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排序方式: 共有1492条查询结果,搜索用时 31 毫秒
991.
992.
Fish tissues from different fishery types (freshwater farmed, seawater farmed and seawater wild) were analyzed for organochlorine pesticides (OCPs), with the aim to further our understanding of bioaccumulation, and reflect the state of different fishery environments. Significantly higher SigmaOCP levels were found in seawater farmed fish than others, and among three freshwater farmed species, the lowest levels occurred in filter-feeding fish (bighead carp). Liver contained the highest SigmaOCP levels, while no significant differences were found among other tissues. Among DDT components, p,p'-DDT was abundant in seawater fish, while for freshwater fish, p,p'-DDE was the predominant congeners, except for northern snakehead (34% for p,p'-DDE and 30% for p,p'-DDT). The new source of DDTs to freshwater fish ponds was partly attributed to dicofol, whereas sewage discharged from the Pearl River Delta and anti-fouling paint were likely the DDTs sources to seawater farmed fish. 相似文献
993.
The previous inexact mixed-integer linear programming (IMILP) method can only tackle problems with coefficients of the objective function and constraints being crisp intervals, while the existing inexact mixed-integer semi-infinite programming (IMISIP) method can only deal with single-objective programming problems as it merely allows the number of constraints to be infinite. This study proposes, an inexact mixed-integer bi-infinite programming (IMIBIP) method by incorporating the concept of functional intervals into the programming framework. Different from the existing methods, the IMIBIP can tackle the inexact programming problems that contain both infinite objectives and constraints. The developed method is applied to capacity planning of waste management systems under a variety of uncertainties. Four scenarios are considered for comparing the solutions of IMIBIP with those of IMILP. The results indicate that reasonable solutions can be generated by the IMIBIP method. Compared with IMILP, the system cost from IMIBIP would be relatively high since the fluctuating market factors are considered; however, the IMILP solutions are associated with a raised system reliability level and a reduced constraint violation risk level. 相似文献
994.
混凝——吸附法处理油墨废水工艺研究 总被引:7,自引:0,他引:7
采用不同无机混凝剂及氧化还原剂对打印机生产中的油墨废水的混凝及脱色效果进行试验比较,确定了实验室工艺条件及各种混凝剂最佳用量及次序。结果表明,该工艺脱色率达100%,CODcr去除率达51%。 相似文献
995.
Yu HY Shen RL Liang Y Cheng H Zeng EY 《Environmental pollution (Barking, Essex : 1987)》2011,159(12):3700-3705
Existing evidence indicated that dichlorodiphenyltrichloroethane (DDT)-containing antifouling paints were an important source of DDT residues to mariculture zones. However, the magnitude of the impact on aquafarming environment has remained largely unknown. In the present study, the concentrations of DDT and its metabolites (designated as DDXs) were determined in harbor sediment and antifouling paint samples collected from a typical mariculture zone in South China. Compositional and concentration correlation analyses implicated the DDT-containing antifouling paints for fishing boat maintenance as an important source of DDT in the mariculture zone. The annual emission of DDXs to the study region was estimated at 0.58 tons/yr. Furthermore, a comparison of the expected DDT loadings in pelagic fish and field measurements indicated that fish feed especially trash fish was a major source of DDTs in the fish body. Nevertheless, the use of DDT-containing antifouling paints should be limited to prevent further deterioration in aquafarming environment. 相似文献
996.
光-Fenton氧化破解剩余污泥和改善污泥脱水性能 总被引:5,自引:1,他引:4
利用紫外光-Fenton(光-Fenton)氧化处理城市剩余污泥,通过上清液的SCOD、多聚糖以及蛋白质浓度表征污泥胞外聚合物(EPS)的破解情况,通过污泥过滤比阻(SRF)和滤饼含水率表征污泥脱水性能的变化。结果表明,光.Fenton氧化破解污泥EPS和改善污泥脱水性能的效能明显优于单独Fenton反应和单独紫外光照射处理。pH为3、反应时间为2h,H2O2投加量为4g/L和Fe^2+投加量为0.6mg/L是光-Fenton氧化处理供试污泥的适宜条件。在适宜处理条件下,污泥上清液中的SCOD、多聚糖和蛋白质浓度分别由67.46mg/L、12.53mg/L和8.62mg/L增加到568.12mg/L、448.62mg/L和292.94mg/L;SRF和滤饼含水率分别由2.4×10^S2/g和88.52%下降至5.26×10^8S^2/g和76.36%。光-Fenton反应在有效破懈污泥的同时,提高了污泥的脱水性能.有利于污泥的减量化。 相似文献
997.
Chen GQ Zou ZJ Zeng GM Yan M Fan JQ Chen AW Yang F Zhang WJ Wang L 《Chemosphere》2011,83(9):1201-1207
A novel coarsening route for extracellularly biosynthesized cadmium nanocrystals was investigated for the first time. In this process, the white rot fungus Coriolus versicolor was employed to take up cadmium ions and synthesize extracellular cadmium crystal particles. The coarsening of the particles was induced by thioacetamide under certain conditions. Scanning electron microscopy showed that the formed cadmium crystal particles were coarsened from about 100 nm to 2-3 μm. The corresponding energy-dispersive X-ray spectra confirmed the presence of proteins in the particles. The maximum removal efficiency of Cd(II) increased from 17% to 87%, and the corresponding sorption capacity of biomass increased from 4 to 24 mg g−1 with the completion of the coarsening process. The properties of the coarsened particles were also examined using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD analysis of fungal mycelial pellets embedded with the coarsened particles confirmed the formation of cubic crystalline cadmium sulfide particles. The TEM results suggest that the coarsened particles were composed of clusters of several smaller particles. The changes in the functional groups on the biomass surface were studied through Fourier transform infrared spectroscopy. Based on the results above, a possible mechanism for the formation and coarsening of cadmium crystal particle is also discussed. 相似文献
998.
Regional dynamics of persistent organic pollutants (POPs) in the Pearl River Delta, China: implications and perspectives 总被引:1,自引:0,他引:1
Zhang K Zhang BZ Li SM Zeng EY 《Environmental pollution (Barking, Essex : 1987)》2011,159(10):2301-2309
The mass transport budgets of 1,1,1-trichloro-2,2-bis(chlorophenyl)ethane (p,p′-DDT) and decabromodiphenyl ether (BDE-209) in the Pearl River Delta, South China were calculated based on previously collected data. Residual p,p′-DDT, mostly related to historical use, has largely settled into soil (780,000 kg), while the soil BDE-209 inventory (44,000 kg) is considerably smaller. Conversely, large amounts of BDE-209 currently used in numerous commercial products have resulted in a much higher atmospheric depositional flux of BDE-209 (28,100 kg/yr) relative to p,p′-DDT (310 kg/yr). The soil inventory of p,p′-DDT is predicted to decrease to half of its current value after 22 years, and the percent area containing soil p,p′-DDT at levels exceeding the effects range-medium (27 ng/g) will decrease from 40% to 20%. Finally, soil BDE-209 inventory will reach an equilibrium value of 940 tons in ∼60 years, when BDE-209 levels in 50% of soil will be above an equivalent risk guideline value (125 ng/g). 相似文献
999.
二鼠李糖脂对白腐菌降解稻草中木质纤维素的影响 总被引:1,自引:0,他引:1
通过固态发酵方式采用白腐菌对稻草中木质纤维素进行降解,并研究了生物表面活性剂二鼠李糖脂对该降解过程的影响。结果表明,不同浓度的二鼠李糖脂能在不同程度上提高降解过程水溶性有机碳的含量,添加0.007%和0.021%二鼠李糖脂的实验组最高TOC(total organic carbon)浓度较对照组分别提高了83.6%和54.5%,这有利于黄孢原毛平革菌的生长,且延缓了菌体的衰退。添加临界胶束浓度0.007%和0.021%浓度的二鼠李糖脂可使LiP(lignin peroxidase)酶活分别提高85.7%和41.2%,二鼠李糖脂对MnP(manganese peroxidase)酶活没有显著影响。生物表面活性剂的介入促进了白腐菌对稻草中木质素的降解,添加0.007%二鼠李糖脂可使木质素降解率提高54%。 相似文献
1000.
Levels and isomer profiles of Dechlorane Plus in the surface soils from e-waste recycling areas and industrial areas in South China 总被引:3,自引:0,他引:3
Zhiqiang Yu Shutao Gao Jingzhi Wang Huiru Li Xiangying Zeng Jiamo Fu 《Environmental pollution (Barking, Essex : 1987)》2010,158(9):2920-2925
Dechlorane Plus (DP) is a highly chlorinated flame retardant. Levels of DP were measured in surface soils from e-waste recycling areas and industrial areas in South China. Higher DP levels were found in e-waste recycling areas (undetectable-47.4 ng/g) than those in industrial areas (0.0336-4.65 ng/g) in South China. The highest DP concentration (3327 ng/g) was found at the e-waste recycling site in Qingyuan, while DP levels fell dramatically with increasing distance away from the recycling site, suggesting that the e-waste recycling activities are an important source of DP emissions. The mean ratios of anti-DP to total DP (fanti) for different sampling areas ranged from 0.58 to 0.76 and showed no significant difference from the ratio for the technical DP products (t-test, p > 0.05). Further intensive studies are needed to investigate the process of DP degradation and its degradation products. 相似文献