全文获取类型
收费全文 | 17709篇 |
免费 | 150篇 |
国内免费 | 118篇 |
专业分类
安全科学 | 463篇 |
废物处理 | 687篇 |
环保管理 | 2129篇 |
综合类 | 2977篇 |
基础理论 | 4360篇 |
环境理论 | 10篇 |
污染及防治 | 4378篇 |
评价与监测 | 1204篇 |
社会与环境 | 1658篇 |
灾害及防治 | 111篇 |
出版年
2022年 | 166篇 |
2021年 | 175篇 |
2020年 | 117篇 |
2019年 | 146篇 |
2018年 | 267篇 |
2017年 | 271篇 |
2016年 | 374篇 |
2015年 | 290篇 |
2014年 | 467篇 |
2013年 | 1359篇 |
2012年 | 574篇 |
2011年 | 758篇 |
2010年 | 612篇 |
2009年 | 704篇 |
2008年 | 796篇 |
2007年 | 826篇 |
2006年 | 703篇 |
2005年 | 645篇 |
2004年 | 569篇 |
2003年 | 566篇 |
2002年 | 529篇 |
2001年 | 684篇 |
2000年 | 524篇 |
1999年 | 287篇 |
1998年 | 193篇 |
1997年 | 223篇 |
1996年 | 214篇 |
1995年 | 260篇 |
1994年 | 253篇 |
1993年 | 210篇 |
1992年 | 186篇 |
1991年 | 218篇 |
1990年 | 231篇 |
1989年 | 205篇 |
1988年 | 154篇 |
1987年 | 148篇 |
1986年 | 158篇 |
1985年 | 133篇 |
1984年 | 154篇 |
1983年 | 140篇 |
1982年 | 157篇 |
1981年 | 137篇 |
1980年 | 134篇 |
1979年 | 150篇 |
1978年 | 95篇 |
1977年 | 102篇 |
1975年 | 103篇 |
1974年 | 89篇 |
1973年 | 102篇 |
1972年 | 99篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
V. N. Godin 《Russian Journal of Ecology》2017,48(5):433-439
The flora of Siberia includes 4500 species, 815 genera, and 123 families of angiosperms. The causes of the relationship between sexual forms and such ecological and biological features of plants as the life form, the mode of pollination, pericarp’s consistency, habitat type, zonal group, and the ecological group in relation to moistening were analyzed and discussed. For the first time, we demonstrated that gynomonoecy in the flora of Siberia was associated with a semiwoody growth form, pollination by wind, and propagation in zonal communities. It was revealed that gynodioecy in Siberia was associated with a semiwoody growth form, circumpolar or Eurasian distribution, and floodplain meadows. It was found that the ratio of dioecious and hermaphrodite plants in the ecological-biological complexes of species directly depends on the frequency of the abundance of species with endemic areas. 相似文献
962.
V. A. Terekhova V. K. Shitikov A. E. Ivanova K. A. Kydralieva 《Russian Journal of Ecology》2017,48(5):417-424
A methodology of substantiating the ecological risk of technogenic soil pollution has been described according to the results of bioindication using microfungal communities. At the first state, the values of the factors under which the frequency of each species is maximal were estimated using ordination methods. The statistical distribution of the species sensitivity was simulated according to these data. The methodology was illustrated using the results of analysis of the toxicity of soil samples from uranium mine dumps (the village of Kadzhi-Sai, Kyrgyzstan). The preliminary estimates of the critical values of six soil pollution indices that provide the defined allowable probability of the ecological risk have been given. 相似文献
963.
M. L. Gitarskiy D. G. Zamolodchikov V. A. Mukhin V. A. Grabar D. K. Diyarova A. I. Ivashchenko 《Russian Journal of Ecology》2017,48(6):539-544
Studies in three typical forest biotopes of the Valdai Upland were performed to evaluate the stocks and surface area of coarse woody debris from spruce and birch (in linear transects), its colonization by xylotrophic fungi (during reconnaissance surveys), and CO2 emission (by a chamber method). The stock and surface area were minimum in a paludal birch forest (46.4 m3/ha and 960 m2/ha) and maximum in a decay area of spruce forest (256.1 m3/ha and 3761 m2/ha, respectively). The assemblages of wood-decay fungi had a composition typically found in southern taiga forests. The total CO2 flux varied from 145 kg C-CO2/ha per year in the paludal birch forest to 462 kg C-CO2/ha per year in small herb–green moss spruce forest. It is concluded that air temperature is an informative predictor of seasonal C-CO2 flux rate from coarse woody debris. 相似文献
964.
Trends in the dynamics of herbivore community related to trophic competition in summer have been analyzed on Wrangel Island. The results show that the trophic spectra overlap considerably, resources are partitioned on the principle “weak competitors after strong competitors,” and community dynamics in the absence of extermination depend on specific competitive advantages related to the width of food spectrum. We conclude that the dynamics of this insular community prior to the establishment of nature reserve on the island have been determined by human activities, as well as the structure of arctic herbivore communities in general. 相似文献
965.
Solid waste is of serious concern in developing countries because of its high rate of generation and the low‐end quality of its management. Inefficient handling of solid wastes may result in deterioration of environmental quality, but it can also result in loss of potential resources. This study reviews current solid waste generation and management in Nigeria and the need for an effective collection, recovery, and recycling policy. Our review is based on literature searches and personal field surveys. Observations showed that uncontrolled electronic waste (e‐waste), agricultural‐waste (agro‐waste), scrap metals, waste polymers, and waste from the transportation sector are prevalent in Nigeria. Recent collection rates were less than 50% of the total solid waste generated (i.e., approximately 40% was collected). With an effective collection system and appropriate policies, the abundance of solid waste in the country could present material recovery and recycling opportunities that would boost the economy and move Nigeria closer to sustainable resource management. 相似文献
966.
Biological treatment of wastewater in aeration tanks: Theoretical bases for process calculations
下载免费PDF全文
![点击此处可从《环境质量管理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This article describes the method, based on the kinetics of enzyme reaction, for calculating treatment rates for wastewater effluents of varied concentrations in mixing aeration tanks and continuous flow aeration tanks. Using this method would make it possible to optimize the parameters of the biological treatment of wastewater. In addition, the authors illustrate that partitioning of the aeration space of the mixing aeration tank in a separate KU‐200 compact installation, which is intended for wastewater treatment from small sources, would make it possible to increase its efficiency by a factor of 1.8. 相似文献
967.
Method for Rapidly Assessing the Overtopping Risk of Bridges Due to Flooding over a Large Geographic Region
下载免费PDF全文
![点击此处可从《Journal of the American Water Resources Association》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yawen Shen Jonathan L. Goodall Steven B. Chase 《Journal of the American Water Resources Association》2017,53(6):1437-1452
Hydraulic events are a leading cause of bridge failures. While these hydraulic events are accounted for in bridge design, changing environmental and land use conditions require continual updating of this risk. For example, after a bridge has been constructed, streamflow can change in unanticipated ways as a result of land use changes, geomorphic changes, and climate change. The objective of this research was to create a screening method able to quickly and inexpensively estimate overtopping risk across a collection of bridges based on the current streamflow conditions. The method uses a geographic information system, nationally available and standardized datasets, and recent regression equations to quantify bridge vulnerability to overtopping for flooding with varying return periods. This screening method could also be used to assist decision makers in updating the Waterway Adequacy field in the National Bridge Inventory, which indicates the overtopping risk of bridges. The method was applied to a portion of the Hampton Roads region of Virginia, United States that includes 475 bridges. The results of the analysis, when combined with transportation data for bridges, aid decision makers to assign further resources to complete more detailed analyses of bridges identified as being at risk for overtopping. 相似文献
968.
Designing and Implementing a Network for Sensing Water Quality and Hydrology across Mountain to Urban Transitions
下载免费PDF全文
![点击此处可从《Journal of the American Water Resources Association》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Amber Spackman Jones Zachary T. Aanderud Jeffery S. Horsburgh David P. Eiriksson Dylan Dastrup Christopher Cox Scott B. Jones David R. Bowling Jonathan Carlisle Gregory T. Carling Michelle A. Baker 《Journal of the American Water Resources Association》2017,53(5):1095-1120
Water resources are increasingly impacted by growing human populations, land use, and climate changes, and complex interactions among biophysical processes. In an effort to better understand these factors in semiarid northern Utah, United States, we created a real‐time observatory consisting of sensors deployed at aquatic and terrestrial stations to monitor water quality, water inputs, and outputs along mountain to urban gradients. The Gradients Along Mountain to Urban Transitions (GAMUT) monitoring network spans three watersheds with similar climates and streams fed by mountain winter‐derived precipitation, but that differ in urbanization level, land use, and biophysical characteristics. The aquatic monitoring stations in the GAMUT network include sensors to measure chemical (dissolved oxygen, specific conductance, pH, nitrate, and dissolved organic matter), physical (stage, temperature, and turbidity), and biological components (chlorophyll‐a and phycocyanin). We present the logistics of designing, implementing, and maintaining the network; quality assurance and control of numerous, large datasets; and data acquisition, dissemination, and visualization. Data from GAMUT reveal spatial differences in water quality due to urbanization and built infrastructure; capture rapid temporal changes in water quality due to anthropogenic activity; and identify changes in biological structure, each of which are demonstrated via case study datasets. 相似文献
969.
Detention Outlet Retrofit Improves the Functionality of Existing Detention Basins by Reducing Erosive Flows in Receiving Channels
下载免费PDF全文
![点击此处可从《Journal of the American Water Resources Association》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Robert J. Hawley James A. Goodrich Nora L. Korth Christopher J. Rust Elizabeth V. Fet Craig Frye Katherine R. MacMannis Matthew S. Wooten Mark Jacobs Rajib Sinha 《Journal of the American Water Resources Association》2017,53(5):1032-1047
By discharging excess stormwater at rates that more frequently exceed the critical flow for stream erosion, conventional detention basins often contribute to increased channel instability in urban and suburban systems that can be detrimental to aquatic habitat and water quality, as well as adjacent property and infrastructure. However, these ubiquitous assets, valued at approximately $600,000 per km2 in a representative suburban watershed, are ideal candidates to aid in reversing such cycles of channel degradation because improving their functionality would not necessarily require property acquisition or heavy construction. The objective of this research was to develop a simple, cost‐effective device that could be installed in detention basin outlets to reduce the erosive power of the relatively frequent storm events (~ < two‐year recurrence) and provide a passive bypass to maintain flood control performance during infrequent storms (such as the 100‐year recurrence). Results from a pilot installation show that the Detain H2O device reduced the cumulative sediment transport capacity of the preretrofit condition by greater than 40%, and contributed to reduced flashiness and prolonged baseflows in receiving streams. When scaling the strategy across a watershed, these results suggest that potential gains in water quality and stream channel stability could be achieved at costs that are orders of magnitude less than comparable benefits from newly constructed stormwater control measures. 相似文献
970.
Iraklis Argyriou Jonathan B. Justice William Latham Robert Warren 《Local Environment》2017,22(12):1461-1478
Cities throughout the world are key sites for energy sustainability activities. However, analysis of such efforts to date has focused on a sub-set of atypical cities: early adopters and/or world cities. This article undertakes a case-study analysis for an ordinary city, Philadelphia, PA in order to assess the extent to which prior research provides adequate policy explanation for ordinary cities and to gain empirical insight on two under-researched aspects: policy actors, and the policy-making and implementation sites (action sites) for urban energy sustainability. Overall, the types of policy drivers, modes of governance, and enabling factors and barriers in the Philadelphia case fit with prior studies. Focusing on actors and action sites, however, offers insight on the city’s relative policy-making approach based on “non-controversy”, the key role of third-sector actors in both policy-making and implementation, and the diversification of action sites through external-level policy-making operationalised locally nevertheless at the expense of reduced control by urban actors. These findings lead to recommendations for urban energy sustainability research and practice. 相似文献