首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   246篇
  免费   0篇
  国内免费   10篇
安全科学   3篇
废物处理   12篇
环保管理   33篇
综合类   44篇
基础理论   57篇
污染及防治   56篇
评价与监测   35篇
社会与环境   16篇
  2023年   2篇
  2022年   21篇
  2021年   10篇
  2020年   6篇
  2019年   7篇
  2018年   4篇
  2017年   14篇
  2016年   5篇
  2015年   6篇
  2014年   12篇
  2013年   23篇
  2012年   8篇
  2011年   14篇
  2010年   12篇
  2009年   14篇
  2008年   10篇
  2007年   9篇
  2006年   11篇
  2005年   9篇
  2004年   7篇
  2003年   3篇
  2002年   4篇
  2001年   1篇
  1997年   1篇
  1996年   1篇
  1995年   2篇
  1994年   3篇
  1992年   1篇
  1991年   1篇
  1989年   1篇
  1988年   2篇
  1980年   2篇
  1979年   4篇
  1978年   1篇
  1976年   5篇
  1975年   1篇
  1974年   4篇
  1973年   3篇
  1972年   2篇
  1971年   2篇
  1967年   1篇
  1965年   1篇
  1964年   1篇
  1962年   1篇
  1961年   1篇
  1959年   1篇
  1955年   1篇
  1953年   1篇
排序方式: 共有256条查询结果,搜索用时 15 毫秒
121.
Economic costs imposed by climatic extremes have been increasing over the years and are expected to follow a similar trend in the coming years as well. Such costs are incurred due to two factors: (1) natural climate variability and anthropogenic climate change and (2) exposure and vulnerability of socio-economic factors. The impact of these factors as identified separately through a ‘normalisation technique’ is analysed in the existing normalisation studies conducted mostly in developed country contexts; these have produced mixed results. However, one needs to enquire about the influence of the above two factors in a developing country context where the anticipated impacts of climate extremes are significant. This study, therefore, makes an attempt to adjust impact data, in terms of the reported population affected and economic damages of three extreme events, namely cyclones, floods and droughts, together for societal changes between 1972 and 2009 in Odisha in eastern India. Further, the second component is analysed in two ways: (1) assuming that exposed socio-economic factors are equally vulnerable similar to the other normalisation studies, i.e. no adaptation and (2) incorporating adaptation in the existing normalisation methods—which has attracted less attention so far in the literature. The results suggest that: (a) both the natural climate variability and the socio-economic factors influence the increasing damages in the recent decades, and (b) when adaptation is introduced in the normalisation model, economic losses have reduced significantly compared to the estimates using the existing normalisation models.  相似文献   
122.
Seven species of genus Avena viz., Avena sativa, Avena strigosa, Avena brevis, Avena vaviloviana, Avena abyssinica, Avena marocana and Avena sterilis were used to study the impact of drought stress on lipid peroxidation and other antioxidant enzymes. Maximum increase in the catalase activity was recorded in A. vaviloviana (129.97%) followed by A. sativa (122.82%) and A. brevis (83.38%) at vegetative stage; however at flowering stage the maximum increase was reported in A. sativa (25.62%) followed by A. sterilis (20.46%) and A. brevis (18.53%). At vegetative stage drought, maximum increase in peroxidase activity was recorded in A. sativa (122.82%) followed by A. brevis (83.38%) and A. sterilis (49.78%). Flowering stage drought, showed maximum increase in A. Sativa (27.09%) followed by A. marocana (23.50%) and A. sterilis (20.46%). A. sativa and A. sterilis showed stress tolerance at both the stages by accumulating higher percentage of peroxidase followed by A. brevis at vegetative and A. marocana at flowering stage. Level of lipid peroxidation in terms of Malondialdehyde (MDA) content was increased in the leaves when plants were subjected to moisture stress. The rate of increase in lipid peroxidation occurs irrespective of stage however; maximum increase was recorded in A. strigosa at both the stages. Avena species which showed high level of MDA content, indicates more lipid peroxidation and more membrane permeability and are comparatively more susceptible for water stress than those which produce less Malondialdehyde (MDA) content at higher magnitude of water stress such species have better capability for moisture stress tolerance.  相似文献   
123.
Legal notification of protected area status follows enforcement which, by and large, curtails resource use and means of livelihood, apart from affecting the sociocultural value system of the local communities, leading to park-reserve-people conflicts. These conflicts are major threats to biodiversity conservation in developing countries and call for changes in conventional strategies for conservation planning and management. The attempts to involve local communities in protected area management usually fail when initiated and directed by outsiders. This paper deals with the present concept of protected area management and focuses on some of the fundamental issues related to indigenous peoples. It offers principles and options which may be followed towards resolving the conflicts arising out of such issues.  相似文献   
124.
The various indigenous uses and structure of chir pine forests were studied in Uttaranchal state of the Indian Republic. A questionnaire survey was conducted in 50 villages of Uttaranchal to gather information on the indigenous uses of chir pine. For the study of community composition and structure of chir pine forest, at least 15 quadrats of 10 x 10 m were selected randomly across various localities, and the number of individuals, along with other dominant tree and shrub species, were enumerated in each quadrat. About 10 indigenous uses of chir pine were prominent in Uttaranchal. Besides resin, an important non-wood product, different parts of chir pine, such as cones, trunk, stems, wood, leaves and bark, were used by the local people. Chir pine is a subject of the folklore and mythology of indigenous cultures in Uttaranchal. Chir pine forest formed three major communities in Uttaranchal viz., sal-pine (Shorea robusta-Pinus roxburghii), pine pure stands and oak-pine (Quercus leucho-trichophora-Pinus roxburghii). These communities sustained various multiple-use trees and shrubs along with various edible mushrooms (eg. Agaricus campestris, Morchella esculenta and Sparassis crispa). The results of this study are discussed in the light of chir pine conservation and management policies.  相似文献   
125.
The aim of this study was to investigate the nephroprotective and antioxidant property of Manasamitra vatakam (MMV) against aluminum (Al)-induced toxicity in rats. The kidney function marker parameters such as serum urea, uric acid, and creatinine were significantly increased in Al-treated rats as compared with controls. Similarly, the antioxidant enzyme activities such as superoxide dismutase, glutathione S-transferase, Na+/K+-ATPase and Mg-ATPase, reduced glutathione were also found significantly increased in Al-treated rats. A significantly decreased level of these parameters was observed in the MMV (orally 100?mg?kg?1 body weight)-treated group along with a reduced level of malonaldehyde, molecular chaperones of an antioxidative stress protein, and mRNA expression of HSP70. The biochemical observations were also supported by histopathological observations. Thus, this study supports the nephroprotective and antioxidant activities of MMV.  相似文献   
126.
Traditional modes of living or sustenance invariably relate to immediate and surrounding resources. Traditional people use many plant resources and have developed subtle and innovative uses for them in order to obtain maximum benefit. Traditional crop varieties and races that evolved over time through trial and error, not only provide basic nutritional requirements, but also food security. While the effects of the green revolution are conspicuous in the lower Himalayas, they are less visible in the study region, the Darma and Johaar valleys in the Kumaun Himalayas. Loss of crop biodiversity has taken place over the years, principally and inadvertently related to changing lifestyle and closure of traditional trade with Tibet after the 1962 Sino-Indian war. Added to this, is a growing demand for medicinal and aromatic plants (MAPs), principally Jambu (Allium stracheyii) and caraway (Carum carvi), whose acreage has increased with the concomitant decline in area under the traditional crops. In addition, the recent discovery of Yar tsa Gumba (Cordyceps sinensis) in the alpine zones of their summer homes has reduced people's interest in sowing, rearing and caring for traditional crops, viz. beans, potatoes, amaranth, whose growing season coincides with the harvesting season of Yar tsa Gumba. The present study attempts to show the causal factors behind the loss in crop biodiversity, as well as the changing lifestyle of these traditional people, vis a vis the changes in polyculture.  相似文献   
127.
The Gulf of Kachchh is characterised by a strong tidal variation and the reef communities are capable of higher exposure time during negative tides. About 11 sites located along the Marine National Park (MNP) from west to east were studied for assessing the present status of live coral cover along with other life-form categories. In the present study, the maximum live coral cover was recorded in Pirotan Island, followed by Laku Point, Mithapur and Boriya reef. Multivariate analyses such as Principal Component Analysis and Correspondence Analysis supported that the contribution of live coral cover was more towards Pirotan Island whereas the contribution of coral species cover was more towards Laku Point. Bray-Curtis cluster analysis categorized all the study sites into four major clusters with 78 % similarity based on life-form categories. Among them, two clusters from western region (one forming site from Mithapur Reef to Lakku Point and another one forming from Ashaba Gugar Reef to Dabdaba Island), the third one combines the western and eastern regions (Boriya Reef to Kalubar Island), the fourth one comprises the eastern region (Narara Reef to Sikka), and one outlier Pirotan Island. Based on coral species cover, two major clusters with 55 % similarity were formed. Among them, one cluster was formed from Pirotan Island to Kalubar Island in the eastern side of MNP and the second one comprised the western region of MNP (Boriya Reef to Laku Point), and one outlier Mithapur Reef. Thirty one species of live corals belonging to 8 families and 18 genera were recorded in the Marine National Park itself during the study period.  相似文献   
128.
129.
130.
Environmental Chemistry Letters - Modern biomass and organic waste are becoming major, carbon-neutral sources of fine chemicals, biomolecules and fuels to replace fossil fuel products. As a...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号