全文获取类型
收费全文 | 6676篇 |
免费 | 45篇 |
国内免费 | 44篇 |
专业分类
安全科学 | 175篇 |
废物处理 | 332篇 |
环保管理 | 777篇 |
综合类 | 940篇 |
基础理论 | 1641篇 |
环境理论 | 1篇 |
污染及防治 | 1657篇 |
评价与监测 | 458篇 |
社会与环境 | 749篇 |
灾害及防治 | 35篇 |
出版年
2023年 | 47篇 |
2022年 | 80篇 |
2021年 | 67篇 |
2020年 | 38篇 |
2019年 | 53篇 |
2018年 | 89篇 |
2017年 | 102篇 |
2016年 | 147篇 |
2015年 | 94篇 |
2014年 | 178篇 |
2013年 | 556篇 |
2012年 | 210篇 |
2011年 | 280篇 |
2010年 | 240篇 |
2009年 | 260篇 |
2008年 | 307篇 |
2007年 | 305篇 |
2006年 | 277篇 |
2005年 | 246篇 |
2004年 | 242篇 |
2003年 | 263篇 |
2002年 | 216篇 |
2001年 | 292篇 |
2000年 | 188篇 |
1999年 | 120篇 |
1998年 | 66篇 |
1997年 | 69篇 |
1996年 | 67篇 |
1995年 | 70篇 |
1994年 | 85篇 |
1993年 | 74篇 |
1992年 | 77篇 |
1991年 | 77篇 |
1990年 | 81篇 |
1989年 | 68篇 |
1988年 | 71篇 |
1987年 | 64篇 |
1986年 | 72篇 |
1985年 | 57篇 |
1984年 | 64篇 |
1983年 | 71篇 |
1982年 | 65篇 |
1981年 | 40篇 |
1980年 | 54篇 |
1979年 | 44篇 |
1978年 | 39篇 |
1977年 | 36篇 |
1976年 | 35篇 |
1974年 | 33篇 |
1973年 | 33篇 |
排序方式: 共有6765条查询结果,搜索用时 937 毫秒
891.
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
892.
Widyarsana I Made Wahyu Rahayu Made Ari Indra 《Journal of Material Cycles and Waste Management》2021,23(5):2051-2064
Journal of Material Cycles and Waste Management - This study aims to identify the amount of solid waste generation, composition, and characteristics of the Buleleng sub-district waste. The results... 相似文献
893.
Tolis Evangelos I. Karanotas Tilemachos Svolakis Grigoris Panaras George Bartzis John G. 《Environmental science and pollution research international》2021,28(37):51232-51241
Environmental Science and Pollution Research - Despite that commuters spend only 5.5% of their time in cabin vehicles, their exposure to harmful air pollutants, originated from the vehicle itself,... 相似文献
894.
Buzmakov S. A. Andreev D. N. Nazarov A. V. Dzyuba E. A. Shestakov I. E. Kuyukina M. S. El’kin A. A. Egorova D. O. Khotyanovskaya Yu. V. 《Russian Journal of Ecology》2021,52(4):267-274
Russian Journal of Ecology - Responses to contamination of several soil types with crude oil were comparatively analyzed in organisms of different trophic groups. Samples of soddy podzolic, light... 相似文献
895.
Russian Journal of Ecology - The variability of the ecological and morphological characteristics of the field vole was studied on samples collected in its two localities of the Southern Urals and... 相似文献
896.
Ronald Sandler 《Conservation biology》2020,34(2):378-385
The ethical issues associated with using genetic engineering and gene drives in conservation are typically described as consisting of risk assessment and management, public engagement and acceptance, opportunity costs, risk and benefit distributions, and oversight. These are important, but the ethical concerns extend beyond them because the use of genetic engineering has the potential to significantly alter the practices, concepts, and value commitments of conservation. I sought to elucidate the broader set of ethical issues connected with a potential genetic engineering turn in conservation and provide an approach to ethical analysis of novel conservation technologies. The primary rationales offered in support of using genetic engineering and gene drives in conservation are efficiency and necessity for achieving conservation goals. The instrumentalist ethical perspective associated with these rationales involves assessing novel technologies as a means to accomplish desired ends. For powerful emerging technologies the instrumentalist perspective needs to be complemented by a form-of-life perspective frequently applied in the philosophy of technology. The form-of-life perspective involves considering how novel technologies restructure the activities into which they are introduced. When the form-of-life perspective is applied to creative genetic engineering in conservation, it brings into focus a set of ethical issues, such as those associated with power, meaning, relationships, and values, that are not captured by the instrumentalist perspective. It also illuminates why the use of gene drives in conservation is so ethically and philosophically interesting. 相似文献
897.
A. M. Guerrero M. Barnes Ö. Bodin I. Chadès K. J. Davis M. S. Iftekhar C. Morgans K. A. Wilson 《Conservation biology》2020,34(3):733-742
Attempts to better understand the social context in which conservation and environmental decisions are made has led to increased interest in human social networks. To improve the use of social-network analysis in conservation, we reviewed recent studies in the literature in which such methods were applied. In our review, we looked for problems in research design and analysis that limit the utility of network analysis. Nineteen of 55 articles published from January 2016 to June 2019 exhibited at least 1 of the following problems: application of analytical methods inadequate or sensitive to incomplete network data; application of statistical approaches that ignore dependency in the network; or lack of connection between the theoretical base, research question, and choice of analytical techniques. By drawing attention to these specific areas of concern and highlighting research frontiers and challenges, including causality, network dynamics, and new approaches, we responded to calls for increasing the rigorous application of social science in conservation. 相似文献
898.
Environmental and Ecological Statistics - This paper illustrates the use of diffusion kernels to estimate smooth density and regression functions defined on highly complex domains. We generalize... 相似文献
899.
900.