全文获取类型
收费全文 | 8084篇 |
免费 | 91篇 |
国内免费 | 244篇 |
专业分类
安全科学 | 159篇 |
废物处理 | 394篇 |
环保管理 | 922篇 |
综合类 | 1359篇 |
基础理论 | 1981篇 |
污染及防治 | 1998篇 |
评价与监测 | 608篇 |
社会与环境 | 950篇 |
灾害及防治 | 48篇 |
出版年
2023年 | 62篇 |
2022年 | 130篇 |
2021年 | 104篇 |
2020年 | 67篇 |
2019年 | 99篇 |
2018年 | 145篇 |
2017年 | 154篇 |
2016年 | 213篇 |
2015年 | 159篇 |
2014年 | 259篇 |
2013年 | 697篇 |
2012年 | 280篇 |
2011年 | 377篇 |
2010年 | 310篇 |
2009年 | 344篇 |
2008年 | 396篇 |
2007年 | 403篇 |
2006年 | 308篇 |
2005年 | 291篇 |
2004年 | 288篇 |
2003年 | 280篇 |
2002年 | 267篇 |
2001年 | 339篇 |
2000年 | 216篇 |
1999年 | 115篇 |
1998年 | 86篇 |
1997年 | 84篇 |
1996年 | 107篇 |
1995年 | 126篇 |
1994年 | 96篇 |
1993年 | 85篇 |
1992年 | 90篇 |
1991年 | 92篇 |
1990年 | 79篇 |
1989年 | 71篇 |
1988年 | 69篇 |
1987年 | 75篇 |
1986年 | 52篇 |
1985年 | 63篇 |
1984年 | 63篇 |
1983年 | 59篇 |
1982年 | 58篇 |
1981年 | 64篇 |
1980年 | 47篇 |
1979年 | 46篇 |
1977年 | 38篇 |
1976年 | 36篇 |
1974年 | 34篇 |
1973年 | 43篇 |
1972年 | 51篇 |
排序方式: 共有8419条查询结果,搜索用时 9 毫秒
991.
Urban farming – a type of urban agriculture focused on entrepreneurial food production – serves multiple functions in neighbourhoods; yet these are not well delineated. Expectations for urban farming often centre on traditional measures of economic development, potentially overlooking other benefits. Through a qualitative case study conducted in Baltimore, Maryland, we sought to understand community perceptions regarding the ways in which urban farms can benefit cities. Interviews with residents, neighbourhood leaders, and urban farmers in three residential neighbourhoods with urban farms revealed the pathways by which community members view farms as improving neighbourhoods. Benefits stemmed from four primary changes urban farms made to study neighbourhoods: creation of public projects welcoming involvement, physical improvement of degraded space, production of local food, and creation of new businesses. These changes led to multiple perceived benefits including increased social connectedness, a transformed physical landscape, improved neighbourhood reputation, increased access to fresh produce, and educational, youth development, and employment opportunities. Our findings demonstrate the importance of a multifunctional paradigm that accounts for social and educational functions in assessing the value of urban farming and bring empirical evidence to the concept of multifunctional agriculture. Urban farms with strong social aims may appear to contribute little to economic development if measured using traditional indicators of success such as job creation or fiscal impacts, but provide numerous other benefits for community development. 相似文献
992.
S. M. El-Bashir I.S. Yahia F. Al-Harbi H. Elburaih F. Al-Faifi N. A. Aldosari 《International Journal of Green Energy》2017,14(3):270-278
MgO nanocrystals were synthesized and doped with different concentrations in poly(methylmethacrylate) (PMMA) to prepare hybrid organic-inorganic coatings based on polymer nanohybrid thin films. The nanoparticles were found to be spherical with 62 nm diameter as determined by X-ray diffraction (XRD) and atomic force microscope (AFM). The coatings were characterized by spectroscopic tools such as optical absorption, transmission and fluorescence spectroscopy. The prepared nanohybrid films were spin-coated on cost-effective luminescent PMMA substrates doped with highly efficient luminescent dyes luminescent solar concentrators (LSCs). The outdoor photostability tests demonstrated enhanced protection against UVA radiation for coated LSCs compared to bare LSC substrates. The current–voltage characteristics of commercially produced LSC prototypes showed that the poor UV response of monocrystalline silicon solar cell can be improved by for LSCs coated by PMMA/MgO nanohybrid films which act as luminescent down shifting layer (LDSL). 相似文献
993.
Howard N. Apsan 《环境质量管理》2013,23(2):61-76
Environmental, Health, and Safety (EHS) managers shoulder additional responsibilities with storm preparedness planning—and play host to storm evacuees 相似文献
994.
Rachnarin Nitisoravut Cao N. D. Thanh Roshan Regmi 《International Journal of Green Energy》2017,14(8):712-723
There is an increasing trend to conduct the researches related to Microbial Fuel Cells (MFCs) in the recent years. Limited power output has been the major obstacle for the practical application and upscaling of MFCs. Attempts have been made on electrode modifications such as anode treatments, cathode modifications with catalysts and bio cathodes developments to produce varying degrees of improved output current depending upon the types of modifications. Power density and Coulombic efficiency have been considered as the important parameters to analyze the system performances. This paper overviews on the advances made in MFCs’ researches focusing on different types of electrodes modifications along with the involved methodology. Furthermore, the system performances of different modified MFCs are compared in terms of the power density and the Coulombic efficiency. 相似文献
995.
996.
997.
N. Anger B. Brouns J. Onigkeit 《Mitigation and Adaptation Strategies for Global Change》2009,14(5):379-398
We investigate the role of domestic allowance allocation and global emissions constraints for the carbon-market impacts of
linking the EU Emissions Trading Scheme (ETS) internationally. Employing a quantitative simulation model of the global carbon
market, we find that the economic benefits from connecting the European ETS to emerging non-EU schemes strongly depend on
the regional allowance allocation of the linking participants: In a world of moderate carbon constraints, an economically
efficient regional allowance allocation induces a much stronger fall in total compliance costs than a sub-optimal (i.e. too
high) domestic allocation of emissions permits. However, a more efficient (i.e. stricter) allocation shifts abatement efforts
and compliance costs to energy-intensive industries which are covered by the domestic ETS. We further find that committing
to ambitious global emissions reduction targets (compatible with stabilizing CO2 concentrations at 450 ppm) induces much stronger regional abatement efforts and substantially higher compliance costs for
the abating regions. In such an ambitious climate policy regime, an efficient domestic allocation of allowances is even more
important from an economic perspective: Here, linking emissions trading schemes diminishes the associated compliance costs
on the largest scale.
相似文献
J. OnigkeitEmail: |
998.
Anna Elofsson Nora Smedby Jörgen Larsson Jonas Nässén 《Journal of Environmental Policy & Planning》2018,20(5):578-594
Global greenhouse gas emissions from air travel (GHG-A) are on the rise, and projections point towards a rapid growth in the coming decades. This study aims to examine how local government (cities), addresses GHG-A in their Sustainable Energy Action Plans (SEAP). To fulfil this aim, over 200 SEAPs were analysed focusing on three issues: (1) Treatment of GHG-A in local emissions inventories; (2) Policy initiatives within this domain; and (3) The cities’ perceptions of the conflicts of interests. Results showed that more than half of the cities acknowledge the challenge of GHG-A, around one third include GHG-A in their emissions inventories, and more than one quarter have initiated policy interventions. To categorise these interventions, we have added a mode ‘governing by agenda setting’ to an existing analytical framework, ‘Modes of governing’. With their authority limited to the local setting, this mode of governing is a common channel for cities to push changes at higher levels. 相似文献
999.
Previous experiments on wild rock doves ( Columba l. livia Gmelin) released within their familiar area revealed an evident effect of fast-shifting, although shifted doves, but not controls, tended to orient homeward. Such an outcome suggested a possible influence of the release time per se on the directional choices of the tested doves. In the present study, this hypothesis was investigated by comparing the orientation of slow-shifted birds to that of two control groups released at different times of the day. As would be expected if doves make use of a time-compensated sun compass, the bearings of shifted birds were deflected clockwise with respect to controls. The time of release itself seemed to influence only the scatter of the vanishing bearings of controls. These findings testify to the substantial similarity of clock-shift effects on the initial orientation of rock doves to those on homing pigeons released from familiar sites. 相似文献
1000.
Mekonnen Gebremichael Emmanouil N. Anagnostou Menberu M. Bitew 《Journal of the American Water Resources Association》2010,46(2):361-366
Gebremichael, Mekonnen, Emmanouil N. Anagnostou, and Menberu M. Bitew, 2010. Critical Steps for Continuing Advancement of Satellite Rainfall Applications for Surface Hydrology in the Nile River Basin. Journal of the American Water Resources Association (JAWRA) 46(2):361-366. DOI: 10.1111/j.1752-1688.2010.00428.x. Abstract: Given the increasingly higher resolution and data accessibility, satellite precipitation products could be useful for hydrological application in the Nile River Basin, which is characterized by lack of reasonably dense hydrological in situ sensors and lack of access to the existing dataset. However, in the absence of both extreme caution and research results for the Nile basin, the satellite rainfall (SR) products may not be used, or may even be used erroneously. We identify two steps that are critical to enhance the value of SR products for hydrological applications in the Nile basin. The first step is to establish representative validation sites in the Nile basin. The validation site will help to quantify the errors in the different kinds of SR products, which will be used to select the best products for the Nile basin, include the errors in decision making, and design strategies to minimize the errors. Using rainfall measurements collected from the unprecedented high-density rain gauge network over a small region within the Nile basin, we indicate that SR estimates could be subject to significant errors, and quantification of estimation errors by way of establishing validation sites is critically important in order to use the SR products. The second step is to identify the degree of hydrologic model complexity required to obtain more accurate hydrologic simulation results for the Nile basin when using SR products as input. The level of model complexity may depend on basin size and SR algorithm, and further research is needed to spell out this dependence for the Nile basin. 相似文献