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841.
The formation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs) from carbon that was produced by the pyrolysis of paper fibers and from
wood charcoal was investigated experimentally. Fibers obtained from filter paper were pyrolyzed at 300° and 800°C to produce
low- and high-temperature carbon samples. The two types of carbon and wood charcoal were mixed with silica (SiO2) and trace copper oxide to produce three synthetic fly ash samples. Experiments to measure the formation of PCCDs/Fs from
the three ash samples were conducted using a bench-scale reactor. The two carbon samples derived from paper fibers generated
more PCDDs/Fs than was generated by the wood charcoal. The PCDDs/Fs generated by the low-temperature carbon and by the wood
charcoal were dominated by the lower-chlorinated PCDFs. Such unique homologue distribution patterns are very similar to those
generated by the open burning of household waste. The high-temperature carbon generated more highly chlorinated PCDDs/Fs.
The effect of pyrolysis temperature on the de novo formation of PCDDs/Fs from residual carbon is discussed. Paper and paper
products contained in household waste are likely to be the source of unburned carbon that contributes to high PCDD/F emissions
in the open burning of household waste. 相似文献
842.
In this study, we examined the role of organizational level as a moderator of the relationships of procedural and distributive justice with seven employee attitudes and behaviors. Based on social identity and resource allocation theories, we suggested an allocational model of authority in organizations. We posited that lower rank encourages a more process‐oriented perspective that emphasizes procedural concerns while higher rank imbues a more result‐oriented perspective that emphasizes distributive outcomes. We considered the cultural context that characterized work relationships in our sample of respondents from a Chinese state‐owned enterprise. Significant sets of interactions supported the predicted relationships of procedural justice with three outcomes at lower levels and distributive justice with four outcomes at higher levels. Implications and extensions of these findings are considered. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
843.
The ability of bone char to adsorb three metal ions, namely, copper(II), zinc(II) and cadmium(II) ions from wastewater has been studied. Three single-component equilibrium systems and three binary equilibrium systems have been measured experimentally. The three single-component equilibrium data were analyzed using the Langmuir and the Sips equilibrium isotherm equations. The Sips isotherm gave a better fit of the experimental data than the Langmuir isotherm based on the sum of squares errors (SSE) analysis. The Cu-Zn, Cu-Cd and Cd-Zn binary equilibrium experimental data were examined by incorporating the Langmuir and the Sips isotherm equations into the ideal adsorbed solution theory (IAST). The solution methods and the predicted results for the three binary systems at different metal ion compositions have been evaluated. In addition, the application of the IAST to the model prediction for the fixed bed system is presented. 相似文献
844.
The effect of cadmium on stage II naupliar larvae of barnacle (Balanus amphitrite Darwin) was investigated. Barnacle larvae were exposed to 0-15 microM CdCl(2) for 24 h. Apoptotic cells were stained by the terminal deoxyribonucleotidyl transferase mediated dUTP nick end labelling (TUNEL) method. Incidence of apoptosis, as measured by numbers of animals with ectopic pattern of apoptosis as well as numbers of apoptotic cells per animal, was assessed using confocal microscopy. An increase in incidence of apoptosis was observed in the experimental animals with an increase in cadmium concentration. Mortality increased, and motility decreased, when barnacle larvae were exposed to an increasing concentration of cadmium. The relationship between the occurrence of apoptosis and swimming behaviour was investigated in larvae exposed to 10 microM CdCl(2). Significant increases in apoptosis were detected in the non-motile and dead nauplii. This study suggested that whole-mount in situ TUNEL method may be used to study increased occurrence of apoptotic cells in crustacean larvae. 相似文献
845.
846.
847.
流动注射在线预富集-火焰原子吸收法测定水样中Cr(Ⅵ)* 总被引:5,自引:0,他引:5
用二乙基硫代氨基磺酸钠(NaDDTC)作为螯合剂的流动注射在线配合C18固相萃取预富集联用火焰原子吸收测定体系,在线分离测定水体中的Cr(Ⅵ),分析试样速率为50个/h,对含Cr(Ⅵ)0.02mg/L和0.15mg/L的标准 溶液进行8次平行测定,其相对标准偏差分别为6.90%和2.18%,相对误差为2.11%-4.75%,方法检测限为4.92ug/L。富集时间为40s,与直接进样比较,灵敏度提高8倍。Cr(Ⅲ)的含量即使达到10mg/L也不影响测定。 相似文献
848.
陈春 《湖南环境生物职业技术学院学报》2008,14(3):83-85
随着知识经济的发展,要求医学图书馆员必须具备较深的相关学科专业知识,知识创新的能力和较高的外语水平,同时要能熟练应用现代信息技术,论述了医学图书馆员核心竞争力的概念、内涵及新形势对馆员核心能力的基本要求,提出了培养医学图书馆员核心能力的途径.参5. 相似文献
849.
基于主成分分析的全国建设用地集约度评价 总被引:4,自引:0,他引:4
建设用地的集约利用是一个基于时空尺度的动态概念.首先了解了1996-2005年期间全国建设用地变化的大背景,然后以全国各省、市、自治区2005年建设用地数据、各种社会经济数据为基础,在总结前人研究的基础上,构建了全国建设用地集约利用评价体系,采用主成分分析的方法,确定了各省、市、自治区建设用地的集约分值,根据标准确定了各自的集约度水平,结合ArcGis将评价结果空间化,进一步分析了集约度的空间差异.针对不同的集约度区域提出了针对性的意见,为区域建设用地集约利用提供指导,促进经济发展.研究结果表明,(1)全国建设用地数量在持续上升,增长率呈现波浪状;(2)建没用地的集约度在空间上存在差异,东部沿海地区的集约度水平要高于中部和西部地区;(3)环境的可持续发展指标是考核建设用地集约利用的重要因素;(4)利用主成分分析的方法在结果评价时比较客观、全面,同时可以很方便地确定权重系数. 相似文献
850.