全文获取类型
收费全文 | 2677篇 |
免费 | 185篇 |
国内免费 | 1172篇 |
专业分类
安全科学 | 211篇 |
废物处理 | 152篇 |
环保管理 | 180篇 |
综合类 | 1688篇 |
基础理论 | 477篇 |
污染及防治 | 990篇 |
评价与监测 | 138篇 |
社会与环境 | 93篇 |
灾害及防治 | 105篇 |
出版年
2024年 | 4篇 |
2023年 | 61篇 |
2022年 | 156篇 |
2021年 | 120篇 |
2020年 | 110篇 |
2019年 | 95篇 |
2018年 | 121篇 |
2017年 | 133篇 |
2016年 | 144篇 |
2015年 | 164篇 |
2014年 | 232篇 |
2013年 | 297篇 |
2012年 | 245篇 |
2011年 | 225篇 |
2010年 | 177篇 |
2009年 | 187篇 |
2008年 | 199篇 |
2007年 | 177篇 |
2006年 | 156篇 |
2005年 | 123篇 |
2004年 | 87篇 |
2003年 | 100篇 |
2002年 | 78篇 |
2001年 | 92篇 |
2000年 | 75篇 |
1999年 | 87篇 |
1998年 | 70篇 |
1997年 | 45篇 |
1996年 | 45篇 |
1995年 | 64篇 |
1994年 | 42篇 |
1993年 | 35篇 |
1992年 | 25篇 |
1991年 | 21篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1976年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有4034条查询结果,搜索用时 31 毫秒
31.
A polyaluminum containing a high concentration of Al13 polymer and active chlorine (PACC) was successfully synthesized by a new electrochemical reactor using Ti/RuO2-TiO2 anodes. PACC can potentially be used as a dual-function chemical reagent for water treatment. The obtained results indicated that the formation of Al13 polymer and active chlorine, were the most active components in PACC responsible for coagulation and disinfection respectively. These components were significantly influenced by electrolyte temperature, current density, and stirring rate. It was observed that high electrolyte temperature favored the formation of Al13. Increasing current density and stirring rate resulted in high current efficiency of chlorine evolution, thus favoring the generation of Al13 and active chlorine in PACC. When the PACC (AlT = 0.5 mol/L, basicity = 2.3) was prepared at the optimum conditions by electrolysis process, the Al13 polymer and active chlorine in product reached above 70% of AlT and 4000 mg/L, respectively. In the pilot scale experiment with raw polyaluminum chloride used as an electrolyte, PACC was successfully prepared and produced a high content of Al13 and active chlorine products. The pilot scale experiment demonstrated a potential industrial approach of PACC preparation. 相似文献
32.
Guanjie Jiang Yonghong Liu Li Huang Qingling Fu Youjun Deng Hongqing Hu 《环境科学学报(英文版)》2012,24(5):919-925
Lead (Pb) chemical fixation is an important environmental aspect for human health. Phosphate rocks (PRs) were utilized as an adsorbent to remove Pb from aqueous solution. Raw PRs and oxalic acid-activated PRs (APRs) were used to investigate the effect of chemical modification on the Pb-binding capacity in the pH range 2.0-5.0. The Pb adsorption rate of all treatments above pH 3.0 reached 90%. The Pb binding on PRs and APRs was pH-independent, except at pH 2.0 in activated treatments. The X-ray diffraction analysis confirmed that the raw PRs formed cerussite after reacting with the Pb solution, whereas the APRs formed pyromorphite. The Fourier Transform Infrared spectroscopy analysis indicated that carbonate (CO32-) in raw PRs and phosphate (PO43-) groups in APRs played an important role in the Pb-binding process. After adsorption, anomalous block-shaped particles were observed by scanning electron microscopy with energy dispersive spectroscopy. The X-ray photoelectron spectroscopy data further indicated that both chemical and physical reactions occurred during the adsorption process according to the binding energy. Because of lower solubility of pyromorphite compared to cerussite, the APRs are more effective in immobilizing Pb than that of PRs. 相似文献
33.
34.
Differences in nitrous oxide fluxes from red soil under different land uses in mid-subtropical China 总被引:1,自引:0,他引:1
Shan LinJaved Iqbal Ronggui Hu Leilei RuanJinshui Wu Jinsong ZhaoPengju Wang 《Agriculture, ecosystems & environment》2012,146(1):168-178
Red soil may play an important role in nitrous oxide (N2O) emissions due to its recent land use change pattern. To predict the land use change effect on N2O emissions, we examined the relationship between soil N2O flux and environmental determinants in four different types of land uses in subtropical red soil. During two years of study (January 2005-January 2007), biweekly N2O fluxes were measured from 09:00 to 11:00 a.m. using static closed chamber method. Objectives were to estimate the seasonal and annual N2O flux differences from land use change and, reveal the controlling factors of soil N2O emission by studying the relationship of dissolved organic carbon (DOC), microbial biomass carbon (MBC), water filled pore space (WFPS) and soil temperature with soil N2O flux. Nitrous oxide fluxes were significantly higher in hot-humid season than in the cool-dry season. Significant differences in soil N2O fluxes were observed among four land uses; 2.9, 1.9 and 1.7 times increased N2O emissions were observed after conventional land use conversion from woodland to paddy, orchard and upland, respectively. The mean annual budgets of N2O emission were 0.71-2.21 kg N2O-N ha−1 year−1 from four land use types. The differences were partly attributed to increased fertilizer use in agriculture land uses. In all land uses, N2O fluxes were positively related to soil temperature and DOC accounting for 22-48% and 30-46% of the seasonal N2O flux variability, respectively. Nitrous oxide fluxes did significantly correlate with WFPS in orchard and upland only. Nitrous oxide fluxes responded positively to MBC in all land use types except orchard which had the lowest WFPS. We conclude that (1) land use conversion from woodland to agriculture land uses leads to increased soil N2O fluxes, partly due increased fertilizer use, and (2) irrespective of land use, soil N2O fluxes are under environmental controls, the main variables being soil temperature and DOC, both of which control the supply of nitrification and denitrification substrates. 相似文献
35.
沁河流域水体污染物时空分异特征及潜在污染源识别 总被引:12,自引:4,他引:8
应用多种多元统计方法对晋城市沁河流域2005—2010年的水质数据(11个监测断面、24个水质指标)进行时空分异特征分析及潜在污染源识别.将聚类分析与判别分析相结合,在空间尺度上识别出重污染区和轻污染区,在时间尺度上识别出水质的年内差异性,揭示并探讨河流水质对降雨延迟的响应现象,进而将时间及空间聚类分析结果有机结合,开展时空联合分析与因子分析,有针对性地进行污染源识别.结果表明,监测断面可分成2类:A组(4个断面)及B组(其余7个断面),其中,丹河污染程度重于沁河,应当作为流域污染控制的重点;全年可分为2个时段:时段Ⅰ(7—11月)和时段Ⅱ(其它月份),时段Ⅰ水质略优于时段Ⅱ,流域面源污染或内源污染较严重;A组的典型污染指标共12项,分别为重金属、有机物、有毒有机物和其他污染物,主要来自于工业点源;B组的典型污染指标共11项,分别为重金属、有机物和生物指标,主要来自于工业和生活点源、生活和农业面源. 相似文献
36.
作为人地关系中"地"对"人"负面作用的核心学科——灾害风险学存在着显著的地理空间尺度差异与尺度效应。本文提出灾害风险尺度耦合的概念与类型,从数据、方法和区划三个方面提出灾害风险研究中的空间降尺度和空间升尺度耦合思路,供同行学者参考。 相似文献
37.
38.
为了科学地设定滩槽易变河段处的桥梁跨径布置方案,针对荆州长江大桥桥区水域河床演变影响通航安全的问题,采用实例调研及历史资料分析的方法,指出滩槽易变河段选址建设的桥梁,其最大风险是滩槽移位导致船舶从通航孔位置移动到非通航孔位置,提出新建桥梁通航孔布置应覆盖深泓和可能成为航道的深槽的摆动范围;根据提出的原则研究拟建的李埠桥区水域的河床演变机制,选定最低通航水位下3.5 m深槽和深泓的摆动范围作为桥跨布置的依据;最终确定的1 120 m桥跨布置方案能够保障河床影响下拟建李埠长江大桥的通航安全。 相似文献
39.
为提升V-Mo/Ti催化剂的脱硝性能,在催化剂制备过程中调节浸渍工艺参数,制备了一系列不同浸渍液pH值的催化剂,采用XRD、N2-吸附脱附、拉曼光谱、UV-Vis、H2-TPR、NH3-TPD等手段对催化剂进行表征,考察了pH值的变化对催化剂物理化学性能的影响,采用固定床微型反应器对催化剂的脱硝性能进行评价。结果表明,降低浸渍液pH值,可以抑制催化剂上VOx物种的聚合,提升催化剂的还原性能,有利于提升催化剂的脱硝效率,降低脱硝反应过程中N2O生成量。同时,浸渍液pH值的变化,也会影响催化剂的酸性性能。当浸渍液pH值低于3.64时,催化剂酸性性能显著降低,造成催化剂脱硝性能降低;当浸渍液pH值控制在3.64时,催化剂的还原性能和酸性性能匹配较好,从而显示了较高的脱硝性能。 相似文献
40.
天津主要纳污及入海河流中有机氯农药的污染现状及特征 总被引:4,自引:0,他引:4
对天津地区永定新河、北排污河和大沽排污河表层水、悬浮物、间隙水样品中的六六六、滴滴涕、七氯等13种有机氯农药进行了分析检测.结果表明,河流中有机氯农药的高污染区主要为天津几大化工厂附近河段,而纪庄子污水处理厂的出水对大沽排污河中的七氯等有机氯农药的含量有所贡献.样品t检验分析表明,秋季和冬季河流中有机氯农药的来源不存在重大差异.不同介质中有机氯农药的组成特征不同,表层水中主要以溶解性较大的六六六为主,而悬浮物中则以滴滴涕、七氯、环氧七氯和异狄氏剂为主.3条河流中的4种不同HCHs异构体以β-HCH的比例最大,说明河流中的HCHs的存在主要是来自于历史遗留;而DDT/DDE和DDT/∑DDTs的比值高于0.5说明近期存在新的DDT使用. 相似文献