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    Environmental Science & Technology

  • 中文名称: 环境科学与技术
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  • ISSN: 0013-936X
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  • 机译 杨树对阿特拉津的吸收与代谢
    摘要:Hybrid poplar trees can uptake, hydrolyze, and dealkylate atrazine to less toxic metabolites. In whole plant studies, the parent compound atrazine and ~(14)C ring-labeled metabolites were extracted from poplar tissues and analyzed via high-pressure liquid chromatography (HPLC) with UV and radiochromatographic detectors in series. The concurrent separation and identification of these metabolites has not been previously reported in higher plants for phytoremediation applications. Unidentified metabolites were also detected. Metabolism of atrazine occurred in poplar roots, stems, and leaves and became more complete with increased residence time in tissues. In poplar cuttings exposed to atrazine for 50 days, the parent compound comprised only 21% of the ~(14)C label in the leaves, while it constituted 59% of ~(14)C activity remaining in the soil. After 80 days, the parent compound remaining in the leaves had decreased to only 10% of the ~(14)C label recovered in the leaves. Preferred metabolic pathways were suggested by relative rates of reaction, and a mathematical model was developed to estimate rate constants for the proposed degradation mechanism. This research provides evidence for vegetative detoxification of contaminants and suggests that phytoremediation of atrazine-contaminated soils may be feasible.
  • 机译 提出统一的欧洲水质监管体系
    • 作者:MARIA BURKE;
    • 刊名:Environmental Science & Technology
    • 1997年第5期
    摘要:A plan to unify European water quality regulations around a system of transboundary water management districts has been endorsed by the European Commission. The proposal, approved Feb. 26, will create "a coherent structure for European Union (EU) water policy and it will systematize the collection of environmental information," said Ritt Bjerregaard, environment commissioner. "It identifies and tackles the two great threats to sustainability: overabstraction and pollution."
  • 机译 冶炼厂影响的挪威峡湾和沿海水域沉积物中多环芳烃分布模式和结局的多元分析
    摘要:The environmental significance of polycyclic aromatic hydrocarbons (PAHs) generated by the production of aluminum and manganese alloys is an important issue in numerous Norwegian fjords. The fate of these compounds have been elucidated by analyzing surface and subsurface sediment samples collected over a 15-year period from seven smelter-affected fjords applying principal component analysis (PCA). Consistent patterns within and between fjords and between production types suggested causal relationships and formed the basis for formulating hypotheses regarding the fate of the compounds. The PCA was able to differentiate between various combustion origins at receptor locations, so far hidden in the traditional treatment of the data restricted to individual fjords. This differentiation reflected industrial processes and most probably cleaning arrangements at the different plants. The source-specific signals were discernible over considerable distances and down to concentrations 3-4 times background levels. Compound-specific transformation reactions occurring during transport and incorporation into the sediments contributed little to the total variance and did not suppress the source-specific signals. This may imply a rather low availability to the bottom fauna and raise questions as to the potential harm inflicted by smelter-generated PAHs.
  • 机译 CH_3Cl / C_2H_4预混火焰中痕量副产物的形成
    摘要:The chemical structure of an atmospheric pressure, fuel-rich (equivalence ratio 3.06), flat flame of a chloromethane and ethylene (CH_3Cl/C_2H_4 = 1.99) has been studied experimentally using both heated microprobe and cold trap sampling techniques followed by high-resolution gas chro-matography/mass spectrometry (GC/MS). The identities and absolute concentrations of more than 50 major and minor hydrocarbon and chlorinated hydrocarbon species have been established, including a large number of aromatics, substituted aromatics, and polycyclic aromatic hydrocarbons (PAHs). Although some chlorinated PAHs were also detected, unsubstituted aromatics dominated the PAH product distribution. Mole fractions determined were in the range of 0.45-2.0 x 10~(-7), with the heaviest PAHs at mass 226 (C_(18)H_(10), benzo[ghi]fluoranthene and cyclopenta-[cd]pyrene). The measurements indicated the selective suppression of certain PAHs, e.g., cyclopenta[cd]pyrene, in the presence of HCl when compared to regular hydrocarbon flames. Heated silica surfaces of the sampling probe and transfer lines were also noted to chlorinate select PAHs, such as pyrene and acenaphthylene. The mole fraction profiles of many of the products first increased, then decreased, and increased again in the post-flame zone. A number of oxygenated aromatics were also detected. These measurements provide new information on the identities and levels of hazardous air pollutants formed in the incineration of chlorinated hydrocarbons and represent useful data for the development and validation of detailed reaction mechanisms.
  • 机译 3-D非均质含水层中非极性有机溶质的场标迁移。
    摘要:Field experiments have indicated that reactive solute plumes released in natural porous media decelerate with time and undergo enhanced spreading. To analyze these and other unresolved transport issues, a methodology is presented to simulate the field-scale transport of dissolved nonpolar organic compounds in 3-D heterogeneous aquifers. This includes the development of a model that couples a stochastic technique for generating 3-D flow fields with a mobile—immobile domain model to account for sorption and intraparticle mass diffusion. The methodology is presented through the analysis of the transport of tetrachlo-roethylene (PCE) at the Borden site, and model results are compared to field data, analytical solutions, and other studies. The input parameters are based on laboratory data reported in the literature. The interpretation of these data is discussed, and the required experimental procedures are identified. The model results for the expected displacement of the plume's centroid (first spatial moment) are nearly identical to those observed in the field and capture the trends in the field data more accurately than previous studies. The observed second spatial moments of the plume are within the 95% confidence intervals generated by the model (based on 2500 realizations). In general, the behavior of the plume can be attributed to the large-scale heterogeneities in the subsurface hydraulic properties, the non-ergodic nature of the plume, the sorption of the solute within the soil matrix, and the intraparticle mass transfer limitations.
  • 机译 海藻酸钙吸收铜离子的平衡和动力学研究
    摘要:Equilibrium and kinetic experiments of copper ion uptake by calcium alginate beads were carried out under different values of pH, ionic strength, initial concentration of copper ion, and amount of calcium alginate. The removal efficiency increases with increasing pH and decreasing ionic strength and initial concentration. The removal of copper occurs rapidly in the first hour, followed by a slow process thattakes about 15 h. The copper ion uptake becomes faster with increasing pH and decreasing initial copper concentration and ionic strength. Mass transport of copper ions plays an important role in the kinetics of uptake. Equilibrium experiments show that surface complex formation is the major mechanism for copper ion uptake. Modeling of equilibrium and kinetics was also conducted based on a surface complexation approach. Modeling results showed that the two-pK Basic Stern model can successfully describe the effect of pH on equilibrium uptake. A diffusion-controlled model can also prqdict the effect of pH on the kinetics.
  • 机译 聚二甲基硅氧烷对环境的影响
    摘要:An extensive monitoring program was conducted to determine the occurrence of polydimethylsiloxane (PDMS) in environmental compartments impacted by consumer waste disposal practices. Eight wastewater treatment plants, representative of those found in North America, were monitored to determine PDMS removal during wastewater treatment. Surface waters, sediments, and sludge-amended soils impacted by wastewater treatment plant effluents and sludges were also monitored for a more complete assessment of the environmental fate of PDMS. Newly developed GPC-ICP and/or HPLC-ICP analytical techniques were used to provide insight into the environmental fate of PDMS and anticipated PDMS degradation products. PDMS was found to be highly removed during wastewater treatment with effluent concentrations, in most cases, below the quantitation limit of the analytical technique ( < 5μg/L). PDMS sludge concentrations ranged from 290 to 5155 mg/ kg and varied as a function of influent concentration and sludge processing method. Sediment levels of < 6 mg/ kg were measured nearthe outfall of the wastewatertreatment plants sampled. Measured sludge-amended agricultural soil concentrations ranged from < 0.41 to 10.4 mg/kg and were lower than expected in most cases based on calculated PDMS loadings via historical sludge application. The lower than expected PDMS concentrations in sludge-amended soil combined with detection of dimethylsilane-1,1-diol, an expected PDMS breakdown product, suggest degradation of PDMS in the soil environment.
  • 机译 环境对阿拉斯加威廉王子湾对岸埃克森·瓦尔迪兹石油微生物降解的影响
    摘要:Biodegradation was a major mechanism for removing oil resulting from the Exxon Valdez oil spill in Prince William Sound, Alaska. For three field seasons, we examined the hexadecane, phenanthrene, and naphthalene mineralization potentials of hydrocarbon-degrading microorganisms and the accompanying hydrocarbon concentrations from intertidal and shallow subtidal sediments. We found that mineralization potentials were not directly dependent on sediment substrate concentrations, but environmental factors influenced the ability of microbial populations to mineralize polycyclic aromatic and aliphatic compounds. These factors included the intensity of physical mixing experienced, the treatments received, and the availability of alternative carbon sources. In 1989, when the Exxon Valdez oil was relatively unweathered and before shoreline treatment was begun, the mineralization potentials of aromatic hydrocarbons were high at many sites even in the presence of alkanes at higher concentrations. However, by 1990, mineralization potentials for alkanes were greater than those for aromatics at oiled sites exposed to terrestrial bio-waxes or fatty acids from the bioremediation process. Therefore, our study shows that sediment chemistry data alone cannot predict the persistence of hydrocarbons following the Exxon Valdez oil spill and demonstrates the need for systematic ecosystem-level studies of the abiotic and biotic factors influencing biodegradation.
  • 机译 土壤中阿特拉津与其他有机物的竞争吸附与模型吸附剂。
    摘要:SIR: We appreciate the comments of Borisover and Graber on our paper. Our dual-mode model is based on a concept of SOM as a 'polymer mesh' phase that ranges continuously from 'rubbery' to 'glassy' in character. Rubbery means relatively more gel-like, expanded, flexible, and highly solvated, while glassy means more condensed, rigid, and less solvated. Small organic molecules are able to penetrate all phases and intermingle with the humic macromolecules. Solid-phase dissolution (partition) sorption occurs in regions where thermal relaxation of the polymer structure is rapid, so that 'sites' are ephemeral and an averaged sorption potential exists, as in a liquid. Dissolution takes place throughout SOM but increases in importance with its rubbery character. Langmuir-type sorption occurs in regions where the rigidity of the humic backbone creates sites that are relatively long-lived. This results in nonlinearity because the sites vary in energy. The concentration of such, sites increases with the glassy character. We have also called this the 'hole-filling' mechanism because we envision the sites as microvoids in analogy with organic polymers; however, their exact nature is irrelevant to the present discussion. Further description and experimental support of the model are given elsewhere. Here, we address point-by-point the comments of Borisover and Graber.
  • 机译 “常识”改革倡议失败
    • 作者:VINCENT LECLAIR;
    • 刊名:Environmental Science & Technology
    • 1997年第5期
    摘要:The automobile and petroleum refining industries have decided to back out of EPA's Common Sense Initiative (CSI), a voluntary program to encourage environmentalists, industry, and states to agree on ways to improve environmental protection controls within specific industry sectors. The withdrawal of these two key industries, and complaints from participants about the pace and direction of the three-year-old initiative, points to problems for what Administrator Carol Browner dubbed a major reform effort for the way pollution is managed.
  • 机译 结合〜(14)C和δ〜(13)C监测石油烃的原位生物降解
    摘要:Measurements of the stable carbon isotope ratios (δ~(13)C) of microbial metabolic end products presents a promising method for monitoring in situ bioremediation of petroleum hydrocarbons. Differences between the δ~(13)C values of hydrocarbons and indigenous carbon sources (e.g., plant matter, soil carbonates) can be exploited to trace the origins of metabolic end products. However, in zones of methanogenesis and/or where the δ~(13)C values of endogenous plant matter overlap those of hydrocarbons, δ~(13)C measurements can produce ambiguous results. In such cases, simultaneous measurement of the radiocarbon (~(14)C) contents of metabolic end products can be used to determine their sources. This method was applied at a gasoline station spill site where hydrocarbons were the only source of ~(14)C-free carbon. Combined δ~(13)C and ~(14)C measurements of soil gas CO_2 and dissolved inorganic carbon in groundwater enabled quantification of carbon inputs. Furthermore, low ~(14)C contents of high δ~(13)C CO_2 were crucial in establishing that the soil gas CO_2 was derived from methanogenesis of hydrocarbons and not shell dissolution. In addition, low ~(14)C content coupled with a 16 per thousand drop in the δ~(13)C values of CO_2 across a semipermeable layer beneath the gas station building confirmed that microbial oxidation of methane was occurring within this zone.
  • 机译 加利福尼亚莫诺湖中甲基溴的细菌氧化
    摘要:The oxidation of methyl bromide (MeBr) in the water column of Mono Lake, CA, was studied by measuring the formation of H~(14)CO_3 from [~(14)C]MeBr. Potential oxidation was detected throughout the water column, with highest rates occurring in the epilimnion (5-12 m depth). The oxidation of MeBr was eliminated by filter-sterilization, thereby demonstrating the involvement of bacteria. Vertical profiles of MeBr activity differed from those obtained for nitrification and methane oxidation, indicating that MeBr oxidation is not simply a co-oxidation process by either nitrif iers or methanotrophs. Furthermore, specific inhibitors of methane oxidation and/or nitrification (e.g., methyl fluoride, acetylene, allyl sulfide) had no effect upon the rate of MeBr oxidation in live samples. Of a variety of potential electron donors added to Mono Lake water, only trimethy-lamine resulted in the stimulation of MeBr oxidation. Cumulatively, these results suggest that the oxidation of MeBr in Mono Lake waters is attributable to trimethylamine-degrading methylotrophs. Neither methyl chloride nor methanol inhibited the oxidation of [~(14)C]MeBr in live samples, indicating that these bacteria directly oxidized MeBr rather than the products of MeBr nucleophilic substitution reactions.
  • 机译 便携式免疫传感器在检测地下水样品中炸药TNT和RDX中的应用
    摘要:In the summer of 1995, the EPA conducted a performance evaluation of several commercially available test kits and two prototype biosensor devices to determine if any of these technologies were feasible as an alternative to the standard EPA SW-846 Method 8330 test for explosives in aqueous samples. These on-site assays offer potential advantages in cost, assay time, and convenience over the traditional analysis via high-performance liquid chroma-tography(HPLC). The continuous flow immunosensor(CFI) was one of the biosensors participating in this trial, which took place at two Superfund sites located on military bases. The CFI uses a small column filled with plastic beads containing immobilized antibodies against the explosive being assayed and a fluorescent dye-labeled explosive analog. Detection occurs when the native explosive in the sample is swept into the column and displaces some of the dye-labeled analog, which is quantified via a fluorometer. Results from these tests showed thatthe CFI could produce data comparable to HPLC with no significant problems with cross-reactivity of the antibodies against other explosives or their breakdown products.
  • 机译 本科工程师的新环境
    • 作者:KATHRYN S. BROWN;
    • 刊名:Environmental Science & Technology
    • 1997年第5期
    摘要:When undergraduate Mary Long graduates from Michigan Technological University next year, she may pursue a wastewater treatment design job in Germany, go to graduate school, or join a U.S. engineering company. An ambitious student, Long is double-majoring in environmental engineering and business. She also studies German. Meet the new environmental engineer. Once the exclusive domain of graduate schools, environmental engineering has swept the undergraduate scene. Five years ago, only a handful of schools offered a bachelor's degree in the field. Today, nearly 20 schools offer programs accredited by the Accreditation Board for Engineering and Technology (ABET).
  • 机译 EPA审查了内分泌干扰物研究
    • 作者:JEFF JOHNSON;
    • 刊名:Environmental Science & Technology
    • 1997年第5期
    摘要:Some 300 peer-reviewed scientific studies of the effects of chemicals on the endocrine systems of humans, laboratory animals, and wildlife are reviewed in an EPA report released March 13. A general research agenda is recommended in the 116-page document. The report highlights the importance of research on chemicals with the potential to disrupt human and animal endocrine systems, according to Robert Huggett, assistant administrator for the Office of Research and Development (ORD), who adds that such an investigation is one of EPA's top five research areas. Huggett emphasized that the document does not conclusively link chemicals to adverse hormonal effects in humans. However, he said, "What we do have is a fairly conclusive body of evidence that links these effects to wildlife, and we are concerned about the potential to affect humans. That is why we are doing this research."
  • 机译 环境温度和E-10燃料对轻型车辆一次排气颗粒物排放的影响
    摘要:During the winter of 1994-1995, the State of Alaska Department of Environmental Conservation conducted a multi-faceted program designed to evaluate the impact of switching from regular gasoline to an E-10 fuel (gasoline with 10% ethanol) in Fairbanks. As part of that program, 10 in-use vehicles were tested on a chassis dynamometer at temperatures of 20, 0, and -20℉ using both fuels. Three of these vehicles were retested in the EPA facilities at Research Triangle Park, NC, under the same conditions. Vehicles were driven over the Urban Dynamometer Driving Schedule of the Federal Test Procedure during testing. PM-10 exhaust emission samples were collected at Fairbanks, and total paniculate samples were obtained at the EPA. Results from both parts of this study indicate that paniculate matter (PM) emission rates increased with decreasing temperature for both fuels. The increase occurred primarily during cold starting and is assumed to be due to enrichment. Paniculate matter emission rates during operation on the E-10 fuel were lower relative to rates obtained during operation on the base gasoline. Exhaust hydrocarbon and PM emissions were well correlated, suggesting that fully phased-in Federal Tier 1 vehicle emission standards will reduce PM emissions from new vehicles and that rich-operating, high emitters can be expected to have high PM emissions.
  • 机译 非离子表面活性剂增强的增溶作用和从阳离子表面活性剂增强的吸收剂区域中回收有机污染物。 1.实验
    摘要:Recent studies have shown that cationic surfactants can be used to increase the organic carbon content of aquifer materials, creating enhanced sorbent zones for hydrophobic organic contaminants (HOCs) migrating in groundwater. The coupling of nonionic surfactant-enhanced solubilization of HOCs to the cationic surfactant-enhanced sorption zone concept is examined as a possible groundwater remediation scheme. The partitioning behavior of 1,2,4-trichloroben-zene (TCB) and Igepal CO 730 (CO 730, a nonionic surfactant), both singly and jointly, were determined in batch hexa-decyltrimethylammonium (HDTMA, a cationic surfactant) chloride-modified aquifer material/water systems. The apparent CO 730 critical micelle concentration (cmc) was found to decrease by a factor of 17 due to nonideal mixed micelle formation in the presence of low aqueous phase HDTMA concentrations that resulted from exposure to HDTMA-modified aquifer material. A greater portion of CO 730 will be present in the micellar psuedophase (the HOC solubilizing phase) as a result of the lowered cmc. The TCB partitioning behavior in the HDTMA-modified aquifer material/water systems was found to be dependent upon the aquifer material organic carbon content, the apparent CO 730 cmc, and the partitioning of TCB between the micellar pseudophase and the bulk aqueous phase containing surfactant monomers. The batch experiments indicate that the micellar pseudophase would be a more favorable partitioning medium for TCB relative to the solid phase organic carbon within an enhanced sorbent zone. One-dimensional column experiments were performed using HDTMA-treated and untreated aquifer materials to determine the transport behavior of CO 730 and to assess the feasibility of using CO 730 to solubilize and recover TCB bound within a cationic surfactant-enhanced sorbent zone. Complete removal ( > 99%) of the bound TCB was achieved using a 12-column pore volume flush of 50 g/L CO 730. The column experiments demonstrated that a nonionic surfactant can effectively remove an HOC from a cationic surfactant-enhanced sorbent zone.
  • 机译 矾土凝结泥浆的表达脱水
    摘要:Filtration followed by expression characteristics of the alum-coagulated clay slurries are first reported in this paper. A strong correlation between alum chemistry and the de-watering efficiency exists. At pH 3, where the positively charged ions are the dominating species, the alum addition has only a minor improvement on dewatering efficiency. At pH 7 and pH 10, where sweep floes enmeshment play the major role, dewatering performance improves continuously as alum dose increases. At pH 5.2, where a charge reversal regime exists, the dewatering efficiency exhibits a reversal phenomenon as well. The overall dewa-terability follows: pH 5.2 > pH 3 > pH 7 > pH 10. A complete test consists of the filtration and expression stages, which are discussed separately. The filtration stage is discussed based on the average specific resistance and the residual moisture in the filtration cake. The expression stage is discussed based on the combined Terzaghi-Voigt rheological model, from which the fraction contributed by the secondary consolidation (B) and the particle creeping factor (η) are evaluated. For the dewatering sake, a lower B and a higher η are desired. Both parameters B and η increase at elevated alum dose and/or lower pH value, while exhibiting a local minimum in charge reversal regime at pH 5.2. The optimal alum dose considering sludge dewaterability is discussed.
  • 机译 在与对流层有关的实验室条件下OH自由基引发的2-丁氧基乙醇的氧化:产品研究和拟议的机理
    摘要:This type of study provides information on the reaction mechanism of the conversion of a substrate molecule, in this case a glycol ether, into its oxidation products under polluted tropospheric conditions. Such detailed pathways for the breakdown of the substrate molecule lead to the generation of photooxidants, mainly ozone, and are essential input data for computer modeling studies used to derive ozone-creating potentials of volatile organic compounds released into the atmosphere. The products formed by the hydroxyl radical-initiated oxidation of 2-butoxyethanol (C_4H_9-OCH_2CH_2OH) have been investigated by irradiating synthetic air mixtures containing the substrate, methyl nitrite, and nitric oxide, at ppm levels in a Teflon bag reactor at room temperature. The decay of reactant and the formation of products were monitored by gas chromatography and by mass spectrometry. The molar yields of the major products (mol of product formed/mol of 2-butoxyethanol consumed) were as follows: butyl formate (HC(O)OCH_2CH_2CH_2CH_3), 0.35 ± 0.11; ethylene glycol monoformate (HC(O)OCH_2CH_2-OH), 0.39 ± 0.18; butoxyacetaldehyde (CH_3CH_2CH_2CH_2-OCH_2C(O)H), 0.12 ± 0.09; 3-hydroxybutyl formate (HC(O)OCH_2-CH_2CHOHCH_3), ~0.20; and propionaldehyde, ~0.2-0.3. The yields of minor products were as follows: 2-propyl-1,3- dioxolane (CH_3CH_2CH_2CHOCH_2CH_2O), 0.025 ± 0.005; ethylene glycol monobutyrate (CH_3CH_2CH_2C(O)OCH_2CH_2OH), ~0.02-0.03; 2-hydroxybutyl formate (HC(O)OCH_2CHOHCH_2-CH_3), ~0.05; acetaldehyde, < 0.05; propyl nitrate, 0.038 ± 0.018; and butyraldehyde, < 0.011. The product distribution is explained by a mechanism involving initial OH attack at the five -CH_2- groups in 2-butoxyethanol followed by the subsequent reactions of the resulting alkyl and alkoxy radicals. The mechanism is analogous to that proposed for 2-ethoxyethanol (Stemmler et al. Environ. Sci. Technol. 1996, 30, 3385-3391), in which the alkoxy radicals predominantly undergo decomposition reactions, but also includes isomerization reactions for the alkoxy radicals that are derived from the butyl side chain in 2-butoxyethanol. The observed products, in conjunction with the proposed mechanism, account for a total molar yield of about 1.1, indicating that all the main routes are accounted for in the degradation of this hydroxy ether. Rate coefficients at room temperature for the reactions of OH radicals with bu-toxyacetaldehyde and 2-propyl-1,3-dioxolane have been determined to be 20.6 x 10~(-12) and 10.8 x 10~(-12) cm~3 molecule~(-1) s~(-1), respectively, with error limits of about ± 40%, in each case.
  • 机译 Cr(Ⅵ)水溶液反应对磁铁矿的表面钝化:XAFS和TEM结果
    摘要:Hexavalent chromium, Cr(Ⅵ), is a contaminant that may be present in groundwaters due to industrial or mining operations. Once in the groundwater, Cr(Ⅵ) is highly mobile, posing hazards to humans as both a toxin and a suspected carcinogen. Magnetite, an Fe~(2+)-bearing oxide mineral common in many aquifers, has recently been studied for its capacity to reduce Cr(Ⅵ) to the less mobile Cr(Ⅲ) in laboratory and field studies. Magnetite persists over millions of years in rocks and soils and might be an excellent material for in-situ remediation of Cr(Ⅵ)-contaminated, magnetite-bearing soils. However, we show that the magnetite surface passivates by reaction with aqueous Cr(Ⅵ) at pH 7, limiting the capacity of magnetite to act as an electron donor for Cr(Ⅵ) reduction at neutral pH.
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