全文获取类型
收费全文 | 642篇 |
免费 | 16篇 |
国内免费 | 4篇 |
专业分类
安全科学 | 51篇 |
废物处理 | 2篇 |
环保管理 | 211篇 |
综合类 | 97篇 |
基础理论 | 152篇 |
环境理论 | 1篇 |
污染及防治 | 70篇 |
评价与监测 | 31篇 |
社会与环境 | 32篇 |
灾害及防治 | 15篇 |
出版年
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 13篇 |
2020年 | 10篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 19篇 |
2016年 | 21篇 |
2015年 | 8篇 |
2014年 | 16篇 |
2013年 | 22篇 |
2012年 | 22篇 |
2011年 | 56篇 |
2010年 | 31篇 |
2009年 | 71篇 |
2008年 | 56篇 |
2007年 | 39篇 |
2006年 | 33篇 |
2005年 | 22篇 |
2004年 | 20篇 |
2003年 | 19篇 |
2002年 | 17篇 |
2001年 | 9篇 |
2000年 | 15篇 |
1999年 | 17篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 21篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1968年 | 1篇 |
排序方式: 共有662条查询结果,搜索用时 15 毫秒
91.
We present a strategy for using an empirical forest growth model to reduce uncertainty in predictions made with a physiological process-based forest ecosystem model. The uncertainty reduction is carried out via Bayesian melding, in which information from prior knowledge and a deterministic computer model is conditioned on a likelihood function. We used predictions from an empirical forest growth model G-HAT in place of field observations of aboveground net primary productivity (ANPP) in a deciduous temperate forest ecosystem. Using Bayesian melding, priors for the inputs of the process-based forest ecosystem PnET-II were propagated through the model, and likelihoods for the PnET-II output ANPP were calculated using the G-HAT predictions. Posterior distributions for ANPP and many PnET-II inputs obtained using the G-HAT predictions largely matched posteriors obtained using field data. Since empirical growth models are often more readily available than extensive field data sets, the method represents a potential gain in efficiency for reducing the uncertainty of process-based model predictions when reliable empirical models are available but high-quality data are not. 相似文献
92.
Dynamics of soil organic matter in primary and secondary forest succession on sandy soils in The Netherlands: An application of the ROMUL model 总被引:2,自引:0,他引:2
M.A. Nadporozhskaya G.M.J. Mohren O.G. Chertov A.S. Komarov A.V. Mikhailov 《Ecological modelling》2006,190(3-4):399-418
We applied the simulation model ROMUL of soil organic matter dynamics in order to analyse and predict forest soil organic matter (SOM) changes following stand growth and also to identify gaps of data and modelling problems. SOM build-up was analysed (a) from bare sand to forest soil during a primary succession in Scots pine forest and (b) on mature forest soil under Douglas fir plantations as an example of secondary succession in The Netherlands. As some of the experimental data were unreliable we compiled a set of various scenarios with different soil moisture regime, initial SOM pools and amount and quality of above and below ground litter input. This allowed us to find the scenarios that reflect the SOM dynamics more realistically. In the Scots pine forest, total litter input was estimated as 0.50 kg m−2 year−1. Two scenarios were defined for the test runs: (a) forest floor moisture regimes—‘dry, mesic and hydric’ and (b) augmenting a root litter pool with three ratios of needles and branches to roots: 1:1, 1:1.5 and 1:2.0. The scenario finally compiled had the following characteristics: (a) climate for dry site with summer drought and high winter moisture of forest floor; (b) a litter input of 0.25 kg m−2 year−1 above ground and 0.50 kg m−2 year−1 below ground; (c) a low nitrogen and ash content in all litter fall fractions. The test runs for the estimation of the initial SOM pools and the amount and proportion of above and below ground litter fall were also performed in the Douglas fir plantation. The inputs of above ground litter tested in various combinations were 0.30 and 0.60 kg m−2 year−1, and below ground litter 0.30, 0.60 and 0.90 kg m−2 year−1. The scenario that fitted the experimental data had an SOM pool of 20–25 kg m−2, an aboveground litter input of 0.6 kg m−2 year−1and a below ground litter input of 0.9 kg m−2 year−1. The long-term simulation corresponded well with the observed patterns of soil organic matter accumulation associated with the forest soil development in primary and secondary succession. During primary succession in Scots pine forest on dry sand there is a consistent accumulation of a raw humus forest floor. The soil dynamics in the Douglas fir plantation also coincide with the observed patterns of SOM changes during the secondary succession, with SOM decreasing significantly under young forest, and SOM being restored in the older stands. 相似文献
93.
94.
Managing mangroves in Bangladesh: A strategy analysis 总被引:1,自引:0,他引:1
Bangladesh, favoured by a tropical climate, houses the world’s largest stretch of mangroves forests (Sundarbans Reserved Forest)
and plantations. Around half of the forests of the country occur in the coastal zone. People extract various goods and services
from the mangroves. Nevertheless the mangrove forests are depleting. Although the extent of the Sundarbans forest has not
changed much, its decline is of a qualitative nature. Mangrove plantations are increasing in area but they are losing growing
stock. To arrest this, Bangladesh has adopted several strategies.
The ‘Sustainable Ecosystem Management’ strategy has now been adopted instead of the ‘Sustained Yield Principle’. Biodiversity
conservation and enhancement has been taken as a key management goal. A zoning system is being developed for both production
and protection purposes. The government facilitates alternative income for the local people by generating activities for the
communities which are dependent on the forest. Different non-governmental organizations collaborate with the government in
reducing the local people’s dependence on the forest. Coastal plantations are erected to protect people from cyclones and
to make the land more suitable for habitation. Through this greening of the coastal belt tree plantation is encouraged in
coastal villages. Coastal embankments are being planted and leased to poor settlers in exchange for routine maintenance of
the embankments. Plantations on newly accreted mud flats help in stabilizing the land, which can later on be settled by victims
of erosion elsewhere. These adopted management measures do not only contribute to forestry resource management but also to
the social, environmental and economic wellbeing of the coastal communities. These efforts are at present being integrated
into an Integrated Coastal Zone Management (ICZM) project. 相似文献
95.
DANIEL C. NEPSTAD†‡ CLAUDIA M. STICKLER†§ ORIANA T. ALMEIDA† 《Conservation biology》2006,20(6):1595-1603
Abstract: Amazon beef and soybean industries, the primary drivers of Amazon deforestation, are increasingly responsive to economic signals emanating from around the world, such as those associated with bovine spongiform encephalopathy (BSE, "mad cow disease") outbreaks and China's economic growth. The expanding role of these economic "teleconnections" (coupled phenomena that take place in distant places on the planet) led to a 3-year period (2002–2004) of historically high deforestation rates. But it also increases the potential for large-scale conservation in the region as markets and finance institutions demand better environmental and social performance of beef and soy producers. Cattle ranchers and soy farmers who have generally opposed ambitious government regulations that require forest reserves on private property are realizing that good land stewardship—including compliance with legislation—may increase their access to expanding domestic and international markets and to credit and lower the risk of "losing" their land to agrarian reform. The realization of this potential depends on the successful negotiation of social and environmental performance criteria and an associated system of certification that are acceptable to both the industries and civil society. The foot-and-mouth eradication system, in which geographic zones win permission to export beef, may provide an important model for the design of a low-cost, peer-enforced, socioenvironmental certification system that becomes the mechanism by which beef and soy industries gain access to markets outside the Amazon. 相似文献
96.
97.
森林火灾是一种破坏性极强的灾害,它与农事活动以及气象条件密切相关,加强其预防与控制具有十分重要的作用和意义。根据2014年~2015年闽东屏南县进行的60次林缘计划烧除试验观测的主要气象要素数据(天晴日数、温度、湿度、风速),建立基于Logistic二元回归的林缘烧除气象条件判别模型进行检验和分析。结果表明,模型判别计划烧除成功与否的预报准确率高(91.7%),主要气象要素对林缘计划烧除成功与否发挥重要作用,其中连续晴天日数为最大影响因子,其次为风速。模型通过检验和验证结果显著,具有预报服务应用价值。 相似文献
98.
Mallory E. Flowers Daniel C. Matisoff Douglas S. Noonan 《Journal of Environmental Planning and Management》2019,62(5):843-861
In a case study that examines the outcomes of a flexible information-based policy, we observe how organizations obtain Leadership in Energy and Environmental Design certification. We use a regression discontinuity analysis to identify practices used to upgrade certification tiers. This analysis reveals preferences for green certification strategies and, we argue, intimates the perceived motivations for green certification. We distinguish practices that potentially confer private gains through returns to efficiency and productivity investments, from practices that only provide public benefits. Data show that organizations strategically certify to avoid high-cost resource use, appeal to key stakeholders, and communicate building and organization quality. Builders upgrading to the highest tiers are more likely to deploy practices with private gains. Results suggest a willingness to extend short time horizons associated with energy-efficiency investments in exchange for marketing benefits. Our discussion notes the capacity for certifications to mitigate market barriers associated with the energy-efficiency gap. 相似文献
99.
100.
Paul L. Ringold Barry Mulder Jim Alegria Raymond L. Czaplewski Tim Tolle Kelly Burnett 《Environmental management》1999,23(2):179-192
adaptive monitoring design. Adaptive monitoring design is an iterative process that refines the specifications for monitoring over time as a result of
experience in implementing a monitoring program, assessing results, and interacting with users. An adaptive design therefore
facilitates ecosystem management. We also discuss lessons of temporal and spatial scales raised by the consideration of a
design for ecosystem management. Three additional issues—integration of information from different sources, institutional
infrastructure, and the roles of individuals working in an interagency setting—are also identified, but not developed in detail. 相似文献