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851.
852.
通过分析国内外研究,阐述了常规洗井和取样(以潜水泵洗井,提桶或贝勒管取样为例)过程的一些弊端,并介绍了一种国内文献中未见的方法—低流速法。该法所采得的样品在代表性方面优势更加明显,获得的数据更加准确。 相似文献
853.
Effect of orchard age on soil nitrogen transformation in subtropical China and implications 总被引:1,自引:0,他引:1
A better understanding of nitrogen transformation in soils could reveal the capacity for biological inorganic N supply and improve the efficiency of N fertilizers. In this study, a 15N tracing study was carried out to investigate the effects of converting woodland to orchard, and orchard age on the gross rates of N transformation occurring simultaneously in subtropical soils in Eastern China. The results showed that inorganic N supply rate was remained constant with soil organic C and N contents increased after converting woodland into citrus orchard and with increasing orchard age. This phenomenon was most probably due to the increase in the turnover time of recalcitrant organic-N, which increased with decreasing soil pH along with increasing orchard age significantly. The amoA gene copy numbers of both archaeal and bacterial were stimulated by orchard planting and increased with increasing orchard age. The nitrification capacity (defined as the ratio of gross rate of nitrification to total gross rate of mineralization) increased following the Michaelis–Menten equation, sharply in the first 10 years after woodland conversion to orchard, and increased continuously but much more slowly till 30 years. Due to the increase in nitrification capacity and unchanged NO3− consumption, the dominance of ammonium in inorganic N in woodland soil was shifted to nitrate dominance in orchard soils. These results indicated that the risk of NO3− loss was expected to increase and the amount of N needed from fertilizers for fruit growth did not change although soil organic N accumulated with orchard age. 相似文献
854.
三唑酮对斑马鱼和稀有鮈鲫不同生长阶段的急性毒性比较 总被引:2,自引:0,他引:2
为探明三唑酮对鱼类不同生长阶段的毒性效应,以斑马鱼和稀有鮈鲫为测试生物,检测了三唑酮对斑马鱼和稀有鮈鲫不同生长阶段的急性毒性差异。研究发现,三唑酮对斑马鱼和稀有鮈鲫胚胎为低毒,其96 h-LC50值分别为21.1(14.4~31.0)和14.2(9.65~20.9)mg·L~(-1);高浓度的三唑酮对斑马鱼和稀有鮈鲫胚胎的孵化有明显的抑制作用,染毒96 h后,23.7 mg·L~(-1)三唑酮组斑马鱼胚胎的孵化率为4.17%,22.5 mg·L~(-1)三唑酮组稀有鮈鲫胚胎的孵化率为33.3%。三唑酮对斑马鱼仔鱼、幼鱼和成鱼为低毒,其96 h-LC50值分别为24.8、21.3、13.1 mg·L~(-1),三唑酮对稀有鮈鲫仔鱼、幼鱼和成鱼为中毒,其96 h-LC50值分别为9.96、7.89、6.89 mg·L~(-1)。因此,三唑酮对斑马鱼和稀有鮈鲫不同生长阶段的毒性效应排序一致,毒性从高到低顺序依次为:成鱼幼鱼仔鱼。试验结果表明,相对于斑马鱼,稀有鮈鲫对三唑酮的毒性作用更为敏感,三唑酮对稀有鮈鲫不同生长阶段的毒性均高于斑马鱼相应生长阶段的毒性。 相似文献
855.
Li-Hong Wang Qunhui Wang Xiao Zhang Weiwei Cai Xiaohong Sun 《Journal of Material Cycles and Waste Management》2013,15(1):1-8
This study uses a bibliometric approach in identifying global research trends related to the anaerobic digestion of biomass for methane production using related literature in the Science Citation Index Expanded database, retrieved from the ISI Web of Science. The data used covers the period 1994–2011. The articles acquired from such literature were concentrated on the general analysis by scientific output, the research performances by countries, institutes, and collaborations, and the research trends by the frequency of author keywords, words in title, words in abstract, and ‘KeyWords plus’. The research outputs of anaerobic digestion for methane had notably increased in the field of environmental sciences, biotechnology and applied microbiology, environmental engineering, energy and fuels, and microbiology, while increased slightly in water resources. The USA with most publications and China with the highest growth rate were compared. Finally, author keywords, words in title and ‘KeyWords plus’ were analyzed contrastively, with the recent hotspots provided. 相似文献
856.
857.
858.
阐述了循环经济的概念、发展过程、现实意义。指出循环经济是针对持续的经济增长对资源和环境压力而提出的一种新的经济发展模式,也是一种新的技术经济范式。论述了经济发展阶段与循环经济、效率与循环经济.生态经济与循环经济的关系。以上海市吴泾化工区循环经济的实践为例,进行了实证分析。 相似文献
859.
Zhangli Cai George A. Sorial Kai Zhang Pascal Saikaly Maher M. Zein Daniel B. Oerther 《Water, Air, & Soil Pollution: Focus》2008,8(3-4):311-321
Microbial communities in trickle bed air biofilters (TBABs) were evaluated under conditions of interchanging the feed volatile
organic compounds (VOCs) and VOC mixtures. Three independent TBABs (Biofilter “A,” “B,” and “C”) were run under interchanging
VOCs conditions with different initial VOCs. Two aromatic compounds (toluene and styrene) and two oxygenated compounds (methyl
ethyl ketone (MEK) and methyl isobutyl ketone (MIBK)) were interchanged as single solutes. Two other TBABs “D” and “E” were
run for two VOC mixtures. Biofilter “D” had a VOC mixture with equal molar ratio of the four components and Biofilter “E”
received a VOC mixture with its composition based on EPA 2003 emission report. Denaturing gradient gel electrophoresis (DGGE)
analysis of 16S rRNA genes was used to assess the microbial richness in TBABs for treating the VOC mixtures and the impact
of interchanging VOCs on the bacterial community structure in the biofilters. The results from DGGE indicated that the microbial
community structure in the biofilter was different after each interchange of VOCs. Some bands of microbial species faded and
some bands were strengthened. For the two TBABs treating VOC mixtures, the microbial species did not show significant difference,
but the richness among these species was different from each other. 相似文献
860.