全文获取类型
收费全文 | 1316篇 |
免费 | 79篇 |
国内免费 | 468篇 |
专业分类
安全科学 | 77篇 |
废物处理 | 109篇 |
环保管理 | 108篇 |
综合类 | 676篇 |
基础理论 | 234篇 |
污染及防治 | 489篇 |
评价与监测 | 77篇 |
社会与环境 | 47篇 |
灾害及防治 | 46篇 |
出版年
2024年 | 4篇 |
2023年 | 14篇 |
2022年 | 55篇 |
2021年 | 49篇 |
2020年 | 42篇 |
2019年 | 53篇 |
2018年 | 48篇 |
2017年 | 62篇 |
2016年 | 58篇 |
2015年 | 99篇 |
2014年 | 109篇 |
2013年 | 138篇 |
2012年 | 117篇 |
2011年 | 113篇 |
2010年 | 93篇 |
2009年 | 83篇 |
2008年 | 121篇 |
2007年 | 89篇 |
2006年 | 68篇 |
2005年 | 58篇 |
2004年 | 54篇 |
2003年 | 47篇 |
2002年 | 43篇 |
2001年 | 30篇 |
2000年 | 27篇 |
1999年 | 29篇 |
1998年 | 26篇 |
1997年 | 23篇 |
1996年 | 22篇 |
1995年 | 16篇 |
1994年 | 13篇 |
1993年 | 14篇 |
1992年 | 13篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1977年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有1863条查询结果,搜索用时 559 毫秒
281.
282.
首先分析我国城市垃圾问题的现状,介绍了我国目前城市垃圾处理技术,并对城市可持续发展垃圾治理问题进行了探讨。 相似文献
283.
Hong Wang Jay Gao Li-Liang Ren Yan Kong He Li Ling Li 《Regional Environmental Change》2013,13(1):115-123
As wildlife habitat is in constant evolution, periodic monitoring is essential to assess its quality. In this study, the change to the red-crowned crane habitat in the Yellow River Delta Nature Reserve was detected from multi-temporal remote sensing data from 1992 to 2008 in a geographic information system. Habitat fragmentation was derived from both physical constraints and human disturbance. The changing habitat quality was assessed against five landscape indices. The results obtained from Landsat TM images indicate that potential habitat shrank 37.9 % during 1992–2001, but recovered 99.4 % by 2008. Suitable habitat shrank by 4,329 ha to a level below that of 1992 despite an increase of 4,747 ha in potential habitat due to an increase of 9,075 ha in fragmented areas. Both landscape indices and the red-crowned crane population reveal that suitable habitat was the most fragmented in 2001, but the least fragmented in 1992. Therefore, it is inadequate to just restore wetland through artificial diversion of channel flow to the Reserve to preserve the crane habitat. Commensurate efforts should also be directed at improving habitat quality by minimizing human activities and spatially juxtaposing water and reed marshes harmoniously inside the Reserve. 相似文献
284.
通过分析老鹰岩滑坡的地质环境特征和形态特征,揭示其形成机制和产生的危害,最后根据该区地质灾害特点,提出了灾后恢复重建的相关建议。 相似文献
285.
Optimizing model for land use/land cover retrieval from remote sensing imagery based on variable precision rough sets 总被引:2,自引:0,他引:2
The suitable spectral mode in remote sensing is often desirable to facilitate the inversion of ecological environment and landscape. This paper put forward an optimizing model based on variable precision rough sets (VPRS) for the land cover discrimination in wetland inventory. In the case study of Lake Baiyangdian which has important ecological functions to the northern China, this model is established successfully according to the domain-experts knowledge. The procedure is as follows. First step is data collection, including remote-sensing data (e.g., Landsat-5 TM bands), the digitized relief maps, and statistical yearbooks. Second, the remote sensing imagery (RSI) and relief maps are co-registered into the same resolution. Third, a condition set, including various attributes is derived from spectral bands, band math or ratio indices based on previous studies, at the same time, the decision set is derived from true land types after investigation and validation. Then, the remote sensing decision table (RSDT) is constructed by linking condition set with decision set according to the sequential pixels in RSI. Fourth, we create one forward greedy searching algorithm based on VPRS to handle this RSDT. After adjusting parameters such as β and knowledge granularity diameter (KGD), we obtain the stable optimized results. Comparative experiments and evaluation show that the discrimination or retrieval accuracy of VPRS model is satisfying (overall accuracy: 87.32% and KHAT: 0.84) and better than original data. Moreover, data dimension has been decreased dramatically (from 12 to 3) and key attributes found by the model may be useful for specific retrieval in wetland inventories. 相似文献
286.
Polycyclic aromatic hydrocarbons in effluents from wastewater treatment plants and receiving streams in Tianjin, China 总被引:1,自引:0,他引:1
Weixiao Qi Huijuan Liu Jiuhui Qu Chengzhi Hu Huachun Lan Michael Berg Huimin Ren Wei Xu 《Environmental monitoring and assessment》2011,177(1-4):467-480
Surface water, suspended particulate matter, pore water, and sediment samples were collected and analyzed for polycyclic aromatic hydrocarbons (PAHs) in Yongding New River, South Drainage Canal and North Drainage Canal, which receive most of wastewater from industrial city of Tianjin. PAH concentrations in effluent samples of wastewater treatment plants (WTP) discharging into the South Drainage Canal and North Drainage Canal were quantified for the first time. The results showed that the discharge of the WTPs recently only contributed to the PAH contamination in the canals near the outlets of the WTPs. PAH levels in sediments of the streams were greatly higher than those in soils by riverbank probably due to receiving large amounts of untreated wastewater. Unusually high benz[a] anthracene concentration strongly influenced the seasonal and spatial variation of total PAH concentrations in South Drainage Canal. Paired samples t test of ??Nap, Fl, Phe, Fluo and ??Nap, Phe, Fluo, Chry concentrations, which were dominant components in the air samples from non-heating and heating season, respectively, in the suspended particulate matters from the streams showed that PAH source from air deposition was more important for Yongding New River than that for South Drainage Canal and North Drainage Canal. Source apportionment based on PAH profiles indicated that coal combustion was the major PAH contamination source, and coke oven sources and wood combustion also contributed to the PAH contamination of the streams. This was further indicated by organic petrography analysis. 相似文献
287.
Yuxue Kong Xurong Bai Jie Wei Yanqin Ren Rui Gao Fahe Chai Hong Li Fei Xu 《环境科学学报(英文版)》2023,123(1):169-182
Polycyclic aromatic hydrocarbons(PAHs) and their nitrated derivatives(NPAHs) attract continuous attention due to their outstanding carcinogenicity and mutagenicity. In order to investigate the diurnal variations, sources, formation mechanism, and health risk assessment of them in heating season, particulate matter(PM) were collected in Beijing urban area from December 26, 2017 to January 17, 2018. PAHs and NPAHs in PM were quantitatively analyzed via gas chromatography-mass spectrometry(GC-MS). ... 相似文献
288.
核算和评估固体垃圾产生和处理及其N2O排放具有重要的现实和指导意义.本研究以中国为例(2008—2017年),建立了固体垃圾产生、处理和N2O排放核算框架.结果表明,10年间中国固体垃圾产生量上升了34.6%,年均6.13亿t,生活垃圾(48.6%)和工业日用品垃圾(24.6%)是主要贡献源;处理格局仍以填埋为主(占53.0%),焚烧为辅(25.5%);堆弃(42.5%)和焚烧(31.2%)是固体垃圾处理中N2O气体的主要排放源,堆肥占21.9%,填埋处理排放最少(4.4%);固体垃圾处理产生的渗滤液逐年增加,渗滤液排放的N2O占固体垃圾处理N2O排放总量的41.7%,生活垃圾产生的渗滤液是其主要排放源.加大垃圾分类处理和资源化利用力度,加强农村生活垃圾处理处置能力、减少垃圾堆弃量及提高垃圾处理技术对固体垃圾的产生及其N2O排放减排至关重要. 相似文献
289.
Herein, Na+ and Ca2+ are introduced to MnO2 through cation-exchange method. The presence of Na+ and Ca2+ significantly enhance the catalytic activity of MnO2 in toluene oxidation. Among them, the Ca-MnO2 catalyst exhibits the best catalytic activity (T50 = 194°C, T90 = 215°C, Ea = 57.2 kJ/mol, reaction rate 8.40 × 10?10 mol/(sec?m2) at 210°C. T50 and T90: the temperature of 50% and 90% toluene conversion; Ea: apparent activation energy) and possess high tolerance against 2.0 vol.% water vapor. Results reveal that the increased acidic sites of the MnO2 sample can enhance the adsorption of gaseous toluene, and the mobility of oxygen species and the content of reactive oxygen species in the catalyst are significantly improved due to the formed oxygen vacancy. Thus these two factors result in excellent catalytic performance for toluene oxidation combining with the weak CO2 adsorption ability. 相似文献
290.
Heart rot is a common soil-borne disease in the pineapple industry, but the situation can be alleviated by the application of bio-fertilizers with beneficial microbiomes. Clarifying the controlling mechanism of bio-organic fertilizer on the high incidence of heart rot is critical in monocultural pineapple cropping patterns. In our study, the soil of continuous cropping pineapple orchards was collected. Three types of carriers (rapeseed cake, peat soil, and coconut bran), biocontrol strains (Bacillus subtilis HL2 and Streptomyces strain HL3), and organic fertilizer (YJ) were composted into different bio-fertilizers (KC, KN, KY, LC, LN, and LY), which were used in pot experiments. The controlling effect of the bio-fertilizer was determined based on the response of pineapple heart rot and bacterial communities to different fertilizing methods. Our results revealed that the incidence of heart rot in bio-fertilizer KC was the lowest, which decreased by 20% and 13.3%, respectively, compared to HF (chemical fertilizer, 16-16-16) and YJ (organic fertilizer). The richness and diversity of soil bacterial communities in all biofertilized treatments (KC, KN, KY, LC, LN, and LY) were significantly higher than those in HF. However, the α-diversity indices of the bio-fertilizers (KC, KN, and KY) were higher than those of LC, LN, and LY, and the bacterial community composition was significantly different. The bacteria GP4, GP6, Bacillus, and Azohydromonas were enriched in KC, KN, and KY, while the relative abundance of Streptomyces increased significantly in LC, LN, and LY. Furthermore, Spearman correlation analysis showed that the relative abundance of these bacterial groups was significantly negatively correlated with the incidence of pineapple heart rot. In summary, the application of bio-organic fertilizers can decrease the incidence of pineapple heart rot by altering the soil bacterial community structure and stimulating beneficial soil microorganisms, which is important for reconstructing the ecological balance in continuous pineapple orchards. © 2022 Authors. All rights reserved. 相似文献