太阳温度与能源的测算和寿命分析

对太阳表面温度利用多种方法进行测算，并按温度随深度递增规律，分析太阳中心温度，利用太阳中心区物理条件和化学成分研究太阳能量的产生和质量的消耗，并对太阳寿命进行推论分析．     

无限计划条件下装备经济寿命测算研究

无限计划是装备发展的理性假设。在同型更新、参数不变的基本假定条件下,构建了无限计划条件下装备经济寿命评估基本模型。然后,在与传统的经济寿命评估测算的结果进行对比分析的基础上,以模型的参数变化对经济寿命和年使用维修保障费用触发点的影响进行静态比较分析与敏感性分析,为装备经济寿命评估提供了一个新的视角,在此基础上可以进一步开展参数不确定性、年使用维修保障费非固定增长情况下经济寿命的测算等问题的研究。     

The p66shc adaptor protein controls oxidative stress response and life span in mammals

Gene mutations in invertebrates have been identified that extend life span and enhance resistance to environmental stresses such as ultraviolet light or reactive oxygen species. In mammals, the mechanisms that regulate stress response are poorly understood and no genes are known to increase individual life span. Here we report that targeted mutation of the mouse p66shc gene induces stress resistance and prolongs life span. p66shc is a splice variant of p52shc/p46shc (ref. 2), a cytoplasmic signal transducer involved in the transmission of mitogenic signals from activated receptors to Ras. We show that: (1) p66shc is serine phosphorylated upon treatment with hydrogen peroxide (H2O2) or irradiation with ultraviolet light; (2) ablation of p66shc enhances cellular resistance to apoptosis induced by H2O2 or ultraviolet light; (3) a serine-phosphorylation defective mutant of p66shc cannot restore the normal stress response in p66shc-/- cells; (4) the p53 and p21 stress response is impaired in p66shc-/- cells; (5) p66shc-/- mice have increased resistance to paraquat and a 30% increase in life span. We propose that p66shc is part of a signal transduction pathway that regulates stress apoptotic responses and life span in mammals.     

高压断路器寿命可靠性判断法

针对在非完全寿命试验条件下判别高压断路器可靠性的方法,为进一步开展相关研究提供理论依据、促进高压电器行业的发展。结合高压断路器寿命分布实例,提出了建立高压断路器寿命可靠性判别模型的基本方法,并应用极大似然函数的数学方法对其进行分析和判别。通过对断路器寿命的均值和方差进行估计,判断出高压断路器首次故障时间。所建立的可靠性判别模型、判定方法及计算结果,对研究和评价高压断路器寿命可靠性等技术参数具有一定的理论价值和实际指导意义。     

Low marine sulphate and protracted oxygenation of the Proterozoic biosphere

Progressive oxygenation of the Earth's early biosphere is thought to have resulted in increased sulphide oxidation during continental weathering, leading to a corresponding increase in marine sulphate concentration. Accurate reconstruction of marine sulphate reservoir size is therefore important for interpreting the oxygenation history of early Earth environments. Few data, however, specifically constrain how sulphate concentrations may have changed during the Proterozoic era (2.5-0.54 Gyr ago). Prior to 2.2 Gyr ago, when oxygen began to accumulate in the Earth's atmosphere, sulphate concentrations are inferred to have been <1 mM and possibly <200 microM, on the basis of limited isotopic variability preserved in sedimentary sulphides and experimental data showing suppressed isotopic fractionation at extremely low sulphate concentrations. By 0.8 Gyr ago, oxygen and thus sulphate levels may have risen significantly. Here we report large stratigraphic variations in the sulphur isotope composition of marine carbonate-associated sulphate, and use a rate-dependent model for sulphur isotope change that allows us to track changes in marine sulphate concentrations throughout the Proterozoic. Our calculations indicate sulphate levels between 1.5 and 4.5 mM, or 5-15 per cent of modern values, for more than 1 Gyr after initial oxygenation of the Earth's biosphere. Persistence of low oceanic sulphate demonstrates the protracted nature of Earth's oxygenation. It links biospheric evolution to temporal patterns in the depositional behaviour of marine iron- and sulphur-bearing minerals, biological cycling of redox-sensitive elements and availability of trace metals essential to eukaryotic development.     

60 m大跨度洞室最小矢跨比研究

大跨度洞室的最小矢跨比是大跨度洞室尺寸设计的重要参考依据,基于能够考虑岩体软化、剪胀、体胀、密度变化等开挖响应特征的Cavehoek本构模型和能够反映不同岩体质量、岩石单轴抗压强度条件下的极限应变标准,对不同地质强度指标GSI、埋深、侧压力系数、结构面等条件下的60 m大跨度洞室的最小矢跨比进行了研究.结果表明,GSI、侧压力系数、埋深3个因素中,GSI对大跨度洞室的最小矢跨比影响最大,侧压力系数和埋深次之;岩体质量越好,最小矢跨比越小,最小矢跨比与侧压力系数和埋深之间并非线性关系.结构面和岩石单轴抗压强度对大跨度洞室最小矢跨比有较大的影响,尤其是缓倾结构面非常不利于大跨度洞室成拱.     

Prokaryotic cells of the deep sub-seafloor biosphere identified as living bacteria

Chemical analyses of the pore waters from hundreds of deep ocean sediment cores have over decades provided evidence for ongoing processes that require biological catalysis by prokaryotes. This sub-seafloor activity of microorganisms may influence the surface Earth by changing the chemistry of the ocean and by triggering the emission of methane, with consequences for the marine carbon cycle and even the global climate. Despite the fact that only about 1% of the total marine primary production of organic carbon is available for deep-sea microorganisms, sub-seafloor sediments harbour over half of all prokaryotic cells on Earth. This estimation has been calculated from numerous microscopic cell counts in sediment cores of the Ocean Drilling Program. Because these counts cannot differentiate between dead and alive cells, the population size of living microorganisms is unknown. Here, using ribosomal RNA as a target for the technique known as catalysed reporter deposition-fluorescence in situ hybridization (CARD-FISH), we provide direct quantification of live cells as defined by the presence of ribosomes. We show that a large fraction of the sub-seafloor prokaryotes is alive, even in very old (16 million yr) and deep (> 400 m) sediments. All detectable living cells belong to the Bacteria and have turnover times of 0.25-22 yr, comparable to surface sediments.     

A unifying framework for dinitrogen fixation in the terrestrial biosphere

Dinitrogen (N(2)) fixation is widely recognized as an important process in controlling ecosystem responses to global environmental change, both today and in the past; however, significant discrepancies exist between theory and observations of patterns of N(2) fixation across major sectors of the land biosphere. A question remains as to why symbiotic N(2)-fixing plants are more abundant in vast areas of the tropics than in many of the mature forests that seem to be nitrogen-limited in the temperate and boreal zones. Here we present a unifying framework for terrestrial N(2) fixation that can explain the geographic occurrence of N(2) fixers across diverse biomes and at the global scale. By examining trade-offs inherent in plant carbon, nitrogen and phosphorus capture, we find a clear advantage to symbiotic N(2) fixers in phosphorus-limited tropical savannas and lowland tropical forests. The ability of N(2) fixers to invest nitrogen into phosphorus acquisition seems vital to sustained N(2) fixation in phosphorus-limited tropical ecosystems. In contrast, modern-day temperatures seem to constrain N(2) fixation rates and N(2)-fixing species from mature forests in the high latitudes. We propose that an analysis that couples biogeochemical cycling and biophysical mechanisms is sufficient to explain the principal geographical patterns of symbiotic N(2) fixation on land, thus providing a basis for predicting the response of nutrient-limited ecosystems to climate change and increasing atmospheric CO(2).     

考虑脉动风速的悬索跨越管桥涡激振动响应及疲劳分析

对悬索跨越管桥涡激振动响应及疲劳进行分析.考虑风速的脉动特性,利用Morison方程推导涡激耦合力,将动力载荷传递到管桥节点对结构动力响应进行分析:依据Miner理论对不同工况下管道和钢丝绳疲劳寿命进行计算.研究结果表明:考虑脉动风速时,随风速变化而变频变幅的涡激载荷力对结构振动的影响有限,并起到抑振的效果:结构的振动响应在4.0,8.0,9.5和11.5 m/s时出现峰值,最大竖向和横向振动幅值分别发生在风向攻角为00和90.时:管道结构的疲劳寿命随风速的增加明显缩短.     

中小跨径桥梁的加宽加固

中小跨径桥梁加宽加固工作的重要性和迫切性日益突出.文章结合工程实例,对中小跨径桥梁的加宽加固方法、技术进行了一些总结和探讨,并对各加宽加固方案进行了比选.     

Discovering the roles of subsurface microorganisms: Progress and future of deep biosphere investigation

The discovery of the marine “deep biosphere”—microorganisms living deep below the seafloor—is one of the most significant and exciting discoveries since the ocean drilling program began more than 40 years ago. Study of the deep biosphere has become a research frontier and a hot spot both for geological and biological sciences. Here, we introduce the history of the discovery of the deep biosphere, and then we describe the types of environments for life below the seafloor, the energy sources for the living creatures, the diversity of organisms within the deep biosphere, and the new tools and technologies used in this research field. We will highlight several recently completed Integrated Ocean Drilling Program Expeditions, which targeted the subseafloor deep biosphere within the crust and sediments. Finally, future research directions and challenges of deep biosphere investigation towards uncovering the roles of subsurface microorganisms will be briefly addressed.     

古希腊先哲教我们生活

雅典奥运会开幕式上的一串串文化符号多么绚丽和迷目。它们似识非识,激起我们探究的欲望。有缘的是,在世界文明体系中,希腊人在重世俗和非宗教性方面与中国人最为相似,因此古希腊“诸子百家”的生活哲学对我们来说也是那么亲切可感。在下面这些优美的故事和哲理中,我们可以辨别哪些属于孔子,哪些属于庄子,先哲们怎样一开始就洞悉了人生的方方面面,我们现在所有的生活观念都无出其右。     

大巴山区大气圈、水圈和生物圈环境研究--大巴山区生态环境研究报告(二)

为保护大巴山区地球生态环境，科学利用这片国土，采用观察和检测的方法，对其进行了研究。对不同地区的大气和水源采样测试分析说明大巴山区大气和水环境质量非常好；森林资源极其丰富，植物带谱明显，森林群落和食物链结构完整；植物没受污染，生物圈环境质量好。     

生命的彩虹——谈《我把太阳迎进祖国》声乐艺术的审美创造

声乐艺术的多媒体传播形式是当代音乐传播中的常见形式。在《我把太阳迎进祖国》这一多媒体声乐作品中 ,歌唱家自由自觉的生命创造 ;真情真意的融注贯通 ;精美精妙的匠心独运 ,充分显示了声乐审美创造的三个重要环节。任何声乐艺术的审美创造 ,都是艺术家用心血、用生命创造的结果 ,其艺术价值本身 ,也是美学价值的综合体现     

伊朗西北部Arasbaran生物圈保护区及邻近地区的天牛种类(鞘翅目:天牛科)

天牛(鞘翅目Coleoptera:天牛科Cerambycidae)为树木重要的钻蛀性害虫.本文研究了伊朗西北部Arasbaran生物圈保护区及邻近地区的天牛种类,采集鉴定了5个亚科26属33种,提供了一些种类的植物寄主.     

Span60在石墨烯润滑油中分子行为及协同作用

石墨烯常被使用在润滑油中,以此提高油的润滑性能,但其在油中极易发生团聚,需要借助分散剂抑制团聚。石墨烯、分散剂及润滑油间分子行为可揭示分散机理、润滑机理及协同作用。本文采用对环境无毒无害的span60作为分散剂,基于分子动力学研究石墨烯润滑油添加span60前后的润滑性能变化,建立氮化硅-润滑油-轴承钢层结构模型,分析span60/石墨烯的含量比、工作温度、压强以及剪切速度等因素对润滑油膜在摩擦副表面吸附能、剪切应力以及形成的类固膜厚度的影响,并通过实验进行验证。分散剂span60与石墨烯在润滑油中起到协同效应,提高了润滑油在Si3N4-GCr15摩擦副表面的润滑能力。当span60/石墨烯含量比为7:1时,润滑效果最好;温度为373 K、压强为102 MPa、剪切速度为25 m?s-1时,润滑油润滑性能最好。添加适量span60可以有效解决石墨烯在润滑油中的团聚问题。石墨烯、分散剂及润滑油间的协同效应受温度、压强及速度的影响。