全文获取类型
收费全文 | 298篇 |
免费 | 10篇 |
国内免费 | 21篇 |
专业分类
安全科学 | 7篇 |
环保管理 | 110篇 |
综合类 | 73篇 |
基础理论 | 52篇 |
环境理论 | 1篇 |
污染及防治 | 29篇 |
评价与监测 | 20篇 |
社会与环境 | 20篇 |
灾害及防治 | 17篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 19篇 |
2017年 | 5篇 |
2016年 | 14篇 |
2015年 | 14篇 |
2014年 | 6篇 |
2013年 | 23篇 |
2012年 | 8篇 |
2011年 | 27篇 |
2010年 | 11篇 |
2009年 | 32篇 |
2008年 | 18篇 |
2007年 | 20篇 |
2006年 | 15篇 |
2005年 | 4篇 |
2004年 | 9篇 |
2003年 | 10篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有329条查询结果,搜索用时 15 毫秒
41.
Incentive-Based Conservation Programs in Developing Countries: A Review of Some Key Issues and Suggestions for Improvements 总被引:2,自引:2,他引:0
Biodiversity conservation in developing countries has been a challenge because of the combination of rising human populations,
rapid technological advances, severe social hardships, and extreme poverty. To address the social, economic, and ecological
limitations of people-free parks and reserves, incentives have been incorporated into conservation programs in the hopes of
making conservation meaningful to local people. However, such incentive-based programs have been implemented with little consideration
for their ability to fulfill promises of greater protection of biodiversity. Evaluations of incentive-based conservation programs
indicate that the approach continually falls short of the rhetoric. This article provides an overview of the problems associated
with incentive-based conservation approaches in developing countries. It argues that existing incentive-based programs (IBPs)
have yet to realize that benefits vary greatly at different “community” scales and that a holistic conceptualization of a
community is essential to incorporate the complexities of a heterogeneous community when designing and implementing the IBPs.
The spatial complexities involved in correctly identifying the beneficiaries in a community and the short-term focus of IBPs
are two major challenges for sustaining conservation efforts. The article suggests improvements in three key areas: accurate
identification of “target” beneficiaries, greater inclusion of marginal communities, and efforts to enhance community aptitudes. 相似文献
42.
Great Basin Land Management Planning Using Ecological Modeling 总被引:1,自引:1,他引:0
This report describes a land management modeling effort that analyzed potential impacts of proposed actions under an updated
Bureau of Land Management Resource Management Plan that will guide management for 20 years on 4.6 million hectares in the
Great Basin ecoregion of the United States. State-and-transition models that included vegetation data, fire histories, and
many parameters (i.e., rates of succession, fire return intervals, outcomes of management actions, and invasion rates of native
and nonnative invasive species) were developed through workshops with scientific experts and range management specialists.
Alternative restoration scenarios included continuation of current management, full fire suppression, wildfire use in designated fire use zones, wildfire use in resilient vegetation types only, restoration with a tenfold budget increase, no restoration treatments, and no livestock grazing. Under all the scenarios, cover of vegetation states with native perennial understory declined and was replaced by tree-invaded
and weed-dominated states. The greatest differences among alternative management scenarios resulted from the use of fire as
a tool to maintain native understory. Among restoration scenarios, only the scenario assuming a tenfold budget increase had
a more desirable outcome than the current management scenario. Removal of livestock alone had little effect on vegetation
resilience. Rather, active restoration was required. The predictive power of the model was limited by current understanding
of Great Basin vegetation dynamics and data needs including statistically valid monitoring of restoration treatments, invasiveness
and invasibility, and fire histories. The authors suggest that such computer models can be useful tools for systematic analysis
of potential impacts in land use planning. However, for a modeling effort to be productive, the management situation must
be conducive to open communication among land management agencies and partner entities, including nonprofit organizations. 相似文献
43.
草履虫──针杆藻群落对混合印染废水净化作用的条件实验 总被引:2,自引:0,他引:2
本文对混合印染废水的静态净化过程,进行了生物群落观察和条件实验。发现废水净化初期以大量细菌和草履虫(以 P. Caudatum为主)繁殖为特征,同时伴生着少量浮游藻类。随着净化过程的进行,细菌和草履虫数量下降,以针杆藻(以 S. aucs为主)为建群种的浮游藻类群落占优势。化学分析表明,净化作用与温度、光照条件及废水起始浓度有关。 相似文献
44.
Numerous studies support that biodiversity predict most to ecosystem functioning, but whether other factors display a more significant direct impact on ecosystem functioning than biodiversity remains to be studied. We investigated 398 samples of the phytoplankton phosphorus resource use efficiency (RUEP = chlorophyll-a concentration/dissolved phosphate) across two seasons in nine plateau lakes in Yunnan Province, China. We identified the main contributors to phytoplankton RUEP and analyzed their potential influences on RUEP at different lake trophic states. The results showed that total nitrogen (TN) contributed the most to RUEP among the nine lakes, whereas community turnover (measured as community dissimilarity) explained the most to RUEP variation across the two seasons. Moreover, TN also influenced RUEP by affecting biodiversity. Species richness (SR), functional attribute diversity (FAD2), and dendrogram-based functional diversity (FDc) were positively correlated with RUEP in both seasons, while evenness was negatively correlated with RUEP at the end of the rainy season. We also found that the effects of biodiversity and turnover on RUEP depended on the lake trophic states. SR and FAD2 were positively correlated with RUEP in all three trophic states. Evenness showed a negative correlation with RUEP at the eutrophic and oligotrophic levels, but a positive correlation at the mesotrophic level. Turnover had a negative influence on RUEP at the eutrophic level, but a positive influence at the mesotrophic and oligotrophic levels. Overall, our results suggested that multiple factors and nutrient states need to be considered when the ecosystem functioning predictors and the biodiversity-ecosystem functioning relationships are investigated. 相似文献
45.
46.
/ Numerous drainages supporting productive salmon habitat are surrounded by active volcanoes on the west side of Cook Inlet in south-central Alaska. Eruptions have caused massive quantities of flowing water and sediment to enter the river channels emanating from glaciers and snowfields on these volcanoes. Extensive damage to riparian and aquatic habitat has commonly resulted, and benthic macroinvertebrate and salmonid communities can be affected. Because of the economic importance of Alaska's fisheries, detrimental effects on salmonid habitat can have significant economic implications. The Drift River drains glaciers on the northern and eastern flanks of Redoubt Volcano. During and following eruptions in 1989-1990, severe physical disturbances to the habitat features of the river adversely affected the fishery. Frequent eruptions at other Cook Inlet region volcanoes exemplify the potential effects of volcanic activity on Alaska's important commercial, sport, and subsistence fisheries. Few studies have documented the recovery of aquatic habitat following volcanic eruptions. The eruptions of Redoubt Volcano in 1989-1990 offered an opportunity to examine the recovery of the macroinvertebrate community. Macroinvertebrate community composition and structure in the Drift River were similar in both undisturbed and recently disturbed sites. Additionally, macroinvertebrate samples from sites in nearby undisturbed streams were highly similar to those from some Drift River sites. This similarity and the agreement between the Drift River macroinvertebrate community composition and that predicted by a qualitative model of typical macroinvertebrate communities in glacier-fed rivers indicate that the Drift River macroinvertebrate community is recovering five years after the disturbances associated with the most recent eruptions of Redoubt Volcano. KEY WORDS: Aquatic habitat; Volcanoes; Lahars; Lahar-runout flows; Macroinvertebrates; Community structure; Community composition; Taxonomic similarity 相似文献
47.
Ecological disturbances of forests by insects have a complex array of associated human dimensions presenting complications
for natural resource decision making and relationships between stakeholders and managers. This article discusses the human
context of forest disturbances by insects by reviewing four cases of bark beetle forest disturbance from British Columbia
in Canada, Bavarian Forest National Park in Germany, the Kenai Peninsula in Alaska, and the north central region of Colorado.
Findings and lessons learned from these studies are outlined along with their implications for managing forest disturbances
by insects in general. Conclusions focus on the need to assess the broad array of impacts and risks perceived by local residents
and the capacity for local action and involvement in managing forest disturbances. Communication and interaction between resource
managers and local stakeholders can facilitate the identification of management priorities and potentially reduce some of
the risks associated with forest disturbances by insects. 相似文献
48.
Strategies for beneficial use of biosolids in New Zealand and elsewhere are currently focused primarily on land application. The long-term success of these and other strategies is dependent not only on technical factors, but also on their environmental, economic, social and cultural sustainability. This paper briefly reviews the situation with respect to biosolids management in New Zealand, where land application is not yet widespread; the rise in public opposition to land application in the United States; and the biosolids industry's approach to public engagement. We argue that, at least until recently, the industry has misinterpreted the nature and meaning of public opposition and thus substituted public relations for public engagement. We argue that genuine public engagement is necessary and that its purpose cannot be to gain public acceptance for an already-decided-upon strategy. It therefore calls for humility among biosolids managers, including a willingness to open up the framing of 'the problem', to acknowledge areas of uncertainty, and to recognise the role of values in 'technical' decision-making. We then present and analyse an example of the use of the scenario workshop process for public participation in biosolids management policy in Christchurch, New Zealand, and conclude that scenario workshops and related methods represent an opportunity to enhance sustainable waste management when certain conditions are met. 相似文献
49.
Loss of grassland species resulting from activities such as off-road vehicle use increases the need for models that predict
effects of anthropogenic disturbance. The relationship of disturbance by military training to plant species richness and composition
on two soils (Foard and Lawton) in a mixed prairie area was investigated. Track cover (cover of vehicle disturbance to the
soil) and soil organic carbon were selected as measures of short- and long-term disturbance, respectively. Soil and vegetation
data, collected in 1-m2 quadrats, were analyzed at three spatial scales (60, 10, and 1 m2). Plant species richness peaked at intermediate levels of soil organic carbon at the 10-m2 and 1-m2 spatial scales on both the Lawton and Foard soils, and at intermediate levels of track cover at all three spatial scales
on the Foard soil. Species composition differed across the disturbance gradient on the Foard soil but not on the Lawton soil.
Disturbance increased total plant species richness on the Foard soil. The authors conclude that disturbance up to intermediate
levels can be used to maintain biodiversity by enriching the plant species pool. 相似文献
50.
Integrated Resource Management: Moving from Rhetoric to Practice in Australian Agriculture 总被引:1,自引:0,他引:1
/ Implementing the concept of sustainability through integrated approaches to natural resource management poses enormous challenges for both the rural communities and government agencies concerned. This paper reviews the underlying rhetoric of sustainable agricultural systems and the integrated resource management paradigm and identifies some of the challenges being experienced in translating this rhetoric into practice. A relatively recently implemented community-based integrated catchment management (ICM) process in a rural community in northeast Australia is examined in terms of some of the lessons learned that may be relevant to other similar integrated resource management (IRM) processes. It reveals a pragmatic, opportunistic, and evolving implementation process based on adaptive learning rather than a more traditional "rational" planning approach. Some essential characteristics of a community-based IRM process are identified, including fostering communication; providing a structure that fosters cooperation and facilities coordination among community, industry, and government agencies; the integration of IRM principles into local government planning schemes; and an emergent strategic approach to IRM program implementation. We conclude by identifying some essential characteristics of an IRM process that can assist a community to adapt to, and manage change for, sustainable resource use. 相似文献