全文获取类型
收费全文 | 298篇 |
免费 | 12篇 |
国内免费 | 6篇 |
专业分类
安全科学 | 14篇 |
废物处理 | 5篇 |
环保管理 | 52篇 |
综合类 | 38篇 |
基础理论 | 70篇 |
污染及防治 | 114篇 |
评价与监测 | 14篇 |
社会与环境 | 8篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 8篇 |
2018年 | 13篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 1篇 |
2013年 | 40篇 |
2012年 | 10篇 |
2011年 | 17篇 |
2010年 | 10篇 |
2009年 | 17篇 |
2008年 | 8篇 |
2007年 | 14篇 |
2006年 | 15篇 |
2005年 | 13篇 |
2004年 | 7篇 |
2003年 | 13篇 |
2002年 | 19篇 |
2001年 | 18篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1974年 | 2篇 |
1967年 | 1篇 |
1964年 | 1篇 |
1954年 | 1篇 |
1919年 | 4篇 |
1918年 | 1篇 |
1913年 | 3篇 |
排序方式: 共有316条查询结果,搜索用时 296 毫秒
71.
Summary Glycosidase inhibitors are widespread in plants and can be sequestered by Lepidoptera, for which they can presumably serve as defences by making the insects indigestible to a range of potential predators. As a result of this study of eight British species of moth and butterfly it was found that glycosidase inhibitors in the insects could then be detected in the larval food plants which were not previously known to contain them; however, some were only detectable in the plants after concentration. In some cases the inhibition of specific glycosidases by Lepidoptera was detected even though the insects had not apparently acquired them from their food plants. Inhibition of-N-acetylglucosaminidase was observed in most of the adult Lepidoptera analysed but further work is required to identify the inhibitors, though they are likely to be nitrogen-containing compounds. Weak anti-HIV activity was also observed in the glycosidase-inhibiting fractions ofAcherontia atropos and the plantUrtica dioica. 相似文献
72.
Chow JC Watson JG Lowenthal DH Magliano KL 《Journal of the Air & Waste Management Association (1995)》2005,55(8):1158-1168
Evaporative loss of particulate matter (with aerodynamic diameter < 2.5 microm, [PM2.5]) ammonium nitrate from quartz-fiber filters during aerosol sampling was evaluated from December 3, 1999, through February 3, 2001, at two urban (Fresno and Bakersfield) and three nonurban (Bethel Island, Sierra Nevada Foothills, and Angiola) sites in central California. Compared with total particulate nitrate, evaporative nitrate losses ranged from < 10% during cold months to > 80% during warm months. In agreement with theory, evaporative loss from quartz-fiber filters in nitric acid denuded samplers is controlled by the ambient nitric acid-to-particulate nitrate ratio, which is determined mainly by ambient temperature. Accurate estimation of nitrate volatilization requires a detailed thermodynamic model and comprehensive chemical measurements. For the 14-month average of PM2.5 acquired on Teflon-membrane filters, measured PM2.5 mass was 8-16% lower than actual PM2.5 mass owing to nitrate volatilization. For 24-hr samples, measured PM2.5 was as much as 32-44% lower than actual PM2.5 at three California Central Valley locations. 相似文献
73.
Measurements of outdoor human exposure to suspended particulate matter (PM) are always constrained by available resources. An effective network design requires tradeoffs between variables measured, the number of sampling locations, sample duration, and sampling frequency. Sampling sites are needed to represent neighborhood and urban spatial scales with minimal influences from nearby sources. Although most PM measurements for determining compliance with standards are taken over 24-h periods every third to sixth day, outdoor human exposure assessment requires measurements taken continuously throughout the day, preferably over durations of 1 h or less. More detailed particle size and chemistry data are also desirable, as smaller size fractions and specific chemicals may be better indicators of adverse health effects than total mass samples. 相似文献
74.
75.
Dianne L. Watson Euan S. Harvey Gary A. Kendrick Kim Nardi Marti J. Anderson 《Marine Biology》2007,152(5):1197-1206
Closure of areas to fishing is expected to result in an increase in the abundance of targeted species; however, changes to
populations of species not targeted by fishermen will depend upon their role in the ecosystem and their relationship with
targeted species. The effects of protection on targeted and non-targeted reef fish species at the Houtman Abrolhos Islands,
Western Australia were studied using baited remote underwater stereo–video cameras. Video images were collected from shallow
(8–12 m) and deep (22–26 m) reef sites inside a Marine Protected Area (MPA) at each of three island groups and from three
replicate fished locations at each of these groups that span a temperate-tropical transition area. The MPAs were established
in 1994 and vary in size from 13.72 km2 at the Pelsaert group in the south to 22.29 km2 at the Easter group to 27.44 km2 at the Wallabi group in the north. The relative abundances of 137 fish species from 42 families were recorded. Large differences
in fish assemblage structure existed between MPA and fished locations, and also between shallow and deep regions. Targeted
fish species Plectropomus leopardus, Lethrinus miniatus, Lethrinus nebulosus, Pagrus auratus and Glaucosoma hebraicum were more abundant inside MPAs than in areas open to fishing. Their abundance inside MPAs was between 1.13 and 8 times greater
than their abundance at fished locations. For non-targeted fish species many were more abundant in areas open to fishing,
e.g. Coris auricularis, Thalassoma lutescens, Thalassoma lunare, Dascyllus trimaculatus, however others were conversely more abundant inside MPAs, e.g. Gymnothorax spp, Kyphosus sydneyanus, Scarus microhinos, Chromis westaustralis, Chaetodon spp. This study demonstrates that the removal of abundant targeted species from an ecosystem by fishing can indirectly impact
non-fished species and alter the trophic structure of fish assemblages.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
76.
77.
78.
79.
80.
S. T. Garnett S. H. M. Butchart G. B. Baker E. Bayraktarov K. L. Buchanan A. A. Burbidge A. L. M. Chauvenet L. Christidis G. Ehmke M. Grace D. G. Hoccom S. M. Legge I. Leiper D. B. Lindenmayer R. H. Loyn M. Maron P. McDonald P. Menkhorst H. P. Possingham J. Radford A. E. Reside D. M. Watson J. E. M. Watson B. Wintle J. C. Z. Woinarski H. M. Geyle 《Conservation biology》2019,33(2):456-468
Although evidence-based approaches have become commonplace for determining the success of conservation measures for the management of threatened taxa, there are no standard metrics for assessing progress in research or management. We developed 5 metrics to meet this need for threatened taxa and to quantify the need for further action and effective alleviation of threats. These metrics (research need, research achievement, management need, management achievement, and percent threat reduction) can be aggregated to examine trends for an individual taxon or for threats across multiple taxa. We tested the utility of these metrics by applying them to Australian threatened birds, which appears to be the first time that progress in research and management of threats has been assessed for all threatened taxa in a faunal group at a continental scale. Some research has been conducted on nearly three-quarters of known threats to taxa, and there is a clear understanding of how to alleviate nearly half of the threats with the highest impact. Some management has been attempted on nearly half the threats. Management outcomes ranged from successful trials to complete mitigation of the threat, including for one-third of high-impact threats. Progress in both research and management tended to be greater for taxa that were monitored or occurred on oceanic islands. Predation by cats had the highest potential threat score. However, there has been some success reducing the impact of cat predation, so climate change (particularly drought), now poses the greatest threat to Australian threatened birds. Our results demonstrate the potential for the proposed metrics to encapsulate the major trends in research and management of both threats and threatened taxa and provide a basis for international comparisons of evidence-based conservation science. 相似文献