首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 78 毫秒
1.
Occurrence of sulfonamide antibiotics in sewage treatment plants   总被引:2,自引:0,他引:2  
The occurrence of sulfonamide antibiotics (SAs) was investigated in the six sewage treatment plants (STPs) of Beijing, China. Of the 13 objective antibiotics, suIfamethoxazole, suIfapyrldine, suIfamerazine, sulfadiazine and suIfamethizol were detected in the influents with the average concentrations of 1.2 ± 0.45, 0.29 ± 0.25, 0.048 ± 0.012, 0.35 ± 0.52 and 0.33 ± 0.21 μg·L^-1, respectively, and those in the effluents were 1.4 ± 0.74, 0.22 ± 0.19, 0.021 ± 0.008, 0.22 ± 0.21and 0.01± 0 μg·L^-1, respectively. SuIfamethoxazole was the predominant compound detected, and was found in all wastewater samples with the other two compounds sulfapyridine and suIfamerazine. It should be noted that suIfadiazine was first reported in wastewatera, and the concentration levels of all detected compounds except for suIfamethizol (detected once in the effluent samples) in the influents were observed to be similar to those in the effluents. From the dsts in this study, it can be found that suIfamethoxazole, suIfapyridine, suIfamerazine and suIfadiazine could be partly removed in anoxic and aerobic treatment unit and vice versa in anaerobic process, which led to their low or even negative removal rates in the effluents. The increase on the concentrations of suIfamethoxazole and suIfapyridine in the effluents was found probably due to the biotransformation of their acetylated forms in anaerobic treatment unit. In addition, it was observed that the biodegradation of suIfamethoxazole and suIfapyridine could partly occur during the anoxic and aerobic process, while suIfamerazine was partly eliminated in the anaerobic and anoxic units.  相似文献   

2.
Isotopic geochemical characteristics of helium in garnet and omphacite of eclogite in the Dabie Mountains are discussed. Concentrations of3He and4He in garnet and omphacite are 3.9 × 10−14–24.0 × 10−14 and 0.48 × 10−7–9.42 × 10−7cm13.g−1, respectively. Values of3He/4He have a range of (1.19–4.63) × 10−7. Helium In the eclogite is derived from both mantle and crust. Isotopic geochemical data of helium indicate that eclogite in the Dabie Mountains might be formed in depleted mantle and the age of the cologite would be Indo-China epoch.  相似文献   

3.
Molecular devices are the ultimate goal in the miniaturization of the electronic technology. Based on the unique properties of DNA (e.g. self-assembly and molecular recognition), people have made great efforts to develop molecular devices in the last few …  相似文献   

4.
A series of experimental methods including 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test, alkaline phosphatase (ALP) activity measurement, mineralized function, Oil Red O stain and measurement were employed to assess the effect of Dy3+ on the osteogenic and adipogenic differentiation of mouse primary bone marrow stromal cells (BMSCs) and the adipogenic trans-differentiation of mouse primary osteoblasts (OBs). The results showed that Dy3+ had no effect on BMSC proliferation at concentrations of 1×10−8 and 1×10−5 mol/L, but inhibited BMSC proliferation at other concentrations. Dy3+ had no effect on OB proliferation at concentrations of 1×10−10 and 1×10−9 mol/L, but inhibited OB proliferation at other concentrations. Dy3+ had no effect on the osteogenic differentiation of BMSCs at concentrations of 1×10−9 and 1×10−7 mol/L, and promoted osteogenic differentiation of BMSCs at other concentrations at the 7th day. The osteogenic differentiation of BMSCs was inhibited by Dy3+ at concentration of 1×10−5 mol/L at the 14th day, but promoted osteogenic differentiation of BMSCs at concentrations of 1×10−9, 1×10−8, 1×10−7 and 1×10−6 mol/L with the maximal effect at concentration of 10−6 mol/L. Dy3+ promoted mineralized function of BMSCs at any concentration. Dy3+ had no effect on adipogenic differentiation of BMSCs at concentration of 1×10−7 mol/L, but inhibited adipogenic differentiation of BMSCs at other concentrations. Dy3+ inhibited adipocytic trans-differentiation of OBs at any concentration, suggesting that Dy3+ had protective effect on bone and the protective effect on bone may be mediated by modulating differentiation of BMSCs away from the adipocyte and inhibiting adipocytic trans-differentiation of OBs which may promote differentiation and mineralization of OBs. These results may be valuable for better understanding the mechanism of the effect of Dy3+ on pathogenesis of osteoporosis. Supported by the Foundation for Key Program of Ministry of Education of China (Grant No. 208018)  相似文献   

5.
The turbulent dissipation along with temperature and salinity was measured on board R/V Dong Fang Hong 2 over the shelf break of the East China Sea from March 7 to 9, 2004. Applying the Turner angle, it is found that the 'diffusive' double diffusion, salt-fingering, and stable stratification coexist in the upper water column of about 50 m. Below that depth, there exists weak salt-fingering. The turbulent dissipation rates are enhanced along the ray paths of M2 internal tides emanating from the shelf break with values ranging from 1.0×10^-9 W·kg^-1 to 1.2×10^-6 W·kg^-1. The corresponding diapycnal mixing rates are from 1×10^-6 m^2· s^-1 to 1×10^-2 m^2· s^-1. The spatially averaged mixing rate over the whole observation section is 2.3×10^-3 m^2· s^-1, which is much larger than 1×10^-5 m^2·s^-1 of the background diapycnal mixing rate in the open ocean.  相似文献   

6.
0 IntroductionThbiep ycroidmipnlee)xru ctahteinoinu mof(Ⅱ r)u t(he Rniuu(mbip,y m)3ai2n +ly) atrnids- t(r2is -,(21’ -,10-phenanthroline)ruthenium(Ⅱ) (Ru(phen)32 +) ,is a kindof sensitive analytical reagent for electrogenerated chemilumi-nescence(ECL) and chemiluminescence(CL) ,on which a par-ticular review has been presented[1]. The earliest publicationon the synthesis of Ru(bipy)32 +appeared in 1936[2], andduringthefollowing30 years ,theinvestigations relatedtothissubstance were only in…  相似文献   

7.
大叶栎营养杯育苗试验   总被引:2,自引:0,他引:2       下载免费PDF全文
2004年1~5月在广西林业科学研究院试验场,选用L9(34)正交进行大叶栎(Castanopsis fissa)试验,考察营养土配方(林下表土,林下表土 草皮灰 农家肥按100:30:20比例混合),林下表土 农家肥 磷肥按100:20:3比例混合)、追肥次数(不追肥,每月追肥1次,每月追肥2次)和营养杯规格(直径×高度:14 cm×12 cm,12 cm×18 cm,10 cm×16 cm),对大叶栎苗木的株高、地径及根系生长的影响,挑选出最佳的大叶栎营养杯育苗组合.结果表明:影响大叶栎苗木生长的主要因素是营养土配方;使用混合比为100:30:20的林下表土 草皮灰 农家肥作营养土,规格为12 cm×18 cm(直径×高度)的营养杯进行育苗,育苗期不追肥,是本次试验的最佳组合.  相似文献   

8.
Zhai  Wei  Sun  XiaoMing  Wu  YunShan  Sun  YanYan  Hua  RenMin  Ye  XianRen 《科学通报(英文版)》2012,57(10):1150-1159
Isotopic abundances and ratios of He and Ar found in inclusion fluids in pyrites formed in the Yaoling-Meiziwo tungsten miner-alization epoch show that the concentration of 4He varies widely,from 1.54×10-7 cm3 STP/g to 2609×10-7 cm3 STP/g.3He is 0.759×10-12 cm3 STP/g-3.463×10-12 cm3 STP/g.3He/4He is 0.0043-4.362 Ra,varying from crustal to mantle values.The concen-tration of 40Ar ranges from 0.624×10-7 cm3 STP/g to 8.89×10-7 cm3 STP/g.The 40Ar/36Ar varies extensively,from 330 to 2952,between atmospheric and crustal or mantle radiogenic values.Mantle-derived He is present in ore-forming fluids and the calcu-lated average proportion of the mantle He is 22%;the maximum is 67%.Our research results show that mantle-derived fluids play a significant role in tungsten mineralization.The fractionation of He and Ar indicate that there was 4He-enriched air-saturated water(MSAW) in the ore-forming fluid.The ore-forming fluid was a mixture of mantle fluid,crustal magmatic fluid and MSAW.The occurrence of a mantle component in ore-forming fluid indicates the large-scale W and Sn mineralization,including Yaol-ing-Meiziwo,in southeastern China was the result of crust and mantle interaction.The underplating or intrusion of voluminous basaltic magma formed by partial melting of the upper mantle provided the necessary heat to cause partial melting of the crust and the generation of voluminous S-type granitic magmas.Crustal magmatic fluid and mantle fluid with high 3He/4He were released from magma crystallization and fractionation,mixed with the circulating modified air-saturated water,and filled the extensional tectonic fractures,leading to the formation of world-class W and Sn deposits in southeastern China.  相似文献   

9.
Gallium, Ge, V, and U are the associated valuable elements in coal. From the 1950s to the 1970s, some researchers in the departments of coal industry and mineral resources of China investigated these elements in coal during geological explorations. The enrichment mechanism and the environmental influence of trace elements in coal have been deeply studied in recent twenty years. With respect to the ore-forming theories and practical utilizations of metals in coal, germanium was furthest studi…  相似文献   

10.
0 IntroductionMaalnadria siusb atr ompajicosr .he aAltrthe pmrisoibnlienmi (n qtihneghtraoopsiucs,QHS,Fig.1) is a sesquiterpene endoperoxide isola-ted fromArtemisia annuaL., an ancient Chineseherbal medicine usedfor treatment of fever and ma-laria.Studies of the structure and activity relation-ship have shownthat endoperoxide groupis essentialfor anti malarial activity of QHS and absence of thismoiety lead to completely loss in activity of thedrug. Many techniques have been developed to de…  相似文献   

11.
Vibrio pacini synthesizes multiple chitinases, of which three have been purified in this study by ammonium sulphate fractionation, chitin affinity chromatography and gel chromatography. Molecular weights of the three chitinases, Chi1, Chi2 and Chi3 are 27×103, 39×103 and 46×103 respectively, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The purified enzymes have optimal activity at pH 7–8, and retain 50% enzymatic activity pH 4–9. The activities of chitinases are inhibited by Pb2+, Fe3+ and Cu2+, and increased by Ca2+, Mg2+ and Mn2+. Chi3 is found to inhibit the growth of six species of fungi. Such characters of chitinase are different from those of any other chitinase that were reported before. Foundation item: Supported by the Key Technologies Research and Development Programme of the Tenth Five-Year Plan of the Nation Scientific and Technological Development (2001 BA708B04-07) Biography: HAN Bao-qin (1963-), female, Professor.  相似文献   

12.
On the gradient observational data of the atmospheric surface layer from September 1997 to December 1998 collected by two sets of Automatic Weather Station (AWS) installed in Gaize and Shiquanhe on the western Tibetan Plateau, mean surface roughness lengths at the two stations above are determined to be 2.7 and 2.9 cm, respectively. The bulk transfer coefficients each day are computed by the profile-flux method, means of the bulk transfer coefficient for momentum (i.e. drag coefficient) in 1998 are 4.83×10−3 and 4.75×103 at the two stations. The surface fluxes of momentum, sensible heat and latent heat each day are further estimated by the bulk formulas, annual mean of these fluxes is 3.4×10−2 and 1.8×102N/m2, 73.1 and 67.2 W/m2, 15.4 and 2.9 W/m2, respectively. The diurnal and seasonal variations are obtained by a composite method and the relationships among the heat transfers between land and atmosphere, plateau monsoon and plateau rain season are also discussed.  相似文献   

13.
Large quantities of di-tert-butyl peroxide (DTBP) have been emitted into the troposphere due to human activities. Its role in the atmospheric photochemical reaction has not been understood. This study presents the results of the photochemical reactions of DTBP and NOx, which have been simulated in a self-made smog chamber under the temperature of (29±1)℃. Both the wall decays of ozone and NO2 could be neglected, compared to the results in simulative experiments. The effective intensity of UV light used in the experiments was 1.28×10-3 s-1, which was expressed by the rate constant of NO2 photolysis in purified air. The reaction mechanism was proposed according to our results and reports of other researchers. The maximum values of incremental reactivity (IR) in the three simulative ex- periments were 9.53×10-2, 5.23×10-2 and 3.78×10-2, respectively. The incremental reactivity decreased with the increase of initial concentrations of DTBP. The IR value of DTBP obtained in this study was comparable to that of acetylene reported in our previous research.  相似文献   

14.
15.
恭城沙田柚果实品质与土壤环境化学的研究   总被引:2,自引:0,他引:2  
刘康怀  李艳红 《广西科学》1997,4(4):271-275
在恭城县城选择三不同情况的沙田柚环境(挂果好,当年产300多个,挂果一般,当年产50个,从不挂果,树龄已有8年,结果无望)采样,分析土壤,果实,树枝叶的常量元素和微量元素,结果表明,恭城沙田柚全糖含量平均值达10%以上,可溶性固形物含量达17%,柠檬酸0.31%,糖酸比和固酸比多在30以上。品质优的沙田柚生长的土壤K2O,P2O5含量分别为1.8003%~2.2125%和0.1524%~0.181  相似文献   

16.
The nonlinear refractive indexesn 2 for the ethanol solutions of 1, 10-phenanthroline (2.0 × 10−3 mol · L−1), [bis(l, 10-phenanthroline) lanthanum (III)] nitrate (1.0 × 10−3 mol · L−1), and [nitrato-fluoracil-bis (1, 10-phenanthroline) lanthanum (III) ] nitrate (1.0 × 10−3 mol · L−1) are first measured, the third-order nonlinear optical susceptibilities χ(3) and 〈γ〉 are calculated, and the mechanisms of the third-order optical nonlinearities enhanced by lanthanum (III) are discussed preliminarily.  相似文献   

17.
The state of Tb3+ is investigated in liposome. When the concentration of PC is below CMC (critical micell concentration), most of Tb3+ is associated with PC, the binding constant is about 3.35×103 L/mol. When the concentration of PC is beyond CMC, most of Tb3+ is dimerized, the dimerization constant is about 3.92×104L/mol. In PC−CH−H2O system, the binding constant of Tb3+−CH complex 2.93×104L/mol is obtained. Biography:Mu Xiao-jing (1974-), female, MS.  相似文献   

18.
在量化江苏省农业生产水足迹、消费水足迹及虚拟水流动基础上,分析与水资源消耗相关的环境影响,以及对人类健康、生态质量及资源的影响。江苏省农业生产水足迹、消费水足迹、虚拟水流出及流入分别为110.97亿m3、37.98亿m3、74.99亿m3和2.00亿m3,前三者主要受水稻和小麦的影响,后者主要受奶类、油料和牛肉的影响;其相关的人类健康影响分别为26.02万DALY、9.30万DALY、17.58万DALY和0.87万DALY,生态质量影响分别为19.02亿m2·a、6.69亿m2·a、12.85亿m2·a和0.53亿m2·a,资源影响分别为0、1.47亿MJ、0和1.47亿MJ。分析结果表明:节水技术应用及节水品种培育有助于减小生产水足迹,消费模式转变有助于降低消费水足迹,贸易结构调整及贸易地区选择有利于改变现有虚拟水流动模式;水足迹及虚拟水流动量值是影响江苏省水资源消费相关环境影响的重要因素,减少水资源消耗,降低农业用水比重,改变产品调入区域等均有助于减小环境影响。  相似文献   

19.
A new chemiluminescence (CL) method for the determination of tetracycline and oxytetracycline is developed, based on the CL reaction of tetracycline and oxytetracycline with Ru (bipy)3 2+ and Ce (IV). In sulfuric acid medium, the CL emission is generated upon continuous oxidtion of Ru(bipy)3 2+ by cerium (IV). The emission intensity is greatly enhanced when tetracycline and oxytetracycline are introduced into the reaction system after acid degradation. Under the optimum conditions, the calibration curves are linear over the range of 8.0×10−8∼4.0×10−6 mol/L for tetracycline and of 2.0×10−7∼4.0×10−5 mol/L for oxytetracycline, with the detection limits are 4.2×10−8 mol/L for tetracycline and 1.5×10−7 mol/L for oxytetracycline, respectively. The proposed method was used for the determination of tetracycline and oxytetracycline in pharmaceutical formulations with good results. Foundation item: Supported by the National Natural Science Foundation of China and the Natural Science Foundation of Hubei Province. Biography: HAH He-you (1962), male, Associate profeddor, Ph.D graduate candidate. Present address, Department of Chemistry, Huainan Teacher's College, Huainan.  相似文献   

20.
The osteoclast plays initiating and vanguard roles in the course of bone remodeling. The resorption and formation of bone is the basic clues of bone remodeling, which results from the mutual dependent functions of osteoclasts and osteoblasts. When the osteoclasts are activated, the bone resorption function is increased. The excess bone resorption leads to osteoporosis, characterized by formation of many hollows, lacunae and tunnels on the bone surface or in depth[1,2]. The differentiation, pro…  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号