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741.
本文介绍了用“计算机扫描计算-图解-梯度搜索法”寻求河流水质数学模型最优参数的研究成果.该法能解决目前存在的用梯度法搜索参数时误差很大的问题. 相似文献
742.
本文针对地震科技情报工作面临的工作困境,提出在新时期,地震科技情报部门如何更好地为防震减灾提供优质服务。地震科技情报工作应充分发挥计算机和网络的作用,加快数字化发展,进行协作化建设,并且强化服务意识,增强信息管理人员的培训。 相似文献
743.
对于地震科学来说,观测是它的立足之本,如果没有观测那就像一个人没有心脏一样。担负观测任务的就是各个地震台站,如何得到真实、可靠、连续的观测数据,是各个地震台站一致追求的目标。提高地震台站的监测水平和运行效率,一方面要加强管理,另一方面要对观测数据进行正确的预处理工作,包括日志的详细记录,各种情况的认真标注等。本文结合南山台实际,以数字化仪器为主,着重谈谈日常管理和数字资料预处理的一些看法。 相似文献
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746.
Previous studies have shown that ultraviolet (UV) A light and the polycyclic aromatic hydrocarbon benzo[a]pyrene (BaP) can synergistically enhance the formation of 8-hydroxy-2'deoxyguanosine (8-OHdG) in living cells. It has been postulated that the underlying mechanism is production of reactive oxygen species (ROS) via photosensitization, but direct evidence supporting this hypothesis has been lacking. This study examined intracellular ROS production in living cells co-exposed to UV-A and BaP as well as the relationship between intracellular production of ROS and formation of 8-OHdG. KB cells were exposed to BaP for 24 h, followed by exposure to UV-A (365 nm) or UV-B (312 nm). The levels of intracellular ROS were directly measured by use of the fluorescent probe dihydrorhodamine 123 (DHR-123) in flow cytometry. Levels of 8-OHdG were measured by high performance liquid chromatography coupled with electrochemical detection (HPLC-ECD). The results demonstrated that UV-B itself induced a much greater level of intracellular ROS than did UV-A alone under the same dose of energy (0.10 mW/cm(2), 20 min). The presence of BaP (13.3 microM) substantially increased ROS production in UV-A-treated cells (2.9-fold), but only slightly enhanced ROS production in UV-B-treated cells (1.3-fold). These results show that BaP acts mainly as a photosensitizer of UV-A, but not UV-B. Furthermore, greater intracellular ROS production was proportional to both BaP concentration and UV-A dosage. There was a linear relationship between ROS production and 8-OHdG formation in cells co-exposed to BaP and UV-A. Results of this study suggest that UV-A and BaP act synergistically to enhance ROS production and formation of 8-OHdG, resulting in increased DNA damage. 相似文献
747.
城市污水处理厂不同工艺段中有机氯农药残留 总被引:3,自引:0,他引:3
建立了基于HLB固相萃取柱和气相色谱 /电子捕获 (GC/ECD)分析城市污水中有机氯农药的分析方法 ,同时分析了北京市高碑店和北小河两个污水处理厂中 4个不同工艺段水体中有机氯农药的浓度。在两个污水处理厂的水体中共检出了 6种有机氯类农药 ,分别是α 六六六、β 六六六、γ 六六六、δ 六六六、艾氏剂和 4 ,4’ 滴滴滴 ,浓度在 1 89—6 9 6ng/L之间。结果表明 ,曝气活性污泥法对六六六类有机氯农药的去除效果较好。 相似文献
748.
749.
Wey MY Lu CY Tseng HH Fu CH 《Journal of the Air & Waste Management Association (1995)》2002,52(4):449-458
Catalyst sorbents based on alumina-supported CuO, CeO2, and CuO-CeO2 were applied to a dry scrubber to clean up the SO2/HCl/NO simultaneously from pilot-scale fluidized-bed incineration flue gas. In the presence of organic compounds, CO and the submicron particles SO2 and HCI removed by the fresh catalyst sorbents and NO reduced to N2 by NH3 under the catalysis of fresh and spent desulfurization/dechloridization (DeSO2/DeHCl) catalyst sorbents (copper compounds, Cu, CuO, and CuSO4) were evaluated in this paper. The fresh and spent catalyst sorbents were characterized by the Brunner-Emmett-Teller method (BET), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), inductively coupled plasma-mass spectrometry (ICP-MS), and the elemental analyzer (EA). The study showed that the performances of CuO, CeO2, and CuO-CeO2/gamma-Al2O3 were better than that of Ca(OH)2. The removal efficiency of SO2 and HCl was 80-95% in the dry scrubber system. Under NH3/NO = 1, NO could not be reduced to N2 because it was difficult to control the ratio of air/fuel in the flue gas. For estimating the feasibility of regenerating the spent catalyst sorbents, BET and EA analyses were used. They indicated that the pore structures were nearly maintained and a small amount of carbon accumulated on their surface. 相似文献
750.
Ambient suspended particulate concentrations were measured at Tzu Yun Yen temple (120 degrees, 34('), 10(") E; 24 degrees, 16('), 12(") N) in this study. This is representative of incense burning and semi-open sampling sites. The Universal-sampler collected fine and coarse particle material was used to measure suspended particulate concentrations, and sampling periods were from 16/08/2001 to 2/1/2002 at Tzu Yun Yen temple. In addition, metallic element concentrations, compositions of PM(2.5) and PM(2.5-10) for incense burning at Tzu Yun Yen temple were also analyzed in this study. The PM(2.5)/PM(10) ratios ranged between 31% and 87% and averaged 70+/-11% during incense the burning period, respectively. The median metallic element concentration order for these elements is Fe>Zn>Cr>Cd>Pb>Mn>Ni>Cu in fine particles (PM(2.5)) at the Tzu Yun Yen temple sampling site. The median metallic element concentration order for these elements is Fe>Zn>Cr>Pb>Cd>Ni>Mn>Cu in coarse particle (PM(2.5-10)) at the Tzu Yun Yen temple sampling site. Fine particulates (PM(2.5)) are the main portion of PM(10) at Tzu Yun Yen temple in this study. From the point of view of PM(10), these data reflect that the elements Fe, Zn, and Cr were the major elements distributed at Tzu Yun Yen temple in this study. 相似文献