Construction of a Metagenomic DNA Library of Sponge Symbionts and Screening of Antibacterial Metabolites   总被引：1，自引：0，他引：1  

CHEN Juan ZHU Tianjiao LI Dehai CUI Chengbin FANG Yuchun LIU Hongbing LIU Peipei GU Qianqun ZHU Weiming 《中国海洋大学学报(英文版)》2006,5(2):119-122

To study the bioactive metabolites produced by sponge-derived uncultured symbionts, a metagenomic DNA library of the symbionts of sponge Gelliodes gracilis was constructed. The average size of DNA inserts in the library was 20 kb. This library was screened for antibiotic activity using paper disc assaying. Two clones displayed the antibacterial activity against Micrococcus tetragenus. The metabolites of these two clones were analyzed through HPLC. The result showed that their metabolites were quite different from those of the host E. coli DH5α and the host containing vector pHZ132. This study may present a new approach to exploring bioactive metabolites of sponge symbionts.  相似文献   

柴达木盆地矿产开发中环境地质问题及防治对策   总被引：2，自引：2，他引：0  

谢娟  张骏  杨军  孙亚乔  成玉祥  李毅 《地球科学与环境学报》2005,27(4):79-82

在柴达木盆地环境现状实际调查基础上，根据调查资料论述了柴达木盆地地区矿产开发引起的主要环境地质问题及其危害。分析了引起土地沙化．土壤盐渍化，水土污染，崩塌地面塌陷，生态环境恶化产生原因，并在地质环境保护方面提出合理化建议，以期为西部开发过程环境保护提供依据。  相似文献   

The Neutrino Telescope Antares     

Juan José Hernández-Rey 《Astrophysics and Space Science》2005,297(1-4):257-267

Whilst the number of observed astrophysical sources of γ-rays is now moderately high, only three astrophysical objects have been studied with neutrinos, namely the Sun, a supernova (SN1987A) and the Earth (its atmosphere). However, astro-neutrinos may give a new boost to astrophysics, similar to the impressive progress provided during the last decades by γ-rays. The ANTARES collaboration aims to build a large neutrino telescope under the Mediterranean Sea at a depth of 2500 m. To reach this goal, a remarkable effort of R&D has been performed in recent years that has culminated in the deployment, connection and operation of two prototype strings. The final detector will be composed of 12 strings and will be ready by 2007.  相似文献   

国外港口物流发展与闽台港口物流对接   总被引：3，自引：0，他引：3  

黄民生  王成超  沈庆琼  徐巍  程娟  吴小勇 《世界地理研究》2008,17(1):105-111

分析福建与台湾港口物流发展现状和存在问题，以及高雄-厦门、高雄-福州海上试航和“两门两马”小三通直航发展态势，指出两岸试航的局限性和港口物流直航的必然性。综合分析鹿特丹、新加坡、安特卫普、釜山、汉堡等世界著名港口物流发展经验，提出对闽台两岸港口物流对接具有可供借鉴经验。针对闽台港口物流发展中存在问题提出了两岸港口资源整合，建立台海港口群；完善集疏运体系，促进港口物流对接；大力发展临港工业，构建环台湾海峡临港工业走廊等措施。  相似文献   

On the use and abuse of Newton's second law for variable mass problems     

Angel R. Plastino  Juan C. Muzzio 《Celestial Mechanics and Dynamical Astronomy》1992,53(3):227-232

We clarify some misunderstandings currently found in the literature that arise from improper application of Newton's second law to variable mass problems. In the particular case of isotropic mass loss, for example, several authors introduce a force that actually does not exist.Facultad de Ciencias Astronómicas y Geofisicas de la Universidad Nacional de La PlataOn a Fellowship from the Comisión de Investigaciones Cientificas de la Provincia de Buenos Aires.Member of the Carrera del Investigador Cientifico del Consejo Nacional de Investigaciones Cientificas y Técnicas de la República Argentina.  相似文献   

Orbital structure of self-consistent triaxial stellar systems     

Roberto O. Aquilano  Juan C. Muzzio  Hugo D. Navone  Alejandra F. Zorzi 《Celestial Mechanics and Dynamical Astronomy》2007,99(4):307-324

We used a multipolar code to create, through the dissipationless collapses of systems of 1,000,000 particles, three self-consistent triaxial stellar systems with axial ratios corresponding to those of E4, E5 and E6 galaxies. The E5 and E6 models have small, but significant, rotational velocities although their total angular momenta are zero, that is, they exhibit figure rotation; the rotational velocity decreases with decreasing flattening of the models and for the E4 model it is essentially zero. Except for minor changes, probably caused by unavoidable relaxation effects, the systems are highly stable. The potential of each system was subsequently approximated with interpolating formulae yielding smooth potentials, stationary for the non-rotating model and stationary in the rotating frame for the rotating ones. The Lyapunov exponents could then be computed for randomly selected samples of the bodies that make up the different systems, allowing the recognition of regular and partially and fully chaotic orbits. Finally, the regular orbits were Fourier analyzed and classified using their locations on the frequency map. As it could be expected, the percentages of chaotic orbits increase with the flattening of the system. As one goes from E6 through E4, the fraction of partially chaotic orbits relative to that of fully chaotic ones increases, with the former surpassing the latter in model E4; the likely cause of this behavior is that triaxiality diminishes from E6 through E4, the latter system being almost axially symmetric. We especulate that some of the partially chaotic orbits may obey a global integral akin to the long axis component of angular momentum. Our results show that is perfectly possible to have highly stable triaxial models with large fractions of chaotic orbits, but such systems cannot have constant axial ratios from center to border: a slightly flattened reservoir of highly chaotic orbits seems to be mandatory for those systems.  相似文献   

3D soft-sediment deformation structures: evidence for Quaternary seismicity in the Madrid basin, Spain     

Pablo G. Silva  Juan C. Cañaveras  Sergio Sanchez-Moral  Javier Lario  Enrique Sanz 《地学学报》1997,9(5-6):208-212

  相似文献   

利用地下水长观资料求解含水层参数   总被引：1，自引：0，他引：1  

王华军  李娟 《地下水》2007,29(6):78-81

以银川平原灌区内的地下水动态观测资料,气象资料和灌溉试验资料为基础,分析了灌区内地下水的时空分布规律,并定量地确定了含水层参数:给水度度μ、潜水临界埋深△0、潜水蒸发系数C,采用此方法还可以推求降雨入渗补给系数a和灌溉回归系数等参数.  相似文献   

青海省共和盆地周缘晚古生代镁铁质火山岩Sr-Nd-Pb同位素地球化学及其地质意义   总被引：4，自引：3，他引：4  

郭安林张国伟  孙延贵程顺有 强娟 《岩石学报》2007,23(4):747-754

青海省共和盆地周缘晚古生代镁铁质火山岩分属阿尼玛卿蛇绿混杂带,宗务隆构造带和苦海-赛什塘带。阿尼玛卿带正常洋中脊玄武岩(N-MORB)样品具有较高的~(87)Sr/~(86)Sr(t)比值(0.7066～0.7084)、高的ε_(Nd)(t)(12.2～12.8)和较低的~(206)Pb/~(204)Pb初始值(17.72～17.79)。这些同位素特征类似于秦岭勉略蛇绿岩带的N-MORB以及印度洋低~(206)Pb/~(204)Pb高~(143)Nd/~(144)Nd N-MORB。该带中的洋岛玄武岩(OIB)的~(87)Sr/~(86)Sr比值为0.7036～0.7044,ε_(Nd)(t)=4.4～4.8,~(206)Pb/~(204)Pb=17.45～17.62。其Sr和Nd同位素比值可与印度洋代表热点构造的洋岛玄武岩对比,但~(206)Pb/~(204)Pb低于印度洋的热点构造玄武岩,因此,具有类似印度洋低~(143)Nd/~(144)Nd比值MORB同位素特征。宗务隆构造带的N-MORB的Sr同位素比值在0.7041～0.7058,ε_(Nd)(t)=6.1～8.4,~(206)Pb/~(204)Pb=17.51～17.90,划归高~(143)Nd/~(144)Nd比值的N-MORB。苦海大陆裂谷玄武岩显示了高的~(87)Sr/~(86)Sr同位素比值(0.7115和0.7104)和低的ε_(Nd)(t)值(-1.7和-2.5),其~(206)Pb/~(204)Pb(17.64和17.46)与上述大洋玄武质岩石无显著区别。上述各岩类的同位素特征反映了它们生成的构造环境和陆壳组分混染的程度。阿尼玛卿带的N-MORB代表了典型的来自亏损地幔源区的洋中脊产物。与勉略带同类岩石可能来自同一源区。OIB可能属于热点构造成因的洋岛产物并与MORB一起构成了阿尼玛卿洋洋壳。宗务隆带MORB同样代表了主要源自相对亏损地幔的洋脊产物并指示宗务隆带曾开裂成洋。苦海大陆裂谷玄武岩极高的Sr和低的Nd同位素比值是陆壳物质组分的强烈印记,这与该类火山岩发育在前寒武纪基底之上不无关系。结合本区大洋玄武岩普遍低的Nb/U和Ce/Pb比值,推测它们可能源自EMII与DMM物质的交代混合。按照习惯的想法,明显的Dupal异常(△~(208)Pb/~(204)Pb值=46～103和△~(207)Pb/~(204)Pb值=4～18;大多样品~(87)Sr/~(86)Sr>0.704)指示这些岩石在空间上代表了来自南半球印度洋位置的古洋壳残余。但是,北半球愈来愈多的Dupal异常的发现有可能指示它们是类似现今东南亚多洋岛构造历经"汇聚式(focused)俯冲"的产物。此外,宗务隆带MORB的Dupal异常指示本区古特提斯域的北界较先前所定还要北推200km。  相似文献   

BCK-代数上的(λ1,λ2)-广义模糊关联理想     

杜娟  廖祖华 《华东地质学院学报》2007,30(4)

给出了BCK代-数上(λ1,λ2)-广义模糊关联理想,模糊关联理想的概念并在此定义下推出了它们的一些重要性质。  相似文献