Isotopic analyses of nitrogenous compounds from the Murchison meteorite: ammonia, amines, amino acids, and polar hydrocarbons

The combined volatile bases (ammonia, aliphatic amines, and possibly other bases), ammonia, amino acids, and polar hydrocarbons were prepared from the Murchison meteorite for isotopic analyses. The volatile bases were obtained by cryogenic transfer after acid-hydrolysis of a hot-water extract and analyzed by combined gas chromatography-mass spectrometry of pentafluoropropionyl derivatives. The aliphatic amines present in this preparation comprise a mixture that includes both primary and secondary isomers through C5 at a total concentration of > or = 100 nmoles g-1. As commonly observed for meteoritic organic compounds, almost all isomers through C5 are present, and the concentrations within homologous series decrease with increasing chain length. Ammonia was chromatographically separated from the other volatile bases and found at a concentration of 1.1-1.3 micromoles g-1 meteorite. The ammonia analyzed includes contributions from ammonium salts and the hydrolysis of extractable organic compounds, e.g., carboxamides. Stable isotope analyses showed the volatile bases to be substantially enriched in the heavier isotopes, relative to comparable terrestrial compounds delta D < or = +1221%; delta 13C = +22%; delta 15N = +93%). Ammonia, per se, was found to have a somewhat lower delta 15N value (+69%) than the total volatile bases; consequently, a higher delta 15N (>93%) can be inferred for the other bases, which include the amines. Solvent-extractable polar hydrocarbons obtained separately were found to be enriched in 15N (delta 15N = +104%). Total amino acids, prepared from a hydrolyzed hot-water extract by cation exchange chromatography, gave a delta 15N of +94%, a value in good agreement with that obtained previously. Nitrogen isotopic data are also given for amino acid fractions separated chromatographically. The delta 15N values of the Murchison soluble organic compounds analyzed to date fall within a rather narrow range (delta 15N = +94 +/- 8%), an observation consistent with their formation, or formation of their precursors, by interstellar chemistry.     

两个自由度的滑块——弹簧模型中的幕式无震滑动

设想了一种两个自由度的滑块——弹簧模型，其中的2个滑块(滑块1和滑块2)由一根弹簧连接，并由一个慢慢移动的传动装置驱动。假设采用与速率和状态相关的摩擦定律，设定摩擦参数，使滑块1发生动态失稳。当摩擦参数接近稳定性转换点时，滑块2就会发生幕式无震滑动。在地震间隔期，当应力累积到大约稳态水平时，滑块2就开始缓慢滑动。随着振幅波动的衰减而成为稳态值，应力和滑动速度会发生准静态振荡。振荡衰减可能是自2001年以来日本东海地区观测到的幕式无震滑动的合理的产生机制。我们还在不同摩擦性质相互作用的双滑块模型的基础上，设想了板块边界上的各种滑动模式。     

From a mountain-rural to a plains-urban society: implications of the 1981 Nepalese Census

Preliminary results of the 1981 Nepal census are analyzed as to urbanization and population movement to the Terai. Noting the substantial shift in the pattern of Nepal's population distribution occurring between 1971-81, and projecting these rates of change for the future, the paper reports a process of transformation wherein Nepal is shifting from a rural hill and mountain society to an urban-subtropical plains (Terai) state. While the flow of migrants to urban areas and the Terai region is well known, the increase in rate of change poses a serious challenge for the Nepalese government. Economic development planning must readjust its goals and assumptions to take into account the massive metamorphosis that is occurring in Nepal. Development efforts aimed at rural hill and mountain areas may need to be reevaluated in light of the changing distribution of population.     

利用潜艇发射的“罗盘号”小卫星进行地震预报研究的总体构想

小卫星系统对探测全球及区域地质断层、研究矿产资源及预报破坏性地震(火山喷发)具有特别重要的意义。第一颗“罗盘”(COMPASS)号小卫星重约80kg,计划发射到400km 高、倾角为79°的圆形轨道上。通过它可实现从地面到空间震前前兆的协调监测,在此基础上可发展自然灾害的监测预报方法。以下就是有关该卫星系统的测量、设备和总体构思的详细介绍。     

在美国太平洋海岸西北部消除惊慌

科学家最近发现有力的证据说明，在过去几千年里，特大地震(震级8～9级)重复发生在美国的太平洋海岸西北部，最近的一次发生在300年前。这个发现已经促使人们加固现有的建筑并修改这个地区的建筑规范。这些措施在未来地震中将挽救生命，减少损失。     

根据局部复发时间探索日本关东和东海地区大地震最可能的位置

检验了这样一个假设:局部地震复发时间极小值T_L和等效的局部概率极大值P_L可用来测绘日本关东和东海地区的凹凸体。在这两个地区,国家地球科学与灾害预防研究所(NIED)的地震目录在M=1.5(M1.5)级以上是完整的。以网格间距为0.01°的各节点20km内的地震计算α值和b值,以此为基础绘出M7目标地震的T_L(P_L)图。只选用了上部33km深度内的地震。在若干地区,随着深度的增加b值显著上升。因此,若整个地壳孕震区的数据混到一起的话,有些T_L(P_L))异常就不会被揭示出来。这样,我们对顶部15km和其余深度范围,以及整个地壳孕震区分别测绘了T_L(P_L)。所得的T_L和P_L图表明,整个区域约有12％呈现出异常短的复发时间。在1890年以来发生的6个M≥6.5的目标浅震中,5个位于T_L<450年的异常区内。我们将此解释为具有异常短T_L的地区勾划出了凹凸体,未来这些地区比其他地区更有可能发生目标地震。该结果系由偶然性造成的可能性几乎不存在。1923年关东特大地震的破裂似乎发端于我们在研究区内所绘出的最为显著的凹凸体之中。一个异常位于未来可能的东海地震破裂区的东北部,另一异常位于其西南角上。计算出的T_L绝对值是不确定的,因为它们取决于计算所用区域的大小。     

Analysis of the Statistical Behaviour of Daily Maximum and Monthly Rainfall Data at New Delhi During Monsoon Period

1．IRt回*CtZOllIndian Summer Monsoon Varlablllty Is a muchdscussed and researched field,yet thereIs a considerable scope IOr further work and It Is understanding．The south—west monsoonwhich contributes more than 75%of the annual ra!nfa!lin a major port!on of Ind!a,Is thespring of!he nallonaleconomy．The ralnmH has Qo sustain山e Increasing needs ofagrlculturelrrlgatlon,the Increasing population and the rapid Industrlallsatlon．It Is lowever noted thatthe monsoon rainfall over differe…     

美国通量科学计划中的美国长期通量观测网(2/98)

1　引言对全球碳循环了解得不够 ,导致未来大气ＣＯ2 浓度预测的不确定性增加。人们一直认为 ,陆地生态系统对矿物燃料燃烧所释放的ＣＯ2 有较大的净吸收 ,并用此解释矿物燃料燃烧和森林砍伐导致大气中ＣＯ2 量增加的原因。海洋对大气中ＣＯ2 有吸收作用 ,但观测事实表明两者并不平衡 ,即所谓的“碳损失”现象。现在人们主张用陆地生态系统对矿物燃料燃烧释放出的ＣＯ2 有较大的净吸收来解释这一现象。大气中ＣＯ2 的累积速率存在较大的年际和 10ａ(年代 )际的时间尺度变化 ,我们目前尚不能确切地定量的解释这些观测事实。因为不同的解释意…     

新疆及邻区Pn速度层析成像

利用新疆及邻区2万多条Pn射线的走时资料,采用层析成像的方法反演该地区上地幔顶部的Pn速度结构.主要结果是:①新疆地区平均h速度为.2km/s,高于中国大陆地区的平均值(.0km/s),速度变化量从-0.3km/s到0.2km/s.②准噶尔盆地是明显的高Pn速度区,高速区与地貌形状吻合较好,最大值达.4km/s;塔里木盆地整体上呈现高速异常二者都可能与盆地是稳定地块、构造活动和变形较弱有关.③在盆地与山脉的交接带即主要的构造活动带,存在较低的Pn速度,可达7.9km/s.④塔里木南缘中部存在一显著的低速区,可能与岩浆活动和构造活动较强有关.⑤上地幔顶部波速各向异性整体上盆地中心较弱,边缘地带较强.新疆南部波速的各向异性可能是因印度板块对欧亚大陆的碰撞使地幔物质向北蠕动的结果.     

运用三维运动学模型对行星际磁场南北分量的预测

提出一种可能产生行星际磁场南北分量扰动的物理机制,并将此物理机制运用于三维运动学模型,对原模型作了改进. 使用改进后的模型模拟研究了1997年5月12日06:30UT爆发的晕状(halo)日冕物质抛射(CME)事件对行星际磁场和等离子体的扰动,以及1978-1981年间17个与CME有关的行星际扰动事件. 在17个事件中有14个事件可准确预测出行星际磁场南北分量的方向,准确率为82%. 结果表明,模型计算出的行星际磁场南北分量的扰动方向与观测的方向是基本一致的.