全文获取类型
收费全文 | 544篇 |
免费 | 22篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 15篇 |
废物处理 | 18篇 |
环保管理 | 123篇 |
综合类 | 35篇 |
基础理论 | 160篇 |
环境理论 | 1篇 |
污染及防治 | 165篇 |
评价与监测 | 32篇 |
社会与环境 | 14篇 |
灾害及防治 | 5篇 |
出版年
2023年 | 6篇 |
2022年 | 5篇 |
2021年 | 4篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 12篇 |
2017年 | 16篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 11篇 |
2013年 | 42篇 |
2012年 | 17篇 |
2011年 | 20篇 |
2010年 | 20篇 |
2009年 | 15篇 |
2008年 | 23篇 |
2007年 | 29篇 |
2006年 | 38篇 |
2005年 | 14篇 |
2004年 | 15篇 |
2003年 | 16篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 10篇 |
1999年 | 12篇 |
1998年 | 8篇 |
1997年 | 14篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1974年 | 5篇 |
1969年 | 3篇 |
1954年 | 2篇 |
排序方式: 共有568条查询结果,搜索用时 15 毫秒
291.
Andrew N. Kadykalo Rachel T. Buxton Peter Morrison Christine M. Anderson Holly Bickerton Charles M. Francis Adam C. Smith Lenore Fahrig 《Conservation biology》2021,35(6):1725-1737
Calls for biodiversity conservation practice to be more evidence based are growing, and we agree evidence use in conservation practice needs improvement. However, evidence-based conservation will not be realized without improved access to evidence. In medicine, unlike in conservation, a well-established and well-funded layer of intermediary individuals and organizations engage with medical practitioners, synthesize primary research relevant to decision making, and make evidence easily accessible. These intermediaries prepare targeted evidence summaries and distribute them to practitioners faced with time-sensitive and value-laden decisions. To be effective, these intermediaries, who we refer to as evidence bridges, should identify research topics based on the priorities of practitioners; synthesize evidence; prepare and distribute easy-to-find and easy-to-use evidence summaries; and develop and maintain networks of connections with researchers and practitioners. Based on a review of the literature regarding evidence intermediaries in conservation and environmental management, as well as an anonymous questionnaire searching for such organizations, we found few intermediaries that met all these criteria. Few evidence bridges that do exist are unable to reach most conservation practitioners, which include resource managers in government and industry, conservation organizations, and farmers and other private landowners. We argue that the lack of evidence bridges from research to practitioners contributes to evidence complacency and limits the use of evidence in conservation action. Nevertheless, several existing organizations help reduce the gap between evidence and practice and could serve as a foundation for building additional components of evidence bridges in conservation. Although evidence bridges need expertise in research and evidence synthesis, they also require expertise in identifying and communicating with the community of practitioners most in need of clear and concise syntheses of evidence. Article Impact Statement: Evidence-based conservation will not be realized without improved access to evidence. We call for intermediary evidence bridges. 相似文献
292.
Ferreira Matheus da Silva Fontes Maurício Paulo Ferreira Pacheco Anderson Almeida Ker João Carlos Lima Hedinaldo Narciso 《Environmental geochemistry and health》2021,43(9):3407-3427
Environmental Geochemistry and Health - The city of Manaus is the biggest industrial city of the north Brazilian region, and a haphazard urbanization process characterizes it. The continuous... 相似文献
293.
294.
Thompson RS Shafer SL Anderson KH Strickland LE Pelltier RT Bartlein PJ Kerwin MW 《Environmental management》2004,34(Z1):S125-S148
Ecoregion classification systems are increasingly used for policy and management decisions, particularly among conservation and natural resource managers. A number of ecoregion classification systems are currently available, with each system defining ecoregions using different classification methods and different types of data. As a result, each classification system describes a unique set of ecoregions. To help potential users choose the most appropriate ecoregion system for their particular application, we used three latitudinal transects across North America to compare the boundaries and environmental characteristics of three ecoregion classification systems [Küchler, World Wildlife Fund (WWF), and Bailey]. A variety of variables were used to evaluate the three systems, including woody plant species richness, normalized difference in vegetation index (NDVI), and bioclimatic variables (e.g., mean temperature of the coldest month) along each transect. Our results are dominated by geographic patterns in temperature, which are generally aligned north-south, and in moisture, which are generally aligned east-west. In the west, the dramatic changes in physiography, climate, and vegetation impose stronger controls on ecoregion boundaries than in the east. The Küchler system has the greatest number of ecoregions on all three transects, but does not necessarily have the highest degree of internal consistency within its ecoregions with regard to the bioclimatic and species richness data. In general, the WWF system appears to track climatic and floristic variables the best of the three systems, but not in all regions on all transects. 相似文献
295.
PCDD/F congener profiles have been used to determine the source of elevated TEQ concentrations in cows' milk collected in the vicinity of several industrial sites. Principal components analysis and modelling of the air-to-milk transfer of individual PCDD/F congeners have shown that the milk fingerprint was related to that of sediment taken from the River Rother adjacent to the farm where the cows had grazed. It is suggested that sediment from the river had been washed onto the grazing land during periods of flooding, and this had been ingested by the grazing cows. This pathway could represent an important route of contaminant intake for livestock grazing on the regularly inundated floodplains of rivers containing contaminated sediments. 相似文献
296.
Gao FF Jin Y Yates SR Papiernik S Anderson MA Yates MV 《Journal of the Air & Waste Management Association (1995)》2001,51(1):49-59
A tall passive flux chamber with a height significantly greater than its horizontal dimensions is proposed for measuring fluxes of volatile organic compounds (VOCs) at the soil surface. The main feature of this tall chamber is the presence of a vertical concentration gradient of the target gas in the chamber. The emission and transport behavior of the target gas in the soil-chamber system are analyzed using the diffusion theory. A mathematical model is developed to estimate the flux from the soil into the tall chamber, providing the target gas establishes a detectable vertical concentration gradient in the chamber. To obtain the data required for calculating flux, only two gas concentrations (C1 and C2) at two heights (h1 and h2) within the chamber need to be measured at the end of a short chamber placement time (tp). To evaluate the applicability of the tall chamber for measuring flux, several laboratory tests have been conducted, using CH2Cl2 and CH3Br as the target gases. The results indicate that the proposed tall chamber has promising potential as a method for measuring fluxes of VOCs at the soil surface. 相似文献
297.
The concentration of water-soluble organic nitrogen (WSON) in precipitation has been measured at seven sites across the United Kingdom, over a period of 1–2 years, using protocols developed in a pilot study. Samples were collected over 1–2 weeks in continuously open funnels made of stainless steel, draining to a glass bottle, and were preserved during and after collection by the addition of thymol. After chemical analysis, samples were excluded from the long-term average if they showed signs of contamination (significant concentrations of K+ or PO4 3?). Two methods of measuring total dissolved N were used, persulphate oxidation and high-temperature chemiluminescence. The latter generally gave the larger values, and has been used to asses the organic component of dissolved N. The long-term data set confirms the original results from the pilot study—organic N contributes between 24 and 40% to the total annual wet deposition of dissolved N across the United Kingdom. The fraction of WSON was greatest at western sites, and was strongly correlated with ammonium concentrations. However, the seasonal pattern across all sites showed a late spring maximum for ammonium and nitrate, but a late summer maximum for WSON. The magnitude of the contribution of WSON to wet-deposited N has implications for the setting and assessment of critical loads for N deposition. 相似文献
298.
Mason LB Amrhein C Goodson CC Matsumoto MR Anderson MA 《Journal of environmental quality》2005,34(6):1998-2004
The Salton Sea is the largest inland water body in California, covering an area of 980 km(2). Inflow to the Salton Sea (1.6 km(3) yr(-1)) is predominately nutrient-rich agricultural wastewater, which has led to eutrophication. Because internal phosphorus release from the bottom sediments is comparatively low and external phosphorus loading to the Salton Sea is high, reduction of tributary phosphorus is expected to reduce algal blooms, increase dissolved oxygen, and reduce odors. Removing both dissolved phosphorus and phosphorus-laden sediment from agricultural drainage water (ADW) should decrease eutrophication. Both alum and polyacrylamide (PAM) are commonly used in wastewater treatment to remove phosphorus and sediment and were tested for use in tributary waters. Laboratory jar tests determined PAM effectiveness (2 mg L(-1)) for turbidity reduction as cationic > anionic = nonionic. Although cationic PAM was the most effective at reducing turbidity at higher speeds, there was no observed difference between the neutral and anionic PAMs at velocity gradients of 18 to 45 s(-1). Alum (4 mg L(-1) Al) reduced turbidity in low energy systems (velocity gradients < 10 s(-1)) by 95% and was necessary to reduce soluble phosphorus, which comprises 47 to 100% of the total P concentration in the tributaries. When PAM was added with alum, the anionic PAM became ineffective in aiding flocculation. The nonionic PAM (2 mg L(-1)) + alum (4 mg L(-1) Al) is recommended to reduce suspended solids in higher energy systems and reduce soluble P by 93%. 相似文献
299.
Robert Anderson 《Resources Policy》1977,3(2):78-86
The belief that forests, minerals, fisheries, and other exhaustible assets are being depleted at excessive rates in a free enterprise society has led to recurrent demands for the regulation of resource exploitation. Many have believed that further regulations are necessary — for example, the conservation movement accepted as basic tenents that most resources were too cheap, were wastefully exploited, and would become exhausted soon. This paper surveys several interrelated issues in resource depletion from an economist's perspective, in particular, whether the articles of faith of the conservation movement are borne out by economic theory and available empirical evidence. Are resources too cheap? Are they wastefully exploited? Will resources become exhausted prematurely? Are we neglecting the needs of future generations? 相似文献
300.
ABSTRACT The abundant, high-quality waters of the Yellowstone River Basin have fostered a strong agricultural-based economy in eastern Montana. The region also contains the nation's largest strippable coal reserves. Numerous conflicts have developed around the mining of coal and in-state conversion of coal into electricity and synthetic fuels – processes that require large volumes of water. Competition for water among industrialists, agriculturalists, and others is a critical state issue. Probable effects of increased water diversions, the nature of water-energy conflicts, and state efforts to control development are discussed. 相似文献