全文获取类型
收费全文 | 20354篇 |
免费 | 183篇 |
国内免费 | 201篇 |
专业分类
安全科学 | 536篇 |
废物处理 | 987篇 |
环保管理 | 2423篇 |
综合类 | 2670篇 |
基础理论 | 5289篇 |
环境理论 | 4篇 |
污染及防治 | 5602篇 |
评价与监测 | 1650篇 |
社会与环境 | 1455篇 |
灾害及防治 | 122篇 |
出版年
2023年 | 92篇 |
2022年 | 215篇 |
2021年 | 217篇 |
2020年 | 139篇 |
2019年 | 177篇 |
2018年 | 328篇 |
2017年 | 322篇 |
2016年 | 525篇 |
2015年 | 362篇 |
2014年 | 573篇 |
2013年 | 1745篇 |
2012年 | 672篇 |
2011年 | 862篇 |
2010年 | 804篇 |
2009年 | 788篇 |
2008年 | 886篇 |
2007年 | 978篇 |
2006年 | 871篇 |
2005年 | 716篇 |
2004年 | 723篇 |
2003年 | 704篇 |
2002年 | 670篇 |
2001年 | 911篇 |
2000年 | 631篇 |
1999年 | 393篇 |
1998年 | 274篇 |
1997年 | 246篇 |
1996年 | 292篇 |
1995年 | 271篇 |
1994年 | 250篇 |
1993年 | 233篇 |
1992年 | 240篇 |
1991年 | 208篇 |
1990年 | 214篇 |
1989年 | 219篇 |
1988年 | 197篇 |
1987年 | 158篇 |
1986年 | 126篇 |
1985年 | 138篇 |
1984年 | 169篇 |
1983年 | 153篇 |
1982年 | 193篇 |
1981年 | 135篇 |
1980年 | 119篇 |
1979年 | 152篇 |
1978年 | 118篇 |
1977年 | 107篇 |
1976年 | 100篇 |
1975年 | 83篇 |
1974年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Corporate environmental practices have been evolving quite rapidly in recent years, as consumers express their preferences for environmentally friendly products and practices, as manufacturers look “upstream” and inquire into their suppliers' environmental practices due to liability and marketing concerns, and as company operating costs increase as a result of new environmental regulations. New corporate efforts are made to anticipate (rather than respond to) outside environmental pressures, to internalize costs, and to find strategic opportunities or competitive advantages based on company or product environmental performance. This article describes a survey and research project designed to explore one aspect of these evolving corporate practices—the use of analytical tools and associated programs, such as life-cycle assessment and design-for-environment—by companies to account for impacts throughout a product'S life-cycle. 相似文献
992.
The article describes the historical development of water tariff policy in Tanzania from the colonial times to present. After
gaining independence, the country introduced “free” water policy in its rural areas. Criticism against this policy was expressed
already in the 1970s, but it was not until the late 1980s that change became unavoidable. All the while urban water tariffs
continued to decline in real terms. In rural and periurban areas of Tanzania consumers often have to pay substantial amounts
of money for water to resellers and vendors since the public utilities are unable to provide operative service. Besides, only
a part of the water bills are actually collected. Now that the free water supply policy has been officially abandoned, the
development of water tariffs and the institutions in general are a great challenge for the country. 相似文献
993.
994.
S. N. Kulshreshtha J. A. Gillies 《Journal of the American Water Resources Association》1993,29(2):257-266
ABSTRACT: Presence of a river in an urban setting may contribute positively to an aesthetically pleasing environment. Such aesthetic effects are not typically linked to specific economic activities and occur, for example, when residents are exposed to a river-view. Qualities enhancing the aesthetic value of the river include the presence of parks, trails, and vegetation along the riverbanks. The value of aesthetic amenities provided by the South Saskatchewan to the City of Saskatoon residents was estimated in this study using non-market methods. The implicit price of the river view was estimated using the Hedonic Price Model, whereas value through willingness to pay for property taxes or higher rents were also estimated using actual market data. The total annual value of the river to the City of Saskatoon through addition of aesthetic amenities was estimated at $1.2 million in 1989 dollars. 相似文献
995.
S. J. Kalkhoff 《Journal of the American Water Resources Association》1993,29(6):989-996
ABSTRACT: A geographic information system (GIS) was used to determine the relation between the stream-water quality and underlying geology in Roberts Creek watershed, Clayton County, Iowa, for base-flow conditions during the spring and summer of 1988–90. Geologic, stream, basin and subbasin boundaries, and water-quality sampling-site coverages were created by digitizing available maps. A contour coverage was created from digital line-graph data. The areal extent of geologic units subcropping in each subbasin was quantified with GIS, and the results then were output and joined with the discharge and water-quality data for statistical analyses. Illustrations showing the geology of the study area and the results of the study were prepared using GIS. By using GIS and a statistical software package, a weak but statistically significant relation was found between the water temperature, pH, and nitrogen concentrations in Roberts Creek and the underlying geology during base-flow conditions. 相似文献
996.
Catherine A. Heaney Barbara A. Israel Susan J. Schurman Elizabeth A. Baker James S. House Margrit Hugentobler 《组织行为杂志》1993,14(5):495-510
The workplace has become the locus of many stress management and stress reduction interventions. However, little attention has focused on how worksite factors affect the implementation and impact of such interventions. In this paper, we investigate the effect of new versus traditional industrial relations practices on the impact of a worksite stress reduction program in a manufacturing setting. More specifically, a participatory action research (PAR) stress project is described and evaluated in two different labor–management relations contexts. One organization is characterized by the emerging ’new‘ industrial relations system where labor–management relations incorporate elements of joint problem-solving. The other organization has a more traditional approach where labor–management relations are formally adversarial. Results indicate that the labor–management relations context did influence the impact of the stress project. Involvement in the PAR stress project enhanced employee participation in decision-making in both contexts. However, involvement in the stress project enhanced employees' perceptions of the climate for participation only in the organization with more cooperative industrial relations. Increases in coworker support and decreases in depressive symptoms were associated with involvement in the PAR stress project in the organization with more adversarial industrial relations. 相似文献
997.
998.
W. B. Kirchner S. Grabowski 《Journal of the American Water Resources Association》1972,8(6):1259-1264
This paper serves as a literature review of manganese in fresh water. The major aspects of manganese occurrence discussed are: (1) sources, (2) geochemistry, (3) manganese-iron relationships, (4) effects on the fauna and flora and (5) detection. 相似文献
999.
ABSTRACT. A multiple-outfall system for cooling water disposal which is distributed along the direction of stream flow is analyzed. The results provide a simple method of preliminary design of a cooling water discharge outfall system and for a quick extimate of water quality of a polluted stream. It is shown that a properly designed distributed discharge system is capable of preventing serious pollution due to localized discharge of wastes and waste heat; however, the final design of the discharge system should take into account alternative schemes of waste heat disposal and their economic consequences. 相似文献
1000.
Five species assemblages of the intertidal infauna of Old Tampa Bay, Florida, USA are identified. Two assemblages are judged to constitute distinct communities, while a third is shown to be an interdigitation of the two communities. Dominance by on species is the prevalent pattern within the assemblages. Numbers of deposit feeders are found to be inversely correlated to that of filter feeders, and both trophic types are found to be correlated to the sediment parameters of median grain size, sorting and skewness. Three transects with three stations each were established along the south side of Courtney Campbell Causeway in Tampa Bay, Florida. A faunal sample (0.4 m2), a sediment sample, and a water sample were taken at each station in September, December, and March of 1968/1969. Sediment samples were wet-seived. Animal samples were reduced to numbers of organisms and biomass per species. Trellis diagrams and correlation tests were generated. Support is shown for the trophic group-amensalims hypothesis, however, the silt-clay fraction is apparently of lesser importance to deposit feeders in Florida sediments than in Buzzards Bay sediments. An attempt is made to relate an analysis of the optimal grain size for filter feeders to the trophic group-amensalism hypothesis. A view of communities as abstractions from continua is more realistic than communities as discrete units. 相似文献