全文获取类型
收费全文 | 3492篇 |
免费 | 214篇 |
国内免费 | 258篇 |
专业分类
安全科学 | 81篇 |
废物处理 | 16篇 |
环保管理 | 851篇 |
综合类 | 1245篇 |
基础理论 | 661篇 |
环境理论 | 51篇 |
污染及防治 | 164篇 |
评价与监测 | 201篇 |
社会与环境 | 534篇 |
灾害及防治 | 160篇 |
出版年
2024年 | 10篇 |
2023年 | 69篇 |
2022年 | 90篇 |
2021年 | 115篇 |
2020年 | 100篇 |
2019年 | 162篇 |
2018年 | 150篇 |
2017年 | 188篇 |
2016年 | 216篇 |
2015年 | 191篇 |
2014年 | 135篇 |
2013年 | 291篇 |
2012年 | 224篇 |
2011年 | 259篇 |
2010年 | 182篇 |
2009年 | 201篇 |
2008年 | 164篇 |
2007年 | 207篇 |
2006年 | 157篇 |
2005年 | 118篇 |
2004年 | 102篇 |
2003年 | 102篇 |
2002年 | 83篇 |
2001年 | 71篇 |
2000年 | 91篇 |
1999年 | 75篇 |
1998年 | 36篇 |
1997年 | 41篇 |
1996年 | 17篇 |
1995年 | 16篇 |
1994年 | 14篇 |
1993年 | 29篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有3964条查询结果,搜索用时 220 毫秒
781.
植物硅酸体研究在黄土古气候恢复中的应用 总被引:2,自引:0,他引:2
地表植被对环境变化的响应最为敏感 ,沉积物中保存的各种植物残余是古环境研究的良好材料 ,植物硅酸体因其特有的物理化学性质 ,成为古气候信息的绝佳载体。在大量现代植物研究基础上 ,科学家们通过对第三纪以来各种沉积物中硅酸体组合的研究 ,较好地恢复了当时的古植被、古气候及其演化特征 ,在缺乏其它化石依据的黄土地层研究中表现更为突出。由于C3、C4 植物具有明显不同的环境适应性和同位素组成 ,地层中C3、C4 植物硅酸体相对含量和稳定同位素的研究也被成功地应用于古气候恢复中。在现代气候—植被类型和土壤植物硅酸体同位素研究基础上 ,利用数理统计方法 ,建立同位素指标与各种气候因子之间的数学关系 ,将为高分辨率黄土古气候定量研究开辟新的途径。 相似文献
782.
Adaptation and mitigation: trade-offs in substance and methods 总被引:2,自引:0,他引:2
Adaptation to climate change and mitigation of climate change are policy substitutes, as both reduce the impacts of climate change. Adaptation and mitigation should therefore be analysed together, as they indeed are, albeit in a rudimentary way, in cost-benefit analyses of emission abatement. However, adaptation and mitigation are done by different people operating at different spatial and temporal scales. This hampers analysis of the trade-offs between adaptation and mitigation. An exception is facilitative adaptation (enhancing adaptive capacity), which, like mitigation, requires long-term policies at macro level. Facilitative adaptation and mitigation not only both reduce impacts, but they also compete for resources. 相似文献
783.
784.
Asbjørn Aaheim Hans A. Kristin Seip Hans M. 《Mitigation and Adaptation Strategies for Global Change》1999,4(1):61-81
Few studies on measures for mitigation of damage caused by man-made emissions to the environment have tried to consider all major effects. We illustrate the importance of an integrated approach by estimating costs and benefits of a proposed energy saving program for Hungary, originally designed to reduce CO2 emissions. The dominant benefit of implementing the program is likely to be reduced health damage from local pollutants. Also reduced costs of material damage and to a lesser extent vegetation damage contribute to make the net benefit considerable. Compared to the reduction in these local and regional effects, the benefits from reducing greenhouse gases are likely to be minor. Since local effects in general occur much earlier after measures have been implemented than effects of increased emissions of greenhouse gases, inclusion of local effects makes evaluation of climate policy less dependent on the choice of discount rate. In our opinion, similar results are likely for many measures originally designed to reduce emissions of greenhouse gases particularly in some areas in developing countries with high local pollution levels. Main uncertainties in the analysis, e.g. in the relationships between damage and pollution level, are discussed. 相似文献
785.
Climate Change Projections for the United States Midwest 总被引:1,自引:0,他引:1
Wuebbles Donald J. Hayhoe Katharine 《Mitigation and Adaptation Strategies for Global Change》2004,9(4):335-363
Environmental and societal factors such asair quality, water quality andavailability, land use changes andexpanding urbanization are alreadyaffecting human health and welfare,agriculture, and natural ecosystems in theMidwestern United States. Over thiscentury, these existing stresses willlikely be exacerbated by climate changesresulting from human activities. It isessential that policy decisions aimed atpreserving the well-being of a region beinformed by a good understanding of theregion's climate, how climate might change,and the uncertainties inherent in futureprojections. Recent updates in climatemodeling expertise and an expanded view ofpossible non-intervention emissionscenarios have narrowed the range of changethat can be expected over the Midwestthroughout the next century in some ways,while broadening it in others. In contrastto previous studies, which generallyconsider a mid-range scenario for futureemissions, this study presents the range ofchange that would result from low to highscenarios for climate change. In this waywe account for uncertainties inanthropogenic forcing on climate change inthe region and quantify the potentialeffects of human actions on future climate.This analysis also combines the latestclimate model projections with historicalrecords of observed climate over the pastcentury, effectively placing potentialchanges in extreme event frequencies suchas heavy rainfall events and temperaturethreshold exceedances within the context ofobserved variability over the past century.The purpose of this study is to provide anupdated picture of the potential impacts ofclimate change on the Midwest to inform theimpact assessment and policy developmentcommunity. From the magnitude of thechanges projected by this study, it isclear that these must be included in futurepolicy decisions in order to ensure thesuccessful adaptation and survival ofexisting human and natural systems in theMidwest. 相似文献
786.
Dale Virginia H. Brown Sandra Calderón Magnolia O. Montoya Arizmendis S. Martínez Raúl E. 《Mitigation and Adaptation Strategies for Global Change》2003,8(4):323-348
To participate in the potential market for carbon credits based on changes in the use and management of the land, one needs to identify opportunities and implement land-use based emissions reductions or sequestration projects. A key requirement of land-based carbon (C) projects is that any activity developed for generating C benefits must be additional to business-as-usual. A rule-based model was developed and used that estimates changes in land-use and subsequent carbon emissions over the next twenty years using the Eastern Panama Canal Watershed (EPCW) as a case study. These projections of changes in C stocks serve as a baseline to identify where opportunities exist for implementing projects to generate potential C credits and to position Panama to be able to participate in the emerging C market by developing a baseline under scenarios of business-as-usual and new-road development. The projections show that the highest percent change in land use for the new-road scenario compared to the business-as-usual scenario is for urban areas, and the greatest cause of C emission is from deforestation. Thus, the most effective way to reduce C emissions to the atmosphere in the EPCW is by reducing deforestation. In addition to affecting C emissions, reducing deforestation would also protect the soil and water resources of the EPCW. Yet, under the current framework of the Clean Development Mechanism (CDM), only credits arising from reforestation are allowed, which after 20 years of plantation establishment are not enough to offset the C emissions from the ongoing, albeit small, rate of deforestation in the EPCW. The study demonstrates the value of spatial regional projections of changes in land cover and C stocks: The approach helps a country identify its potential greenhouse gas (GHG) emission liabilities into the future and provides opportunity for the country to plan alternative development pathways. It could be used by potential project developers to identify which types of projects will generate the largest C benefits and provide the needed baseline against which a project is then evaluated. Spatial baselines, such as those presented here, can be used by governments to help identify development goals. The development of such a baseline, and its expansion to other vulnerable areas, well positions Panama to respond to the future market demand for C offsets. It is useful to compare the projected change in land cover under the business-as-usual scenario to the goals set by Law 21 for the year 2020. Suggested next steps for analysis includeusing the modeling approach to exploreland-use, C dynamics and management ofsecondary forests and plantations, soilC gains or losses, sources ofvariability in the land use and Cstock projections, and other ecologicalimplications and feedbacks resulting fromprojected changes in land cover. 相似文献
787.
Adaptation is nowrecognized as an inevitable component ofthe overall climate change responsestrategy. For a developing region likesub-Saharan Africa with low greenhouse gasemissions and high vulnerability to theimpacts of climate change, the importanceof adaptation in climate change policy iseven more fundamental. This paper examined alook at the adaptational preparedness ofthe sub-Saharan African region to climatechange. Clearly evident in theenvironmental strategy and developmentfocus of these countries is lack ofrecognition of the need to adapt, poorincentive to adapt and low capacity toadapt to climate change. This furtherexacerbates their vulnerability and hasimplications for the global climate changeresponse strategy. Unfortunately, fewattempts have been made to understand thestructural reasons underlying the pervasivepattern of adaptational unpreparedness inthe region, neither has there been acomprehensive and systematic analysis ofhow to remedy this problem. This paper is acontribution in this regard. It alsohighlights the factors to whichinternational community need to payattention, if it truly wishes to make itsefforts at adaptation more global inscope. 相似文献
788.
青藏高原东北部气候变化的异质性及其成因 总被引:1,自引:1,他引:1
利用1961-2016年西宁等青藏高原东北部13个气象台站气温、降水等气象资料以及国家气候中心发布的南海季风指数、西伯利亚高压指数等大气环流特征量数据,分析近56年来气候变化与高原主体的差异性及其可能的气候成因。研究表明:近56年来青藏高原东北部气候变暖趋势十分显著,年平均气温气候倾向率高达0.39 ℃/10 a,呈现出三次明显的阶梯性增高态势,并于1994年前后发生了由冷到暖的突变,同时具有明显的空间差异性;年降水量及四季降水量均没有明显变化趋势,虽然经历了2002年左右由少到多的变化,但并未出现明显突变,年降水量具有3年、5年的准周期,而年降水日数微弱减少,降水强度呈增加趋势;该区域气候变化的年际波动主要受到东亚季风、高原季风和南海季风的年际振荡及其相互作用的影响,而西风环流的作用并不明显,植被覆盖的恢复既是对2002年以来降水量增加的具体反应,同时也对于气候变暖趋势起到了一定的缓和作用。 相似文献
789.
Yin Xiaolong 《环境科学学报(英文版)》1995,7(2):129-137
Recoveryandchemicalutilizationofcarbondioxidefromfossil-fuelburningindustrialsourcesYinXiaolong(DepartmentofAppliedChemistry,... 相似文献
790.
Climate change adaptation in the ski industry 总被引:4,自引:0,他引:4
Daniel Scott Geoff McBoyle 《Mitigation and Adaptation Strategies for Global Change》2007,12(8):1411-1431
Regardless of the success of climate change mitigation efforts, the international community has concluded that societies around
the world will need to adapt to some magnitude of climate change in the 21st century. While some economic sectors (e.g., agriculture,
water resources and construction) have been actively engaged in climate change adaptation research for years, adaptation has
received scant consideration within the tourism-recreation industry. This is particularly the case for adaptation by tourism
operators (supply-side). One exception where progress on supply-side climate adaptation has been made is the ski industry.
This paper provides a brief overview of the literature on the implications of climate change for the international ski industry
and how adaptation by ski area operators has been treated within these studies. This is followed by an inventory of climate
adaptation practices currently used by ski industry stakeholders, including the historical development of certain key adaptations
and constraints to wider use. The characteristics of ski areas with higher adaptive capacity are identified. Considering the
highly competitive nature of the ski industry and the generally low climate change risk appraisal within the industry, climate
change adaptation is anticipated to remain individualistic and reactive for some time. With only a few exceptions, the existing
climate change literature on winter tourism has not considered the wide range of adaptation options identified in this paper
and has likely overestimated potential damages. An important task for future studies is to develop methodologies to incorporate
adaptation so that a more accurate understanding of the vulnerability of the international ski industry can be ascertained. 相似文献