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Fabrice Cazier Paul Genevray Dorothée Dewaele Habiba Nouali Anthony Verdin Frédéric Ledoux Adam Hachimi Lucie Courcot Sylvain Billet Saâd Bouhsin Pirouz Shirali Guillaume Garçon Dominique Courcot 《环境科学学报(英文版)》2016,28(6):45-56
Atmospheric aerosol samples(PM_(2.5–0.3), i.e., atmospheric particles ranging from 0.3 to2.5 μm) were collected during two periods: spring–summer 2008 and autumn–winter 2008–2009, using high volume samplers equipped with cascade impactors. Two sites located in the Northern France were compared in this study: a highly industrialised city(Dunkirk) and a rural site(Rubrouck). Physicochemical analysis of particulate matter(PM) was undertaken to propose parameters that could be used to distinguish the various sources and to exhibit seasonal variations but also to provide knowledge of chemical element composition for the interpretation of future toxicological studies. The study showed that PM2.5–0.3concentration in the atmosphere of the rural area remains stable along the year and was significantly lower than in the urban or industrial ones, for which concentrations increase during winter.High concentrations of polycyclic aromatic hydrocarbons(PAHs), dioxins, furans and dioxin like polychlorinated biphenyls(DL-PCBs), generated by industrial activities, traffic and municipal wastes incineration were detected in the samples. Specific criteria like Carbon Preference Index(CPI) and Combustion PAHs/Total PAHs ratio(CPAHs/TPAHs) were used to identify the possible sources of atmospheric pollution. They revealed that paraffins are mainly emitted by biogenic sources in spring–summer whereas as in the case of PAHs, they have numerous anthropogenic emission sources in autumn-winter(mainly from traffic and domestic heating). 相似文献
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为探讨高浓度臭氧(O_3)对气溶胶生成与老化过程的影响,本研究利用单颗粒气溶胶质谱仪(SPAMS)于2018年10月在广东省鹤山大气环境超级监测站进行观测.观测期间根据O_3浓度的高低,定义了高臭氧浓度(P_H)时段和低臭氧浓度(P_L)时段,其中P_H时段O_3平均浓度为117μg·m~(-3),P_L时段平均浓度为25μg·m~(-3).依据化学组成的不同,观测期间单颗粒主要包含老化元素碳颗粒(EC-aged)、二次颗粒(Sec)和老化有机碳颗粒(OC-aged).P_H时段单颗粒总数(348 085)高于P_L时段(224 797),且P_H时段Sec颗粒(37.1%)的占比显著高于P_L时段(27.8%),而EC-aged颗粒(32.1%)则低于P_L时段(44.1%),OC-aged颗粒(13.5%)略高于P_L时段(10.4%).含硝酸盐(nitrate)和硫酸盐(sulfate)的颗粒数浓度在P_H时段有显著的昼夜变化,而在P_L时段无昼夜变化,Sec颗粒和EC-aged颗粒中硝酸盐和硫酸盐的峰面积P_H时段高于P_L时段,表明在P_H时段通过二次反应过程生成硝酸盐和硫酸盐的量多于P_L时段.此外,Sec颗粒中硝酸盐和硫酸盐的峰面积显著高于EC-aged颗粒,表明Sec颗粒的老化程度更深.本研究选取了乙酸根(~(59)CH_3CO~-_2)和乙二醛(~(73)C_2HO~-_3)来代表醛酮化合物在单颗粒气溶胶中的变化特征.P_H时段Sec和OC-aged颗粒中~(59)CH_3CO~-_2和~(73)C_2HO~-_3的数浓度与峰面积显著高于P_L时段,且在P_H时段呈现显著的日变化特征,峰值出现在O_3浓度高峰后2 h,在P_L时段峰值显著降低,该变化趋势与Sec和OC-aged颗粒的数浓度变化特征相同,表明高浓度O_3有利于VOCs氧化生成~(59)CH_3CO~-_2和~(73)C_2HO~-_3.综上,高臭氧浓度时段光化学反应较强,二次气溶胶组分的含量显著增加,光化学反应增强是P_H时段臭氧浓度升高和单颗粒中二次组分增加的主要原因. 相似文献
524.
广州城区秋季大气PM_(2.5)中主要水溶性无机离子分析 总被引:1,自引:1,他引:1
分别在广州市中心城区高楼顶(距地50m)和交通干线路边(距地1.2m),于2006年秋季连续一周采集了大气PM2.5样品,对比分析了SO42-、NO3-、Cl-、F-、Na+、NH4+、Ca2+、K+、Mg2+等9种水溶性无机离子含量。结果表明,楼顶相对充分混合大气中PM2.5的质量浓度范围59.5~129.5μg/m3,均值为83.7μg/m3;交通干线路边大气PM2.5的质量浓度范围为108.4~132.2μg/m3,均值为121.1μg/m3。9种离子总浓度平均达到50.9(楼顶)和44.1(路边)μg/m3,占PM2.5质量浓度的60.8%(楼顶)和36.4%(路边)。SO42-和NO3-为水溶性无机离子主要组成,其占PM2.5质量浓度的比例均是楼顶高于路边,显示二次气溶胶对楼顶充分混合大气中PM2.5有较大贡献,而路边样品中一次来源贡献相对较大。计算表明采样期间海盐对广州大气PM2.5中的水溶性组分贡献较小。NH4+当量浓度远小于SO42-和NO3-的当量浓度,中和度远1,反映PM2.5酸性较强,且楼项PM2.5粒子酸性高于路边样品。 相似文献
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为提高电场对细颗粒物的捕集效率,实现颗粒物超低排放要求,本试验采用喷雾与电场分区设计,搭建了预混喷雾湿式电除尘试验装置,以增强颗粒与液滴之间的凝聚作用,试验探究了电场电压、极板间距、电场风速、喷雾压力及入口浓度等参数对除尘效率的影响规律.结果表明;除尘效率随着电场电压增加,除尘效率提升,增幅先升高后降低,最后趋于平稳;减小极板间距或电场风速,能够提高除尘效率,但降低了处理风量;随着喷雾压力增大,除尘效率先增加后减小,当压力值为6MPa时,除尘效果最佳;粉尘入口浓度对除尘效率的影响程度较低,对于粒径小于2.5μm的颗粒物去除效率最高达98.5%.综上,预混喷雾湿式电除尘效果相比单一喷雾或静电除尘具有显著的增强,对于颗粒物超低排放装置的设计具有重要参考价值. 相似文献
527.
为了解济南市大气颗粒物的粒径分布特征,于2009年10月利用多级撞击式颗粒物采样器(MOUDI)进行了大气颗粒物采集,采用离子色谱仪分析了其中水溶性离子浓度.结果表明,SO42-、NO3-、NH4+和Ca2+是主要的水溶性离子,浓度总和约占总水溶性离子浓度的92%.SO42-、NO3-、NH4+、K+和Cl-浓度随时间变化较为显著,浓度变化主要原因是受风速以及气流来源方向的影响.SO42-和NH4+主要集中在细粒子中,其浓度呈单模态分布,随着颗粒物中含量的升高其峰值从0.32~0.56 μm粒径段逐渐移动到1~1.8 μm粒径段.NO3-浓度呈双峰分布,细粒子中的NO3-随着浓度的升高峰值从0.56~1μm粒径段移动到1~1.8μm粒径段,粗粒子中的峰值出现在3.2~5.6μm粒径段. NH4+可以完全中和细粒子中的SO42-和NO3-,在细粒子中主要以(NH4)2SO4和NH4NO3的形式存在. 相似文献
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The mechanism of flow turbulence, sediment supply conditions, and sediment transport patterns that affect the adsorption of cadmium ions onto sediment particles in natural waters are experimentally simulated and studied in this study both in batch reactors and in a turbulence simulation tank. By changing the agitation conditions, the sediment transport in batch reactors can be categorized into bottom sediment-dominated sediment and suspended sediment-dominated sediment. It is found that the adsorption rate of bottom sediment is much less than that of suspended sediment, but the sediment transport pattern does not affect the final (equilibrium) concentration of dissolved cadmium. This result indicates that the parameters of an adsorption isotherm are the same regardless of the sediment transport pattern. In the turbulence simulation tank, the turbulence is generated by harmonic grid-stirred motions, and the turbulence intensity is quantified in terms of eddy diffusivity, which is equal to 9.84F(F is the harmonic vibration frequency) and is comparable to natural surface water conditions.When the turbulence intensity of flow is low and sediment particles stay as bottom sediment, the adsorption rate is significantly low, and the adsorption quantity compared with that of suspended sediment is negligible in the 6 h duration of the experiment. This result greatly favors the simplification of the numerical modeling of heavy metal pollutant transformation in natural rivers. When the turbulence intensity is high but bottom sediment persists, the rate and extent of descent of the dissolved cadmium concentration in the tank noticeably increase, and the time that is required to reach adsorption equilibrium also increases considerably due to the continuous exchange that occurs between the suspended sediment and the bottom sediment.A comparison of the results of the experiments in the batch reactor and those in the turbulence simulation tank reveals that the adsorption ability of the sediment, and in particular the adsorption rate, is greatly over-estimated in the batch reactor. 相似文献