全文获取类型
收费全文 | 469篇 |
免费 | 26篇 |
国内免费 | 36篇 |
专业分类
安全科学 | 25篇 |
废物处理 | 2篇 |
环保管理 | 131篇 |
综合类 | 113篇 |
基础理论 | 149篇 |
环境理论 | 1篇 |
污染及防治 | 22篇 |
评价与监测 | 13篇 |
社会与环境 | 40篇 |
灾害及防治 | 35篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 16篇 |
2020年 | 14篇 |
2019年 | 13篇 |
2018年 | 12篇 |
2017年 | 18篇 |
2016年 | 31篇 |
2015年 | 22篇 |
2014年 | 11篇 |
2013年 | 22篇 |
2012年 | 11篇 |
2011年 | 36篇 |
2010年 | 22篇 |
2009年 | 35篇 |
2008年 | 27篇 |
2007年 | 46篇 |
2006年 | 24篇 |
2005年 | 23篇 |
2004年 | 23篇 |
2003年 | 19篇 |
2002年 | 9篇 |
2001年 | 12篇 |
2000年 | 19篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有531条查询结果,搜索用时 437 毫秒
441.
Rachelle L. Haddock Michael S. Quinn 《Journal of Environmental Planning and Management》2016,59(7):1205-1224
This paper describes efforts to bridge the gap between the existing research and proposed recreation access management for public lands in southwestern Alberta, Canada. Recreation access management has been identified as a complex problem and public consultation is one element in addressing the complexity. An Internet-based survey (n = 945) examined the acceptability and desirability of public consultation processes to assist with access management planning. Non-parametric tests indicate significant differences in desirability of public consultation types existed for all variables except gender. Respondents expressed the desire for a diversity of public consultation approaches with a strong preference for face-to-face field visits. Mechanisms for engagement in access management planning should be based on public consultation preferences to ensure broad, on going engagement and subsequent user acceptance and compliance. 相似文献
442.
At the mid-twentieth century the pace of the transformation of the Swedish forest increased. New methods; large-scale clearcutting, mechanization of logging and planting of seedlings were developed. Chemicals were used to control insects and unwanted tree species. The aims of this study were to elucidate the timing, chain of events and the spatial extent of the large-scale spraying of phenoxy acids in Swedish forests and the drivers for this practice. More than 700 000 hectares of productive forest land was sprayed and the main driving force was a strong will to transform the forest into high-yield coniferous forest plantations. We conclude that; (1) the use of herbicides in forestry in Sweden was done on a very large scale in the period 1948–1984, (2) the ecosystem legacy of herbicide spraying must be investigated and (3) a homogenous cadre of like-minded professionals working across commercial companies, state agencies and universities is dangerous.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01660-5. 相似文献
443.
Forestry development in China has undergone a series of reforms over the past six decades. This article examines temporal changes in forest resources and policies, the current status of forestry, and future challenges toward sustainable forest management in China. Excessive logging in the 1950s to 1980s badly damaged the nation’s forests, but the adoption of enlightened forest policies in the late 1990s has led to increases in China’s total forest area and growing stock. Forest degradation was ecologically and economically costly, and rehabilitation processes have become increasingly more expensive. The low quality and young age of forest resources, loss of natural forests, and more difficulties in afforestation and reforestation pose severe challenges for China’s sustainable forestry. It is critically important for China to enhance forest productivity through intensive management, strengthen enforcement, and educational programs for protecting and restoring natural forests, narrow the gap between domestic timber supply and rapidly expanding consumption, improve coordinating networks for management, finance, and technology transfer, and accelerate efforts to clarify and stabilize tenure arrangements for non-state forests. China’s experience and lessons in forestry may be helpful for other developing countries that are seeking to achieve the goal of sustainable forest management. 相似文献
444.
Sebastian Vincent Grevsmühl 《Environmental Communication: A Journal of Nature and Culture》2018,12(1):71-83
In 1985, just over 30 years ago, the “ozone hole” made its appearance in the press as a truly global environmental threat. As one of the most important environmental issues of the twentieth century, the “ozone hole” is also a remarkable metaphorical, visual, and imaginary construction. This essay examines the historical trajectory of the famous “ozone hole” from its birth within the astronomical community at the beginning of the twentieth century to its contemporary framing as a global environmental threat. The article provides evidence why metaphors constitute a valuable object of historically informed studies of scientific practice, and shows in particular how metaphorical landscapes shift over time, mapping at the same time larger social and political developments. The essay ends by showing how scientific images and metaphorical framings interact and how they shape scientific and popular discourse on nature, as well as our understanding of the global environment. 相似文献
445.
油气长输管道定量风险评价 总被引:2,自引:1,他引:1
管道风险评价普遍采用以Kent打分法为代表的定性方法,笔者提出了一种新方法,即定量风险评价(QRA),采用基于管道失效历史数据库和已有成熟的数值模型,进行管道失效概率分析和失效后果分析,并以此方法在某输气管道上进行了验证,最后得到管段的绝对风险和人口密集段的个人风险,并进行了风险预测。研究表明,QRA受人员主观判断影响较小,计算方法科学合理,结果量化,对进行检测与维护维修资源的分配具有很好的指导意义。 相似文献
446.
Concerns over the increasing popularity of wilderness recreation have resulted in attempts to determine the amount of use that different areas can tolerate without adverse affects to the resource. Early attempts to establish recreational carrying capacities focused on managers' assessments of biophysical impacts. The perceptions of wilderness visitors, however, are now considered integral to capacity decisions. This study used a stress appraisal framework to understand wilderness visitors' perceptions of on-site conditions. It was based on the premise that negative appraisals of wilderness conditions produce stress and that individual perceptions vary based on personal and situational characteristics. The purpose of the study was to assess the validity of a wilderness-hassles appraisal scale by testing hypothesized relationships between experience-use history (EUH), place attachment, and stress appraisal. Data collection occurred through a postal survey of hikers (n = 385) contacted in the High Peaks and Pemigewasset Wilderness Areas during the summer of 2004. An exploratory factor analysis indicated that stress appraisal is a multi-dimensional construct. Validity testing procedures were restricted to those dimensions that were consistent between study areas and provided partial support for the hassles scale. As hypothesized, EUH did not influence perceptions of wilderness conditions. Place attachment, on the other hand, was positively correlated with stressful appraisals of social and managerial conditions. Although Kruskall Wallis tests revealed significant differences in visitors' perceptions of managerial conditions between study sites, perceptions of social conditions did not vary significantly. Implications for management and recommendations for further refinement of the wilderness hassles construct are discussed. 相似文献
447.
We used data from a long-term study (15 years) of fallow deer to report for the first time the lifetime mating success, overall
variance in lifetime mating success, and age-specific mortality levels of males. Fallow bucks that gain matings have higher
social dominance rank, higher rates of fighting, and invest more in vocal display during the breeding season than unsuccessful
males. Therefore, we examined if mating was associated with trade-offs in terms of survival, lifespan, and mating potential.
We found that the variance in lifetime mating success was very high: 34 (10.7%) males mated, and of those, the 10 most successful
males gained 73% of all matings (n=934). Mortality rates were generally high and only 22.3% (71/318) of males reached social maturity, i.e., 4 years. The oldest
male was 13 years old. We found that fallow bucks that mated were not more likely to die during the following year, did not
suffer from a reduction in lifespan, and did not incur lower mating success later in life as a result of mating during the
early years of social maturity. Our results show that mating males at age 5 years (and possibly 9 years) may be more likely
to survive than non-mating males. Additionally, the number of matings gained by males during the first years of social maturity
was positively correlated with lifespan. We suggest that mating males are of higher quality than non-mating males because
they are not more likely to incur trade-offs as a result of their increased reproductive efforts.
Received: 9 November 1999 / Revised: 30 April 2000 / Accepted: 27 May 2000 相似文献
448.
同位素技术在环境科学研究中的应用进展 总被引:2,自引:0,他引:2
综述了近年来同位素技术在国内外环境科学研究中的应用状况,简要介绍了同位素技术的应用原理与分析方法。总结了放射性同位素技术和稳定同位素技术在环境史重建、污染物示踪及源解析等方面的应用,重点介绍了稳定同位素技术在水、大气和土壤污染物源解析中的应用进展。对未来同位素技术在环境科学研究中的应用进行了展望,提出了多种同位素联合解析、建立和完善定量源解析模型等建议。 相似文献
449.
Seismic risk assessment of piping systems, as a group of vulnerable facilities in oil refineries, is mostly based on the single-variable fragility curves. However, it is well-known that the fragility curves, developed based on a single intensity measure (IM), are not much reliable. For increasing the confidence level of seismic risk assessment of piping systems, it was tried, in this study, to develop double-variable fragility functions by using peak ground acceleration (PGA) and peak ground velocity (PGV) together as the IMs. For this purpose, the piping system of the ISOMAX Unit of Tehran oil refinery was considered, and modeled by a powerful finite element analysis program under various loadings, including gravity, pressure and seismic loads. For seismic analyses 157 set of three-component earthquake records were employed, with PGA and PGV values varying respectively from around 0.1 g–0.6 g and 10 cm/s to 60 cm/s. By using the nonlinear time histories analyses results, two single-IM fragility curves and one double-IM fragility surface were developed based on the probability of exceedance of the maximum created stress, considered as the ‘damage index’, from the allowable stress. The results indicate that using PGA and PGV jointly, as the IMs in the development of fragility functions, provides more reliable vulnerability estimations. For example, the single-IM fragility function gives, for PGA = 0.2 g, a probability of exceedance of 75%, while by using the double-IM fragility function this probability may change from 30% for PGV = 10 cm/s to 95% for PGV = 60 cm/s. 相似文献
450.
流域土地利用变化的水质响应研究进展 总被引:2,自引:0,他引:2
探讨流域土地利用变化的水质响应,有利于从源头上控制水污染。不同学者在多种边界条件下研究了流域土地利用变化的水质响应,发现流域土地利用变化是造成河流水质发生变化的重要原因。根据是否可以将土地利用活动概化为点状,流域土地利用变化的水质响应研究可分为点状土地利用的水质响应和非点状土地利用的水质响应。准确边界土地利用的水质响应一般是研究流域土地利用空间特征和土地利用结构与水质变化的关系。对于用全流域尺度还是用缓冲区的尺度分析土地利用的水质响应更准确仍存在争论。水域边缘几何形状影响了土地利用与水质的关系。 相似文献