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991.
The production of chloranil is regarded as a potentially significant source of unintentional POPs. This research aimed to identify the contamination levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), hexachlorobenzene (HxCBz), pentachlorobenzene (PeCBz) and polychlorophenols in chloranil samples and identify the formation pathways. The toxicity equivalent (TEQ) values for PCDD/Fs in the chloranil samples ranged from 163 to 1 540 200 pg I-TEQ g−1, while the PCB TEQ values ranged from 1.9 to 3.3 pg WHO-TEQ g−1. High levels of HxCBz, PeCBz and polychlorophenols were also detected in the chloranil samples. The average emission factors were 522.2 mg I-TEQ t−1 (PCDD/Fs), 0.0026 mg WHO-TEQ t−1 (PCBs), 32.6 mg t−1 (HxCBz), and 136.6 mg t−1 (PeCBz). The PCDD/Fs and PCBs are thought to be formed from the polychlorophenols and polychlorobenzenes generated during the chloranil production process. Purification of the chloranil products can reduce the unintentional POPs releases and protect the environment. 相似文献
992.
应用PCR-DGGE方法,追踪了汉沽工业废水处理中好氧工艺的活性污泥系统中微生物群落结构动态变化过程及其微生物群落结构组成。研究结果表明:系统中的微生物群落结构随水质变化而变化,随着培养时间的延长,微生物群落结构趋于稳定,分别属于5大类群,与γ、δ、α、ε变形杆菌(Proteobacterias)、芽孢杆菌(Bacilli)的亲缘关系较近。其中γ变形杆菌是该废水处理过程中的主要菌群,包括Pseudomonas sp.、Rheinheimera sp.、Citrobacter sp.、Klebsiella sp.、Enterbacte-riaceae、Stenotrophomonas maltophilia、Acinetobacter。在整个系统中uncultured Pseudomonas sp.、Halobacillus sp.、Pseudomonassp.、Pseudomonas stutzeri、Acinetobacter sp.可稳定存在于系统中,为该污水处理系统中的优势微生物。因此,提高Halobacillussp.、Pseudomonas sp.、Pseudomonas stutzeri、Acinetobacter sp.菌属在系统中的数量和质量,有利于提高废水生化处理的效果。 相似文献
993.
为了减轻对后续处理中超滤膜的污染,采用电絮凝法处理油田生化出水,降低油田生化出水中的有机物含量。研究了电流强度、曝气时间和pH值对水中总有机碳(TOC)和浊度除去效果的影响以及pH值随曝气时间的变化趋势,通过红外光谱对絮凝处理前后水中总溶解固体进行了分析,优化了电絮凝的工艺条件。研究表明,当水流速度控制在50mL/s,电流强度为2 A,500 mL絮凝出水的曝气时间为30 min时,整套絮凝工艺对TOC的去除率为48%,浊度去除率为42.9%,COD去除率为44%。 相似文献
994.
采用脱色菌Citrobacter sp. CK3,以活性红KN-3B染料为处理对象,在厌氧批式反应条件下,系统考察了pH值,温度和染料浓度对脱色反应速度的影响;通过动力学模拟及反应过程中染料的UV-Vis扫描图分析,探讨了脱色反应机理。结果表明:Citrobacter sp. CK3对活性红KN-3B的脱色反应的适宜pH为7~9;脱色反应速度在温度为32℃时达到最大。染料初浓度从57 mg/L逐渐增大到458 mg/L时脱色率逐渐降低。脱色过程中染料的偶氮键发生断裂,脱色反应符合二级反应动力学。 相似文献
995.
活性炭孔隙结构在其甲苯吸附中的作用 总被引:4,自引:0,他引:4
选用4种商用活性炭(AC),利用氮气绝热吸附、扫描电子显微镜(SEM)和傅立叶变换红外光谱(FTIR)测试了活性炭的物化性质。以甲苯为吸附质,在温度为298.15 K下进行了静态和动态吸附实验,研究了活性炭孔结构对其吸附性能、吸附行为、表面覆盖率和吸附能的影响。结果表明:活性炭的比表面积和孔容是其吸附性能主要影响因素,孔径在0.8~2.4 nm之间的孔容和甲苯吸附量之间存在较好的线性关系,且线性斜率随甲苯浓度增加而变大。甲苯吸附行为符合Langmuir吸附等温模型和准一阶动力学方程式。活性炭孔结构是甲苯吸附速率的主要制约因素。在甲苯快速吸附阶段,微孔为吸附速率主要制约因素,在甲苯颗粒内扩散阶段,微孔和表面孔为吸附速率的主要制约因素,在吸附末尾阶段,中孔和大孔为吸附速率的主要制约因素。4种活性积炭对甲苯的吸附能随其比表面变大而变大。 相似文献
996.
997.
This paper examines the issue of ancillary benefits by linking sulfur dioxide (SO2) emission to CO2 emission using a panel of 29 Chinese provinces over the period 1995–2007. In the presence of non-stationarity and cointegrating
properties of these two data series, this paper applies the panel cointegration techniques to examine both the long-run and
short-run elasticities of SO2 with respect to CO2. The major findings are that: (1) there exhibits a stable long-run equilibrium relationship between the SO2 and CO2 emission with the long-run elasticity being 2.15; (2) there exists a short-run relationship between these two emissions with
the short-run elasticity being 0.04. In addition, following an exogenous shock that causes a deviation from the long-run equilibrium,
it would take approximately 15 years for SO2 emission to revert toward the long-run equilibrium path with an average annual convergence rate of 6.5%; (3) the derived
ancillary benefits that is generated from one metric ton of CO2 emission reduction, are 11.77 Yuan (approximately US1.7) in the short run and 196.16 Yuan (US 1.7) in the short run and 196.16 Yuan (US 30) in the long run. These
findings are not only crucial from the econometric modeling perspective, but also have important policy implications. 相似文献
998.
Since China’s economic reform in 1978, the cities of China have experienced rapid expansion and urbanization, thereby profoundly
transforming the spatial pattern of urban land use in the karst regions, particularly in the urban mountainous area within
city, and urbanization has had and continues to have a negative impact on urban mountain area in cities of China. With the
rapid development of urbanization and civilization in these regions, environmental degradation has been increasingly serious,
especially in the urban karst mountain area, thereby resulting in the destruction and breakage of urban hills that induce
serious natural hazard, i.e., flood hazard. 相似文献
999.
Tang X Chen J Wang WH Liu TW Zhang J Gao YH Pei ZM Zheng HL 《Environmental pollution (Barking, Essex : 1987)》2011,159(12):3784-3792
This study characterized the changes of nitric oxide (NO) production during the growth of Microcystis aerugrinosa, a cyanobacterium which usually cause cyanobacterial blooms. Results showed a drastic NO release accompanying with cell density and Chl-a content sharp rises when M. aerugrinosa grew from fifth day to sixth day. Moreover, high N:P ratio accelerated the cyanobacterial growth and NO burst. Sodium nitroprusside, an exogenous NO donor, promoted M. aerugrinosa growth with the optimal concentration of 0.1 mg/L. Experiments by supplementing with sodium nitrite and l-arginine demonstrated NO production in M. aerugrinosa cells was mainly through nitrate reductase (NR) pathway while minorly through NO synthase pathway. All these data suggested M. aerugrinosa produced increasing NO during its growth mainly by NR pathway, during which NO positively regulated the growth of M. aerugrinosa. 相似文献
1000.
Wang H Ouyang Z Chen W Wang X Zheng H Ren Y 《Environmental pollution (Barking, Essex : 1987)》2011,159(8-9):2127-2137
Transpiration rates of six urban tree species in Beijing evaluated by thermal dissipation method for one year were correlated to environmental variables in heat, water, and pollutant groups. To sort out colinearity of the explanatory variables, their individual and joint contributions to variance of tree transpiration were determined by the variation and hierarchical partitioning methods. Majority of the variance in transpiration rates was associated with joint effects of variables in heat and water groups and variance due to individual effects of explanatory group were in comparison small. Atmospheric pollutants exerted only minor effects on tree transpiration. Daily transpiration rate was most affected by air temperature, soil temperature, total radiation, vapor pressure deficit, and ozone. Relative humidity would replace soil temperature when factors influencing hourly transpiration rate was considered. 相似文献