全文获取类型
收费全文 | 18681篇 |
免费 | 222篇 |
国内免费 | 179篇 |
专业分类
安全科学 | 538篇 |
废物处理 | 587篇 |
环保管理 | 2762篇 |
综合类 | 4189篇 |
基础理论 | 4406篇 |
环境理论 | 17篇 |
污染及防治 | 4790篇 |
评价与监测 | 995篇 |
社会与环境 | 668篇 |
灾害及防治 | 130篇 |
出版年
2022年 | 159篇 |
2021年 | 206篇 |
2019年 | 138篇 |
2018年 | 294篇 |
2017年 | 299篇 |
2016年 | 383篇 |
2015年 | 300篇 |
2014年 | 391篇 |
2013年 | 1347篇 |
2012年 | 567篇 |
2011年 | 769篇 |
2010年 | 553篇 |
2009年 | 661篇 |
2008年 | 714篇 |
2007年 | 777篇 |
2006年 | 704篇 |
2005年 | 575篇 |
2004年 | 588篇 |
2003年 | 609篇 |
2002年 | 520篇 |
2001年 | 597篇 |
2000年 | 405篇 |
1999年 | 291篇 |
1998年 | 216篇 |
1997年 | 225篇 |
1996年 | 235篇 |
1995年 | 244篇 |
1994年 | 258篇 |
1993年 | 216篇 |
1992年 | 224篇 |
1991年 | 211篇 |
1990年 | 239篇 |
1989年 | 209篇 |
1988年 | 183篇 |
1987年 | 183篇 |
1986年 | 172篇 |
1985年 | 190篇 |
1984年 | 176篇 |
1983年 | 189篇 |
1982年 | 181篇 |
1981年 | 183篇 |
1980年 | 168篇 |
1979年 | 168篇 |
1978年 | 157篇 |
1977年 | 142篇 |
1976年 | 139篇 |
1974年 | 150篇 |
1973年 | 130篇 |
1972年 | 131篇 |
1967年 | 125篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
871.
Silvestre García de Jalón Ana Iglesias Ruth Cunningham Juan I. Pérez Díaz 《Regional Environmental Change》2014,14(3):1229-1242
Agricultural water management needs to evolve in view of increased water scarcity, especially when farming and natural protected areas are closely linked. In the study site of Doñana (southern Spain), water is shared by rice producers and a world heritage biodiversity ecosystem. Our aim is to contribute to defining adaptation strategies that may build resilience to increasing water scarcity and minimize water conflicts among agricultural and natural systems. The analytical framework links a participatory process with quantitative methods to prioritize the adaptation options. Bottom-up proposed adaptation measures are evaluated by a multi-criteria analysis (MCA) that includes both socioeconomic criteria and criteria of the ecosystem services affected by the adaptation options. Criteria weights are estimated by three different methods—analytic hierarchy process, Likert scale and equal weights—that are then compared. Finally, scores from an MCA are input into an optimization model used to determine the optimal land-use distribution in order to maximize utility and land-use diversification according to different scenarios of funds and water availability. While our results show a spectrum of perceptions of priorities among stakeholders, there is one overriding theme that is to define a way to restore part of the rice fields to natural wetlands. These results hold true under the current climate scenario and even more so under an increased water scarcity scenario. 相似文献
872.
873.
Thalita Rangueri de Barros Sandro Donnini Mancini José Lázaro Ferraz 《Environment, Development and Sustainability》2014,16(2):415-429
A study was made of the composition of wastes collected from the pipes of the stormwater drainage system of Sorocaba, SP, Brazil (600 thousand inhabitants). A total of 10 samples weighing at least 100 kg each were sorted into 19 items to determine the fraction that can be considered natural (earth/sand, stones, organic matter, and water, the latter determined after oven-drying the samples) and the anthropogenic fraction (the remaining 15 items, especially construction and demolition wastes and packaging). Soil/sand was found to be the main item collected (52.5 % dry weight), followed by the water soaked into the waste (24.3 %), which meant that all the other wastes were saturated in mud, whose contents varied from 6.4 % (glass) to 87.2 % (metalized plastics packaging). In general, 83 % of the collected wastes can be classified as “natural,” but the remaining 17 % represent 2,000 kg of the most varied types of wastes discarded improperly every day on the streets of the city. This is an alarming amount of wastes that may clog parts of the drainage systems, causing troubles for all the population (like flooding) and must be strongly considered in municipal solid wastes management and in environmental education programs. 相似文献
874.
P. M. S. Jayathilaka Peeyush Soni Sylvain R. Perret H. P. W. Jayasuriya Vilas M. Salokhe 《Regional Environmental Change》2012,12(1):55-68
Climate change is the main global challenge of this century; it is therefore imperative to identify its effects on agriculture
in developing countries. This research makes spatial assessment of climate change effect on major plantation crops in Sri
Lanka, with emphasis on crop suitability of tea, rubber, and coconut. Geo-referenced maps of spatial and temporal changes
in crop suitability and production potentials are generated and compared. Data pertaining to six agro-ecological zones under
the study area are analyzed for a period of 1980–2007. Crop suitability maps are generated amalgamating yield maps and climatic
factors maps using AHP in multi-criteria analysis under two time frames of 1980–1992 and 1993–2007. Percent change in crop
suitability and crop yield classes is calculated based on five crop suitability and five crop yield classes during two time
frames. Dynamics of climatic parameters and crop yield are recognized using geo-referenced maps. The suitability maps of the
two time frames are compared to identify the changes with each crop in conjunction with changes in the prevailing climate
and yield. Geographic shift of suitability, yield, and climate classes are examined. Net gain or loss in crop production is
quantified. Long-term annual rainfall significantly decreased in mid-country wet zone, whereas the mean temperature of the
study area increased by 1.4°C. Results clearly showed that the climate and yield can be meaningfully related to the crop suitability
and management. 相似文献
875.
Corruption is a threat to the purpose of humanitarian assistance. Until fairly recently, humanitarian assistance has not been considered an important arena in broader efforts aimed at curbing corruption, and corruption has not always been considered a particularly important concern for humanitarian assistance despite the obviously challenging nature of the context of humanitarian emergencies. Corruption, though, is a threat to humanitarian action because it can prevent assistance from getting to the people who most need it, and because it can potentially undermine public support for such assistance. This paper examines perceptions of corruption and its affects, documents best practices, and outlines gaps in understanding. It suggests recommendations for improving the capacity of humanitarian agencies to prevent and manage the risk of corruption. Agencies have taken steps to combat corruption and improve accountability--downwards and upwards--but scope remains for improvement and for greater sharing of learning and good practice. 相似文献
876.
W. Strauss 《Journal of the Air & Waste Management Association (1995)》2013,63(10):424-426
A new surface condenser and carbon adsorber has been developed which provides arc economic solution to the problem of odours from dry rendering plants. 相似文献
877.
W. L. Faith 《Journal of the Air & Waste Management Association (1995)》2013,63(11):459-460
Commercial cattle-feeding is a large industry in the United States. In California, for instance, there are more than 500 commercial feedlots. Each of these lots handles from less than 500 to more than 50,000 head of cattle at one time. With the urban and suburban explosion, feedlots that were at one time many miles from residential centers are now “just across the street.” Naturally the high odor level from improperly operated yards gives rise to considerable complaint and citizen indignation. A variety of methods to reduce odor to an acceptable level have been tried with varying results. A highly satisfactory procedure is based on “good housekeeping” practices, frequent removal of fecal material, and abatement of residual odor by spraying the lots at designated intervals with a solution of potassium permanganate. Details of the method are discussed. 相似文献
878.
Marvin W. Jackson 《Journal of the Air & Waste Management Association (1995)》2013,63(12):697-702
An investigation has been made of the suitability of a nondispersive infrared analyzer and two flame-ionization analyzers for measuring the total hydrocarbon concentrations of automobile exhaust gas. The investigation consisted of measuring relative responses of various hydrocarbons, checking for possible exhaust gas interferences and finally comparing exhaust hydrocarbon concentrations indicated by the flame-ionization analyzer to those indicated by the infrared analyzer. The infrared analyzer has high relative responses for parraffins and low responses for olefins, acetylenes, and aromatics. Also, the infrared indicated hydrocarbon concentrations must be corrected for exhaust water vapor interference. When the flameionization analyzers are operated at conditions that result in approximately uniform response to hydrocarbons and low oxygen interference, the exhaust hydrocarbon concentrations indicated by either flameionization analyzer are better approximations of the total hydrocarbon concentration than those indicated by the infrared analyzer. 相似文献
879.
Walter W. Heck John A. Dunning 《Journal of the Air & Waste Management Association (1995)》2013,63(2):112-114
The sensitivity of tobacco and/or pinto bean to ozone, as an air pollutant, is increased by growing plants in a shortened photoperiod under reduced light intensity and in a light potting mix. Sensitivity also is influenced by carbon dioxide concentration, time of day, and age of plant at time of exposure. Plants are more severely injured by a given dose under continuous exposure than when the exposure is split into two time periods. Tobacco shows cumulative development of injury when exposed to low concentrations intermittently over several days. 相似文献
880.
The purpose of Manual APM-3 is to provide a guide which will help increase the uniformity between various surveys, and thereby increase the useability of the data by others. 相似文献