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581.
Kate A. Berry Nancy L. Markee Michael J. Stewart Gary R. Giewat 《Journal of the American Water Resources Association》1996,32(5):1089-1099
ABSTRACT: This study examines the social construction of county commissioners' knowledge about water. Factors that influence what commissioners know about water include each commissioner's personal characteristics, education, experience in natural resources management, involvement in policy making, and use and evaluation of various sources of information. This study focused on county commissioners representing rural, mixed, and urban counties in Arizona, Nevada, and Utah and collected data through mail surveys and interviews. County commissioners in the survey were well educated; however, few had taken college courses directly addressing technical, management, or legal aspects of water issues. Approximately one-third had direct experience in farming and ranching; nearly two-thirds indicated that farming and ranching played a major role in their communities. Respondents had experience with a broad range of water policy issues. In evaluating thirteen information sources in terms of their frequency of use, relevancy, and reliability, respondents assessed fellow commissioners and local government staff and managers most positively and nonprofit organizations most negatively. The media was also broadly rated as less relevant and reliable than other sources of information. The commissioners in the study expressed a high level of general concern about water issues and a strung preference for local sources of information. 相似文献
582.
Primary amebic meningoencephalitis (PAM) is a fatal disease of the central nervous system caused primarily by the free-living ameba,Naegleria fowleri. PAM is primarily associated with swimming in various types of fresh water. World literature was reviewed in order to derive a risk analysis model that would be helpful in the management of PAM. The management of PAM risk is difficult, and the prevention of PAM is almost impossible. However, it is reassuring that the cases and risks estimated by the risk model are usually small, with individual annual risk on the order of 10–6. 相似文献
583.
Elisabeth N. Bui Gary J. HancockScott N. Wilkinson 《Agriculture, ecosystems & environment》2011,144(1):136-149
This paper reviews water-borne soil erosion in Australia in the context of current environmental policy needs. Sustainability has emerged as a central tenet of environmental policy in Australia and water-borne hillslope soil erosion rates are used as one of the indicators of agricultural sustainability in State of the Environment reporting. We review attempts to quantify hillslope erosion rates over Australia and we identify areas at risk of exceeding natural baseline rates. We also review historical definitions of sustainable, or ‘tolerable’ erosion rates, and how to set these rates. There are many ways to estimate hillslope erosion and these can create confusing results. Moreover their application for land management purposes requires nuanced interpretations that ultimately depend on the desired objective of decision-makers. Soil is the earth surficial material that serves as a medium for plant growth and the notion of tolerable soil erosion arose historically to assess the impact of soil loss on agricultural uses. However now that the impact of erosion on aquatic ecosystems been recognized as a major concern for Australia, the concept of tolerable erosion needs to be revised. Here we discuss three definitions of tolerable soil erosion, following recent literature. We derive estimates of long-term agricultural sustainability based on natural soil production rates and discuss this in relation to other defined land-management objectives such as aquatic ecosystem health. We conclude that the desired objectives of land managers must be clearly articulated before questions of ‘where to invest to control erosion’ and ‘how to assess return-on-investment’ can be answered. 相似文献
584.
585.
Nasreen Islam Khan David Bruce Ravi Naidu Gary Owens 《Environmental geochemistry and health》2009,31(Z1):221-238
Dietary intake of water and food has been identified as one of the major pathways for arsenic (As) exposure in the rural population
of Bangladesh. Therefore, realistic assessment and measurement of dietary intake patterns are important for the development
of an accurate estimate of As exposure and human health risk assessment. One important consideration is to identify an appropriate
tool for measuring dietary intake. In this study an interviewer-administered Food Frequency Questionnaire (FFQ) was implemented
to determine age and gender specific dietary intake. The developed FFQ was unique because it developed a synergy between field
dietary assessment and As concentration measurements in various environmental media. The resulting integrated database provided
an accurate framework for the process of As exposure and human health risk assessment. The preliminary results reported here
from the FFQ demonstrated that this technique could be used in rural areas as a tool to assess As exposure and the associated
human health risk. 相似文献
586.
587.
588.
Robert K Hall Peter Husby Gary Wolinsky Olof Hansen Michiko Mares 《Environmental monitoring and assessment》1998,51(1-2):357-367
The Central Valley of California contains critical habitat for many aquatic and terrestrial biological resources. The purpose of this R-EMAP project was to assess the effects from a highly modified agriculturally dominated landuse area on the aquatic resources of the lower portion of the Central Valley watersheds. The study area is 24,346 mi2 and comprises the Sacramento Valley and San Joaquin Valley watersheds to the 1,000 ft. elevation contour. Populations of interest are man-made conveyances and wadeable natural streams. There are 40,756 miles of streams and constructed conveyances within the Central Valley as designated by RF3 database. Sample sites were selected to represent 14,399 miles of streams and sloughs, and 16,697 miles of constructed conveyances. 相似文献
589.
590.
Gary C. White 《Environmental and Ecological Statistics》2008,15(1):89-99
Program MARK provides > 65 data types in a common configuration for the estimation of population parameters from mark-encounter
data. Encounter information from live captures, live resightings, and dead recoveries can be incorporated to estimate demographic
parameters. Available estimates include survival (S or ϕ), rate of population change (λ), transition rates between strata (Ψ), emigration and immigration rates, and population
size (N). Although N is the parameter most often desired by biologists, N is one of the most difficult parameters to estimate precisely without bias for a geographically and demographically closed
population. The set of closed population estimation models available in Program MARK incorporate time (t) and behavioral (b) variation, and individual heterogeneity (h) in the estimation of capture and recapture probabilities in a likelihood framework. The full range of models from M
0 (null model with all capture and recapture probabilities equal) to M
tbh
are possible, including the ability to include temporal, group, and individual covariates to model capture and recapture
probabilities. Both the full likelihood formulation of Otis et al. (1978) and the conditional model formulation of Huggins
(1989, 1991) and Alho (1990) are provided in Program MARK, and all of these models are incorporated into the robust design
(Kendall et al. 1995, 1997; Kendall and Nichols 1995) and robust-design multistrata (Hestbeck et al. 1991, Brownie et al.
1993) data types. Model selection is performed with AICc (Burnham and Anderson 2002) and model averaging (Burnham and Anderson
2002) is available in Program MARK to provide estimates of N with standard error that reflect model selection uncertainty. 相似文献