Carbon isotopic record of foraminifers in surface sediments from the South China Sea and its significance

Since the 1990s, the papers and data involved withthe South China Sea (SCS) have been emerging in largenumbers in the world as people pay more attention to thepaleoceanography of the SCS. There have been more than100 cores mentioned in papers containing p…     

抵御蠕虫攻击的一种方法-Honeypot系统

Internet大面积遭受蠕虫攻击的事件时有发生，针对这种问题，引入Honeypot技术，结合入侵检测系统(IDS)、数据挖掘提出了一种解决办法：将Honeypot置于DMZ中，利用其欺骗地址空间技术覆盖服务器中没有用到的IP地址，捕获蠕虫；IDS监控流入网络的数据包，对入侵作出反映；系统日志异地保存。该系统能有效抵御目前已经出现的蠕虫攻击，同时对新出现的目前未知的蠕虫攻击也有很好的防御效果。     

Na(THF)2(μ2-η5-Cp)(η5,η5,η1-Cp3Yb)(THF)]n: The synthesis and X-ray structure of an anionic organolanthanidepolymer formed via self-assembly

Cp2Yb·2THF reacts with CpNa in 1：1 molar ratio in THF at 40℃ for 2 h, and the in situ generated anionic divalent complex NaYbCp3（THF）n reacts further with an excess of CpH at 40℃ for 48h, after work-up, affording the trivalent anionic ytterbium complex[Na（THF）2（μ2-η^5-Cp） （η^5, η^5,η^1-Cp3Yb）（THF）]n：（1） by oxidation reaction of Cp2Yb with CpH. Crystal structure determination reveals that complex 1 has one-dimension polymeric chains of distinct Na（THF）2（μ2-η^5-Cp） （η^5, η^5,η^1-Cp3Yb）（THF） units, which were formed by the coordination of the bridging Cp ligand with Cp3Yb＇THF and Na（THF）2 in η^5,η^5 mode via self-assembly.     

Chemical composition of decomposing stumps in successive rotation of Chinese fir （Cunninghamia lanceolata （Lamb.） Hook.） plantations

Decomposition of stumps in successive rotation of Chinese fir （Cunninghamia lanceolata （Lamb.） Hook.） plantations was studied using a chronosequenee approach. The results showed that decomposition rate constant of Chinese fir stump was 0.02695 as calculated from Olson＇s model. The N content of stump increased during the first two-year decomposition. When the dead stump C/N ratio was 463.2 ± 27.3, the stumps started to release N. The pattern of P release was similar to that for N. However, K content of stumps showed a consistent declining trend over time during the whole decomposition. ^13C nuclear magnetic resonance spectroscopy with cross polarization and magic-angle spinning （^13C CPMAS-NMR） was used to analyse organic carbon （C） components in decomposing stumps. The ^13C CPMAS-NMR spectra of stumps displayed that stump was dominated by cellulose and hemieellulose. The spectra also showed the accumulation of intensity in alkyl C, aromatic C, and earboxyl C spectral regions, which was expected as the labile cellulose and hemieellulose components in O-alkyl C spectral region were selectively decomposed first.     

A high-performance thermoacoustic refrigerator operating in room-temperature range

The working principle of an efficient travelling- wave thermoacoustic refrigerator operating in room-temperature range has been analyzed and an experimental set-up has been built. The experiment showed that suppressing DC-flow streaming was very critical to efficient operation, and an elastic membrane was used to solve the problem successfully. At the most efficient operating point, the novel thermoacoustic refrigerator achieved a cooling capacity of about 80 W at -20℃, with a much higher efficiency than previously developed standing-wave thermoacoustic refrigerator.     

机动目标空间合群仿真

为了解决空间合群和战场中的事件检测问题，提出了一种新的机动目标的空间群生成算法．该算法通过一级融合获得的信息来定义特征相似度，即归属相似度、位置相似度和速度相似度，并将这些相似度再次融合以求得合群结果．由于测量空间的不确定性被映射到了模糊相似度空间，因此通过模糊匹配机制可解决测量空间的不确定性问题．仿真结果表明，所提算法能实时完成多个级别的空间合群融合，其计算复杂度也比较低，而且在空间合群的态势评估中获得了比较好的结果．     

西部干旱区生态建设

中国西部拥有广阔的土地、丰富的资源、神奇的自然风光、多彩的民族风情，但同时也面临着干旱的气候、贫乏的水资源、稀少的植被、荒漠化的土地、频发的沙尘暴等一系列生态与环境问题。事实上，西部地区的自然环境一度有过良好的状态。但在漫长的历史进程中，由于受到开垦过度、人口剧增及自然条件变迁的影响，西部地区已经成为我国生态最为脆弱的地区．特别是西部干旱区，脆弱的生态与环境问题已经成为制约区域可持续发展的重要因素。关注和推进西部干旱区生态建设，不仅对西部开发起着重大的作用，对我国中东部地区的发展也有着长远的影响。     

Rational design of glycerol dehydratase： Swapping the genes encoding the subunits of glycerol dehydratase to improve enzymatic properties

1,3-propanediol (1,3-PD) is an important material for chemical industry,and there has been always much interest in the production of 1,3-PD using all possible routes. The genes encoding glyc-erol dehydratase (GDHt) from Citrobacter freundii,Klebsiella pneumoniae and metagenome were cloned and expressed in E. coli. All glycerol dehy-dratases but the one from metagenome could be detected to show enzyme activities. In order to im-prove the enzymatic properties of GDHts,the genes encoding α and β-γ subunits were cloned,and the enzyme characteristics were evolved by rational de-sign based on their 3D structures which were con-structed by homology modeling. Six heteroenzymes were obtained by swapping the α subunit genes of these three different-source-derived GDHts. The pH,thermal stability and Vmax of some heteroenzymes were dramatically improved by 2―5 times compared with the wild one (GDHtKP). The GDHt cloned from metagenome,originally proved to be with no enzyme activity,was converted into active enzyme by swap-ping its subunits with other different GDHts. In addi-tion,the effect of subtle 3D structural changes on the properties of the enzyme was also observed.     

Magnetic properties of highroad-side pine tree leaves in Beijing and their environmental significance

This is a report on magnetic properties of highroad-side tree (Pinus pumila Regel) leaves collected along an expressway linking Beijing City and the Capital International Airport and further focus on their environmental contributions. A series of rock magnetic experiments show that the primary mag-netic mineral of leaf samples was identified to be magnetite,in the pseudo-single domain (PSD) grain size range 0.2―5.0 μm. On the other hand,magnet-ite concentration and grain size in leaves are ascer-tained to decrease with increasing of sampling dis-tance to highroad asphalt surface,suggesting that high magnetic response to traffic pollution is localized within a distance of some two meters away from highroad asphalt surface. Although magnetic suscep-tibility is ordinarily regarded as a simple,rapid and low-cost method for monitoring traffic pollution,saturation isothermal remanent magnetization (SIRM) can be treated as a valid proxy for monitoring air par-ticulate matter (PM) when samples are magnetically weak. It is believed that a synthetic rock magnetic study is an effective method for determining concen-tration and grain size of ferromagnets in the atmos-pheric PM,and then it should be a rapid and feasible technique for monitoring atmospheric pollution.     

棉花床土调制剂对棉花苗田土壤肥力的影响

为了探明不同配方的棉花床土调制剂对棉花苗田土壤肥力的影响,于2005年4月在湖南农业大学实验基地对2004年筛选的4个新配方进行棉花育苗试验。研究结果表明,处理1、2较处理3、4棉花苗床肥力提高,杀菌剂和生长调节剂对土壤成分的肥力没有影响。因此,处理1、2对棉苗生长有促进作用。