全文获取类型
收费全文 | 1088篇 |
免费 | 150篇 |
国内免费 | 551篇 |
专业分类
安全科学 | 112篇 |
废物处理 | 203篇 |
环保管理 | 82篇 |
综合类 | 944篇 |
基础理论 | 202篇 |
污染及防治 | 191篇 |
评价与监测 | 49篇 |
社会与环境 | 5篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 16篇 |
2022年 | 35篇 |
2021年 | 43篇 |
2020年 | 39篇 |
2019年 | 43篇 |
2018年 | 47篇 |
2017年 | 45篇 |
2016年 | 59篇 |
2015年 | 72篇 |
2014年 | 104篇 |
2013年 | 107篇 |
2012年 | 111篇 |
2011年 | 76篇 |
2010年 | 61篇 |
2009年 | 82篇 |
2008年 | 56篇 |
2007年 | 85篇 |
2006年 | 104篇 |
2005年 | 76篇 |
2004年 | 62篇 |
2003年 | 59篇 |
2002年 | 62篇 |
2001年 | 58篇 |
2000年 | 43篇 |
1999年 | 46篇 |
1998年 | 36篇 |
1997年 | 23篇 |
1996年 | 34篇 |
1995年 | 19篇 |
1994年 | 29篇 |
1993年 | 15篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有1789条查询结果,搜索用时 781 毫秒
321.
负载型燃烧催化剂La_(0.8)Ce_(0.2)CoO_3/Ce_(0.8)Zr_(0.2)O_2制备及性能研究 总被引:1,自引:0,他引:1
以复合氧化物La0.8Ce0.2CoO3为活性组分,Ce0.8Zr0.2O2固溶体为载体,采用柠檬酸络合法制备出负载型燃烧催化剂La0.8Ce0.2CoO3/Ce0.8Zr0.2O2。用XRD、BET和SEM对其进行表征,考察了焙烧温度、反应时间、反应温度及H2S存在对催化剂活性的影响。结果表明,载体表面形成了均一的钙钛矿相;该负载型催化剂对二甲苯完全氧化反应具有较高的催化活性,有良好的热稳定性、操作稳定性和强的抗H2S毒化能力。这可能是载体与负载组分之间密切的协同作用所导致。 相似文献
322.
Oxidation inhibition of sulfite in dual alkali FGD system 总被引:1,自引:0,他引:1
MO Jian-song WU Zhong-biao CHENG Chang-jie GUAN Bao-hong ZHAO Wei-rong 《环境科学学报(英文版)》2007,19(2):226-231
A laboratory-scale well-mixed thermostatic reactor with continuously blasting air was used to investigate the oxidation inhibition of sulfite in dual alkali flue gas desulfurization (FGD) system. The effects of operating parameters such as pH value and catalyst concentration on the oxidation were studied. Sodium thiosulfate was used in the system, and was found that it significantly inhabited the sulfite oxidation. In the absence of catalyst, sodium thiosulfate at 12.67 mmol/L had an inhibition efficiency of approximately 98%. While in the presence of catalyst, sodium thiosulfate at 26.72 mmol/L had an inhibition efficiency less than 85.0%. The oxidation reaction order of sulfite in the sodium thiosulfate was determined to be -1.90 and 4).55 in the absence and presence of the catalyst, respectively. Apparent activation energy of oxidation inhibition was calculated to be 53.9 kJ/mol. Pilot tests showed that the consumption rate of thiosulfate agreed well with the laboratory-scale experimental results. 相似文献
323.
废FCC催化剂对水中铅离子的连续吸附及脱附 总被引:1,自引:0,他引:1
通过测定吸附等温线,考察了Pb2+在废FCC(流化催化裂化)催化剂上的吸附性能及规律,结果表明,Pb2+在废FCC催化剂上的吸附规律可用Langmuir和Frundlich模式描述,吸附呈单分子层形式且容易进行。又通过填充床吸附试验,对Pb2+的连续吸附及脱附情形作了考察。结果表明,在温度为15℃、pH为5.13、过柱速率为3.0mL/min、径高比为2.25.0条件下,吸附柱具备适宜的生产周期,连续吸附操作可行,柱效率可达75.9%;在温度为15℃、采用2mol/L稀盐酸作脱附剂,过柱速率为5.0mL/min的条件下,吸附剂易于脱附再生,脱附效率可达78.1% 相似文献
324.
二氧化硫和硫酸盐是硫的重要存在形式,是影响环境空气质量的重要大气污染物.硫酸盐气溶胶是影响全球气候变化的重要大气组分,大气中的硫酸盐气溶胶生命周期短,其浓度空间差异大、时间变化显著.在区域尺度乃至全球尺度研究其迁移转化和区域交叉影响,具有十分重要的科学意义.本研究以2010年SO_2全球排放清单为基础,应用国际通用大气化学模式(Mozart-4),模拟全球大气硫的迁移转化及其季节变化和空间分布特征,并分析全球不同区域间的交叉影响.结果表明:1SO_2柱浓度全球年均值为424.73μg S·m~(-2),中东及南亚最高,达3629.27μg S·m~(-2),南美最低,为181.06μg S·m~(-2).2硫酸盐柱浓度全球年均值为1572.86μg S·m~(-2),东亚年均硫酸盐柱浓度最高,达4556.58μg S·m~(-2),南美最低,为1014.33μg S·m~(-2).3冬季SO_2柱浓度高于其他春夏秋3季,夏季硫酸盐柱浓度高于冬季,主要是由于冬季低温使SO_2不易转化为硫酸盐.4硫酸盐表现出明显的全球迁移特征,全球各区域间交叉影响显著.东亚的净输出量最大,达4.01 Tg S·a~(-1).非洲、中亚及俄罗斯硫酸盐柱浓度的外源影响比例分别高达80.54%和73.00%. 相似文献
325.
326.
Voltammetric curve studies on aqueous Na2S solution in the presence of three types of surfactants are presented. Presence of anodic surfactant (HTAB) in creases anode current density and makes the corresponding anode peak potential shift to more negative. Potentials of the reduction of elemental sulfur to intermediates Sx2-shift to more negative with the increasing of HTAB concentrations. In the presence of HTAB, the anode current density at 77oC increases more than at 34oC. The electrolysis indicates that anodic product sulfur loosely adhered to the graphite electrode surface when HTAB is added to the anolyte. The total efficiency of producing sulfur is high after several times of cycle electrolysis.The results show that anode passivation is minimized in the presence of HTAB. The depassivation effect of HTAB is discussed. 相似文献
327.
XIE Jian-jun YANG Xue-min ZHANG Lei DING Tong-li SONG Wen-li LIN Wei-gang 《环境科学学报(英文版)》2007,19(1):109-116
This paper presents the experimental investigations of the emissions of SO2, NO and N2O in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The influence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N2O were proposed. 相似文献
328.
329.
V2O5/TiO2催化剂中毒机理的试验研究 总被引:1,自引:0,他引:1
选择性催化还原(SCR)催化剂是SCR烟气脱硝技术的核心,是整个SCR系统脱硝效率和经济性的决定因素.本文工作的主要研究思路是以钒钛SCR催化剂为研究对象,研究了H2O和SO2,以及相同含量下K、Na、Ca、Pb的氧化物对钒钛催化剂NO转化率的影响.H2O的存在会抑制V2O5/TiO2催化剂脱硝活性,而SO2在一定程度上促进(V2O5/TiO2)催化剂的SCR脱硝反应,提高NO转化率;碱金属K对钒钛催化剂的钝化作用都是最强,K2O和Na2O的掺入会抑制钒钛催化剂上V2O5的还原能力,而CaO和PbO的掺入对钒钛催化剂上V2O5的还原能力影响较小. 相似文献
330.
A series of WO3/CeO2 (WOx/CeO2) catalysts were synthesized by wet impregnation of ammonium metatungstate on a CeO2 support. The resulting solid acid catalysts were characterized by X-ray diffraction (XRD), UV-Vis spectroscopy (UV-Vis), Raman spectroscopy (Raman), in-situ Fourier transform infrared spectroscopy (in-situ FT-IR) of ammonia adsorption, NH3-TPD, H2 temperature-programmed reduction (H2-TPR), NH3/NO oxidation and activity measurements for NOx reduction by NH3 (NH3-SCR). The results show that polytungstate (WOx) species are the main species of tungsten oxide on the surface of ceria. The addition of tungsten oxide enhances the Brönsted acidity of ceria catalysts remarkably and decreases the amount of surface oxygen on ceria, with strong interaction between CeO2 and WOx. As a result, the N2 selectivity of NH3 oxidation and NH3-SCR at high temperatures (> 300℃) is enhanced. Therefore, a wide working temperature window in which NOx conversion exceeds 80% (NOx conversion > 80%) from 200 to 450℃, is achieved over 10 wt.% WOx/CeO2 catalyst. A tentative model of the NH3-SCR reaction route on WOx/CeO2 catalysts is presented. 相似文献