全文获取类型
收费全文 | 427篇 |
免费 | 5篇 |
国内免费 | 3篇 |
专业分类
安全科学 | 10篇 |
废物处理 | 16篇 |
环保管理 | 47篇 |
综合类 | 79篇 |
基础理论 | 117篇 |
污染及防治 | 123篇 |
评价与监测 | 22篇 |
社会与环境 | 20篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 13篇 |
2015年 | 16篇 |
2014年 | 17篇 |
2013年 | 33篇 |
2012年 | 28篇 |
2011年 | 35篇 |
2010年 | 12篇 |
2009年 | 25篇 |
2008年 | 30篇 |
2007年 | 17篇 |
2006年 | 21篇 |
2005年 | 13篇 |
2004年 | 17篇 |
2003年 | 20篇 |
2002年 | 10篇 |
2001年 | 11篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有435条查询结果,搜索用时 15 毫秒
151.
152.
We investigated the seasonal patterns of denitrification rates and potentials in soil profiles along the topohydrosequence formed at the upland-wetland interface in three riparian wetlands with different vegetation cover (i.e., forest, understory vegetation, and grass). Denitrification was measured using the acetylene inhibition method on soil cores and slurries, which provided a means of comparing the relative activity of this process in different locations. We evaluated, on a seasonal basis, the respective importance of the vegetative cover and the hydromorphic gradient as factors limiting denitrification. Regardless of the season, vegetation type, or lateral position along each topohydrosequence in the riparian wetlands, strong significant gradients of both in situ and potential denitrification rates were measured within a soil profile. Results confirm that the upper organic soil horizon is the most active, when in contact with the ground water. In deeper soil horizons, denitrification activity was low (from 0.004 to 0.5 mg N kg(-1) dry soil d(-1)), but contributed significantly to the reduction of ground water NO3- load along the riparian ground water flowpath (from 9.32 to 0.98 mg NO3-N L(-1)). Along the soil topohydrosequence, the denitrifying community of the upper soil horizons did not vary significantly on a seasonal basis despite the large seasonal ground water fluctuations. Along each topohydrosequence, the denitrification-limiting factor gradually shifted from anaerobiosis to NO3- supply. In situ denitrification rates in the forested, understory vegetation and grass sites were not significantly different. This result emphasizes the importance of the topography of the valley rather than the vegetation cover in controlling denitrification activity in riparian wetlands. 相似文献
153.
Estimating parameters of neutral communities: from one single large to several small samples 总被引:3,自引:0,他引:3
The neutral theory of S. P. Hubbell postulates a two-scale hierarchical framework consisting of a metacommunity following the speciation-drift equilibrium characterized by the "biodiversity number" theta, and local communities following the migration-drift equilibrium characterized by the "migration rate" m (or the "fundamental dispersal number" I). While Etienne's sampling formula allows simultaneous estimation of theta and m from a single sample of a local community, its applicability to a network of (rather small) samples is questionable. We define here an alternative two-stage approach estimating theta from an adequate subset of the individuals sampled in the field (using Ewens' sampling formula) and m from community samples (using Etienne's sampling formula). We compare its results with the simultaneous estimation of theta and m (one-stage estimation), for simulated neutral samples and for 50 1-ha plots of evergreen forest in South India. The one-stage approach exhibits problems of bias and of poor differentiability between high-theta, low-m and low-theta, high-m solution domains. Conversely, the two-stage approach yielded reasonable estimates and is to be preferred when several small, scattered plots are available instead of a single large one. 相似文献
154.
155.
Towards a framework for assessment and management of cumulative human impacts on marine food webs 下载免费PDF全文
Sylvaine Giakoumi Benjamin S. Halpern Loïc N. Michel Sylvie Gobert Maria Sini Charles‐François Boudouresque Maria‐Cristina Gambi Stelios Katsanevakis Pierre Lejeune Monica Montefalcone Gerard Pergent Christine Pergent‐Martini Pablo Sanchez‐Jerez Branko Velimirov Salvatrice Vizzini Arnaud Abadie Marta Coll Paolo Guidetti Fiorenza Micheli Hugh P. Possingham 《Conservation biology》2015,29(4):1228-1234
Effective ecosystem‐based management requires understanding ecosystem responses to multiple human threats, rather than focusing on single threats. To understand ecosystem responses to anthropogenic threats holistically, it is necessary to know how threats affect different components within ecosystems and ultimately alter ecosystem functioning. We used a case study of a Mediterranean seagrass (Posidonia oceanica) food web and expert knowledge elicitation in an application of the initial steps of a framework for assessment of cumulative human impacts on food webs. We produced a conceptual seagrass food web model, determined the main trophic relationships, identified the main threats to the food web components, and assessed the components’ vulnerability to those threats. Some threats had high (e.g., coastal infrastructure) or low impacts (e.g., agricultural runoff) on all food web components, whereas others (e.g., introduced carnivores) had very different impacts on each component. Partitioning the ecosystem into its components enabled us to identify threats previously overlooked and to reevaluate the importance of threats commonly perceived as major. By incorporating this understanding of system vulnerability with data on changes in the state of each threat (e.g., decreasing domestic pollution and increasing fishing) into a food web model, managers may be better able to estimate and predict cumulative human impacts on ecosystems and to prioritize conservation actions. 相似文献
156.
Pierre Canetto 《International journal of occupational safety and ergonomics》2013,19(2):141-153
Occupational noise specialists do not generally recommend hearing protection devices (HPDs) as a preferred solution to noise risk prevention. Nevertheless, these devices are widely used and are in fact often necessary. Selection of an HPD should take into account comfort and the capacity for perceiving external signals, when they are worn. Current European regulations require that HPD attenuation be considered, when comparing noise exposure to limit values. However, HPD attenuation is effectively unknown under real-world conditions. Some methods are designed to give approximate attenuation values and these provide results within a wide statistical range. Field measurement methods and current standards have been developed to deal with this situation. The specific characteristic of impulse noise requires establishment of dedicated criteria and tools for HPD selection and testing. This paper introduces a number of avenues for research, which could be of assistance in improving HPD selection, qualification and design. 相似文献
157.
158.
159.
Sauphanor B Franck P Lasnier T Toubon JF Beslay D Boivin T Bouvier JC Renou M 《Die Naturwissenschaften》2007,94(6):449-458
The behavioral and electroantennographic responses of Cydia pomonella (L.) to the ripe pear volatile ethyl (2E,4Z)-2,4-decadienoate (Et-E,Z-DD), were compared in insecticide-susceptible and -resistant populations originating from southern France. A dose–response
relationship to this kairomonal attractant was established for antennal activity and did not reveal differences between susceptible
and resistant strains. Conversely, males of the laboratory strains expressing metabolic [cytochrome P450-dependent mixed-function
oxidases (mfo)] or physiological (kdr-type mutation of the sodium-channel gene) resistance mechanisms exhibited a significantly
higher response to Et-E,Z-DD than those of the susceptible strain in a wind tunnel experiment. No response of the females to this kairomone could be
obtained in our wind-tunnel conditions. In apple orchards, mfo-resistant male moths were captured at significantly higher
rates in kairomone-baited traps than in traps baited with the sex pheromone of C. pomonella. Such a differential phenomenon was not verified for the kdr-resistant insects, which exhibited a similar response to both
the sex pheromone and the kairomonal attractant in apple orchards. Considering the widespread distribution of metabolic resistance
in European populations of C. pomonella and the enhanced behavioral response to Et-E,Z-DD in resistant moths, the development of control measures based on this kairomonal compound would be of great interest for
the management of insecticide resistance in this species. 相似文献
160.
Johansson Clotilde Bataillard Philippe Biache Coralie Lorgeoux Catherine Colombano Stéfan Joubert Antoine Défarge Christian Faure Pierre 《Environmental science and pollution research international》2022,29(11):15966-15982
Environmental Science and Pollution Research - Permanganate is an oxidant usually applied for in situ soil remediation due to its persistence underground. It has already shown great efficiency for... 相似文献