全文获取类型
收费全文 | 8111篇 |
免费 | 296篇 |
国内免费 | 314篇 |
专业分类
安全科学 | 335篇 |
废物处理 | 117篇 |
环保管理 | 2407篇 |
综合类 | 2598篇 |
基础理论 | 865篇 |
环境理论 | 7篇 |
污染及防治 | 167篇 |
评价与监测 | 162篇 |
社会与环境 | 1831篇 |
灾害及防治 | 232篇 |
出版年
2024年 | 12篇 |
2023年 | 64篇 |
2022年 | 116篇 |
2021年 | 151篇 |
2020年 | 149篇 |
2019年 | 132篇 |
2018年 | 118篇 |
2017年 | 215篇 |
2016年 | 206篇 |
2015年 | 171篇 |
2014年 | 212篇 |
2013年 | 545篇 |
2012年 | 441篇 |
2011年 | 517篇 |
2010年 | 380篇 |
2009年 | 340篇 |
2008年 | 308篇 |
2007年 | 500篇 |
2006年 | 501篇 |
2005年 | 417篇 |
2004年 | 404篇 |
2003年 | 383篇 |
2002年 | 389篇 |
2001年 | 310篇 |
2000年 | 339篇 |
1999年 | 278篇 |
1998年 | 202篇 |
1997年 | 176篇 |
1996年 | 121篇 |
1995年 | 121篇 |
1994年 | 88篇 |
1993年 | 89篇 |
1992年 | 58篇 |
1991年 | 27篇 |
1990年 | 35篇 |
1989年 | 12篇 |
1988年 | 16篇 |
1987年 | 11篇 |
1986年 | 17篇 |
1983年 | 7篇 |
1982年 | 23篇 |
1981年 | 8篇 |
1980年 | 15篇 |
1979年 | 20篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1975年 | 7篇 |
1974年 | 7篇 |
1973年 | 6篇 |
1971年 | 14篇 |
排序方式: 共有8721条查询结果,搜索用时 814 毫秒
651.
Marc O. Ribaudo C. Edwin Young 《Journal of the American Water Resources Association》1989,25(1):71-78
ABSTRACT: A framework for estimating the water quality benefits from soil erosion was developed. The framework is based on the linkages between soil erosion and offsite damages. The linkages are: erosion on the field, movement of eroded materials to waterways, impact of discharged material on water quality parameters, impact of water quality changes on ability of water to provide economic services, and the economic value of the changes in water use. These linkages need to be modeled in order to estimate the water quality benefits from reductions in soil erosion. Methods for modeling each link on a geographic level, which enables the analyses of national soil conservation, were examined. Areas where data or models were found to be lacking include transport of sediment and nutrients to water systems, impact of discharged materials on water quality parameters, and impact of water quality on ability of water to provide economic services. An economic evaluation of 1983 soil conservation programs was presented as an example of how the framework could be used. A number of simplifying assumptions were made to represent links that could not be modeled with available data. 相似文献
652.
B. Lussier G. E. Mohr I. C. Goulter 《Journal of the American Water Resources Association》1989,25(1):111-116
ABSTRACT: The techniques of conflict analysis derived from game theory were applied to the Shoal Lake water supply conflict in southeastern Manitoba, Canada. The issue of conflict is the desire of an Indian Band in the area to build cottage lots near the intake for water supply for the City of Winnipeg. The City of Winnipeg contends that such a development would seriously affect the quality of water supplied to the City, thereby increasing its treatment costs significantly. The four major players defined for the conflict are the City of Winnipeg, Indian Band No. 40, the Province of Manitoba, and the Federal Department of Indian and Northern Affairs. The results of the conflict analysis suggest that the introduction of the provincial and federal government into the conifict will not assist significantly in its resolution and that further progress on the resolution is unlikely until the results of Federal Environment Assessment Review office hearing become available. 相似文献
653.
654.
本文论述了贵州省的野生生物资源概况,揭示了资源开发利用存在的问题,并对资源的开发利用与保护提出了建议。 相似文献
655.
Teresa N. Malafi Marlene A. Devine Larry L. Lesher 《Journal of Polymers and the Environment》1994,2(4):219-223
This paper summarizes a study evaluating the acceptance and perceived performance of disposable cutlery made from starch-based biodegradable resins relative to nondegradable polystyrene cutlery. Two hundred forty-three sailors onboard three U.S. Navy vessels ate their lunch using either biodegradable cutlery made with resins manufactured by one of two commercial companies or polystyrene cutlery. The cutlery was rated on several sensory and performance dimensions as well as for overall acceptability. Results indicated that sailors rated both the biodegradable and the polystyrene utensils as easy to hold. There were also no differences in the perceived ease of using each of the spoons. However, compared to the polystyrene utensils, both types of biodegradable utensils were viewed as less sturdy, as having a less attractive color, and as being less acceptable overall. The biodegradable forks and knives were also rated as more difficult to use for piercing and cutting food than the polystyrene ones. In addition, several significant differences emerged between the two types of biodegradable cutlery. The results are discussed in terms of the need for continued consumer testing of products developed from biodegradable polymeric materials. 相似文献
656.
Fourteen streams in the Sierra Nevada in the USA were sampled to determine whether diversions of streamflow for hydroelectric development had caused significant changes in riparian vegetation. Several streams showed significant differences in vegetation cover, community composition, or community structure between pairs of diverted and undiverted reaches. On some streams, environmental conditions rather than streamflow diversions may have been responsible for vegetation differences. Streams in the Sierra Nevada respond individualistically to diversions. Prediction of vegetation responses must take into consideration environmental characteristics of specific stream reaches. 相似文献
657.
Indonesia is a major exporter of tropical hardwoods. The country's goal is to establish integrated wood industries by reducing the export of unprocessed sawlogs. The value of hardwood sawlog exports has decreased by twothirds in 1986 dollars since 1978, while the value of hardwood sawnwood and plywood exports has increased sixfold. Sawlog exports are now banned. This article contrasts the official governmental policy on forest industry development with the operational realities of doing business in Indonesia. 相似文献
658.
The paper examines characteristics of science parks in the face of employment decline, raising doubts about the scale of their success. The paper re‐examines previous research on the existence and causes of long waves of economic growth and decline and concludes that if these are not generated by innovations in production, then it should not be surprising that science parks have not lived up to expectations. 相似文献
659.
Ulf Wiberg 《Journal of Environmental Planning and Management》1986,29(2):70-74
The computer and telecommunications technology has created new opportunities for developing interaction between offices and enterprises located far away from each other. Even if the market forces favour concentration to R & D centres in the big cities and in university towns, there are expectations that the distance over‐bridging qualities of the new technology can create development opportunities for sparsely populated peripheral areas. In this paper the interplay between the new technology and other important factors in the local and regional environment are discussed with the focus on both opportunities and restrictions. 相似文献
660.
John E. Keith Rangesan Narayanan 《Journal of the American Water Resources Association》1988,24(6):1247-1256
ABSTRACF: Examination of a series of studies of the economically efficient water allocations in the Upper Colorado River, Yellowstone River, and Great Basins indicate that water is not a serious general physical constraint on the development of energy resources, so long as public institutions do not hinder the exchange of water rights in markets. Energy development will cause limited impacts on other water-using sectors, principally agriculture. There appears to be little reason to develop large-scale water storage facilities, even during periods of reduced water production. Water storage developments appear to be necessary only when institutional constraints severely restrict water rights markets and transfers. 相似文献