首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   35711篇
  免费   348篇
  国内免费   244篇
安全科学   828篇
废物处理   1697篇
环保管理   5211篇
综合类   5674篇
基础理论   9692篇
环境理论   16篇
污染及防治   8079篇
评价与监测   2473篇
社会与环境   2472篇
灾害及防治   161篇
  2022年   172篇
  2021年   187篇
  2019年   196篇
  2018年   1849篇
  2017年   1777篇
  2016年   1720篇
  2015年   525篇
  2014年   559篇
  2013年   1940篇
  2012年   1207篇
  2011年   2389篇
  2010年   1576篇
  2009年   1528篇
  2008年   1969篇
  2007年   2422篇
  2006年   996篇
  2005年   872篇
  2004年   813篇
  2003年   956篇
  2002年   894篇
  2001年   973篇
  2000年   702篇
  1999年   442篇
  1998年   354篇
  1997年   311篇
  1996年   346篇
  1995年   388篇
  1994年   365篇
  1993年   322篇
  1992年   336篇
  1991年   313篇
  1990年   342篇
  1989年   328篇
  1988年   268篇
  1987年   263篇
  1986年   241篇
  1985年   272篇
  1984年   278篇
  1983年   274篇
  1982年   272篇
  1981年   260篇
  1980年   226篇
  1979年   214篇
  1978年   199篇
  1977年   187篇
  1976年   183篇
  1975年   160篇
  1974年   191篇
  1973年   174篇
  1972年   164篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Biodiversity offsets aim to counterbalance the residual impacts of development on species and ecosystems. Guidance documents explicitly recommend that biodiversity offset actions be located close to the location of impact because of higher potential for similar ecological conditions, but allowing greater spatial flexibility has been proposed. We examined the circumstances under which offsets distant from the impact location could be more likely to achieve no net loss or provide better ecological outcomes than offsets close to the impact area. We applied a graphical model for migratory shorebirds in the East Asian–Australasian Flyway as a case study to explore the problems that arise when incorporating spatial flexibility into offset planning. Spatially flexible offsets may alleviate impacts more effectively than local offsets; however, the risks involved can be substantial. For our case study, there were inadequate data to make robust conclusions about the effectiveness and equivalence of distant habitat-based offsets for migratory shorebirds. Decisions around offset placement should be driven by the potential to achieve equivalent ecological outcomes; however, when considering more distant offsets, there is a need to evaluate the likely increased risks alongside the potential benefits. Although spatially flexible offsets have the potential to provide more cost-effective biodiversity outcomes and more cobenefits, our case study showed the difficulty of demonstrating these benefits in practice and the potential risks that need to be considered to ensure effective offset placement.  相似文献   
2.

Food loss and waste is a major issue affecting food security, environmental pollution, producer profitability, consumer prices, and climate change. About 1.3 billion tons of food products are yearly lost globally, with China producing approximately 20 million tons of soybean dregs annually. Here, we review food and agricultural byproducts with emphasis on the strategies to convert this waste into valuable materials. Byproducts can be used for animal and plant nutrition, biogas production, food, extraction of oils and bioactive substances, and production of vinegar, wine, edible coatings and organic fertilizers. For instance, bioactive compounds represent approximately 8–20% of apple pomace, 5–17% of orange peel, 10–25% of grape seeds, 3–15% of pomegranate peel, and 2–13% of date palm seeds. Similarly, the pharmaceutical industry uses approximately 6.5% of the total output of gelatin derived from fish bones and animal skin. Animals fed with pomegranate peel and olive pomace improved the concentration of deoxyribonucleic acid and protein, the litter size, the milk yield, and nest characteristics. Biogas production amounts to 57.1% using soybean residue, 53.7% using papaya peel, and 49.1% using sugarcane bagasse.

  相似文献   
3.
Environmental Science and Pollution Research - A Correction to this paper has been published: https://doi.org/10.1007/s11356-021-13406-7  相似文献   
4.
Environmental Science and Pollution Research - With the use of different multivariate statistical analysis methods, spatio-temporal fluctuations in the water parameters of Tiru reservoir located at...  相似文献   
5.
In this laboratory study different combinations of bed (sand, pebble gravel [gravel], and a mix of sand and gravel) and flow (typical and overtopping) were experimented with to investigate the impact of porous deflectors in flow diversity, water quality, and fish performance in prismatic open channels. Deflectors changed the gradually varied flow to a rapidly varied flow, as a sudden change in the water depth was observed at the deflectors, and this change was large for smooth beds. With the presence of gravel, the scouring near the downstream deflector was almost twice that of the sand bed, and with the scouring at its own upstream deflector, irrespective of whether the flow was typical or overtopping. This behavior was a result of sand mobilization due to shear stress and sand mobilization aided gravel transport. The mixed bed showed less gravel movement compared to the gravel-only bed. The percentage of sediment washed out was minor for all bed scenarios, indicating that sediment transport was local. Relative to the sand bed without deflectors (representing a typical urban canal), deflectors resulted in reduced and improved water quality (in terms of sediment load) for sand, and mixed bed, respectively. The fishes found refuge and were comfortable in the pool areas created by deflectors unlike in channels without deflectors where they showed exhaustion.  相似文献   
6.
Environmental Chemistry Letters - The rise of bacterial resistance to common clinical antibiotics is calling for alternative techniques to synthesize antibacterial drugs with high biodegradability....  相似文献   
7.
River flooding impacts human life and infrastructure, yet provides habitat and ecosystem services. Traditional flood control (e.g., levees, dams) reduces habitat and ecosystem services, and exacerbates flooding elsewhere. Floodplain restoration (i.e., bankfull floodplain reconnection and Stage 0) can also provide flood management, but has not been sufficiently evaluated for small frequent storms. We used 1D unsteady Hydrologic Engineering Center's River Analysis System to simulate small storms in a 5 km-long, second-order generic stream from the Chesapeake Bay watershed, and varied % channel restored (starting at the upstream end), restoration location, restoration bank height (distinguishes bankfull from Stage 0 restoration), and floodplain width/Manning's n. Stream restoration decreased (attenuated) peak flow up to 37% and increased floodplain exchange by up to 46%. Floodplain width and % channel restored had the largest impact on flood attenuation. The incremental effects of new restoration projects on flood attenuation were greatest when little prior restoration had occurred. By contrast, incremental effects on floodplain exchange were greatest in the presence of substantial prior restoration, setting up a tradeoff. A similar tradeoff was revealed between attenuation and exchange for project location, but not bank height or floodplain width. In particular, attenuation and exchange were always greater for Stage 0 than for bankfull floodplain restoration. Stage 0 thus may counteract human impacts such as urbanization.  相似文献   
8.
9.
10.
In contradistinction to the ideas of Lynn White and others who have long suggested that the Judeo-Christian tradition fosters a ‘dominion over nature’ ethos, a number of scholars have recently argued that there has been a ‘greening of Christianity’. Largely missing from this debate is strong evidence at the individual level as to whether Christians have in fact adopted deeper environmental concerns over time. This study provides such evidence through an examination of longitudinal data from Gallup’s annual surveys on the environment. The analysis reveals little evidence that Christians have expressed more environmental concern over time. In fact, across many measures, Christians tend to show less concern about the environment. This pattern holds across Catholic, Protestant and other Christian denominations and for differing levels of religiosity. These findings support a conclusion that there has not been a discernible ‘greening of Christianity’ among the American public.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号