全文获取类型
收费全文 | 107677篇 |
免费 | 2136篇 |
国内免费 | 6930篇 |
专业分类
安全科学 | 5052篇 |
废物处理 | 4381篇 |
环保管理 | 15406篇 |
综合类 | 31129篇 |
基础理论 | 28896篇 |
环境理论 | 73篇 |
污染及防治 | 20076篇 |
评价与监测 | 6187篇 |
社会与环境 | 4193篇 |
灾害及防治 | 1350篇 |
出版年
2023年 | 676篇 |
2022年 | 1582篇 |
2021年 | 1557篇 |
2020年 | 1238篇 |
2019年 | 1370篇 |
2018年 | 1726篇 |
2017年 | 1921篇 |
2016年 | 2851篇 |
2015年 | 2766篇 |
2014年 | 3909篇 |
2013年 | 10913篇 |
2012年 | 3676篇 |
2011年 | 3948篇 |
2010年 | 4489篇 |
2009年 | 4575篇 |
2008年 | 3348篇 |
2007年 | 2956篇 |
2006年 | 3367篇 |
2005年 | 2967篇 |
2004年 | 3086篇 |
2003年 | 2966篇 |
2002年 | 2503篇 |
2001年 | 2680篇 |
2000年 | 2502篇 |
1999年 | 1936篇 |
1998年 | 1714篇 |
1997年 | 1734篇 |
1996年 | 1796篇 |
1995年 | 1843篇 |
1994年 | 1666篇 |
1993年 | 1511篇 |
1992年 | 1475篇 |
1991年 | 1382篇 |
1990年 | 1331篇 |
1989年 | 1254篇 |
1988年 | 1093篇 |
1987年 | 1011篇 |
1986年 | 1005篇 |
1985年 | 1080篇 |
1984年 | 1174篇 |
1983年 | 1179篇 |
1982年 | 1188篇 |
1981年 | 1115篇 |
1980年 | 944篇 |
1979年 | 933篇 |
1978年 | 827篇 |
1977年 | 717篇 |
1976年 | 652篇 |
1973年 | 658篇 |
1972年 | 655篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
Morsheda Akhter Sagar Kumar Dutta Palash Kumar Dhar Jamil Ahmed Mohammed Nazrul Islam Khan Md. Khairul Amin Jahidul Islam 《环境质量管理》2023,32(4):149-160
Catalytic activity of spinel ferrite in breaking down toxic dye materials are promising due to their uniqueness. In this study, aluminum-doped copper zinc ferrite, Cu0.4Zn0.6-xAlxFe2O4 (x = 0.0, 0.2, 0.4, 0.6), a catalyst for toxic dye degradation is synthesized through chemical co-precipitation route. The formation of the spinel ferrite catalyst is initially confirmed by Fourier transform infrared spectra, which shows the frequency of metal-oxygen bond vibration at 539 and 427 cm−1 attributed to the tetrahedral and octahedral sites respectively. Higher intensity sharp peak of X-ray diffraction for (311) plane is the evidence for the phase purity and the formation of spinel ferrite. The crystallite size is found to decrease with the increase of Al3+ ion. The surface structure of the obtained particles is investigated using a scanning electron microscope. Analyses of the material's magnetic characteristics using a vibrating sample magnetometer (VSM) revealed that it is, in fact, a soft magnet, as evidenced by the loop of its hysteresis, which is narrow. The catalytic degradation of methylene blue dye under the mechanism of the photo-Fenton process is studied with the obtained spinel ferrites and the result is found to be as high as 96.5%. The process follows pseudo-second order kinetics and the Langmuir isotherm. 相似文献
12.
Russian Journal of Ecology - A new method for assessing the response of biota to climatic changes in the ecosystem has been tested. In the Central Forest Natural Biosphere Reserve, the average... 相似文献
13.
Yang Jian Hong Chen Xing Yi Zheng Zixuan Li Zaixing Zhao Xiumei Qi Chenhao 《Environmental science and pollution research international》2021,28(7):7621-7635
Environmental Science and Pollution Research - Hydrothermal liquefaction (HTL) of biomass used HTL reaction under high temperature and pressure to produce bio-oil. This technology is considered as... 相似文献
14.
Journal of Material Cycles and Waste Management - The iron ore tailing (IOT) is an industrial waste, in which large accumulations represent a serious environmental threat. To reduce the... 相似文献
15.
Helena Wedin Ellinor Niit Zaheer Ahmad Mansoor Anna Rúna Kristinsdottir Hanna de la Motte Christina Jönsson Åsa Östlund Christofer Lindgren 《Journal of Polymers and the Environment》2018,26(9):3603-3612
The chemical recycling of cellulosic fibres may represent a next-generation fibre–fibre recycling system for cotton textiles, though remaining challenges include how to accommodate fibre blends, dyes, wrinkle-free finishes, and other impurities from finishing. These challenges may disrupt the regeneration process steps and reduce the fibre quality. This study examines the impact on regenerated viscose fibre properties of a novel alkaline/acid bleaching sequence to strip reactive dyes and dimethyloldihydroxyethyleneureas (DMDHEU) wrinkle-free finish from cotton textiles. Potentially, such a bleaching sequence could advantageously be integrated into the viscose process, reducing the costs and environmental impact of the product. The study investigates the spinning performance and mechanical properties (e.g., tenacity and elongation) of the regenerated viscose fibres. The alkaline/acid bleaching sequence was found to strip the reactive dye and DMDHEU wrinkle-free finish from the cotton fabric, so the resulting pulp could successfully be spun into viscose fibres, though the mechanical properties of these fibres were worse than those of commercial viscose fibres. This study finds that reactive dyes and DMDHEU wrinkle-free finish affect the viscose dope quality and the regeneration performance. The results might lead to progress in overcoming quality challenges in cellulosic chemical recycling. 相似文献
16.
Progress and challenges in consolidating the management of Amazonian protected areas and indigenous territories
下载免费PDF全文
![点击此处可从《Conservation biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Effective management refers to the ability of a protected area or indigenous territory to meet its objectives, particularly as they relate to the protection of biodiversity and forest cover. Effective management is achieved through a process of consolidation, which among other things requires legally protecting sites, integrating sites into land‐use planning, developing and implementing management and resource‐use plans, and securing long‐term funding to pay for recurrent costs. Effectively managing all protected areas and indigenous territories in the Amazon may be needed to avoid a deforestation tipping point beyond which regional climatic feedbacks and global climate change interact to catalyze irreversible drying and savannization of large areas. At present, protected areas and indigenous territories cover 45.5% (3.55 million km2) of the Amazon, most of the 60–70% forest cover required to maintain hydrologic and climatic function. Three independent evaluations of a long‐term large‐scale philanthropic initiative in the Amazon yielded insights into the challenges and advances toward achieving effective management of protected areas and indigenous territories. Over the life of the initiative, management of sites has improved considerably, particularly with respect to management planning and capacity building, but few sites are effectively managed and many lack sufficient long‐term financing, adequate governance, support of nongovernmental organizations, and the means to withstand economic pressures. The time and money required to complete consolidation is still poorly understood, but it is clear that philanthropic funding is critical so long as essential funding needs are not met by governments and other sources, which could be on the order of decades. Despite challenges, it is encouraging that legal protection has expanded greatly and management of sites is improving steadily. Management of protected areas in other developing countries could be informed by improvements that have occurred in Amazonian countries. 相似文献
17.
针对AVHRR NDVI和MODIS NDVI数据集中不同数据产品间的差异和区域适应性问题,利用2003~2013年重叠时间段MODIS Terra/Aqua的NDVI Collection 5(C5)和Collection 6(C6)产品以及AVHRR NDVI中的GIMMS NDVI3g产品,选择汉江流域典型区域进行数据对比分析。通过关联指数IOAs(Index of Association)来评价各数据在季节波动上的一致性;采用Mann Kendall检验分析各数据的长期趋势差异。结果表明,在季节性变化上,同一卫星不同版本产品之间的关联性相对较高。在年际变化上,GIMMS产品相对MODIS 产品,仅能检出部分NDVI变化趋势。在地表覆被异质性相对较高地区,GIMMS产品的长期变化趋势检出率较低。MODIS Terra的NDVI C5产品受传感器退化影响,表现出相对较高的减少趋势。
关键词: GIMMS NDVI;MODIS NDVI;Mann Kendall检验;趋势分析 相似文献
18.
Simas Angélica Mores Rúbia Steffens Juliana Dallago Rogério Marcos Kunz Airton Michelon William Fongaro Gislaine Viancelli Aline 《Environmental Chemistry Letters》2019,17(1):495-499
Environmental Chemistry Letters - Swine production generates large volumes of wastewater, rich in organic matter, nutrients and pathogens. Electrodisinfection is used to remove organic matter and... 相似文献
19.
Shu-Yii Wu Yong-Fang Liu Ya-Chieh Li Chun-Min Liu 《International Journal of Green Energy》2015,12(10):1025-1030
The CO2 absorption capacities of potassium glycinate, potassium sarcosinate (choline, proline), mono-ethanolamine (MEA), and tri-ethanolamine were evaluated to find the optimal absorbent for separating CO2 from gaseous products by a CO2 purification process. The absorption loading, desorption efficiency, cost, and environmental tolerance were assessed to select the optimal absorbent. MEA was found to be the optimum absorbent for separating the CO2 and H2 mixture in gaseous product. The maximum absorption loading rate was 0.77 mol CO2 per mol MEA at temperature of 20°C and absorbent concentration of 2.5 mol/L, whereas desorption efficiency was 90% by heating for 3 h at 130°C. MEA was found to be an optimal absorbent for the purification process of CO2 during gaseous production. 相似文献
20.