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   1790篇
  免费   17篇
  国内免费   23篇
安全科学   46篇
废物处理   62篇
环保管理   244篇
综合类   401篇
基础理论   346篇
环境理论   1篇
污染及防治   512篇
评价与监测   95篇
社会与环境   109篇
灾害及防治   14篇
  2023年   18篇
  2022年   18篇
  2021年   29篇
  2020年   21篇
  2019年   25篇
  2018年   47篇
  2017年   50篇
  2016年   60篇
  2015年   72篇
  2014年   76篇
  2013年   84篇
  2012年   80篇
  2011年   115篇
  2010年   97篇
  2009年   99篇
  2008年   90篇
  2007年   98篇
  2006年   80篇
  2005年   54篇
  2004年   80篇
  2003年   44篇
  2002年   64篇
  2001年   67篇
  2000年   30篇
  1999年   17篇
  1998年   17篇
  1997年   25篇
  1996年   19篇
  1995年   31篇
  1994年   19篇
  1993年   6篇
  1992年   14篇
  1991年   24篇
  1990年   11篇
  1989年   18篇
  1988年   7篇
  1987年   4篇
  1985年   5篇
  1984年   5篇
  1982年   10篇
  1981年   10篇
  1979年   9篇
  1970年   6篇
  1969年   4篇
  1966年   3篇
  1965年   4篇
  1962年   3篇
  1960年   4篇
  1959年   3篇
  1954年   3篇
排序方式: 共有1830条查询结果,搜索用时 352 毫秒
601.
This paper describes a European wide assessment of element budgets, using available data on deposition, meteorology and soil solution chemistry at 121 Intensive Monitoring plots. Input fluxes from the atmosphere were derived from fortnightly or monthly measurements of bulk deposition and throughfall, corrected for canopy uptake. Element outputs from the forest ecosystem were derived by multiplying fortnightly or monthly measurements of the soil solution composition at the bottom of the root zone with simulated unsaturated soil water fluxes. Despite the uncertainties in the calculated budgets, the results indicate that: (i) SO4 is still the dominant source of actual soil acidification despite the generally lower input of S than N, due to the different behaviour of S (near tracer) and N (strong retention); (ii) base cation removal due to man-induced soil acidification is limited; and (iii) Al release is high in areas with high S inputs and low base status.  相似文献   
602.
603.
604.
A simplistic aggregate model of global economic activity supports a 50-year visioning exercise with targets defined in terms of aggregate measures of global equity (convergence) and sustainability (contraction). Some ambitious combinations of these targets turn out to be infeasible even under the most favorable modeling assumptions. No contraction target (no reduction in fossil fuel consumption relative to the present) was possible, for example, if international capital transfers pushed per capita incomes in low-income countries above 33% of levels achieved in high-income countries. Lower prices for renewable alternatives to exhaustible resources generally made sustainability targets easier to achieve, but lower prices for renewable resources also made equity targets more difficult to achieve. Improved substitution between capital and labor made equity targets easier to achieve in relative terms, but improved substitution between capital and labor could make any given sustainability target more or less difficult to achieve. All the results suggest that it is possible to overstate the purported conflict between achieving sustainability and equity targets. The very transfers of international capital that would promote relative equity between high-income and low-income countries could also work to spread the incidence of achieving any sustainability target more evenly across their boundaries.Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.  相似文献   
605.
606.
607.
Climate change is expected to increase the frequency and intensity of natural disasters. Adaptation investments are required in order to limit the projected increase in natural disaster risks. Adaptation measures can reduce risk partially or completely eliminate risk. The literature on behavioural economics suggests that individuals rarely undertake measures that limit risk partially, while they may place a considerable value on measures that reduce risk to zero. This is studied for a case of adaptation to climate change and its effects on flood risk in the Netherlands. In particular, we examine whether households are willing to invest in elevating newly built structures when this is framed as eliminating flood risk. The results indicate that a majority of homeowners (52%) is willing to make a substantial investment of €10,000 to elevate a new house to a level that is safe to flooding. Differences between willingness to pay (WTP) for flood insurance and WTP for risk elimination through elevation indicate that individuals place a considerable value on the latter adaptation option. This study estimates that the “safety premium” which individuals place on risk elimination is approximately between €35 and €45 per month. The existence of a safety premium has important implications for the design of climate change adaptation policies. The decision to invest in elevating homes is significantly correlated with the expected negative effects of climate change, perceptions of flood risks, individual risk attitudes, and living close to a main river.  相似文献   
608.
609.
This paper examines the effects of growing land pressure on the distribution and quality of cropland allocations on customary tenured land (CTL) in Swaziland. Within the wider Sub‐Saharan context, the reform of indigenous tenure systems is now generally seen as a process of adaptation rather than replacement. The legal recognition of (existing and future) user rights is considered a practical way forward. This essentially rights‐based approach may divert attention from technical inadequacies indigenous systems may have, particularly under conditions of increasing land pressure. The case of CTL substantiates such shortcomings. CTL has seen a marked growth in population and land allocations since Independence. This had led to concerns on the land distribution efficiency in view of the improved agricultural production required to sustain the increasing number of rural households. By analysing historical changes in the number, size and quality of cropland allocations in selected rural communities, this paper demonstrates the occurrence of a high degree of inconsistency in cropland distribution at the community level, as well as inefficient land distribution at higher levels of scale. These shortcomings threaten the sustainability of the local agricultural production systems, and will need to be addressed in any meaningful reform process.  相似文献   
610.
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