全文获取类型
收费全文 | 1341篇 |
免费 | 16篇 |
国内免费 | 22篇 |
专业分类
安全科学 | 65篇 |
废物处理 | 49篇 |
环保管理 | 296篇 |
综合类 | 172篇 |
基础理论 | 303篇 |
污染及防治 | 325篇 |
评价与监测 | 109篇 |
社会与环境 | 50篇 |
灾害及防治 | 10篇 |
出版年
2023年 | 11篇 |
2022年 | 21篇 |
2021年 | 23篇 |
2020年 | 21篇 |
2019年 | 14篇 |
2018年 | 24篇 |
2017年 | 21篇 |
2016年 | 33篇 |
2015年 | 29篇 |
2014年 | 43篇 |
2013年 | 131篇 |
2012年 | 44篇 |
2011年 | 80篇 |
2010年 | 48篇 |
2009年 | 58篇 |
2008年 | 63篇 |
2007年 | 89篇 |
2006年 | 54篇 |
2005年 | 42篇 |
2004年 | 44篇 |
2003年 | 46篇 |
2002年 | 49篇 |
2001年 | 33篇 |
2000年 | 20篇 |
1999年 | 17篇 |
1998年 | 20篇 |
1997年 | 23篇 |
1996年 | 18篇 |
1995年 | 10篇 |
1994年 | 16篇 |
1993年 | 21篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 14篇 |
1989年 | 15篇 |
1988年 | 7篇 |
1987年 | 11篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 14篇 |
1980年 | 5篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1975年 | 10篇 |
1974年 | 5篇 |
1972年 | 4篇 |
1956年 | 4篇 |
排序方式: 共有1379条查询结果,搜索用时 15 毫秒
91.
Integrated Resource Management: Moving from Rhetoric to Practice in Australian Agriculture 总被引:1,自引:0,他引:1
/ Implementing the concept of sustainability through integrated approaches to natural resource management poses enormous challenges for both the rural communities and government agencies concerned. This paper reviews the underlying rhetoric of sustainable agricultural systems and the integrated resource management paradigm and identifies some of the challenges being experienced in translating this rhetoric into practice. A relatively recently implemented community-based integrated catchment management (ICM) process in a rural community in northeast Australia is examined in terms of some of the lessons learned that may be relevant to other similar integrated resource management (IRM) processes. It reveals a pragmatic, opportunistic, and evolving implementation process based on adaptive learning rather than a more traditional "rational" planning approach. Some essential characteristics of a community-based IRM process are identified, including fostering communication; providing a structure that fosters cooperation and facilities coordination among community, industry, and government agencies; the integration of IRM principles into local government planning schemes; and an emergent strategic approach to IRM program implementation. We conclude by identifying some essential characteristics of an IRM process that can assist a community to adapt to, and manage change for, sustainable resource use. 相似文献
92.
Bruce B. Johnson 《Journal of the American Water Resources Association》1981,17(1):129-132
ABSTRACT: The accounting and repayment practices employed by the Water and Power Resources Service (WPRS) greatly distort the actual resource allocation process and the ultimate repayment to the Federal Treasury. Through a series of transfers of capital repayment obligations to future development with modest or no interest charges, the repayment is reduced to only a fraction of the amount implied. In the case of the Pick-Sloan Missouri Basin Program, the public subsidy of hydroelectric power is estimated to be $2 for every $1 of repayment. For irrigation investment, the direct repayment to the Federal Treasury is less than 10 percent of the annualized cost of the public investment, with irrigators repaying at a rate of less than $0.03 for every dollar of public expenditure. 相似文献
93.
Irreversible environmental changes are occurring along the Colorado River in the Grand Canyon as a result of regulation of the river flow by the Glen Canyon Dam. The questions of primary importance in managing this great natural resource are 1) in what manner and how rapidly are the physical and ecological adjustments taking place, and 2) is the increased use of the river for recreational boating contributing to the degradation? Human use along the Colorado River is limited, for the most part, to the relic, pre-dam fluvial deposits colloquially called “beaches.” With the new river regime these deposits are positioned well above the present high-water stage, 27,000 cubic feet/second (cfs), or 765 cubic meters/second (cms), so they are not replenished periodically as they were prior to construction of the dam in 1963. The dominant natural processes now are aeolian sand transport and mass wasting. The float-trip passengers use the river beaches for hiking, camping, and. lunch stops. At the most desirable sites thirty to forty people camp on the beaches each night over a four to five month season. Human impact includes incorporation of campsite litter, burial of chemically treated waste, and the direct stress associated with people walking on the vegetation and unstable sedimentary deposits. Results of our investigations indicate that the rate of degradation at the most heavily used sites exceeds the capacity of aeolian processes to reestablish natural landscapes. Therefore, careful management of float trjps is needed if these environments are to be maintained in a natural state rather than a “sand-box” state. 相似文献
94.
Roy W. Koch Thomas G. Sanders H. J. Morel-Seytoux 《Journal of the American Water Resources Association》1982,18(5):815-821
ABSTRACT: The detection of change in a hydrologic varaible, particularly water quality, is a current problem. A method is presented for testing whether there has been a shift in the mean of a hydrologic variable based on the well established bivariate normal distribution theory. In this technique, the dependent, or target, and the independent, or control, variables are formed as weighted linear combinations of the mean values at a number of locations in a selected target and control area. The weighting factors are determined based on a mathematical programming technique which minimizes the conditional coefficient of variation thereby minimizing the number of observations required to detect a change of a preselected magnitude in the mean of the target area. The result is a situation where a savings in the number of observations required to detect a change is a consequence of adding more stations: the space-time tradeoff. Two applications of the technique are presented, the first using electrical conductivity (EC) data from two sets of river basins and the second using EC data from a set of basins as the target variable and annual discharge as the control. The results indicate that a significant savings in time can be achieved by using this method. 相似文献
95.
Kundu CR Roychoudhury S Capcarova M 《Journal of environmental science and health. Part. B》2011,46(8):691-696
The effect of malathion [diethyl(dimethoxythiophosphorylthio)succinate] at sublethal concentration (0.006 ppm) on intestinal parameters of cricket frog (Fejervarya limnocharis) was studied for 24 hrs to 240 hrs of exposure and remarkable histopathological alterations were observed. The study on intestinal parameters revealed acute pathological conditions in the intestinal wall. The toxic effect became evident as the cytoplasm of the cells disintegrated and the cells became empty and vacuolated. The cell membranes were also ruptured. Degenerative changes of the absorptive surface (villi) of the intestine in the different periods of exposure were pronounced. Severe atrophic nature (necrotic mucosa) of the intestine began from 48 hrs onwards to 96 hrs of exposure. 相似文献
96.
Penetration of herbicides to groundwater in an unconfined chalk aquifer following normal soil applications 总被引:1,自引:0,他引:1
Johnson AC Besien TJ Bhardwaj CL Dixon A Gooddy DC Haria AH White C 《Journal of contaminant hydrology》2001,53(1-2):101-117
The persistence and penetration of the herbicides isoproturon and chlorotoluron in an unconfined chalk aquifer has been monitored over a 4-year period through soil sampling, shallow coring and groundwater monitoring. Chlorotoluron was applied on plots as a marker compound, having never been used previously on that, or surrounding fields. The fieldsite had a 5 degree slope with soil depths of 0.5 to 1.5 m and a water table between 20 and 5 m from the soil surface. Where the water table was deepest (9-20 m below surface (mbs)) little or no positive herbicide detections were made. However, where the water table was at only 4-5 mbs, a regular pesticide signal of around 0.1 microg/l for isoproturon and chlorotoluron could be distinguished. Over the winter recharge period automatic borehole samplers revealed a series of short-lived peaks of isoproturon and chlorotoluron reaching up to 0.8 microg/l. This is consistent with a preferential flow mechanism operating at this particular part of the field. Such peaks were occurring over 2 years after the last application of these compounds. Shallow coring failed to uncover any significant pesticide pulse moving through the deep unsaturated zone matrix at the fieldsite. 相似文献
97.
Recreational impact was measured on eight beaches in Glen Canyon National Recreation Area and 15 beaches in Grand Canyon National Park using permanently located transects and plots. Recreational impact indices included densities of human trash and charcoal and a measure of sand discoloration due to charcoal. Significant increases in the indices occurred on several Glen Canyon beaches over a seven-month period. Sand discoloration became significantly higher over all Glen Canyon beaches during the same time period. All indices were significantly higher in Glen Canyon than on similar Grand Canyon beaches. These differences are probably due to differences in: (a) level of impacts tolerated by the respective management regimes and, (b) in the number of user days among the two National Park Service administrative units. Management alternatives are presented for reversing the present trends of recreational impact on Glen Canyon beaches. 相似文献
98.
99.
Eric M. Fujita David E. Campbell W. Patrick Arnott Ted Johnson Will Ollison 《Journal of the Air & Waste Management Association (1995)》2014,64(7):743-758
Human exposures to criteria and hazardous air pollutants (HAPs) in urban areas vary greatly due to temporal-spatial variations in emissions, changing meteorology, varying proximity to sources, as well as due to building, vehicle, and other environmental characteristics that influence the amounts of ambient pollutants that penetrate or infiltrate into these microenvironments. Consequently, the exposure estimates derived from central-site ambient measurements are uncertain and tend to underestimate actual exposures. The Exposure Classification Project (ECP) was conducted to measure pollutant concentrations for common urban microenvironments (MEs) for use in evaluating the results of regulatory human exposure models. Nearly 500 sets of measurements were made in three Los Angeles County communities during fall 2008, winter 2009, and summer 2009. MEs included in-vehicle, near-road, outdoor, and indoor locations accessible to the general public. Contemporaneous 1- to 15-min average personal breathing zone concentrations of carbon monoxide (CO), carbon dioxide (CO2), volatile organic compounds (VOCs), nitric oxide (NO), nitrogen oxides (NOx), particulate matter (<2.5 μm diameter; PM2.5) mass, ultrafine particle (UFP; <100 nm diameter) number, black carbon (BC), speciated HAPs (e.g., benzene, toluene, ethylbenzene, xylenes [BTEX], 1,3-butadiene), and ozone (O3) were measured continuously. In-vehicle and inside/outside measurements were made in various passenger vehicle types and in public buildings to estimate penetration or infiltration factors. A large fraction of the observed pollutant concentrations for on-road MEs, especially near diesel trucks, was unrelated to ambient measurements at nearby monitors. Comparisons of ME concentrations estimated using the median ME/ambient ratio versus regression slopes and intercepts indicate that the regression approach may be more accurate for on-road MEs. Ranges in the ME/ambient ratios among ME categories were generally greater than differences among the three communities for the same ME category, suggesting that the ME proximity factors may be more broadly applicable to urban MEs.
Implications:Estimates of population exposure to air pollutants extrapolated from ambient measurements at ambient fixed site monitors or exposure surrogates are prone to uncertainty. This study measured concentrations of mobile source air toxics (MSAT) and related criteria pollutants within in-vehicle, outdoor near-road, and indoor urban MEs to provide multipollutant ME measurements that can be used to calibrate regulatory exposure models. 相似文献
100.
Photostabilizers for azadirachtin-A (a neem-based pesticide) 总被引:2,自引:0,他引:2
Johnson S Dureja P Dhingra S 《Journal of environmental science and health. Part. B》2003,38(4):451-462
Photostability of azadirachtin-A (a neem based pesticide) has been studied without and with adding stabilizers such as ter. butyl-p-cresol, 8-hydroxy quinoline and ter. butyl hydroquinone as thin film on glass surface and on leaf surface under sunlight and UV light. Half-life of azadirachtin has been found to be 48 min and 3.98 days as thin film under UV light and sunlight and 2.47 days on leaf surface, respectively. 8-Hydroxy quinoline and ter. butyl hydroquinone have been found effective in controlling degradation of azadirachtin under both sunlight and UV light with half-life of 44.42 and 35.90 days under sunlight, and 55.80 and 48.50 h under UV light, respectively. Whereas ter. butyl-p-cresol has been found effective A only under sunlight. Significant decreases in antifeedant and insect growth regulatory activity against third instar larvae of Spodopterra litura has been observed with azadirachtin when exposed to sunlight and UV light. However, by the addition of above stabilizers, the biological activity of azadirachtin-A has been retained even after 24 h of irradiation under UV light and up to 30 days of exposure to sunlight. 相似文献