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排序方式: 共有1936条查询结果,搜索用时 500 毫秒
971.
天文因素与中国大陆大震趋势研究 总被引:5,自引:0,他引:5
全面分析了20世纪发生于中国大陆的7.0级以上大地震与天文因素的关系,分析结果表明,20世纪中国大陆71%的大地震发生于月亮轨道(白道)与赤道交角变小的阶段,这说明月亮轨道运行至这一位置时将会是中国地震的活跃期.太阳活动及地球自转亦均与中国大地震的发生密切相关,太阳活动的谷年普遍都有大地震发生;地球自转速度加快时大地震多,20世纪地球自转速度加快时段发生的大地震占72%.经互相关分析发现,中国大陆大震活动滞后于太阳黑子相对数峰年约6年,滞后于地球自转最快年约12年.文中最后根据目前月亮白赤交角的变化,以及太阳活动与地球自转预测中国大陆下一个大地震活动幕可能开始于2006年,并有可能延续至2015年.在此期间内,中国大陆将会有多个M≥7.0的地震发生. 相似文献
972.
Patrizia Sadocco Silvia Nocerino Ernestina Dubini-Paglia Alberto Seves Graziano Elegir 《Journal of Polymers and the Environment》1997,5(1):57-65
An extracellular poly(3-hydroxybutyrate) (PHB) depolymerase was purified fromAureobacterium saperdae cultural medium by using hydrophobic interaction chromatography. The isolated enzyme was composed of a single polypeptide
chain with a molecular mass of 42.7 kDa as determined by SDS-PAGE and by native gel filtration on TSK-HW-55S. The enzyme was
not a glycoprotein. Its optimum activity occurred at pH 8.0 and it showed a broad pH stability, ranging from pH 3 to pH 11.N-Bromosuccinamide and 2-hydroxy-5-nitrobenzyl bromide completely inactivated the enzyme, suggesting the involvement of tryptophan
residues at the active site of the protein. The enzyme was very sensitive to diisopropyl fluorophosphate and diazo-dl-norleucine methyl ester, showing the importance of serine and carboxyl groups. The modification of cysteine residues byp-hydroxy mercuricbenzoate did not cause a loss of activity, whereas dithiothreitol rapidly inactivated the enzyme, revealing
the presence of disulfide bonds.A saperdae depolymerase acted on the surface layer of PHB films and the degradation proceeded by surface erosion releasing monomers
and dimers of 3-hydroxybutric acid. The degradation of PHB films byA. saperdae depolymerase was partially inhibited in the presence of excess amounts of enzyme. This phenomenon, already observed by Mukaiet al. with poly(hydroxyalkanoates) depolymerases fromAlcaligenes faecalis, Pseudomonas pickettii, andComamonas testosteroni, was analyzed according to the kinetic model proposed by these authors. The experimental data evidenced a general agreement
with the kinetic model, although higher initial degradation rates were found withA. saperdae depolymerase. 相似文献
973.
本文介绍了四川原煤及其废渣与制品的γ辐射剂量率、附加γ辐射人均年有效剂量量。同时,用低本底Ge(Li)多道γ能谱仪测定了原煤、矸粉与矸砖,煤渣与煤渣砖、粉煤灰及粘土砖等样品中的天然放射性核素~(238)U,~(232)Th,~(226)Ra,~(40)K的比活度。经比较和研究,找出了这些物质的放射性水平及它们彼此之间的规律。 相似文献
974.
出舱活动过程中航天员的热舒适性分析 总被引:1,自引:0,他引:1
分析了出舱活动中航天员- 服装系统的热平衡,阐述了影响航天员热舒适性的因素及热舒适性的评价标准,并对美国航天员舱外活动的冷应激的人体工程学问题进行了讨论。还指出了提高航天员热舒适性有待解决的几个关键问题。 相似文献
975.
Stéphanie Ponsart Jean Coudane Anne des Rieux Michel Vert 《Journal of Polymers and the Environment》2003,11(2):31-37
Novel (-caprolactone)-based copolymers of different compositions were synthesized by allowing methyl iodide to react with the polycarbanion that resulted from the action of lithium diisopropylamide on poly(-caprolactone) in THF at –70°C under argon atmosphere. The copolymers were characterized by various techniques, namely 1H nuclear magnetic resonance, size exclusion chromatography, differential scanning calorimetry, x-ray diffraction and viscoelasticimetry. They were submitted to hydrolytic and lipase-catalyzed enzymatic degradation in comparison with genuine PCL. The Young modulus depended on the degree of methylation. In contrast, loss angle and glass transition temperature did not depend on this parameter. It is shown that the lipase-catalyzed degradation of methylated PCL is much slower than in the case of genuine PCL. 相似文献
976.
The impact of disturbance from construction work around Cardiff Bay, south Wales, on the densities and feeding behavior of
seven waterbird species was studied over an 11-year period. Construction of a barrage across the mouth of the bay has subsequently
resulted in its impoundment; other major works included the construction of a bridge carrying a divided highway. Construction
work disturbance significantly reduced the densities of five species—green-winged teal (Anas crecca), Eurasian oystercatcher (Haematopus ostralegus), dunlin (Calidris alpina), Eurasian curlew (Numenius arquata), and common redshank (Tringa totanus)—on adjacent intertidal mudflats, and thus the overall carrying capacity of the bay. Construction work also reduced the feeding
activity of Eurasian oystercatcher, dunlin, and common redshank on these mudflats. The possible impact of the loss of birds
from these mudflats upon the populations that the bay supported is discussed. Evidence from other local studies suggests that
the displacement of common redshank from these mudflats did not contribute to a decline in this species. 相似文献
977.
断裂研究是区域和场地稳定性评价以及工程抗震设计中的一项重要的基础性工作。对于有断裂通过的工程场地,从断裂、场地土层和工程三者相互作用的角度出发,开展有针对性的场地断裂活动效应及地震稳定性研究,对保证工程的安全建设和可靠运行有着极为重要的现实意义。本文试以宿迁三线船闸的建设为例,对场地断裂活动效应的风险进行分析与评价。 相似文献
978.
本文运用医学地理学、医学气象学及医学磁学等新兴交叉学科的基本原理,分析武汉市36a来机动车辆交通事故与太阳黑子相对数的相关关系。结果表明:二者之间既有11a周期的正相关变化规律,又有22a周期的负相关变化规律。并对太阳黑子活动影响交通事故发生的可能机理进行了初讨。 相似文献
979.
森林火灾重灾时段对太阳活动,厄尔尼诺,南方涛动异常的响应 总被引:5,自引:0,他引:5
本文根据天地生相互作用原理,研究了黑龙江近40多年来森林火灾灾情年际变化规律,发现森林火灾重灾时段(年)与太阳活动谷年及其次年基本同步,与ENSO密切相关;三者是形成“重灾时段”的重大天地生原因。 相似文献
980.
This paper analyzes five major causes of park-people conflicts that have occurred in Nepal's Royal Chitwan National Park.
The causes include illegal transactions of forest products from the park, livestock grazing in the park, illegal hunting and
fishing, crop damage, and threats to human and animal life caused by wild animals from the park. The conflicts indicate a
reciprocal relationship between the park and local people. They reflect the attitudes of local people and representatives
of the park authority whose priorities and objectives largely diverge. The results show that people settled adjacent to the
park are heavily dependent on its resources. Even in places where some, albeit few alternative sources exist, local people
continue to trespass the park boundary as these sources are inadequate to ensure the fulfillment of local people's resource
needs. Illegal transactions of resources continue throughout the year; however, they are less intense during summer due to
flooding caused by the Rapti River, which forms the park boundary towards the northern section where this study is conducted.
The frequency of local people's visits to the park is mainly determined by their age, distance between homesteads and park,
and volume of crop loss caused by wild animals. Crop damage is the function of size of landholding, distance, and frequency
of crop raid. Local people claim that they have no intention of letting their livestock graze in the park; however, the dense
vegetation of the park attracts livestock grazing on riverbanks just outside the open park boundary. Many head of livestock
are killed by carnivores of the park. Human casualties are mainly caused by sloth bear (Melursus ursinus), tiger (Panthera tigris), wild pig (Sug scrofa), and rhinoceros (Rhinoceros unicornis). There had been some earlier attempts to reconcile the conflicts by offering local people different kinds of compensations;
however, these were unsuccessful measures. An integrated approach is essential if efforts to resolve the park-people conflicts
are to succeed. The government is in the process of launching a project that aims to resolve the inherent problems with such
an approach. Suggestions are made to incorporate some key elements, such as maintaining effective communication between various
parties and the potential for wildlife conservation among local people. 相似文献