全文获取类型
收费全文 | 15169篇 |
免费 | 166篇 |
国内免费 | 135篇 |
专业分类
安全科学 | 523篇 |
废物处理 | 645篇 |
环保管理 | 2221篇 |
综合类 | 2908篇 |
基础理论 | 3509篇 |
环境理论 | 8篇 |
污染及防治 | 3860篇 |
评价与监测 | 976篇 |
社会与环境 | 721篇 |
灾害及防治 | 99篇 |
出版年
2022年 | 131篇 |
2021年 | 138篇 |
2020年 | 109篇 |
2019年 | 133篇 |
2018年 | 226篇 |
2017年 | 246篇 |
2016年 | 355篇 |
2015年 | 272篇 |
2014年 | 370篇 |
2013年 | 1159篇 |
2012年 | 479篇 |
2011年 | 647篇 |
2010年 | 512篇 |
2009年 | 586篇 |
2008年 | 629篇 |
2007年 | 699篇 |
2006年 | 622篇 |
2005年 | 518篇 |
2004年 | 517篇 |
2003年 | 506篇 |
2002年 | 462篇 |
2001年 | 522篇 |
2000年 | 377篇 |
1999年 | 264篇 |
1998年 | 162篇 |
1997年 | 186篇 |
1996年 | 156篇 |
1995年 | 204篇 |
1994年 | 204篇 |
1993年 | 168篇 |
1992年 | 168篇 |
1991年 | 179篇 |
1990年 | 151篇 |
1989年 | 153篇 |
1988年 | 153篇 |
1987年 | 130篇 |
1986年 | 101篇 |
1985年 | 121篇 |
1984年 | 142篇 |
1983年 | 152篇 |
1982年 | 144篇 |
1981年 | 129篇 |
1980年 | 111篇 |
1979年 | 122篇 |
1978年 | 102篇 |
1977年 | 89篇 |
1976年 | 84篇 |
1975年 | 96篇 |
1974年 | 104篇 |
1965年 | 75篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Large‐scale change in human values and associated behavior change is believed by some to be the ultimate solution to achieve global biodiversity conservation. Yet little is known about the dynamics of values. We contribute to this area of inquiry by examining the trajectory of values affecting views of wildlife in North America. Using data from a 19‐state study in the United States and global data from the Schwartz Value Survey, we explored questions of value persistence and change and the nature of attitudinal responses regarding wildlife conservation issues. We found support, based on subjects’ ancestry, for the supposition that domination is a prevalent American value orientation toward wildlife that has origins in European Judeo‐Christian traditions. Independent of that effect, we also found indications of change. Modernization is contributing to a shift from domination to mutualism value orientations, which is fostering attitudes less centered on human interests and seemingly more consistent with a biocentric philosophy. Our findings suggest that if value shift could be achieved in a purposeful way, then significant and widespread behavior change believed necessary for long‐term conservation success may indeed be possible. In particular, greater emphasis on mutualism values may help provide the context for more collaborative approaches to support future conservation efforts. However, given the societal forces at play, it is not at all clear that human‐engineered value shift is tenable. Instead of developing strategies aimed at altering values, it may be more productive to create strategies that recognize and work within the boundaries of existing values. Whereas values appear to be in a period of flux, it will be difficult to predict future trends without a better understanding of value formation and shift, particularly under conditions of rapid social‐ecological change. 相似文献
92.
Mahmoud Marwa M. Sanad Eman F. Hamdy Nadia M. 《Environmental science and pollution research international》2021,28(28):36984-37000
Environmental Science and Pollution Research - The discovery of microRNAs (miRNAs) 20 years ago has advocated a new era of “small molecular genetics.” About 2000 miRNAs are present that... 相似文献
93.
Abdelnour Sameh A. Yang Chun-Yan Swelum Ayman A. Abd El-Hack Mohamed E. Khafaga Asmaa F. Abdo Mohamed Shang Jiang-Hua Lu Yang-Qing 《Environmental science and pollution research international》2020,27(31):38472-38490
Environmental Science and Pollution Research - Global warming is considered as the main environmental stress affecting ecosystems as well as physiological and biochemical characteristics, and... 相似文献
94.
Christian Mrz Felipe S. Freitas Johan C. Faust Jasmin A. Godbold Sian F. Henley Allyson C. Tessin Geoffrey D. Abbott Ruth Airs Sandra Arndt David K. A. Barnes Laura J. Grange Neil D. Gray Ian M. Head Katharine R. Hendry Robert G. Hilton Adam J. Reed Saskia Rühl Martin Solan Terri A. Souster Mark A. Stevenson Karen Tait James Ward Stephen Widdicombe 《Ambio》2022,51(2):370
Unprecedented and dramatic transformations are occurring in the Arctic in response to climate change, but academic, public, and political discourse has disproportionately focussed on the most visible and direct aspects of change, including sea ice melt, permafrost thaw, the fate of charismatic megafauna, and the expansion of fisheries. Such narratives disregard the importance of less visible and indirect processes and, in particular, miss the substantive contribution of the shelf seafloor in regulating nutrients and sequestering carbon. Here, we summarise the biogeochemical functioning of the Arctic shelf seafloor before considering how climate change and regional adjustments to human activities may alter its biogeochemical and ecological dynamics, including ecosystem function, carbon burial, or nutrient recycling. We highlight the importance of the Arctic benthic system in mitigating climatic and anthropogenic change and, with a focus on the Barents Sea, offer some observations and our perspectives on future management and policy. 相似文献
95.
By mechanical-biological treatment (MBT) of residual municipal solid waste the behaviour of landfills can be significantly improved. After MBT the organic content (COD and BOD5), total organic carbon, and total nitrogen in the leachate, as well as the gas production rate, are reduced to values lower than 90% of the fresh untreated waste. The volume of the stabilized material to be disposed on landfills decreases enormously, by up to 70%. The monitoring effort for a landfill constructed under these conditions is reduced to a minimum and the stabilized material can be used in other ways, as material for reforestation, for cover material or for thermal utilization to produce energy. Environmental conditions are important in MBT, as well as waste characteristics. This paper describes the results of a pilot project of MBT performed in Rio de Janeiro, Brazil. The results have shown that this technology can be used successfully in developing countries, with economy for the society and important results for the environment. 相似文献
96.
Influence of dairy manure addition on the biological and thermal kinetics of composting of greenhouse tomato plant residues 总被引:2,自引:0,他引:2
A laboratory-scale bioreactor was used to investigate the influence of dairy manure addition (as an inoculum and a carbon source) on the biological and thermal kinetics of the composting process of tomato plant residues-wood shavings mixture. Urea was added (as a nitrogen source) to correct the initial C:N ratio to 30:1 and the initial moisture content was also adjusted to 60%. The result of this study indicated that manure addition to the tomato residues-wood shavings mixture is a good source of macro and micronutrients required for supporting the composting microorganisms. Manure addition increased the rate of temperature increase and the duration of maximum temperature and reduced the lag and the peak time, all of which resulted in a significant reduction in the retention time. However, thermophilic temperature (> or = 40 degrees Celsius) was only achieved with 30%, 40% and 50% manure addition for 3, 7 and 9h. Total carbon reductions were in the range of 9.4-10.8% and TKN reductions were in the range of 3.4-6.0%. Neither the nitrogen nor the moisture content were limiting factors as the C:N ratio remained in the range of 26:1 to 28:1 and the moisture content remained within the optimum range of 58-61%. The maximum temperature of each mixture correlated with the reduction of total carbon, but carbon availability was a limiting factor in these experiments. In order to attain and sustain a thermophilic phase during the composting process, the addition of a readily available carbon source to the tomato should be investigated and carbon type (carbohydrates, proteins and fats) should be taken into account. 相似文献
97.
98.
99.
Long-term water quality records for assessing natural variability, impact of management, and that guide regulatory processes to safeguard water resources are rare for California oak woodland rangelands. This study presents a 20-yr record (1981-2000) of nitrate-nitrogen (NO(3)-N) and suspended sediment export from a typical, grazed oak woodland watershed (103 ha) in the northern Sierra Nevada foothills of California. Mean annual precipitation over the 20-yr period was 734 mm yr(-1) (range 366-1205 mm yr(-1)). Mean annual stream flow was 353 mm y(-1) (range 87-848 mm yr(-1)). Average annual stream flow was 48.1 +/- 16% of precipitation. Mean annual NO(3)-N export was 1.6 kg ha(-1) yr(-1) (range 0.18-3.6 kg ha(-1) yr(-1)). Annual NO(3)-N export significantly (P < 0.05) increased with increasing annual stream flow and precipitation. Mean daily NO(3)-N export was 0.004 kg ha(-1) d(-1) (range 10(-5) to 0.55 kg ha(-1) d(-1)). Mean annual suspended sediment export was 198 kg ha(-1) yr(-1) (range 23-479 kg ha(-1) yr(-1)). There was a positive relationship (P < 0.05) between annual suspended sediment export, annual stream flow and precipitation. Mean daily suspended sediment export was 0.54 kg ha(-1) d(-1) (range 10(-4) to 155 kg ha(-1) d(-1)). Virtually no sediment was exported during the dry season. The large variation in daily and annual fluxes highlights the necessity of using long-term records to establish quantitative water quality targets for rangelands and demonstrates the difficulty of designing a water quality monitoring program for these ecosystems. 相似文献