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111篇 您的检索式:作者名="John Shaw"
    题名 作者 年代 出处 被引量
1中国黄土磁性矿物特征及其古气候意义显示文摘最直观、最直接的古气候记录莫过于陆相黄土地层,它由许多黄土和古土壤层叠覆而成,详细地记录了第四纪以来的古气候变化。黄土高原中部黄土和古土壤的风化和发育程度可以用磁学参数,如磁化率等来描述。本文作者对甘肃西峰剖面约13万年以来的黄土地层做了详细采样,测量其磁滞回线各参数,频率磁化率、低场和高场磁化率、温度磁化率、磁组构等参数。研究表明,黄土与古土壤中的磁性矿物组分相似而且稳定。磁铁矿、赤铁矿和磁赤铁矿(主要是磁铁矿)的含量及其颗粒大小决定了它们的磁学特征。黄土和古土壤的磁学性质差别主要受成土过程中形成细小磁铁矿的影响。刘秀铭 刘东生 John Shaw 1993第四纪研究1993,13,3:172
2Magnetostratigraphy and palaeoclimate of Red Clay sequences from Chinese Loess Plateau显示文摘Two Red Clay profiles near Xi’ an and Xifeng were investigated in an attempt to determine magne-tostratigraphic and palaeoclimatic records. The results show that aeolian dust accumulation and the related East Asia palaeomonsoon system had begun by 6.5 Ma, and it is deduced that the Tibetan Plateau had reached a significant elevation at that time. The late Tertiary palaeoclimatic history of the Red Clay as reflected by magnetic susceptibility is reconstructed during the period of 6.5-2.5 Ma. Stepwise increase in susceptibility of aeolian dust accumulation appears to have a close correlation to the uplift processes of the Tibetan Plateau. The remarkable increase of aeolian dust accumulation at 3.2 Ma appears to be due to the influence of global ice volume on the East Asia monsoon. Palaeomonsoon variation during the late Tertiary as recorded in the Red Clay sequences from the Chinese Loess Plateau can be regarded as the product of a number of interacting factors, such as uplift of the Tibetan Plateau,孙东怀 刘东生 陈明扬 安芷生 John Shaw 1997Science China Earth Sciences1997,40,4:27
3构造楔形体的识别与勘探--以准噶尔盆地南缘为例显示文摘构造楔形体的形成需要两个条件,一是两条相互连接的断层,二是这两条断层的位移传递方向相反。当反向传递的位移量切割了上覆地层,通常在楔形体前翼形成具指示意义的背斜构造,此类背斜可作为判断深部构造楔形体存在的直接依据。准噶尔盆地南缘3排背斜内带的构造楔形体模式非常典型,并表现为'混序'的特征。在山前深部楔形体沿侏罗系西山窑组煤层向北扩展过程中,部分位移量沿构造楔顶部的反冲断层向南消减,并切割上覆地层形成第一排背斜带,另一部分位移量则继续向北传递,在断坡位置引发褶皱变形,形成第二排和第三排背斜带。在总位移量保持稳定的前提下,这3排背斜带在走向上的此消彼长反映了位移量在南、北两个方向上的转换。准噶尔盆地南缘第二、三排背斜带中—新生界内部发育多个小型的构造楔形体,这些互相叠置的楔形构造横向延伸不大,但有可能构成独立的成藏系统,具有不同的油气水特征,从而造成同一个背斜带不同部位的含油气性迥异。在油气勘探中应通过加强地震采集、处理和解释攻关,力求精细刻画各个楔形构造在三维空间的展布,再针对已落实的楔形体展开钻探。管树巍 李本亮 何登发 John H. Shaw 陈竹新 2009地学前缘2009,16,3:25
4磁赤铁矿的几种类型与特点分析显示文摘随着环境磁学的广泛开展和应用,最近20年来磁赤铁矿(γ-Fe2O3)被人们所日益熟悉.现在它已经被发现是一种地表十分常见的矿物,与磁铁矿常常相伴随,是氧化透水通气环境的很好指示矿物.它也是制造音乐和录像磁带的重要磁性材料,在工业有很广泛的用途.磁赤铁矿的人工合成一般由磁铁矿通过在低于300℃的氧化环境中加热几个小时甚至几天时间来形成.它受热不稳定而产生化学变化的磁学性质是其重要特点,即加热到250℃之后该矿物一般就会被不同程度转变成为赤铁矿.因此实际上无法测量其居里点.后来对人工合成磁赤铁矿样品研究进一步发现,该矿物受热可以部分热稳定,居里温度约为645℃.本文通过不同粒度人工磁铁矿系列样品进行热磁测量实验时发现,超细粒级(假单畴(PSD)和多畴(MD)细粒)磁铁矿在快速加热过程中,形成了完全热稳定的磁赤铁矿.而且,用同样的样品在另外加热炉中快速加热到700℃高温,并且在该温度停留10min,然后冷却下来,也可以达到相同的效果.即由此两个过程形成的磁赤铁矿,再从室温加到700℃的居里温度测量过程几乎达到百分之百可逆,即完全对热稳定性特点.我们用X衍射和穆斯堡尔谱技术来鉴定和确认加热前的磁铁矿和快速加热形成的磁赤铁矿(和赤铁矿),并且比较其磁铁矿的磁滞迴线、高温磁化强度、低温热退磁和低温磁化率特性,结果表明,这种过程通过超细磁铁矿加热快速氧化形成完全可逆具有热稳定性质的磁赤铁矿,可能暗示着在某些加热环境形成的磁赤铁矿也可能携带热剩磁.根据磁赤铁矿是否受热不稳定及其表现形式,将它详细分成4种类型探讨分析.受热后部分稳定和完全稳定的磁赤铁矿应当具备携带热剩磁的能力.人工合成磁赤铁矿的温度与其反应时间可能有个互补关系.磁赤铁受热后稳定与否可能与多种因素有关,如受纯度大小、受热温度高低和时间长短等影响,粒度大小可能也是重要因素之一.磁赤铁矿可能如同磁铁矿,也有不同粒级超顺磁(SP)、单畴(SD)和MD对应着不同的磁学特点.细粒PSD氧化的人工磁铁矿在低温磁学测量显示为Verwey转换被'抑制'的现象,其根本原因可能是,氧化后磁铁矿的内核直径实际上已经达到或者接近该矿物的SD粒径,所以它的Verwey转换显得被'抑制'.刘秀铭 John SHAW 蒋建中 Jan BLOEMENDAL Paul HESSE Tim ROLPH 毛学刚 2010中国科学:地球科学2010,40,5:20
5楔形构造在山前冲断构造位移量消减中的作用——以准噶尔盆地南缘为例显示文摘介于复活的天山造山带与稳定的准噶尔克拉通之间的准噶尔盆地南缘前陆冲断带,是印度板块与欧亚大陆碰撞的远距离效应产物,也是新近纪以来青藏高原隆升并向北推挤的直接结果。前陆冲断带吸收了来自造山带的水平缩短构造位移量后,克拉通一侧构造趋于稳定。准噶尔盆地南缘与世界上多数前陆冲断带构造地质特征相似,通过区域地震剖面的精细构造几何学和运动学解析,发现其中的楔形构造非常典型,是前陆冲断带内部冲断构造位移量消减的主要方式之一,控制着前陆冲断带分布范围和变形方式。准噶尔盆地南缘构造变形主要由南侧的天山造山带向北逆掩冲断,但是大部分冲断构造位移量是通过楔形构造反向传递后消减。紧邻天山北麓的齐古-喀拉扎-昌吉等构造带,山前深部的楔形体沿侏罗系西山窑组煤层向北扩展过程中,部分位移量沿构造楔顶部的反冲断层向南消减,并切割上覆地层形成第一排背斜带,另一部分位移量则继续向北传递,在断坡位置引发褶皱变形,形成霍-玛-吐第二排构造带和安集海-呼图壁第三排背斜带。准噶尔盆地南缘第二、三排构造带中-新生界内部发育多个小型的构造楔型体,这些互相叠置的楔型构造横向延伸不大,加大了构造变形的复杂性和构造圈闭识别的难度。李本亮 管树巍 陈竹新 John H Shaw 雷永良 王丽宁 赵星 2012地质学报2012,86,6:18
6Risk factors for post-ERCP pancreatitis: A prospective, multicenter study显示文摘Martin L. Freeman James A. DiSario Douglas B. Nelson M.Brian Fennerty John G. Lee David J. Bjorkman Carol S. Overby Johannes Aas Michael E. Ryan Gary S. Bochna Michael J. Shaw Harry W. Snady Robert V. Erickson Joseph P. Moore Joseph P. Roel 2001Gastrointestinal Endoscopy2001,,4:5
7Red Cell Distribution Width as a Novel Prognostic Marker in Heart Failure显示文摘G. Michael Felker Larry A. Allen Stuart J. Pocock Linda K. Shaw John J.V. McMurray Marc A. Pfeffer Karl Swedberg Duolao Wang Salim Yusuf Eric L. Michelson Christopher B. Granger 2007Journal of the American College of Cardiology2007,,1:5
8Hypothetical model of dynamic biomarkers of the Alzheimer’s pathological cascade显示文摘Clifford R Jack David S Knopman William J Jagust Leslie M Shaw Paul S Aisen Michael W Weiner Ronald C Petersen John Q Trojanowski 2010Lancet Neurology2010,,1:4
9Magnetic polarity ages of the fossil-bearing strata at the Sihetun section,West Liaoning:A preliminary result显示文摘Rock-magnetic and palaeomagnetic studies have been carried out on the interval of famous fossil-bearing sedimentary rocks and its overlying basalts and underlying basalts at the Sihetun section, West Liaoning Province. Normal polarity was obtained for the sedimentary interval and the underlying basalts, while reversed polarity was found in the overlying basalts. Taking account of the new 40Ar/39Ar ages (Swisher et al., 1999), we classified the fossil-bearing sedimentary interval into the Barremian M3n zone (Early Cretaceous age). Several abnormal horizons on magnetic properties, probably corresponding to the tuffs, were observed in the fossil-bearing sedimentary interval. This implies that the massive bio-extinction may link to dramatic environmental changes that were caused by volcanic eruptions.PAN Yongxin ZHU Rixiang John Shaw ZHOU Yaoxiu 2001Chinese Science Bulletin2001,46,17:4
10Analysis on variety and characteristics of maghemite显示文摘Maghemite (γ-Fe2O3) is a very common mineral at the earth’s surface and also an important material for making music and video tapes. Maghemite is usually synthesized from magnetite under oxidizing conditions after a few hours or a few days below a temperature of 300°C. The magnetic property of thermal instability and the chemical action after heating is an important character for maghemite. That is, it will become hematite in certain proportion after being heated above 250°C. Maghemite is therefore actually unable to have its Curie temperature measured. But late using synthetic sample, maghemite was further found partially thermal stable with a measurable Curie temperature ~645°C. During our thermally magnetic experiments for a set of synthetic magnetite, we found that extra fined grain size (pseudo single domain (PSD) and small multi-domain (MD), mainly 1-10 μm) magnetite was formed to a completely thermally stable maghemite. This maghemite can also be produced by heating the same powder up to 700°C in an oven and keeping this temperature for 10 min, then cooling it down. When the generated maghemite by these two ways is heated from room temperature to 700°C, it shows almost fully reversible, or thermally stable. We used X-ray powder diffraction and Mssbauer spectroscopy to confirm the identity of this maghemite and compared its magnetic hysteresis, high temperature magnetization, low temperature thermal demagnetization, and low temperature susceptibility with those of the original preheated magnetite. Such quickly oxidized maghemite by heating to high temperature implies some types of maghemite formed in certain natural condition can carry a thermal remnant magnetization (TRM). Four types of maghemite were characterized and discussed according to their thermal stability. Among them, partially stable and fully thermally stable maghemite after heating should possess capability of carrying TRM. There is possibly a compensation of synthetizing maghemite between heating temperature and heating duration. The thermal stability of maghemite may be affected by a few factors, such as its purity (stoichiometry), heating temperature and duration. The grain size may be one of important factors. Maghemite might be similar to magnetite, having various magnetic properties corresponding to its grain size categories such as superparamagnetic (SP), single domain (SD) and MD. Low temperature measurement for PSD fine grain of synthetic magnetite shows a phenomenon of Verwey transition 'suppressed', its fundamental causes could be that the core diameter of oxidized magnetite is actually reach or approach SD size, so that its Verwey transition is shown 'suppressed'.SHAW John BLOEMENDAL Jan HESSE Paul ROLPH Tim 2010Science China Earth Sciences2010,53,8:3
11Meeting report:a hard look at the state of enamel research显示文摘The Encouraging Novel Amelogenesis Models and Ex vivo cell Lines(ENAMEL) Development workshop was held on 23 June 2017 at the Bethesda headquarters of the National Institute of Dental and Craniofacial Research(NIDCR). Discussion topics included model organisms, stem cells/cell lines, and tissues/3 D cell culture/organoids. Scientists from a number of disciplines,representing institutions from across the United States, gathered to discuss advances in our understanding of enamel, as well as future directions for the field.ophir d klein olivier duverger wendy shaw rodrigo s lacruz derk joester janet moradian-oldak megan k pugach j timothy wright sarah e millar ashok b kulkarni john d bartlett thomas gh diekwisch pamela den besten james p simmer 2017International Journal of Oral Science2017,9,4:3
12AMPK Phosphorylates and Inhibits SREBP Activity to Attenuate Hepatic Steatosis and Atherosclerosis in Diet-Induced Insulin-Resistant Mice显示文摘Yu Li Shanqin Xu Maria M. Mihaylova Bin Zheng Xiuyun Hou Bingbing Jiang Ogyi Park Zhijun Luo Etienne Lefai John Y.-J. Shyy Bin Gao Michel Wierzbicki Tony J. Verbeuren Reuben J. Shaw Richard A. Cohen Mengwei Zang 2011Cell Metabolism2011,,4:2
13Incremental Prognostic Value of Myocardial Perfusion Single Photon Emission Computed Tomography for the Prediction of Cardiac Death: Differential Stratification for Risk of Cardiac Death and Myocardial Infarction显示文摘Rory Hachamovitch Daniel S. Berman Leslee J. Shaw Hosen Kiat Ishac Cohen J. Arthur Cabico John Friedman George A. Diamond 1998Circulation1998,,6:2
14B/M极性转换过程与虚磁极转移路径显示文摘利用超导磁力仪对西峰黄土剖面记录的布容/松山(B/M)地磁极性转换过程的高分辨率研究表明,B/M极性转换经历了由负极性到正极性的五次反复倒转;转换过程中地磁场的强度衰减到正常值的约30%,场强的衰减是极性转换的前奏,而地磁场方向完全倒转后的场强恢复,是转换的最后一幕;极性转换所需的时间约2万年,从场强的开始衰减到反向恢复则需要更长的时间;极性转换的虚地磁极(VGP)转移路径大多连续,并落于一定的径度带内,包括美洲径度带、大西洋径度带和非洲径度带。西峰剖面记录的B/M转换VGP路径并未落入美洲和印度洋这两个高密径度带内。孙东怀 John Shaw 郑洪波 马醒华 Tim Rolph 1994自然科学进展(国家重点实验室通讯)1994,4,4:2
15Sleep-disordered breathing and type 2 diabetes显示文摘Jonathan E. Shaw Naresh M. Punjabi John P. Wilding K. George M.M. Alberti Paul Z. Zimmet 2008Diabetes Research and Clinical Practice2008,,1:2
16Risk factors for post-ERCP pancreatitis: A prospective, multicenter study显示文摘Martin L. Freeman James A. DiSario Douglas B. Nelson M.Brian Fennerty John G. Lee David J. Bjorkman Carol S. Overby Johannes Aas Michael E. Ryan Gary S. Bochna Michael J. Shaw Harry W. Snady Robert V. Erickson Joseph P. Moore Joseph P. Roel 2001Gastrointestinal Endoscopy2001,,4:2
17Nodule Mining-three Miles Deep显示文摘JOHN L SHAW 1993Marine Georesources and Geotechnology1993,,1:1
18Active fault-related fold-ing beneath an alluvial terrace in the southern Longmen Shan range front,Sichuan basin,China:Implications for seismic hazard 显示文摘Wang M M Jia D John H Shaw 2013Bulletin of the Seismological Society of America2013,103,4:1
19The CT-STAT (Coronary Computed Tomographic Angiography for Systematic Triage of Acute Chest Pain Patients to Treatment) Trial显示文摘James A. Goldstein Kavitha M. Chinnaiyan Aiden Abidov Stephan Achenbach Daniel S. Berman Sean W. Hayes Udo Hoffmann John R. Lesser Issam A. Mikati Brian J. O’Neil Leslee J. Shaw Michael Y.H. Shen Uma S. Valeti Gilbert L. Raff 2011Journal of the American College of Cardiology2011,,14:1
20Financial Aspects of Economic Development显示文摘Gurley John and Edward Shaw 1955American Economic Review1955,,45:1
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