全文获取类型
收费全文 | 3535篇 |
免费 | 179篇 |
国内免费 | 272篇 |
专业分类
安全科学 | 141篇 |
废物处理 | 15篇 |
环保管理 | 952篇 |
综合类 | 1747篇 |
基础理论 | 327篇 |
环境理论 | 1篇 |
污染及防治 | 145篇 |
评价与监测 | 223篇 |
社会与环境 | 340篇 |
灾害及防治 | 95篇 |
出版年
2024年 | 6篇 |
2023年 | 38篇 |
2022年 | 52篇 |
2021年 | 79篇 |
2020年 | 119篇 |
2019年 | 80篇 |
2018年 | 73篇 |
2017年 | 105篇 |
2016年 | 134篇 |
2015年 | 116篇 |
2014年 | 151篇 |
2013年 | 181篇 |
2012年 | 193篇 |
2011年 | 259篇 |
2010年 | 166篇 |
2009年 | 233篇 |
2008年 | 205篇 |
2007年 | 242篇 |
2006年 | 197篇 |
2005年 | 149篇 |
2004年 | 129篇 |
2003年 | 153篇 |
2002年 | 137篇 |
2001年 | 102篇 |
2000年 | 143篇 |
1999年 | 118篇 |
1998年 | 95篇 |
1997年 | 59篇 |
1996年 | 32篇 |
1995年 | 59篇 |
1994年 | 23篇 |
1993年 | 36篇 |
1992年 | 27篇 |
1991年 | 14篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1974年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有3986条查询结果,搜索用时 367 毫秒
901.
Aquaculture tenures or leases have become an increasingly important management tool for regulating access rights to coastal and offshore marine habitat. Tenure, as a form of private property rights to marine space, is generally considered a prerequisite for aquaculture development, as are the associated exclusive access rights which provide necessary incentives for producers to invest in infrastructure. The shellfish industry in British Columbia (BC), Canada, is presented as a case study of a transition from a primarily common property wild fishery to a rights‐based system for aquaculture. In BC, seafood production has grown substantially during the past two decades as a result of aquaculture production. However, despite the inherent economic advantages of the tenuring system for increasing seafood production, rights to aquaculture sites in BC remain highly controversial, particularly in response to environmental concerns and infringements on Aboriginal territorial claims. Shellfish farming has, to‐date, been far less controversial than salmon farming; however, shellfish aquaculture has not been uniformly adopted across the province, and analyses of industry capacity or economic opportunities for coastal communities have failed to adequately explain development patterns. This paper, which identifies perceptions of the risks and benefits of the shellfish aquaculture tenuring system, presents the results of 56 interviews conducted with individuals involved in shellfish production in BC. Results indicate that heightened perceptions of risk about shellfish aquaculture tenuring are related to unresolved Aboriginal territorial claims, economic dependence on wild shellfish resources, as well as place‐based values favouring access to wild resources. Underlying values and cultural understandings also strongly shape public perceptions of the risks of aquaculture, and as such, influence local decisions to either accept or resist industry growth. In this case, interviewees' risk perceptions were found to be more important indicators of the potential for industry expansion than studies of capacity or economic cost‐benefit analyses. 相似文献
902.
以安徽省泗县开发区为例,从土地利用状况、用地效益、管理绩效和可持续发展状况4个方面构建开发区土地集约利用评价指标体系,运用GIS技术、特尔斐法,选择评价模型确定权重后对泗县开发区进行土地集约利用评价,研究泗县开发区土地集约利用状况.结果显示,泗县开发区土地集约利用总体水平为中等集约利用,土地利用状况和用地效益度方面存在着一定问题.基于反映的问题,提出相应的措施. 相似文献
903.
This paper provides an overview of the emerging role of Aboriginal people in Sustainable Forest Management (SFM) in Canada over the past decade. The 1996 Royal Commission on Aboriginal Peoples (RCAP) provided guidance and recommendations for improving Aboriginal peoples' position in Canadian society, beginning with strengthening understanding and building relationships between Aboriginal and non-Aboriginal parties. This paper explores the extent to which advances in Aboriginal/non-Aboriginal relationships and Aboriginal forestry have been made as a result of RCAP's call for renewed relationships based on co-existence among nations. Such changes have begun to alter the context in which Aboriginal/non-Aboriginal relationships exist with respect to SFM. While governments themselves have generally not demonstrated the leadership called for by RCAP in taking up these challenges, industry and other partners are demonstrating some improvements. A degree of progress has been achieved in terms of lands and resources, particularly with co-management-type arrangements, but a fundamental re-structuring needed to reflect nation-to-nation relationships has not yet occurred. Other factors related to increasing Aboriginal participation in SFM, such as the recognition of Aboriginal and treaty rights, are also highlighted, along with suggestions for moving Aboriginal peoples' SFM agenda forward in the coming years. 相似文献
904.
经济转型是资源型城市实现可持续发展的必然过程,而经济转型时机对城市转型路径与转型效果具有重要影响。以资源型城市生命周期曲线为工具,尝试从资源开发时序、产业结构演进、空间结构演化和生态环境变化四个维度构建经济转型时机的理论分析框架,并以大庆市为实证,探究大庆市所处的经济转型时机,以期为大庆市制定经济转型策略提供理论依据,并对国内资源型城市经济转型时机的判断提供思路和启示。 相似文献
905.
Network particle tracking (NPT), building on the foundation of network environ analysis (NEA), is a new development in the definition of coherence relations within and between connected systems. This paper evaluates three ecosystem models in a comparison of throughflow- and storage-based NEA and NPT. Compartments in models with high indirect effects and Finn cycling showed low correlation of NEA storage and throughflow with particle repeat visits and numbers of particles in compartments at steady state. Conversely, the correlation between NEA and NPT results was high with two models having lower indirect effects and Finn cycling. Analysis of ecological orientors associated with NEA showed NPT to fully support conventional NEA results when the common conditions of donor control and steady state are satisfied. Particle trajectories are recorded in the new concept of a particle “passport”. Ability to track and record particle in-system histories enables views of multiple scales and opens the possibility of making pathway-dependent modeling decisions. NPT may also enable modeling of time, allowing integration of Newtonian, organismal and stochastic modeling perspectives in a single comprehensive analysis. 相似文献
906.
基于2015年大连市初中学校教育统计数据,利用熵值法、耦合协调度模型和空间插值分析法,从市域内校际间对大连市初中师资力量与教育成效耦合协调的空间特征进行了研究。结果表明:①师资力量高低分离、抱团分布,教育成效呈现核心高、边缘低的格局。②师资力量与教育成效的耦合度总体水平较高,以高水平耦合为主,空间上基本覆盖整个大连市。③协调度上,勉强协调与初级协调为主,空间呈现明显的中心—外围分布趋势,其中勉强协调占大部分。④学校类型具体划分为6种协调类型,呈核心—外围的圈层分布模式,其中核心城区为师资高成效高的中级协调。 相似文献
907.
Rural-urban land conversion is a universal phenomenon in the rapid process of economic development and urban growth. The welfare of farmers who lost their farmland attracted a widespread concern within the society and academia. However, further research about differentiated policies according to the characteristics of different farmer groups is still need to be conducted. This article divides the land-lost farmers into three age groups: younger than 45, 45–65, and more than 65. It proposes a welfare index system including eight functional areas based on different age groups of affected farmers, taking four districts of Wuhan City as case study area. Fuzzy mathematics method is used to derive the aggregated welfare effect index. Our analysis show that the overall welfare levels of land-lost farmers of all age groups declined, but with a varying degree, with the level of welfare in those farmers who are 45–65 years old, younger than 45 years old, and older than 65 years old decreased by 18.7%, 16.6%, and 12.7%, respectively. The direction and degree of effects on the functional activity index varies among different groups. Economic conditions, living environment, health, and social participation of all age groups decrease while social security and housing conditions increase. On the other hand, development opportunities, social communication, and leisure have different changing directions in different age stages. These results call for differentiated and tailor-made compensation policies for land-lost farmers, towards improving the welfare levels of all farmers and reduce the disparity among them. 相似文献
908.
Peter H. Koehn 《国际发展与全球生态学杂志》2013,20(4):380-396
Perpetuation of the South-North divide over climate change threatens to undermine the sustainability of the planet's vulnerable ecosystems. The current focus of international attention is on the USA and the PRC since both countries are in a position to negate or clinch the global warming mitigation efforts of the rest of the world community and because the two governments are primarily responsible for the entrenched global impasse over greenhouse gas (GHG) abatement. This contribution illustrates how transnational non-state actors, specifically Chinese American transmigrants, can make a difference in surmounting the US-China divide over GHG emissions, even in a time of state stalemate. Specific opportunities to shape sustainable development outcomes are explored by reference to energy efficiency, renewable energy, transportation, GHG capture, and public education projects. The discussion shows that, by teaming up with the NGOs, universities, foundations and firms engaged in or contemplating involvement in GHG emission mitigation projects in China, Chinese Americans from many walks of life who can manoeuvre skilfully along the climate change frontier occupy a potentially decisive position in terms of supporting sustainable development. 相似文献
909.
Xue-Yan Liu Hua-Yun Xiao You-Yi Li Hong-Wei Xiao Yan-Li Wang 《Environmental pollution (Barking, Essex : 1987)》2010,158(6):2273-2281
Epilithic mosses are characterized by insulation from substratum N and hence meet their N demand only by deposited N. This study investigated tissue C, total Chl and δ13C of epilithic mosses along 2 transects across Guiyang urban (SW China), aiming at testing their responses to N deposition. Tissue C and total Chl decreased from the urban to rural, but δ13Cmoss became less negative. With measurements of atmospheric CO2 and δ13CO2, elevated N deposition was inferred as a primary factor for changes in moss C and isotopic signatures. Correlations between total Chl, tissue C and N signals indicated a nutritional effect on C fixation of epilithic mosses, but the response of δ13Cmoss to N deposition could not be clearly differentiated from effects of other factors. Collective evidences suggest that C signals of epilithic mosses are useful proxies for N deposition but further works on physiological mechanisms are still needed. 相似文献
910.
This paper examines the historic development of the Brazilian sugarcane ethanol sector and the largely successful attempt to create a sustainable, renewable fuel for the transport sector. The policy that resulted from this process is an example of meeting the need for sustainable transport through the consideration of location‐specific characteristics and appropriate policy. The paper then questions the current and expected trajectory of the sugarcane ethanol sector with the focus on one key question: can sustainability be exported? In this analysis, the paper identifies new threats to the sustainability of Brazilian sugarcane ethanol and potential “opportunity costs” incurred in further development and internationalization of the sector. The paper concludes that exporting sugarcane ethanol may bring unanticipated deleterious consequences, which in turn means that both policy and theory need to be more precise about how sustainable transport is defined and bounded by time and space. 相似文献