全文获取类型
收费全文 | 1228篇 |
免费 | 72篇 |
国内免费 | 495篇 |
专业分类
安全科学 | 88篇 |
废物处理 | 58篇 |
环保管理 | 128篇 |
综合类 | 696篇 |
基础理论 | 235篇 |
污染及防治 | 405篇 |
评价与监测 | 72篇 |
社会与环境 | 52篇 |
灾害及防治 | 61篇 |
出版年
2024年 | 3篇 |
2023年 | 27篇 |
2022年 | 82篇 |
2021年 | 59篇 |
2020年 | 60篇 |
2019年 | 48篇 |
2018年 | 55篇 |
2017年 | 74篇 |
2016年 | 55篇 |
2015年 | 60篇 |
2014年 | 90篇 |
2013年 | 120篇 |
2012年 | 100篇 |
2011年 | 130篇 |
2010年 | 83篇 |
2009年 | 82篇 |
2008年 | 81篇 |
2007年 | 69篇 |
2006年 | 81篇 |
2005年 | 56篇 |
2004年 | 38篇 |
2003年 | 29篇 |
2002年 | 48篇 |
2001年 | 39篇 |
2000年 | 43篇 |
1999年 | 35篇 |
1998年 | 18篇 |
1997年 | 26篇 |
1996年 | 16篇 |
1995年 | 17篇 |
1994年 | 11篇 |
1993年 | 20篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1795条查询结果,搜索用时 0 毫秒
711.
712.
713.
铂、钯蜂窝催化剂高温老化对甲醇深度氧化的影响 总被引:1,自引:0,他引:1
本研究对铂、钯蜂窝催化剂及分别添加助化剂CeO_2或WO_3,并于500℃、700℃、900℃或1100℃下经受热老化4h后,考察催化剂比表面、晶相结构及其对甲醇深度氧化活性、产物分布及反应动力学网络变化的情况。实验证明,添加CeO_2后,降低了铂催化剂的耐高温性能,但对钯催化剂无明显影响。添加WO_3,降低了钯催化剂对甲醇的氧化活性。经X-线衍射分析证明,在1100℃高温下,WO_3与堇青石载体中的氧化镁和氧化钙发生强相互作用,生成了相应的钨酸盐。甲醇氧化反应动力学研究表明,甲醇在新鲜和高温热老化的铂催化剂上,反应动力学网络表示式是有区别的。 相似文献
714.
催化光度法测定地下水中超痕量锰 总被引:1,自引:0,他引:1
本文基于氨三乙酸为活化剂,Mn(Ⅱ)对KIO_4氧化次甲基氯的催化效应,建立了一个测定超痕量Mn(Ⅱ)的新方法.本法的检出限为1×10~(-10)g/ml,测定范围为0~40ng/25ml,用于地下水中痕量Mn(Ⅱ)的测定,结果令人满意. 相似文献
715.
Weidong Wang Jun Zheng Zhongqiong Wang Rongbin Zhang Qinghua Chen Xinfeng Yu Chengqing Yin 《环境科学学报(英文版)》2016,28(1):119-133
Shijiuyang Constructed Wetland(110 hm~2) is a drinking water source treatment wetland with primary structural units of ponds and plant-bed/ditch systems. The wetland can process about 250,000 tonnes of source water in the Xincheng River every day and supplies raw water for Shijiuyang Drinking Water Plant. Daily data for 28 months indicated that the major water quality indexes of source water had been improved by one grade. The percentage increase for dissolved oxygen and the removal rates of ammonia nitrogen, iron and manganese were 73.63%, 38.86%, 35.64%, and 22.14% respectively. The treatment performance weight of ponds and plant-bed/ditch systems was roughly equal but they treated different pollutants preferentially. Most water quality indexes had better treatment efficacy with increasing temperature and inlet concentrations. These results revealed that the pond–wetland complexes exhibited strong buffering capacity for source water quality improvement. The treatment cost of Shijiuyang Drinking Water Plant was reduced by about 30.3%. Regional rainfall significantly determined the external river water levels and adversely deteriorated the inlet water quality, thus suggesting that the "hidden" diffuse pollution in the multitudinous stream branches as well as their catchments should be the controlling emphases for river source water protection in the future. The combination of pond and plant-bed/ditch systems provides a successful paradigm for drinking water source pretreatment. Three other drinking water source treatment wetlands with ponds and plant-bed/ditch systems are in operation or construction in the stream networks of the Yangtze River Delta and more people will be benefited. 相似文献
716.
Wei Li Longjun Wang Fan Liu Xiaoliang Liang Xionghan Feng Wenfeng Tan Lirong Zheng Hui Yin 《环境科学学报(英文版)》2016,28(7):18-27
Al substitution in goethite is common in soils, and has strong influence on the structure and physicochemical properties of goethite. In this research, a series of Al-doped goethites were synthesized, and characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The adsorption behavior of these samples towards PO43 − was also investigated. Characterization results demonstrated that increasing Al content in goethite led to a reduction in crystallinity, increase in specific surface area (SSA), and morphology change from needle-like to granular. Rietveld structure refinement revealed that the lattice parameter a remained almost constant and b slightly decreased, but c was significantly reduced, and the calculated crystal density increased. EXAFS analysis demonstrated that the Fe(Al)–O distance in the structure of the doped goethites was almost the same, but the Fe–Fe(Al) distance decreased with increasing Al content. Surface analysis showed that, with increasing Al content, the content of OH groups on the mineral surface increased. The adsorption of phosphate per unit mass of Al-doped goethite increased, while adsorption per unit area decreased owing to the decrease of the relative proportion of (110) facets in the total surface area of the minerals. The results of this research facilitate better understanding of the effect of Al substitution on the structure and properties of goethite and the cycling of phosphate in the environment. 相似文献
717.
718.
Comparative Analysis of Inundation Mapping Approaches for the 2016 Flood in the Brazos River,Texas
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)
Jiaqi Zhang Yu‐Fen Huang Dinuke Munasinghe Zheng Fang Yin‐Phan Tsang Sagy Cohen 《Journal of the American Water Resources Association》2018,54(4):820-833
Accurate and timely flood inundation maps serve as crucial information for hydrologists, first‐responders, and decision makers of natural disaster management agencies. In this study, two modeling approaches are applied to estimate the inundation area for a large flooding event that occurred in May 2016 in the Brazos River: (1) Height Above the Nearest Drainage combined with National Hydrograph Dataset Plus (NHDPlus‐HAND) and (2) International River Interface Cooperative — Flow and Sediment Transport with Morphological Evolution of Channels (iRIC‐FaSTMECH). The inundation extents simulated from these two modeling approaches are then compared against the observed inundation extents derived from a Landsat 8 satellite image. The simulated results from NHDPlus‐HAND and iRIC‐FaSTMECH show 56% and 70% of overlaps with the observed flood extents, respectively. A modified version of the NHDPlus‐HAND model, considering networked catchment behaviors, is also tested with an improved fitness of 67%. This study suggests that NHDPlus‐HAND has the potential for real‐time continental inundation forecast due to its low computational cost and ease to couple with the National Water Model. Better performance of NHDPlus‐HAND can be achieved by considering the inter‐catchment flows during extreme riverine flood events. Overall, this study presents a comprehensive examination made of remote sensing compared with HAND‐based inundation mapping in a region of complex topography. 相似文献
719.
Yin Heliang Sun Tong Yao Lan Jiao Yan Ma Li Lin Lin Graff J Carolyn Aleya Lotfi Postlethwaite Arnold Gu Weikuan Chen Hong 《Environmental science and pollution research international》2021,28(30):40424-40430
Environmental Science and Pollution Research - Currently, 2019-nCoV has spread to most countries of the world. Understanding the environmental factors that affect the spread of the disease COVID-19... 相似文献
720.
Chuanbin Yin 《中国人口.资源与环境(英文版)》2017,15(2):157-166
In this study, we measure the environmental efficiency of western China in 2000–2014 by the super-efficiency slacks-based measure model which considers the undesirable outputs. The results show that the environmental efficiency of western China is low and rank behind in the national level. The environmental efficiency is lower than the traditional efficiency which reflects that the economic growth in 2000–2014 has paid high environmental costs. The difference between the traditional efficiency and environmental efficiency experienced “inverted U”-type trend change. The environmental efficiency of the western provinces presented differentiated developing trend and the differences between the western provinces were enlarging. The environmental efficiency of the western regions was not only lower than that in the eastern regions with a big gap but also lower than that in the central regions. Through the convergence test, we found that the environmental efficiency gap between the western and the eastern regions was gradually expanding; meanwhile, the environmental efficiency gap between the central and the western regions was narrowing. This paper also analyzes the determinants of environmental efficiency by the tobit model and then addresses. 相似文献