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991.
992.
Aharonian F Akhperjanian AG Bazer-Bachi AR Beilicke M Benbow W Berge D Bernlöhr K Boisson C Bolz O Borrel V Braun I Breitling F Brown AM Chadwick PM Chounet LM Cornils R Costamante L Degrange B Dickinson HJ Djannati-Ataï A Drury LO Dubus G Emmanoulopoulos D Espigat P Feinstein F Fontaine G Fuchs Y Funk S Gallant YA Giebels B Gillessen S Glicenstein JF Goret P Hadjichristidis C Hauser D Hauser M Heinzelmann G Henri G Hermann G Hinton JA Hofmann W Holleran M Horns D Jacholkowska A de Jager OC 《Nature》2006,439(7077):695-698
The source of Galactic cosmic rays (with energies up to 10(15) eV) remains unclear, although it is widely believed that they originate in the shock waves of expanding supernova remnants. At present the best way to investigate their acceleration and propagation is by observing the gamma-rays produced when cosmic rays interact with interstellar gas. Here we report observations of an extended region of very-high-energy (> 10(11) eV) gamma-ray emission correlated spatially with a complex of giant molecular clouds in the central 200 parsecs of the Milky Way. The hardness of the gamma-ray spectrum and the conditions in those molecular clouds indicate that the cosmic rays giving rise to the gamma-rays are likely to be protons and nuclei rather than electrons. The energy associated with the cosmic rays could have come from a single supernova explosion around 10(4) years ago. 相似文献
993.
994.
Shuttle avoidance training decreased the cAMP content of rat brain (excluding hippocampus and caudate nucleus), amygdala and hypothalamus. Stimulation by tones alone had a similar effect, but only in the brain fraction. Pseudoconditioning or footshocks alone had no effect. 相似文献
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997.
A Design View on Research in Social Sciences 总被引:2,自引:2,他引:0
Research in social sciences has not had the same impact as research in natural sciences and several authors are critical of social science research methods. In order to elucidate this problem, the author analyzes the purpose of research in general and in social sciences in particular. The author makes reference to various research methods that are suggested and used in social sciences. Social science research differs from research in natural sciences. It differs not only in being dependent on actions of human individuals but also because systems in social sciences are a complex mixture of Hard and Soft systems. The paper argues that research in Human Activity Systems should focus on design. This view changes the research perspective and the demands on the research methods to be used. The author suggests a method based on focusing decision settings combined with Action Research. 相似文献
998.
David N. O’Dwyer Bethany B. Moore 《Cellular and molecular life sciences : CMLS》2017,74(23):4305-4314
Periostin is a protein that plays a key role in development and repair within the biological matrix of the lung. As a matricellular protein that does not contribute to extracellular matrix structure, periostin interacts with other extracellular matrix proteins to regulate the composition of the matrix in the lung and other organs. In this review, we discuss the studies exploring the role of periostin to date in chronic respiratory diseases, namely asthma and idiopathic pulmonary fibrosis. Asthma is a major health problem globally affecting millions of people worldwide with significant associated morbidity and mortality. Periostin is highly expressed in the lungs of asthmatic patients, contributes to mucus secretion, airway fibrosis and remodeling and is recognized as a biomarker of Th2 high inflammation. Idiopathic pulmonary fibrosis is a fatal interstitial lung disease characterized by progressive aberrant fibrosis of the lung matrix and respiratory failure. It predominantly affects adults over 50 years of age and its incidence is increasing worldwide. Periostin is also highly expressed in the lungs of idiopathic pulmonary fibrosis patients. Serum levels of periostin may predict clinical progression in this disease and periostin promotes myofibroblast differentiation and type 1 collagen production to contribute to aberrant lung fibrosis. Studies to date suggest that periostin is a key player in several pathogenic mechanisms within the lung and may provide us with a useful biomarker of clinical progression in both asthma and idiopathic pulmonary fibrosis. 相似文献
999.
O. B. Sheynin 《Archive for History of Exact Sciences》1971,7(3):217-243
Summary Probabilistic ideas and methods from Newton's writings are discussed in § 1: Newton's ideas pertaining to the definition of probability, his probabilistic method in chronology, his probabilistic ideas and method in the theory of errors and his probabilistic reasonings on the system of the world.
Newton's predecessors and his influence upon subsequent scholars are dealt with in §2: beginning with his predecessors the discussion continues with his contemporaries Arbuthnot and De Moiver, then Bentley. The section ends with Laplace, whose determinism is seen as a development of the Newtonian determinism.An addendum is devoted to Lambert's reasoning on randomness and to the influence of Darwin on statistics. A synopsis is attached at the end of the article.Abbreviations
PT abridged
Philosophical Transactions of the Royal Society 1665–1800 abridged. London, 1809
- Todhunter
I. Todhunter, History of the mathematical theory of probability, Cambridge, 1865
To the memory of my mother, Sophia Sheynin (1900–1970) 相似文献
1000.
1998年7月17日,位于太平洋西南洋域位的新几内亚岛海岸线遭受了一场三波浪阵接连猛袭的海啸灾难,排山倒海般疾驰而来的波浪阵使至少2500人被无情卷走而丧生……每当一场破坏性海啸灾难突发在全球任一位城时,科斯特斯·西诺勒基斯就会迅速接通电话安排赶赴灾发现场的飞行。作为一名流体动力学工程师,科斯特斯·西诺勒基斯多年来一直在从事海啸灾难课题的研究工作。由于最近这些年份自然界海啸灾难发生的次数较多,他手头也因此而积累了大量第一手有关海啸原始数据。仅在1992~1997年期间,太平洋海域就发生了九次因地震而引起的海啸灾难,… 相似文献