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711.
Response of successive three generations of cotton bollworm, Helicoverpa
armigera (Hübner), fed on cotton bolls under elevated CO2 总被引:1,自引:0,他引:1
The growth, development and consumption of successive three generations of cotton bollworm, Helicoverpa armigera (Htibner), fed on cotton bolls grown under elevated CO2 (double-ambient vs. ambient) in open-top chambers were examined. Significant decreases in protein, total amino acid, water and nitrogen content and increases in free fatty acid were observed in cotton bolls. Changes in quality of cotton bolls affected the growth, development and food utilization of H. armigera. Significantly longer larval development duration in three successive generations and lower pupal weight of the second and third generations were observed in cotton bollworm fed on cotton bolls grown under elevated CO2. Significantly lower fecundity was also found in successive three generations of H. armigera fed on cotton bolls grown under elevated CO2. The consumption per larva occurred significant increase in successive three generations and frass per larva were also significantly increased during the second and third generations under elevated CO2. Significantly lower relative growth rate, efficiency of conversion of ingested food and significant higher relative consumption rate in successive three generations were observed in cotton bollworm fed on cotton bolls grown under elevated CO2. Significantly lower potential female fecundity, larval numbers and population consumption were found in the second and third generations of cotton bollworm fed on cotton bolls grown under elevated CO2. The integrative effect of higher larval mortality rate and lower adult fecundity resulted in significant decreases in potential population consumption in the latter two generations. The results show that elevated CO2 adversely affects cotton bolls quality, which indicates the potential population dynamics and potential population consumption of cotton bollworm will alleviate the harm to the plants in the future rising CO2 atmosphere. 相似文献
712.
In order to investigate the feasibility of sequential removal NO and SO_2 using non-thermal plasma and adsorbent simultaneously,the removal of NO and SO_2 from dry gas stream(NO/SO_2/N_2/O_2)with very little O_2 using non-thermal plasma was investigated using a coaxial dielectric barrier discharge.Comparative experiments were carried out in the dry gas stream with and without Ar respectively at O_2 concentration of 0.1%.The results showed that NO could be removed remarkably and it would be enhanced in the presence of Ar in the dry gas stream.It seems that SO_2 could not be removed unless there is Ar in the dry gas stream.The mechanism of removal of NO and SO_2 in the dry gas stream was discussed. 相似文献
713.
第二代农民工及其市民化研究 总被引:39,自引:0,他引:39
农民工市民化是基于乡城劳动力两阶段转移的“中国路径”而提出的现实课题。第二代农民工不仅是一个在社会经济特征和个人特征方面与第一代农民工有着诸多显警不同的流动群体。而且也是最有市民化意愿和亟需市民化的群体。基于现有理论的局限性和中国特殊的现实提出了农民工市民化的命题并深入探讨了其内涵。进而在此基础上考察了第二代农民工的特征、第二代农民工的市民化进程及其面临的挑战。最后就第二代农民工市民化的进程环节和制度创新提出了针对性的对策建议。 相似文献
714.
715.
基于87台中小型燃烟煤层燃炉(£70MW)的燃料特性分析数据和SO2排放实测数据,研究了锅炉出力、过量空气系数、燃煤硫含量对燃烧过程中SO2初始排放浓度的影响,分析了燃煤锅炉SO2排放现状,讨论了我国中小型燃煤锅炉SO2排放管理控制的潜力和可行性.结果表明,在锅炉运行负荷³80%的条件下,SO2初始排放浓度与燃煤硫含量之间具有显著的线性相关性,与锅炉出力和过量空气系数无关;分别有94%和87%的实测锅炉可以满足国家现行排放标准规定的第I和第II时段SO2最高允许排放浓度. 相似文献
716.
Flue gas from coal combustion contains significant amounts of volatile selenium (Se). The capture of Se in the flue gas desulfurization
(FGD) scrubber unit has resulted in a generation of metal-laden residues. It is important to determine Se speciation to understand the
environmental impact of its disposal. A simple method has been developed for selective inorganic Se(IV), Se(VI) and organic Se
determination in the liquid-phase FGD residues by hydride generation atomic fluorescence spectrometry (AFS). It has been determined
that Se(IV), Se(VI) and organic Se can be accurately determined with detection limits (DL) of 0.05, 0.06 and 0.06 g/L, respectively.
The accuracy of the proposed method was evaluated by analyzing the certified reference material, NIST CRM 1632c, and also by
analyzing spiked tap-water samples. Analysis indicates that the concentration of Se is high in FGD liquid residues and primarily exists
in a reduced state as selenite (Se(IV)). The toxicity of Se(IV) is the strongest of all Se species. Flue gas desulfurization residues pose a
serious environmental risk. 相似文献
717.
为了探究亚硝酸盐生成方式对短程硝化反硝化除磷颗粒系统的影响,采用2组同规格SBR反应器分别在连续和间歇曝气方式下使亚硝酸盐连续生成和间歇生成,考察其运行过程中脱氮除磷效果、污泥物理特性和微生物群落结构.结果表明,亚硝酸盐间歇生成后随即消耗,具有更好和更稳定的脱氮除磷性能,特别在TN去除上,第72 d后TN平均去除率为92.07%.碳源利用效率(以P/COD计)集中在0.21~0.22mg·mg-1,碳源利用充分,进一步促进反硝化除磷.颗粒粒径分布集中,大小均匀,具有规则的形状和清晰的边界.微生物群落分析表明,亚硝酸盐间歇生成的系统微生物群落丰富度和多样性更高,同时富集了更多DPAOs菌属(Dechloromonas和Pseudomonas),与Nitrosomonas共同作用使短程硝化与反硝化除磷达到动态平衡,实现系统稳定运行. 相似文献
718.
提高突发事件应急处置效率是保障公路交通安全服务水平的关键问题之一。在充分研究突发事件应急救援机制、预案管理及信息采集和共享机制的基础上,分析应急管理与服务的基本需求,以信息处理为主线,设计公路突发事件应急预案自动生成系统的主要功能及架构,包括应急预案管理、预案评估分析、预案自动生成与优化等3大功能,系统基于CBR技术开发,并通过实例验证了系统的可行性。通过对智能管理、辅助决策等功能的强化,进一步明确信息与公路突发事件应急管理及服务间的逻辑与业务关系,有利于进一步提升整体公路交通安全服务水平。 相似文献
719.
本文利用氢化物发生-原子荧光光谱法分析技术测定土壤中的总汞,样品用(1+1)的王水试剂在沸水浴中加热消解,最后经离心分离处理,取上清液待测。该方法检出限为0.002μg/kg,测定上限为0.400 mg/kg。 相似文献
720.
Heavy metal distribution and chemical speciation in tailings and soils around a Pb-Zn mine in Spain 总被引:17,自引:0,他引:17
Rodríguez L Ruiz E Alonso-Azcárate J Rincón J 《Journal of environmental management》2009,90(2):1106-1116
Soil pollution by lead, zinc, cadmium and copper was characterized in the mine tailings and surrounding soils (arable and pasture lands) of an old Spanish Pb-Zn mine. Sixty soil samples were analyzed, determining the total metal concentration by acid digestion and the chemical fractionation of Pb and Zn by the modified BCR sequential extraction method. Samples belonging to mine waste areas showed the highest values, with mean concentrations of 28,453.50 mg kg(-1) for Pb, 7000.44 mg kg(-1) for Zn, 20.57 mg kg(-1) for Cd and 308.48 mg kg(-1) for Cu. High concentrations of Pb, Zn and Cd were found in many of the samples taken from surrounding arable and pasture lands, indicating a certain extent of spreading of heavy metal pollution. Acidic drainage and wind transport of dust were proposed as the main effects causing the dispersion of pollution. Sequential extraction showed that most of the Pb was associated with non-residual fractions, mainly in reducible form, in all the collected samples. Zn appeared mainly associated with the acid-extractable form in mine tailing samples, while the residual form was the predominant one in samples belonging to surrounding areas. Comparison of our results with several criteria reported in the literature for risk assessment in soils polluted by heavy metals showed the need to treat the mine tailings dumped in the mine area. 相似文献