全文获取类型
收费全文 | 935篇 |
免费 | 26篇 |
国内免费 | 83篇 |
专业分类
安全科学 | 20篇 |
废物处理 | 7篇 |
环保管理 | 307篇 |
综合类 | 276篇 |
基础理论 | 186篇 |
环境理论 | 1篇 |
污染及防治 | 36篇 |
评价与监测 | 27篇 |
社会与环境 | 148篇 |
灾害及防治 | 36篇 |
出版年
2024年 | 2篇 |
2023年 | 13篇 |
2022年 | 13篇 |
2021年 | 11篇 |
2020年 | 10篇 |
2019年 | 20篇 |
2018年 | 20篇 |
2017年 | 20篇 |
2016年 | 32篇 |
2015年 | 33篇 |
2014年 | 31篇 |
2013年 | 74篇 |
2012年 | 41篇 |
2011年 | 47篇 |
2010年 | 39篇 |
2009年 | 36篇 |
2008年 | 22篇 |
2007年 | 48篇 |
2006年 | 39篇 |
2005年 | 45篇 |
2004年 | 47篇 |
2003年 | 51篇 |
2002年 | 30篇 |
2001年 | 47篇 |
2000年 | 42篇 |
1999年 | 39篇 |
1998年 | 22篇 |
1997年 | 31篇 |
1996年 | 30篇 |
1995年 | 21篇 |
1994年 | 15篇 |
1993年 | 15篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有1044条查询结果,搜索用时 15 毫秒
921.
SUMMARY Plantain (Musa AAB), a primary food crop in Ghana, is a key component in sustainable agricultural systems in high rainfall zones. Recently, there has been a substantial yield decline and reduction in plantation life. To elucidate the context in which intervention strategies should be developed, a Participatory Rural Appraisal (PRA) was conducted at five villages in the major plantain-producing belt of Ghana. The importance of plantain as a preferred food was confirmed, although farmers tended to sell plantain for cash income, using cheaper, less preferred alternatives for home consumption. Farmers identified decreasing soil fertility, the high cost of labour for weeding, pests and diseases, lack of good quality planting material and marketing-related issues as the major production constraints. Due to declining productivity in less fertile regions, plantain has been replaced with other food crops such as cassava and maize. Farmers overestimated the importance of insect pests but were unaware of the extensive damage that could be caused by nematodes and the foliar disease, black sigatoka. They observed, however, that pest damage is more severe when soil fertility is poor. Clearly, integrated pest management is likely to be most effective when practiced within the context of cropping systems management; sustainable strategies that are being developed for resource-limited plantain farmers in Ghana are discussed. 相似文献
922.
Tesfamicheal Wossen Thomas Berger Teferi Mequaninte Bamlaku Alamirew 《国际发展与全球生态学杂志》2013,20(6):477-483
Soil loss, nutrient depletion and land degradation contribute to the skimpy performance of smallholder agriculture and pose serious policy challenges in developing countries. Surprisingly, natural resource management practices that enhance sustainability while improving productivity have not been fully adopted despite continuous efforts of promotion. Using data collected from 2901 farm households in the Farmers Innovation Fund (FIF) of the World Bank, this study examines factors delaying adoption of resource management and farming practices from the perspective of social learning and network size. Specifically, the study aims at identifying the extent to which differences in network structure matter in providing opportunities to learn about new ways of sustainable resource management practices using regression analysis. The result confirms that social network size plays a significant role in enhancing adoption of natural resource management practices. Moreover, external sources of information such as extension provision play a crucial role in enhancing adoption of resource management practices. Thus, future endeavours should link extension services to informal networks to enhance adoption of sustainable natural resource management practices. 相似文献
923.
R. K. Sinha 《国际发展与全球生态学杂志》2013,20(4):278-284
SUMMARY In India, since ancient times, several members of the flora and fauna have been identified with particular personalities of the Hindu pantheon and are worshipped. Many wild animals, such as tigers, lions and elephants, and birds such as the peacock, owl and swan have been revered as the vehicles of Gods and Goddesses and worshipped. Several trees, such as mango, coconut, khejri, emblica, tamarind, ashoka, madhuca and wood apple, and herbs such as basil are considered highly sacred and worshipped. This belief and these practices continue in one form or another even today in certain sections of Indian society, particularly the rural folk and the aboriginal tribes living in the forest. Nature worship is a form of tribal belief and the faith of these laymen has helped to conserve many natural ecosystems in India. They have preserved many pristine forests—called ‘sacred groves’ in their original forms. Sacred groves are rich in biodiversity. They are the last refuge of the rare flora and fauna which have otherwise disappeared from the modern world. Sacred groves have become part of the ‘biosphere reserves’ of India. 相似文献
924.
循环型农业是一种新的农业经济发展模式,宝应县是全国唯一的国家有机食品基地示范县。文中介绍了循环型农业的内涵和特征,概述了宝应县有机农业循环经济的现状,通过对已实施的三种有机农业循环产业链模式的研究,结果表明,宝应县有机农业循环产业链模式能使农业废弃物资源化,并能有效地控制宝应县的农业面源污染,实现经济与环境持续发展。 相似文献
925.
Hieu M. Dang Ngan T. T. Nguyen Yoshihiko Inagaki Jarkko Akkanen Yutaka Sakakibara 《毒物与环境化学》2019,101(7-8):420-432
AbstractThe lakes of Hanoi are important water resources for urban agriculture. The concentrations of 17α-ethinylestradiol in the water of three major lakes were found to range from 0.1 to 9.1?ng/L, peaking during the rainy season. Effects at levels from 1?ng/L to 1?µg/L on the germination of mung bean (Vigna radiata) and bok choy (Brassica rapa) were studied. Soaking the seeds in solutions containing 17α-ethinylestradiol at 10?ng/L and higher increased the germination rate of mung bean but not of bok choy. For the latter, irrigation after sowing with solutions containing 17α-ethinylestradiol at 10?ng/L and higher accelerated germination. Abbreviations: MNRE: Ministry of Natural Resources and Environment; PE60: Population equivalent; USGS: U.S. Geological Survey; SPE: Solid phase extraction; EDTA: Disodium ethylenediaminetetraacetate; HPLC: High performance liquid chromatography; ELISA: Enzyme-linked immunosorbent assay; DOM: Dissolved organic matter; EEQ: Estradiol equivalent 相似文献
926.
Recent research indicates that sustainability assessment tools (SAT) for farms need to be contextually adapted to be acceptable and useful. Focusing specifically on social sustainability, this study sought to identify important aspects of relevance for Swedish (livestock) farmers’ social situation and compare these aspects with social indicators used in three existing SATs (RISE, SAFA, IDEA). A survey revealed that social issues of key importance for the self-reported overall life satisfaction of Swedish livestock farmers are: having a good financial situation, having a similar standard of living as others, not experiencing too much stress, having meaningful work, having decent working hours, and having a desirable family situation. Of the three SATs evaluated, RISE appears best equipped to capture the social situation of Swedish farmers but does not fully address the aspect of finding work meaningful. SAFA and IDEA both fail to capture many aspects of importance for describing the social situation of Swedish farmers. We present a novel method for testing the relevance of social indicators for farmers in a specific context. Applying this method before choosing, applying, and adapting SATs for farm-level sustainability assessments would increase the relevance of the social sustainability dimension, but deeper stakeholder engagement than offered by our survey is needed. 相似文献
927.
西北干旱区发展节水农业保障体系研究 总被引:1,自引:0,他引:1
水资源短缺已成为西北干旱区严重的制约因素之一.实施节水型农业模式,成为促进西北干旱区农业持续发展、生态环境保护乃至整个社会经济发展的必要选择.结合西北干旱区水资源开发利用的现状和节水农业发展中存在的主要问题,构建了西北干旱区节水型农业发展的保障体系:加强宣传培训,提高节水农业意识;制定科学规划,促进农业持续发展;构建完整体系,支持节水农业发展;健全法律制度,保障节水农业发展. 相似文献
928.
929.
Agriculture is the largest source of nutrients into surface waters in Finland, and yet relatively little is known about the
actual impact of the agricultural load on the state of lakes. We analysed the water quality data of 20 Finnish agricultural
lakes and found that they had higher levels of nutrients, chlorophyll a and turbidity than did the other types of lakes (e.g. those receiving point-source load) in the national monitoring network
(the Finnish Eurowaternet). Currently, six of the agricultural lakes can be classified as eutrophic and 14 as hypertrophic.
Trend analysis (based on Kendall's tau-b) indicated that during 1976–2002 the water quality of the lakes either remained constant or showed signs of increasing
eutrophication and elevated turbidity. Decreasing nutrient concentrations were found only in one intensively restored lake.
In none of the lakes had the chlorophyll a concentration decreased. The results of the trend analysis are compatible with the recent finding that, despite vigorous
efforts, the nutrient load from agriculture has not declined in Finland. Recovery of the most eutrophied agricultural lakes
would call for a drastic reduction in the external nutrient load, possibly supplemented with in-lake restoration. 相似文献
930.