全文获取类型
收费全文 | 769篇 |
免费 | 17篇 |
国内免费 | 11篇 |
专业分类
安全科学 | 34篇 |
废物处理 | 19篇 |
环保管理 | 182篇 |
综合类 | 114篇 |
基础理论 | 206篇 |
环境理论 | 2篇 |
污染及防治 | 156篇 |
评价与监测 | 40篇 |
社会与环境 | 28篇 |
灾害及防治 | 16篇 |
出版年
2023年 | 10篇 |
2022年 | 10篇 |
2021年 | 27篇 |
2020年 | 14篇 |
2019年 | 30篇 |
2018年 | 22篇 |
2017年 | 32篇 |
2016年 | 34篇 |
2015年 | 21篇 |
2014年 | 24篇 |
2013年 | 66篇 |
2012年 | 39篇 |
2011年 | 38篇 |
2010年 | 35篇 |
2009年 | 34篇 |
2008年 | 43篇 |
2007年 | 32篇 |
2006年 | 40篇 |
2005年 | 27篇 |
2004年 | 28篇 |
2003年 | 18篇 |
2002年 | 28篇 |
2001年 | 24篇 |
2000年 | 14篇 |
1999年 | 9篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有797条查询结果,搜索用时 542 毫秒
221.
222.
223.
224.
225.
Shannon Sullivan Elizabeth Mccann Raymond De Young Donna Erickson 《Journal of Agricultural and Environmental Ethics》1996,9(2):123-143
Farmers have been characterized as people whose ties to the land have given them a deep awareness of natural cycles, appreciation for natural beauty and sense of responsibility as stewards. At the same time, their relationship to the land has been characterized as more utilitarian than that of others who are less directly dependent on its bounty. This paper explores this tension by comparing the attitudes and beliefs of a group of conventional farmers to those of a group of organic farmers. It was found that while both groups reject the idea that a farmer’s role is to conquer nature, organic farmers were significantly more supportive of the notion that humans should live in harmony with nature. Organic farmers also reported a greater awareness of and appreciation for nature in their relationship with the land. Both groups view independence as a main benefit of farming and a lack of financial reward as its main drawback. Overall, conventional farmers report more stress in their lives although they also view themselves in a caretaker role for the land more than do the organic farmers. In contrast, organic farmers report more satisfaction with their lives, a greater concern for living ethically, and a stronger perception of community. Finally, both groups are willing to have their rights limited (organic farmers somewhat more so) but they do not trust the government to do so. 相似文献
226.
Stephan G. Custer Phillip Fames John P Wilson Robert D. Snyder 《Journal of the American Water Resources Association》1996,32(2):393-405
ABSTRACT: Average annual precipitation for the period 1961–1990 was estimated for a mountainous region in Montana with a Laplacian thin-plate spline (ANUSPLIN) and compared to a hand-drawn map. Input data included latitude, longitude, and elevation from a three-arc-second U.S. Geological Survey Digital Elevation Model of the Bozeman and Billings 1 × 2 topographic quadrangles and precipitation data at 96 stations. The two maps are similar in appearance. Digital comparison of the two maps with ARC/INFO's Grid tools shows that mean annual precipitation for the hand-contoured map is 22.9 inches and for the ANUSPLIN map is 23.7 inches. Of the 5,760,000 cells, 53 percent showed no difference between ANUSPLIN and hand-drawn maps; 19 percent showed a two-inch difference, and 28 percent showed more than 2 inches difference. Input data and model output at the same location are not different (standard deviation 1.77, p-value 0.76). Hand-drawn maps show two inches more precipitation during the 1961–90 period than during the 1941–1970 period. Similarly, measured data at 73 sites for the period 1961–1990 are on average 2.4 inches higher than the same stations during the 1941–1970 period. The difference is significant (p-value > 0.0001). 相似文献
227.
Computer simulation provides a powerful tool for comparing alternative designs of remediation processes. The software package FLUENT copes successfully with subsurface three-dimensional flow fields, multiple and directional permeabilities, wide spatial variations in subsurface gas velocities, and the presence of surface structures. FLUENT can provide an invaluable method for comparing remediation efficiencies among competing design alternatives. This article features case studies to illustrate the benefits that simulation studies provide before and during the initiation of remedial actions using bioventing. 相似文献
228.
ABSTRACTSustainability has emerged as a central concept for discussing the current state of the human-environment system and planning for its future. To delve into the depths of sustainability means to talk about ecology, economy, and equity as fundamentally interconnected. However, each continues to be colonised by normative epistemologies of ecological sciences, neoclassical economics, and development, suggesting that with enough science and development, a more equitable sustainability is achievable. In our analysis, place emerges as an alternative epistemology through which to analyze sustainability. Place exists at multiple spatial and temporal scales, understood through direct observation of boundaries, processes and patterns, phenomenologically through individual experience, and as a complex hybrid: always emerging through interactions among individuals and institutions. Despite the ubiquity of place in the socio-ecological literature, the complexity of place in relation to sustainability is under-theorised, and in as much as sustainability happens or does not happen in real places rather than in policies and models, a place-based sustainability framework is necessary to move forward. To address this gap, we developed the emplacement framework, consisting of four domains: displacement, misplacement, replacement, and emplacement. Each domain is dynamic, constructing place as praxis, and reframing sustainability as a site of collective inquiry and choices. Our goal is to facilitate the active and on-going practices of place-based research and engagement among scholars, activists, and other community members by providing a structure for transdisciplinary dialogue and the application of transdisciplinary research to enable better decision-making. 相似文献
229.
Elizabeth L. White 《Journal of the American Water Resources Association》1976,12(2):351-370
ABSTRACT. The interrelationships between the runoff characteristics of watersheds (expressed as the mean annual flood), standard basin parameters (area, drainage properties, and relief), and the parameters which describe the solutional modification of the basins (carbonate rock fractions, sinkhole development, and measures of internal drainage) were used to group 62 carbonate watersheds. Simple binary correlations were obtained by direct plotting of the data. This was followed by multivariate analyses: factor and cluster analyses. Following the cluster analysis, which separated the basins into three groups, the variance within each group was examined again by binary correlations and by factor analysis. Prediction equations for those basins underlain by dolomite rock [QBAR = 12.4 TOT1.01] and for those basins underlain by carbonate rock with very little surface expression [QBAR = 43.5 TOT0.87] were proposed. Basins underlain by karstic limestone had a large amount of variance within the data set; therefore no prediction equation could be obtained. (QBAR = mean annual flood, cfs; TOT = total length of all blue lines shown on topographic maps, miles.) 相似文献
230.
W. M. Snyder 《Journal of the American Water Resources Association》1980,16(1):22-30
ABSTRACT: Sliding polynomials differ from other piecewise interpolation and smoothing methods in their functional continuity at the nodes. This functional continuity was used to establish optional spacing of nodes and optional boundary controls in data smoothing while still maintaining mathematically continuous rates or gradients. Cyclic as well as noncyclic data can be smoothed. Variance of the individual nodal values. derived through least-squares optimization, can be calculated using the rigorously determined weighting coefficients between data points and nodes. Such nodal variances are estimates of localized uncertainty in the data which complement the localization of smoothing through use of piecewise functions. Choice of controls in smoothing and calculation of variance have been incorporated in a computer program for user convenience. 相似文献