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881.
Gravitational lensing is a powerful tool for the study of the distribution of dark matter in the Universe. The cold-dark-matter model of the formation of large-scale structures (that is, clusters of galaxies and even larger assemblies) predicts the existence of quasars gravitationally lensed by concentrations of dark matter so massive that the quasar images would be split by over 7 arcsec. Numerous searches for large-separation lensed quasars have, however, been unsuccessful. All of the roughly 70 lensed quasars known, including the first lensed quasar discovered, have smaller separations that can be explained in terms of galaxy-scale concentrations of baryonic matter. Although gravitationally lensed galaxies with large separations are known, quasars are more useful cosmological probes because of the simplicity of the resulting lens systems. Here we report the discovery of a lensed quasar, SDSS J1004 + 4112, which has a maximum separation between the components of 14.62 arcsec. Such a large separation means that the lensing object must be dominated by dark matter. Our results are fully consistent with theoretical expectations based on the cold-dark-matter model.  相似文献   
882.
Lipophilic tea polyphenols (LTP) were prepared by catalytic esterifieation of green tea polyphenols (GRIP) with hexadeeanoyl chloride. A novel long-chain aeyl-derivative of epigalloeateehin-3-o-gallate(EGCG) was first isolated from purification of LTP by high-speed eountereurrent ehromatography (HSCCC)using a solvent system composed of n-hexane-ethyl acetate-methanol-water ( 1 : 1 : 1 : 1, v/v) . The moleeularstructure of the acyl-derivative, Epigallocatechin-3-O-gallate-4‘-O-hexadeeanate , was elucidated by meansof elemental analysis, IR, 1H-NMR and MS spectra.  相似文献   
883.
计算机在处理蒙文信息过程中的一些问题的探讨   总被引:1,自引:1,他引:0  
讨论了用计算机处理蒙文信息过程中遇到的一些问题,并提出了解决这些问题的可行性方案。  相似文献   
884.
The optical storage characteristics of a new kind of organic photochromic material棗pyrrylfulgide were experimentally investigated in the established parallel optical data storage system. Using the pyrrylfulgide/PMMA film as a photon-mode recording medium, micro-images and encoded binary digital data were recorded, readout and erased in this parallel system. The storage density currently reaches 3?107 bit/cm2. The recorded information on the film can be kept for years in darkness at room temperature.  相似文献   
885.
Human lysozyme is a 130-aa (amino acid) alkaline polypeptide, and has both anti-bacterial and anti-viral properties which make it an important component of human natural immunity system. As a first step toward the ultimate goal of improving the anti-bacterial properties of bovine and ovine milk, a transgenic mouse that contains the genomic DNA sequence of the human lysozme gene has been generated for the first time. From 83 mice generated by microinjection, a total of 6 positive transgenic mice were identified by PCR and Southern blot. F1 mice positive for transgene in lines were also detected by PCR. This shows that transgene could be transmitted from founder transgenic mice to their offspring. Recombinant human lysozyme (rHlys) was found in the whey of 3 female positive transgenic mice by Western blot. The highest concentration of rHlys for transgenic mice was 0.2mg/mL. The antibacterial activity of the whey for transgenic mice was highly enhanced up to 0.4 times as much as that of human, while that of non-transgenic mouse was very low. Although the lysozyme activity of transgenic mice is still lower than that of human, the rHlys exhibits the same specific activity as that of human lysozyme. It provides a strong basis for further studies into the possible application of rHlys express in mammary gland.  相似文献   
886.
Universe, ecosystem, social system, etc. are evolving systems. The evolving processes of thesesystems have gradual small changes and rapid drastic changes with uncertainties under the constraintsof environment. Systems, as a whole, are evolving toward complexity, diversity and variety withfluctuations and jumps. New order emerges from "mutations". The evolution is bothchance-dependent and path-dependent. In this paper three basics: entropy, information and noise areemphasized with regard to system evolution which is a field that can give people wisdom to solvesystem problems with domain knowledge.  相似文献   
887.
运用随机网络理论 ,构建了在现代高技术战争条件下 ,“红、兰”军双方激烈对抗时 ,公路军事交通运输勤务系统运行过程的 GERT网络模型 ,并举例求出了其解析解 .在此基础上 ,提出了演习 (或战争 )时 ,公路军事交通运输保障的“失败”概率与“转移”(战术、战役或战略转移 )概率的概念 ,并对其因素构成及其相互关系进行了剖析 .  相似文献   
888.
黑洞熵公式的简单推导   总被引:4,自引:3,他引:1  
 Black hole is treated as 2-D membrane. Starting from the usual state equation of thermal radiation, the black hole entropy is technically computed, and the result that is proportional to the area of horizon is briefly obtained.  相似文献   
889.
It is very necessary for the investigation on mechanism of windblown sand movement to understand and find out effective measures of preventing and reducing danger of windblown sands,which also deals with some general characters and hot spots in the scient  相似文献   
890.
中国是经济发展最快的发展中国家之一,一方面快速发展的经济使人民生活不断提高,另一方面环境污染、尤其是环境化学物的严重污染对人体健康带来多种危害,包括呼吸系统疾病、神经系统疾病、肿瘤、出生缺陷等,甚至死亡。毋庸置疑,严重的环境污染可导致受害的众多民众失去健康和劳动能力,甚至丧失生命,是重大的社会问题乃至国际化问题,如著名的英国伦敦烟雾事件、美国洛杉矶汽车尾气事件以及日本新泻的水俣病.  相似文献   
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