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501.
铜、锌和锰抑制蛋白核小球藻生长的毒性效应 总被引:41,自引:1,他引:40
运用评价化学品毒性藻类测试的标准实验方法 ,得到铜、锌和锰对蛋白核小球藻生长的安全浓度分别为31.8μg/L、65.0μg/L和 5.5mg/L ,抑制蛋白核小球藻生长的 96h EC50 分别为 67.3μg/L、473.0 μg/L和 17.0mg/L .实验结果表明无论从安全浓度还是从 96h EC50 考虑 ,都证明抑制蛋白核小球藻生长的毒性由大到小的顺序是铜 >锌 >锰 .不同金属离子与藻细胞的不同亲和性是导致金属离子抑制蛋白核小球藻生长毒性差异的主要原因 . 相似文献
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503.
The total carbon(C) and total nitrogen(N) content of suspended matter in a small undisturbed headwater drainage basin in the New Territories of Hong Kong has been monitored. Mean C and N contents were 12.85 % and 0.99% respectively for 132 samples. Samples collected under stableflow conditions had mean C and N contents of 12.81% and 1.06% respectively. Stormflow samples had mean C and N values of 12.86% and 0.97% respectively,which were very similar to the levels observed under stableflow conditions. The mean C: N ratios of 12.47 and 13.39 for stableflow and stormflow also reveal little difference according to hydrologic conditions. When all the data is considered little difference is observed in C and N according to the season. However, in winter there is a significant difference in C and N content between stable and stormflow samples. When C and N are plotted against water level the scattergraphs suggested that as stage increases the percentage of C and N in the suspended matter declines.Scattergraphs of C and N against suspended sediment concentration reveal a negative association. Comparison has been made between fresh leaf C, N and C/N ratio for trees and shrubs and the suspended matter. Fresh leaves do not appear to contribute significantly to suspended matter. The C/N ratio of suspended matter would also seem to exclude woody material and algae as sources of suspended matter. 相似文献
504.
In this paper, removal of NOx(namely DeNOx) from flue gas by radical injection combined with NaOH solution(26% by weight of NaOH in water) scrubbing was investigated. The experimental results showed that the steady streamer corona occurs through adjusting the flow rate of the oxygen fed into the nozzles electrode. The vapor in the oxygen has influence on the V-I characteristics of corona discharge. Both HNO2 and HNO3 come into being in the plasma reactor and the DeNOx efficiency in the plasma reactor is more than 60%. The overall DeNOx efficiency of the whole system reaches 81.7 % when the NaOH solution scrubbing is collaborated. 相似文献
505.
A continuous photo-Fenton process has been used for the degradation of gaseous dichloromethane (DCM). By absorbing gaseous DCM into a reactive Fenton mixture, the scrubbing and degradation processes could be completed in the one reactor. Operating with a Dark Fenton solution did not result in removal of DCM any better than simply using MilliQ water. This was because the Fe(II) quickly converted to Fe(III) but was unable to regenerate. After a short time, the Fenton process was no longer operating and the DCM quickly accumulated in the reaction solution, preventing further accumulation due to a decreasing concentration gradient in the reactive solution. However, by using UV light and increasing the retention time from 20 to 50 s, there was sufficient time for the reactive solution to regenerate and continuous operation could achieve at least 65% removal of DCM from the gaseous phase at ambient temperature. 相似文献
506.
The levels of PCBs in different types of food (fish, shellfish, meat, rice, vegetables, and fruits) were analyzed to determine the dietary intake of 37 PCBs for local residents and e-waste workers (all lactating mothers) at Taizhou (China), a major electronic waste scrapping center, in particular for recycling transformers. The exposure to PCBs through dietary intake in Taizhou was estimated at 92.79 ngkg(-1)d(-1), contributed by consumption of freshwater fish (28%), rice (28%), meat (17%), shellfish (9%), vegetables (8%), egg (4%) and marine fish (2%). With regards to WHO-PCB-TEQ values, freshwater fish (40%), shellfish (24%), duck liver (18%) and rice (12%) were the main dietary sources with total daily intake (9.78 pg WHO-PCB-TEQ kg(-1)d(-1)), exceeding the FAO/WHO Tolerable Daily Intake (70 pg TEQkg(-1)body(-1)wt(-1)month(-1)). 相似文献
507.
森林生态系统在碳循环中的作用 总被引:9,自引:0,他引:9
描述了森林生态系统的碳循环及其在全球碳循环中的作用,说明了森林生态系统在碳循环中的作用主要取决于森林生态系统的生物量、林产品、植物枯枝落叶和根系碎屑以及森林土壤。最后,阐明了中国森林生态系统碳循环的研究现状和趋势。 相似文献
508.
509.
污泥渗水砖的制备研究 总被引:2,自引:0,他引:2
结合压制成型和传统的烧结砖工艺,实验以城市生活污泥、黄河淤泥、煤矸石及砂为原料,制备渗水铺地砖。通过正交试验得到最优工艺参数为w(黄河淤泥)∶ww(煤矸石)∶w(污泥)∶w(砂)=33%∶22%∶15%∶30%、成型压力为20 MPa、烧结温度为1 100℃、保温时间为1.5 h,骨料砂的粒径为1~2 mm。制备的成品抗压强度为21.8 MPa,渗水系数为1.03×10-2 cm/s。并对成型压力及烧结温度对渗水砖抗压强度及渗水系数的影响进行了讨论。 相似文献
510.