinated ethene (CE) concentrations at a public supply well. The model was built by telescoping a calibrated regional three‐dimensional MODFLOW model to the capture zone of a public supply well that has a history of CE contamination. The local model was then used to simulate the interactions between naturally occurring organic carbon that acts as an electron donor, and dissolved oxygen (DO), CEs, ferric iron, and sulfate that act as electron acceptors using the Sequential Electron Acceptor Model in three dimensions (SEAM3D) code. The modeling results indicate that asymmetry between rapidly rising and more gradual falling concentration trends over time suggests a DNAPL rather than a dissolved source of CEs. Peak concentrations of CEs are proportional to the volume and composition of the DNAPL source. The persistence of contamination, which can vary from a few years to centuries, is proportional to DNAPL volume, but is unaffected by DNAPL composition. These results show that monitoring CE concentrations in raw water produced by impacted public supply wells over time can provide useful information concerning the nature of contaminant sources and the likely future persistence of contamination.  相似文献   
528.
天然气开发在实际过程中大多是区域滚动开发,对流域的水环境安全可能形成较大的影响和隐患.运用主成分分析法对区域内各部分环境特征和国家环境质量标准进行分析、处理、排序,能够识别区域内各部分的环境质量变化情况,为区域环境管理和风险预防提供理论基础.以川东盆地,沱江和涪江上游德阳地区天然气区域开发为例,分析天然气开采对区域内各部分地表水环境质量的影响.可知在选定的4个水质参数中,pH值和COD两个主成分能够代表开发前所有监测信息的93.02%,开发后的95.09%.研究结果表明,在加强环境保护的前提下,区域天然气开发不会影响区域水质;同时也证明在区域水环境安全评价中主成分分析法是一种非常有效、快速的方法.  相似文献   
529.
Abstract: Concentrating tourism activities can be an effective way to closely manage high‐use parks and minimize the extent of the effects of visitors on plants and animals, although considerable investment in permanent tourism facilities may be required. On coral reefs, a variety of human‐related disturbances have been associated with elevated levels of coral disease, but the effects of reef‐based tourist facilities (e.g., permanent offshore visitor platforms) on coral health have not been assessed. In partnership with reef managers and the tourism industry, we tested the effectiveness of concentrating tourism activities as a strategy for managing tourism on coral reefs. We compared prevalence of brown band disease, white syndromes, black band disease, skeletal eroding band, and growth anomalies among reefs with and without permanent tourism platforms within the Great Barrier Reef Marine Park. Coral diseases were 15 times more prevalent at reefs with offshore tourism platforms than at nearby reefs without platforms. The maximum prevalence and maximum number of cases of each disease type were recorded at reefs with permanently moored tourism platforms. Diseases affected 10 coral genera from 7 families at reefs with platforms and 4 coral genera from 3 families at reefs without platforms. The greatest number of disease cases occurred within the spatially dominant acroporid corals, which exhibited 18‐fold greater disease prevalence at reefs with platforms than at reefs without platforms. Neither the percent cover of acroporids nor overall coral cover differed significantly between reefs with and without platforms, which suggests that neither factor was responsible for the elevated levels of disease. Identifying how tourism activities and platforms facilitate coral disease in marine parks will help ensure ongoing conservation of coral assemblages and tourism.  相似文献   
530.
This paper utilizes an inclusive community based sustainability framework with a focus on a resort destination in providing a potential model for more inclusive long-range destination planning and implementation. Four diverse, but interrelated areas of sustainable tourism were specified in this framework for a more comprehensive process including ecological, cultural, economic and socio-community sustainability. In addition a strategic community driven structure, which provides direction, information and practices, serves the purpose of integrating and implementing the framework. The unique tourism destination, Noosa in Australia is used as an example of embracing sustainable tourism as a community and as part of a larger focus on the four key components of sustainability. By viewing sustainable community attributes as assets, all of which are important to manage, enhance and/or conserve, it is expected that the resort community will continue to attract visitors to feel connected and committed to experiencing its lifestyle, sense-of-community and natural features while also contributing to community sustainable stewardship and a strong tourism economy. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. Dr. Richins is Chair of the Graduate Program within the School of Travel Industry Management at University of Hawaii. He holds a Ph.D. from James Cook University in Australia and a B.S. and M.S. from University of Oregon. Previously he held leadership positions for over 15 years in Australian and New Zealand including Waikato University, University of Newcastle and University of the Sunshine Coast. He was also Chair of the Resort Management program at Sierra Nevada College in Nevada.  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