自由基、超氧化物歧化酶(SOD)及抗衰老

自由基是一类含有一个不成对的电子的具有高度活性的物质,体内过多的自由基对机体具有伤害作用并引起衰老,超氧化物歧化酶（SOD）能有效地清除自由基,从而起到抗衰老的作用。     

氧自由基与疾病

医学研究表明,几乎所有慢性疾病都与人体内累积过多的自由基有关.阐述了氧自由基对机体的作用,分析了与氧自由基有关疾病的发病原因.提出从饮食、保持良好生活习惯等方面来增强抗氧化能力和对含氧自由基疾病防治的基本方法,以期减少自由基在体内的累积,达到强身健体的目的.     

体内自由基，算得出来吗？

“我有必要补充抗氧化剂吗?怎么样才会知道自己体内自由基是否过高?”“我每天吃维生素C、E,蜂胶、麦苗粉、葡萄籽萃取物等几十种抗氧化产品,深怕体内自由基过高会致癌,但却不知道每天这样补下来到底效果如何?”当愈来愈多的学术报告指出,自由基与所有慢性病的产生有密切关系之际,自由基的克星——抗氧化补充剂便成了现代人养生保健不可或缺的产品,不过补进去的抗氧化剂到底对身体的帮助有多少呢?可能真正清楚的实在不多。     

抗氧化剂的体外化学发光分析

ＤＮＡ 氧化损伤可导致多种类型疾病的产生, 并可能与细胞的衰老过程直接相关． 体内自由基代谢和清除失衡将致使ＤＮＡ氧化损伤增加, ＤＮＡ 修复能力下降． 内源和外源性的抗氧化剂可清除过多的自由基, 使ＤＮＡ免受损伤． 抗氧化作用是一个很复杂的反应, 药物抗氧化能力的大小取决于其夺氢反应、还原作用及生成自由基的稳定性等诸因素． 本文采用Ｐｈｅｎ － Ｃｕ － ＶＣ－ Ｈ２Ｏ２ － ＤＮＡ体外化学发光体系, 研究了多种抗氧化剂对ＤＮＡ 损伤的保护作用, 并对其药物结构与抗氧化能力进行了分析．     

流动注射化学发光分析研究油茶总皂苷清除活性氧能力

活性氧自由基是人体生命活动过程中生物化学反应的中间产物。如果体内的活性氧自由基产生过多或清除过慢，则对生物分子造成一定的损害。导致各种相关疾病的发生。利用Liebermann反应对所提取的油茶总皂苷进行定性分析，用流动注射化学发光分析法分别测定其清除不同体系下产生的羟自由基的能力、超氧阴离子自由基的能力，并用天然抗氧化剂抗坏血酸作对照，实验结果显示油茶总皂苷具有较强的清除活性氧能力，对化学反应生成的活性氧自由基具有较好的清除作用。     

果蔬抗衰的新发现

人在呼吸过程中,以氧作为代谢活动的燃料,其中38％的氧被消耗了,但有2％的氧却化为氧自由基,如超氧阴离子自由基、羟自由基等。这些自由基的化学性质特别活跃,能攻击细胞膜上的不饱和脂肪酸,产生过氧化物,使细胞膜受损伤、分解,同时发生蛋白质变性,还会引起一系列对细胞有破坏性的连锁反应,这就是人类机体衰老的机理。科学研究已探明,人体内部在进化过程中已形成了比较完善的防御系统,其中有各种抗氧化酶,如超氧化歧酶、过氧化氢酶、过氧化物酶等,能够清除体内过多的自由     

运动对自由基及抗氧化能力的影响

运动对自由基与抗氧化能力影响的研究是运动人体科学的一个重要课题。运动过程中血红蛋白自氧化、缺血再灌注、线粒体电子漏等原因导致了体内自由基增多。当体内自由基含量超过了抗氧化能力时会对机体构成伤害。本文对运动过程中自由基的产生机制,不同强度运动对自由基代谢的影响,不同训练方法对抗氧化能力的影响等方面进行了综述。     

植物高光胁迫与自由基代谢研究进展

本文综述了植物在高光胁迫下体内自由基引发的伤害,以及植物自由基清除系统对自由基伤害的防御。从自由基代谢的角度来观察植物高光胁迫下的反应     

烟害新说

一口烟引发万亿个自由基科学家发现,自由基在人体内可引起疾病和早衰,一口香烟的烟雾中含自由基百万个数量级,烟雾在体内再激发自由基,总计一口烟的自由基数目不低于万亿。然而人体清除自由基的能力有限,加上自身疾病、年龄增长等因素,自由基在体内积聚会发生或加重病情,加速衰老。     

植物体中的自由基

概述了自由基的概念、类型、产生途径、作用机理及植物体内抗自由基氧化系统的组成和作用机制．     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.