全文获取类型
收费全文 | 425篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 10篇 |
废物处理 | 15篇 |
环保管理 | 43篇 |
综合类 | 71篇 |
基础理论 | 77篇 |
污染及防治 | 153篇 |
评价与监测 | 29篇 |
社会与环境 | 31篇 |
灾害及防治 | 2篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 2篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 18篇 |
2015年 | 15篇 |
2014年 | 10篇 |
2013年 | 26篇 |
2012年 | 23篇 |
2011年 | 19篇 |
2010年 | 14篇 |
2009年 | 23篇 |
2008年 | 26篇 |
2007年 | 35篇 |
2006年 | 28篇 |
2005年 | 30篇 |
2004年 | 37篇 |
2003年 | 25篇 |
2002年 | 16篇 |
2001年 | 10篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1975年 | 2篇 |
1961年 | 1篇 |
1959年 | 1篇 |
1949年 | 1篇 |
1944年 | 1篇 |
1942年 | 1篇 |
1940年 | 2篇 |
1939年 | 1篇 |
1936年 | 1篇 |
1933年 | 2篇 |
1925年 | 1篇 |
排序方式: 共有431条查询结果,搜索用时 546 毫秒
61.
Wittgren HB Castensson R Gipperth L Joelsson A Jonasson L Pettersson A Thunvik R Torstensson G 《Ambio》2005,34(3):237-247
Despite political efforts, diffuse pollution from agriculture continues to be the single largest source of nitrogen (N) emissions into the aquatic environment in many countries and regions. This fact, and the recent enactment of a new Swedish environmental code, led to the design of a study targeted at the evaluation of new N pollution abatement strategies. An actor game was chosen as the key component of the study, with a focus on four major goals: to test the implementability of legally binding environmental quality standards for nitrate concentration in groundwater and N transport to the sea, to find sets of agriculturally feasible and cost-effective measures to decrease N loads, to investigate the possibilities for collective action through negotiated and institutionalized actor cooperation, and to investigate the role of mathematical modeling in environmental N management. Characteristics from the agriculturally dominated catchment of Genevads?n (224 km2) on the southwest coast of Sweden served as the playing field for the actor game. The most noteworthy result from the study was that it appeared to be possible to meet ambitious environmental N standards with less economically drastic measures than anticipated by most of the participants. The actor game was shown to be a good method for learning about the new Swedish environmental code and its application and for gaining deeper insight into the issues of N management. In addition, the actor game functioned as an arena for gaining a more thorough understanding of the views of different stakeholders. 相似文献
62.
Possibilities for improving nitrogen use from organic materials in agricultural cropping systems 总被引:1,自引:0,他引:1
Nitrogen release from organic nutrient sources in soil is influenced by a range of factors such as soil temperature and moisture, and chemical composition of the organic material. Chemical composition can, to a certain degree, be controlled to increase the synchronization of nitrogen (N) release with plant N demand, whereas climatic factors cannot be controlled and so must be taken into account when planning management measures. In this paper, we discuss different ways to affect N release through manipulation of the chemical composition of fresh or pretreated plant materials and animal manures, timing of incorporation, and intentional distribution during application. We conclude by giving an overview of off-farm options that may need to be implemented to achieve improved use of N, especially in agricultural systems with surplus N. 相似文献
63.
After the break-up of the Soviet system, the divergence in forest management among Soviet republics became obvious. While the forest sectors of the Baltic States have been fundamentally changed, Russia has not been able to develop an institutional framework that would fit the prerequisites for social-ecological resilience. It is argued that sustainable development requires institutional frameworks that have the capacity to adapt and learn, and thus to treat policies as experiments that are constantly assessed and readjusted. This, however, requires a participatory approach and in this respect the Baltic States are believed to be on a more promising track. Finally, it is concluded that only to the extent that suitable institutional frameworks will be developed will social-ecological resilience be a significant feature of the natural resources management in the former communist countries. 相似文献
64.
Regional differences in the occurrence of understorey species reflect nitrogen deposition in Swedish forests 总被引:3,自引:0,他引:3
Possible links between the occurrence of Vaccinium myrtillus, V. vitis-idaea and Deschampsia flexuosa and rates of nitrogen deposition were investigated in 557 coniferous forest stands. In areas with high N-deposition, V. myrtillus was less frequent, less abundant and more susceptible to the leaf pathogen Valdensia heterodoxa than in areas with lower levels of N-deposition. The occurrence of V. vitis-idaea was also strongly negatively correlated with increasing N-deposition, but no such trend was found for D. flexuosa. In regions with high N-deposition, V. myrtillus was more common in stands dominated by Scots pine than in stands dominated by Norway spruce. This was not the case in regions with lower levels of N-deposition. The patterns observed accord with results from N-addition experiments that demonstrate significant effects on vegetation, caused by N-deposition. The data suggest that even low rates of N-deposition may decrease the abundance of the most dominant species in coniferous forest ground flora. 相似文献
65.
Callaghan TV Björn LO Chernov Y Chapin T Christensen TR Huntley B Ims RA Johansson M Jolly D Jonasson S Matveyeva N Panikov N Oechel W Shaver G Schaphoff S Sitch S Zöckler C 《Ambio》2004,33(7):469-473
An assessment of impacts on Arctic terrestrial ecosystems has emphasized geographical variability in responses of species and ecosystems to environmental change. This variability is usually associated with north-south gradients in climate, biodiversity, vegetation zones, and ecosystem structure and function. It is clear, however, that significant east-west variability in environment, ecosystem structure and function, environmental history, and recent climate variability is also important. Some areas have cooled while others have become warmer. Also, east-west differences between geographical barriers of oceans, archipelagos and mountains have contributed significantly in the past to the ability of species and vegetation zones to relocate in response to climate changes, and they have created the isolation necessary for genetic differentiation of populations and biodiversity hot-spots to occur. These barriers will also affect the ability of species to relocate during projected future warming. To include this east-west variability and also to strike a balance between overgeneralization and overspecialization, the ACIA identified four major sub regions based on large-scale differences in weather and climate-shaping factors. Drawing on information, mostly model output that can be related to the four ACIA subregions, it is evident that geographical barriers to species re-location, particularly the distribution of landmasses and separation by seas, will affect the northwards shift in vegetation zones. The geographical constraints--or facilitation--of northward movement of vegetation zones will affect the future storage and release of carbon, and the exchange of energy and water between biosphere and atmosphere. In addition, differences in the ability of vegetation zones to re-locate will affect the biodiversity associated with each zone while the number of species threatened by climate change varies greatly between subregions with a significant hot-spot in Beringia. Overall, the subregional synthesis demonstrates the difficulty of generalizing projections of responses of ecosystem structure and function, species loss, and biospheric feedbacks to the climate system for the whole Arctic region and implies a need for a far greater understanding of the spatial variability in the responses of terrestrial arctic ecosystems to climate change. 相似文献
66.
Two methods for the determination of total organic halogen (TOX), orginating from bleaching of pulp, in receiving waters have been compared. One of the methods (AC/MC) is based on adsorption of the halogenated matter onto an activated carbon sorbent. The halogen is determined by a microcoulometric technique after combustion of the carbon. The other method (XAD/PT) uses an XAD resin as sorbent and the determination of the halogen is carried out by potentiometric titration after a schöniger combustion of the resin eluate.Both methods showed good performance for samples consisting of spent bleach liquors diluted with distilled, fresh and brackish water. The repeatability was very good with a relative standard deviation less than a few per cent. The detection limit of the AC/MC method is about 0.1 μmol/1 and for the XAD/PT method about ten times higher. The AC/MC method gave in most cases 10–20% higher TOX concentrations compared to the XAD/PT method. 相似文献
67.
Lars Gunnar Sillén 《Die Naturwissenschaften》1942,30(22):318-324
68.
Monica A. Sundset Perry S. Barboza Thomas K. Green Lars P. Folkow Arnoldus Schytte Blix Svein D. Mathiesen 《Die Naturwissenschaften》2010,97(3):273-278
Reindeer (Rangifer tarandus) eat and utilize lichens as an important source of energy and nutrients in winter. Lichens synthesize and accumulate a wide
variety of phenolic secondary compounds, such as usnic acid, as a defense against herbivores and to protect against damage
by UV-light in solar radiation. We have examined where and to what extent these phenolic compounds are degraded in the digestive
tract of the reindeer, with particular focus on usnic acid. Three male reindeer were given ad libitum access to a control
diet containing no usnic acid for three weeks and then fed lichens ad libitum (primarily Cladonia stellaris) containing 9.1 mg/g DM usnic acid for 4 weeks. Usnic acid intake in reindeer on the lichen diet was 91–117 mg/kg BM/day.
In spite of this, no trace of usnic acid or conjugates of usnic acid was found either in fresh rumen fluid, urine, or feces.
This suggests that usnic acid is rapidly degraded by rumen microbes, and that it consequently is not absorbed by the animal.
This apparent ability to detoxify lichen phenolic compounds may gain increased importance with future enhanced UV-B radiation
expected to cause increased protective usnic acid/phenol production in lichens. 相似文献
69.
Kines P Andersen LP Spangenberg S Mikkelsen KL Dyreborg J Zohar D 《Journal of Safety Research》2010,41(5):399-406
Background
The construction industry is one of the most injury-prone industries, in which production is usually prioritized over safety in daily on-site communication. Workers have an informal and oral culture of risk, in which safety is rarely openly expressed. This paper tests the effect of increasing leader-based on-site verbal safety communication on the level of safety and safety climate at construction sites. Method: A pre-post intervention-control design with five construction work gangs is carried out. Foremen in two intervention groups are coached and given bi-weekly feedback about their daily verbal safety communications with their workers. Foremen-worker verbal safety exchanges (experience sampling method, n = 1,693 interviews), construction site safety level (correct vs. incorrect, n = 22,077 single observations), and safety climate (seven dimensions, n = 105 questionnaires) are measured over a period of up to 42 weeks. Results: Baseline measurements in the two intervention and three control groups reveal that foremen speak with their workers several times a day. Workers perceive safety as part of their verbal communication with their foremen in only 6-16% of exchanges, and the levels of safety at the sites range from 70-87% (correct observations). Measurements from baseline to follow-up in the two intervention groups reveal that safety communication between foremen and workers increases significantly in one of the groups (factor 7.1 increase), and a significant yet smaller increase is found when the two intervention groups are combined (factor 4.6). Significant increases in the level of safety are seen in both intervention groups (7% and 12% increases, respectively), particularly in regards to 'access ways' and 'railings and coverings' (39% and 84% increases, respectively). Increases in safety climate are seen in only one of the intervention groups with respect to their 'attention to safety.' No significant trend changes are seen in the three control groups on any of the three measures. Conclusions: Coaching construction site foremen to include safety in their daily verbal exchanges with workers has a significantly positive and lasting effect on the level of safety, which is a proximal estimate for work-related accidents. It is recommended that future studies include coaching and feedback at all organizational levels and for all involved parties in the construction process. Building client regulations could assign the task of coaching to the client appointed safety coordinators or a manager/supervisor, and studies should measure longitudinal effects of coaching by following foremen and their work gangs from site to site. 相似文献70.
The invasive red alga Gracilaria vermiculophylla has quickly spread across Europe, but it is unclear whether its success is based on a high tolerance to variations in environmental conditions or to the absence of native grazers that feed on this alga. We tested whether native invertebrate grazers prefer native algae to G. vermiculophylla. Feeding preferences of three common herbivores were quantified when offered G. vermiculophylla and native Fucus vesiculosus, Ceramium virgatum, and Ulva intestinalis in no-, two- and multiple-choice trials. Herbivore growth was measured when fed each of the algae separately. Grazers consumed G. vermiculophylla in no-choice trials, but avoided generally this alga when having a choice. U. intestinalis was always preferred over G. vermiculophylla, and grazers fed with U. intestinalis grew faster than those fed with G. vermiculophylla. We conclude that grazers avoid G. vermiculophylla to most native algae, which may benefit G. vermiculophylla in northern European estuaries. 相似文献