Evaporation of the Nerve Agent GB From Common Matrices: A Model‐System Study          下载免费PDF全文

Ishay Columbus  Itzhak Marcovitch  Shlomi Elias  Lea Yehezkel  Dana Marder  Victoria Nahum 《洁净——土壤、空气、水》2018,46(4)

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Chloride source delineation in an urban-agricultural watershed: Deicing agents versus agricultural contributions     

Andrew Oberhelman  Eric W. Peterson 《水文研究》2020,34(20):4017-4029

Analyses (n = 525) of chloride (Cl⁻), bromide (Br⁻), nitrate as nitrogen (NO₃-N), sodium (Na⁺), calcium (Ca²⁺) and potassium (K⁺) in stream water, tile-drain water and groundwater were conducted in an urban-agricultural watershed (10% urban/impervious, 87% agriculture) to explore potential differences in the signature of Cl⁻ originating from an urban source as compared with an agricultural source. Only during winter recharge events did measured Cl⁻ concentrations exceed the 230 mg/L chronic threshold. At base flow, nearly all surface water and tile water samples had Cl⁻ concentrations above the calculated background threshold of 18 mg/L. Mann–Whitney U tests revealed ratios of Cl⁻ to Br⁻ (p = .045), to NO₃-N (p < .0001), to Ca²⁺ (p < .0001), and to Na⁺ (p < .0001) to be significantly different between urban and agricultural waters. While Cl⁻ ratios indicate that road salt was the dominant source of Cl⁻ in the watershed, potassium chloride fertilizer contributed as an important secondary source. Deicing in watersheds where urban land use is minimal had a profound impact on Cl⁻ dynamics; however, agricultural practices contributed Cl⁻ year-round, elevating stream base flow Cl⁻ concentrations above the background level.  相似文献   

Analysis of Multiple Tourist Agents’ Symbiotic Relationship on the View of Tourist Enterprises Based on a Grey Correlation Model: A Case Study of Qinghai Lake,China     

XIANG Cheng  TANG Zhongxia  LIU Menglin  SHAO Li 《资源与生态学报(英文版)》2019,10(3):335-344

Tourism symbiosis is a social phenomenon consisting of many complex factors, and the reciprocal cooperation among multiple tourist agents at tourist destinations is the crux of the sustainable development of tourism. This study is from the perspective of tourist enterprises, and introduces the Symbiosis Theory of genecology. A quantitative evaluation is used to analyze both the equilibrium state of the combined symbiotic behavior routes and the behavior patterns of tourist enterprises with local governments, community residents, tourists and tourist enterprises around Qinghai Lake. The findings reveal: (1) the symbiotic behavior routes of the multiple tourist agents “E→G-R-T-E” in the Qinghai Lake area are constituted of intense symbiotic indications, while the maximum dimensionality of symbiotic interest of “E→G-R-T-E” is still in the state of disequilibrium and dissymmetry; (2) the symbiotic model of multiple tourist agents “E→G-R-T-E” in the Qinghai Lake area is an asymmetrically positive symbiotic model. It is proposed that, by establishing symbiotic mechanisms for guidance, decisions, supervisory control and profit distribution, the participation mechanism for multiple agents “E-G-R-T” can be further standardized. Moreover, tourist enterprises should be regarded as the primary agents to optimize the symbiotic model for “E→G-R-T-E” through the reinforcement of integrative supply and the construction of integrative effect, and finally promote the integrative symbiotic model of symmetrical reciprocity of the E-R-G-T model “driven by scenic areas, responsive to community residents, affected by local governments and enjoyed by tourists.”  相似文献   

红树林沉积物来源链霉菌HA6菌株发酵条件的优化   总被引：1，自引：0，他引：1  

肖静  洪专 《台湾海峡》2011,30(4):589-593

HA6菌株是分离自红树林沉积物中具有强抗菌活性的链霉菌．为提高其抗菌活性物质的产量,通过单因子试验及正交试验法对其包括发酵培养基的组成、接种量、通气量和发酵时间等发酵条件进行优化．研究表明其最佳摇瓶发酵培养基配方为：麦芽提取物质量为2．00g、可溶性淀粉质量为3．00g、豆饼粉质量为2．00g、（NH4）：SO。质量为1．00g、NaCl质量为3．00g、CaC03质量为0．50g、蒸馏水体积为100cm^3;最优发酵条件为：500em。摇瓶装液体积为150em。,接种量为8％,培养温度为28℃,初始pH为7．5,转速为200r／rain,培养时间为5d．  相似文献   

Circulating planning ideas from the metropole to the colonies: understanding South Africa's segregated cities through policy mobilities     

Astrid Wood 《Singapore journal of tropical geography》2019,40(2):257-271

In the early part of the twentieth century, South African cities were segregated in accordance with British city planning concepts that embodied the belief that social order can be manipulated through the urban form. This paper surveys the history of South African planning practices to understand the spread of segregation policies and practices. Whereas scholars tend to agree that the apartheid city (post?1948) is a more highly organized and structured version of the colonial city (pre?1910), the literature lacks consensus on the development of the segregated city (1910?1948) within South Africa. How did concepts of segregation circulate and why was it implemented with such consistency? Accordingly, this paper employs concepts of policy mobilities to trace historical configurations in South Africa to international influences. The focus on the circuits of knowledge explains how concepts and designs transplanted from elsewhere helped create the form of South African cities today. Understanding the movement of planning ideas through policy mobilities furthers geographical understandings of historical circulation processes, the role of the local actors, and policy mobilities failure. This history of learning also challenges the assumption that South African cities are unique and in so doing opens the doors for knowledge sharing between postcolonial cities.  相似文献   

国际海洋药物研究动态与发展趋势     

吕阳 《海洋科学》2018,42(10):94-102

文章用文献计量与科学知识图谱方法呈现海洋药物研究态势与热点,旨在为海洋药物研究提供参考。本文以SCIE(Science Citation Index Expanded)为数据源,以1980～2017年海洋药物领域论文为研究对象,采用文献计量与知识图谱可视化分析方法,结合Excel、VOSviewer软件,对论文年代分布、研究机构、期刊、作者、高被引论文及研究热点进行分析。结果表明,海洋药物研究的热点方向为海洋天然产物、抗菌活性、细胞毒性、海绵等,应重点关注海洋天然产物及其抗菌药理作用的研究。世界范围内关于海洋药物研究的论文数量呈逐年上升趋势,美国在该领域研究占据绝对优势,其发文量、总被引和H指数均占绝对地位。该领域主要发文期刊为《Marine Drugs》、《Journalof Natural Products》。发文机构中中国科学院位列世界第一,但整体论文质量欠佳,中国在该领域研究水平有待加强,论文影响力仍需提高。  相似文献   

Solid Phase Extraction of Trace Elements in Water and Tissue Samples on a Mini Column with Diphenylcarbazone Impregnated Nano‐TiO2 and Their Determination by Inductively Coupled Plasma Optical Emission Spectrometry          下载免费PDF全文

Sıtkı Baytak  Zikri Arslan 《洁净——土壤、空气、水》2015,43(6):822-829

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Antibacterial activity of extracts from <Emphasis Type="Italic">Zostera marina</Emphasis> against pathogens of <Emphasis Type="Italic">Apostichopus japonicus</Emphasis> skin ulceration disease     

Yang Liu  Guoliang Jiang  Zhiqiang Wu 《中国海洋大学学报(英文版)》2010,9(1):68-70

The purpose of this study was to investigate the antibacterial activity of extracts from Zostera marina against the pathogens of Apostichopus japonicus skin ulceration disease. When 95% ethanol (v/v) solvent was used to extract Zostera marina at 50°C, aqueous extract (ZA) showed obvious bacteriostatic effects on the tested bacterial strains (inhibition halo diameters between 8.23 mm and 13.62 mm), whereas the ethyl acetate extract (ZE) was almost inactive. The minimal inhibitory concentration (MIC) of ZA against four pathogens were homogeneous at 12.8 g L⁻¹. ZA components were analyzed by thin layer chromatography (TLC) assay and six fractions were obtained. In another study, the six fractions showed inhibitory effects against the tested bacteria while their functions seemed to counteract the ZA activity.  相似文献   

抗菌肽对凡纳滨对虾生长和机体免疫的影响   总被引：1，自引：0，他引：1  

宋理平  胡斌  王爱英  冒树泉  张延华  潘晓玲 《广东海洋大学学报》2010,30(3):28-32

基础饲料(对照组)中添加10g/kg抗菌肽制剂喂养体重0.10±0.01g、体长2.17±0.11cm的凡纳滨对虾(Penaeus vannamei)30d,进行10d的水浴攻毒(鳗弧菌10~8/mL),探讨饲料中添加抗菌肽对凡纳滨虾生长、成活率、免疫保护率,以及肌肉中溶菌酶活性、超氧化物歧化酶活性、总抗氧化能力的影响。结果表明:饲料中添加抗菌肽可显著提高凡纳滨对虾相对增重率、成活率和对致病菌的免疫保护率(P<0.05),但对饲料系数无显著影响(P>0.05);未受外界微生物刺激时,饲料中添加抗菌肽对凡纳滨对虾总抗氧化能力有促进作用(P<0.05),受外界微生物刺激后,饲料中添加抗菌肽喂养凡纳滨对虾可提高对虾超氧化物歧化酶活性(P<0.05)和总抗氧化能力(P<0.01)。因此饲料中添加抗菌肽喂养凡纳滨对虾可提高其机体非特异性免疫。  相似文献   

Chelant‐assisted Phytostabilization of Paint‐contaminated Residential Sites     

Syam S. Andra  Dibyendu Sarkar  Sumathi K. M. Saminathan  Rupali Datta 《洁净——土壤、空气、水》2010,38(9):803-811

Following the basic incubation study, a greenhouse experiment was conducted to elucidate the efficiency of vetiver grass (Vetiveria zizanioides L.), with or without chelating agents, in remediating lead (Pb)‐contaminated soils from actual residential sites where Pb‐based paints were used. Because the primary factor affecting Pb phytoavailability in soils is soil pH, we used two soil types widely varying in pH that have total Pb concentrations above 1500 mg kg^?1 soil. Lead‐contaminated, low pH, acidic soils were collected from residential sites in Baltimore, MD and high pH, alkaline soils were collected from residential sites in San Antonio, TX. Based on the soil characterization results, two most appropriate soils (one from each city, having similar Pb levels but variable soil physico‐chemical properties) were selected for this study. Ethylenediaminetetraacetic acid (EDTA) and [S,S′]ethylenediaminedisuccinate (EDDS) were applied at 5, 10, and 15 mmol kg^?1 soil. Lead uptake and translocation in vetiver was determined on day 10 after chelants addition. Plant and soil analysis show that EDTA treated soils have maximum Pb uptake and lower total soil Pb levels. Prediction models developed for exchangeable Pb show a strong correlation for total Pb accumulated in vetiver grass. Results of the sequential chemical extraction of the soils at both initial and final time‐points, indicates a significant mobilization of Pb by the two chelants from carbonate‐bound fraction to exchangeable pool. Information on physico‐chemical properties of contaminated residential soils help in predicting Pb phytoextraction and thus further help in calibrating a successful chelant‐assisted phytoremediation model.  相似文献