全文获取类型
收费全文 | 9719篇 |
免费 | 899篇 |
国内免费 | 2079篇 |
专业分类
安全科学 | 2313篇 |
废物处理 | 114篇 |
环保管理 | 1291篇 |
综合类 | 5340篇 |
基础理论 | 1209篇 |
环境理论 | 1篇 |
污染及防治 | 563篇 |
评价与监测 | 710篇 |
社会与环境 | 412篇 |
灾害及防治 | 744篇 |
出版年
2024年 | 76篇 |
2023年 | 283篇 |
2022年 | 403篇 |
2021年 | 480篇 |
2020年 | 461篇 |
2019年 | 440篇 |
2018年 | 362篇 |
2017年 | 451篇 |
2016年 | 529篇 |
2015年 | 573篇 |
2014年 | 588篇 |
2013年 | 748篇 |
2012年 | 796篇 |
2011年 | 899篇 |
2010年 | 586篇 |
2009年 | 655篇 |
2008年 | 470篇 |
2007年 | 633篇 |
2006年 | 605篇 |
2005年 | 429篇 |
2004年 | 307篇 |
2003年 | 308篇 |
2002年 | 256篇 |
2001年 | 211篇 |
2000年 | 212篇 |
1999年 | 177篇 |
1998年 | 125篇 |
1997年 | 123篇 |
1996年 | 83篇 |
1995年 | 105篇 |
1994年 | 59篇 |
1993年 | 61篇 |
1992年 | 37篇 |
1991年 | 31篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 15篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Performance evaluation of Health, Safety and Environment (HSE) is the measurement of a company's achievement in HSE management. In order to receive a comprehensive and objective evaluation result, it is necessary to consider all evaluation factors and experts at different levels when HSE performance assessment is conducted. To improve conventional HSE performance evaluation, where weighted average method was used, a Fuzzy Comprehensive Evaluation (FCE) method is used in this study by taking experts' weights into account. Further, an HSE operating performance assessment system is designed to simplify manual and complex assessment process and generate charts and analysis reports automatically. Finally, a case of petrochemical enterprise is used to illustrate the effectiveness of the method and system. 相似文献
2.
CARMEL L. WITTE§ MICHAEL J. SREDL† REW S. KANE§‡ LAURA L. HUNGERFORD†† 《Conservation biology》2008,22(2):375-383
Abstract: We examined factors that may independently or synergistically contribute to amphibian population declines. We used epidemiologic case–control methodology to sample and analyze a large database developed and maintained by the Arizona Game and Fish Department that describes historical and currently known ranid frog localities in Arizona, U.S.A. Sites with historical documentation of target ranid species ( n = 324) were evaluated to identify locations where frogs had disappeared during the study period (case sites) and locations where frog populations persisted (control sites). Between 1986 and 2003, 117 (36%) of the 324 sites became case sites, of which 105 were used in the analyses. An equal number of control sites were sampled to control for the effects of time. Risk factors, or predictor variables, were defined from environmental data summarized during site surveys and geographic information system data layers. We evaluated risk factors with univariate and multifactorial logistic-regression analyses to derive odds ratios (OR). Odds for local population disappearance were significantly related to 4 factors in the multifactorial model. Disappearance of frog populations increased with increasing elevation (OR = 2.7 for every 500 m, p < 0.01). Sites where disappearances occurred were 4.3 times more likely to have other nearby sites that also experienced disappearances (OR = 4.3, p < 0.01), whereas the odds of disappearance were 6.7 times less (OR = 0.15, p < 0.01) when there was a source population nearby. Sites with disappearances were 2.6 times more likely to have introduced crayfish than were control sites (OR = 2.6, p = 0.04). The identification of factors associated with frog disappearances increases understanding of declines occurring in natural populations and aids in conservation efforts to reestablish and protect native ranids by identifying and prioritizing implicated threats. 相似文献
3.
我国矿业"走出去"风险勘探问题分析与建议 总被引:1,自引:0,他引:1
根据我国资源条件和经济发展的需要以及获取国外资源的方式进行比较分析得知,我国非常有必要到国外进行风险勘探。虽然我国经历了多年境外风险勘探的实践和探索,但是步伐缓慢,在实践中面临很多问题。对此,作者提出了我国境外风险勘探问题的建议。 相似文献
4.
WILLIAM E. HOGSETT JAMES E. WEBER DAVID TINGEY ANDREW HERSTROM E. HENRY LEE JOHN A. LAURENCE 《Environmental management》1997,21(1):105-120
/ The risk tropospheric ozone poses to forests in the United States is dependent on the variation in ozone exposure across the distribution of the forests in question and the various environmental and climate factors predominant in the region. All these factors have a spatial nature, and consequently an approach to characterization of ozone risk is presented that places ozone exposure-response functions for species as seedlings and model-simulated tree and stand responses in a spatial context using a geographical information systems (GIS). The GIS is used to aggregate factors considered important in a risk characterization, including: (1) estimated ozone exposures over forested regions, (2) measures of ozone effects on species' and stand growth, and (3) spatially distributed environmental, genetic, and exposure influences on species' response to ozone. The GIS-based risk characterization provides an estimation of the extent and magnitude of the potential ozone impact on forests. A preliminary risk characterization demonstrating this approach considered only the eastern United States and only the limited empirical data quantifying the effect of ozone exposures on forest tree species as seedlings. The area-weighted response of the annual seedling biomass loss formed the basis for a sensitivity ranking: sensitive-aspen and black cherry (14%-33% biomass loss over 50% of their distribution); moderately sensitive-tulip popular, loblolly pine, eastern white pine, and sugar maple (5%-13% biomass loss); insensitive-Virginia pine and red maple (0%-1% loss). In the future, the GIS-based risk characterization will include process-based model simulations of the three- to 5-year growth response of individual species as large trees with relevant environmental interactions and model simulated response of mixed stands. The interactive nature of GIS provides a tool to explore consequences of the range of climate conditions across a species' distribution, forest management practices, changing ozone precursors, regulatory control strategies, and other factors influencing the spatial distribution of ozone over time as more information becomes available.KEY WORDS: Ecological risk assessment; GIS; Ozone; Risk characterization; Forests; Trees 相似文献
5.
Integration of Environmental Assessment into the Regional Development Planning Process of the Galilee 总被引:2,自引:0,他引:2
/ The Galilee region on the northern edge of Israel constitutes more than 15% of the state's territory, supplies more than half of its drinking water needs, and is an important recreational resource and destination for Israelis. One of the main objectives of the plan for the Galilee was to devise a regional physical and economic development strategy for the years 1992-2007 that would arrest the trend of emigration of its residents, attract newly arrived immigrants to the region, and at the same time protect natural resources and environmental quality. This paper is limited to discussion of the environmental aspects of the plan. It analyzes spatial concepts for distribution of projected population growth, evaluates environmental impacts of alternative plans, and proposes a decision-making framework and tools for minimizing natural resources loss from development at the local level. Assessment of potential environmental impacts generated quantitative data of natural resources areas. Application of the data in the plan evaluation stage showed that the alternative that concentrated most of the new development in central Galilee was the second-best choice environmentally, but was preferred as the best choice for overall qualities. The planning study offers an alternative environmental impact assessment (EIA) process to the one presently used in Israel by incorporating environmental considerations at the initial plan-making stage and not at the plan-approval stage. It demonstrated that in order to be effective, environmental assessment and land-use planning should be seen as one effort that is integrated from the start and in each stage of the plan-making process.KEY WORDS: Environmental assessment; Development planning; Galilee 相似文献
6.
岷江都江堰段水环境容量计算及水质综合评价 总被引:3,自引:0,他引:3
岷江水域兼有灌溉,供水,发电等多重功能。本文对岷江都江堰段水环境现状进行了模糊综合评价,并计算了水环境容量。 相似文献
7.
Robert B. Olshansky 《Environmental management》1996,20(1):11-23
The California Environmental Quality Act (CEQA) has evolved from a mini-NEPA, first enacted in 1970, into a procedural act
that affects the approval process of all large developments in California. In 1990, California local governments produced
over 1600 environmental impact reports and 30,000 initial studies under CEQA. Because of its widespread use, CEQA has periodically
drawn the attention of the state legislature, most recently in 1993, when over 60 CEQA reform bills were introduced. This
paper describes the CEQA process and evaluates its success at meeting its explicit and implicit goals. The research includes
a statewide survey of CEQA practice, sent to the planning departments of all 513 local governments in California in 1991.
Survey respondents agreed that CEQA helps in evaluating environmental impacts, reducing impacts, informing the public, and
coordinating public agency review. It is effective in reducing the environmental impacts of individual projects, but is not
as effective in improving environmental quality on an areawide scale. This research concludes that CEQA has led to positive
outcomes and is not as deeply flawed as many of its critics claim. Still, CEQA as currently designed may not be the optimal
vehicle for ensuring environmental quality. 相似文献
8.
目前环境影响评价普遍存在滞后现象和水平低及周期长等问题,提出广泛开展环评法宣传教育;加强环评队伍建设,提高环评人员的素质;把环评纳入总量控制轨道,突出浓度与总量同时评价;大众参与以及进一步规范和完善环境影响报告书的审批等对策与措施. 相似文献
9.
E. Conrad Lamon Song S. Qian Daniel D. Richter 《Journal of the American Water Resources Association》2004,40(5):1219-1229
ABSTRACT: Dynamic linear models (DLM) and seasonal trend decomposition (STL) using local regression, or LOESS, were used to analyze the 50‐year time series of suspended sediment concentrations for the Yadkin River, measured at the U.S. Geological Survey station at Yadkin College, North Carolina. A DLM with constant trend, seasonality, and a log10 streamflow regressor provided the best model to predict monthly mean log10 suspended sediment concentrations, based on the forecast log likelihood. Using DLM, there was evidence (odds approximately 69:1) that the log10 streamflow versus log10 suspended sediment concentration relationship has changed, with an approximate 20 percent increase in the log10 streamflow coefficient over the period 1981 to 1996. However, sediment concentrations in the Yadkin River have decreased during the decade of the 1990s, which has been accompanied by a concomitant increase in streamflow variability. Although STL has been shown to be a versatile trend analysis technique, DLM is shown to be more suitable for discovery and inference of structural changes (trends) in the model coefficient describing the relationship between flow and sediment concentration. 相似文献
10.