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921.
本文分析了30例肺癌的 MRI 及手术病理分期的结果。结果表明:MRI 能够比较准确地显示肿块的大小、范围、部位及叶以上支气管的受累情况;容易显示胸壁、纵隔、隔肌及远处转移,对胸壁受侵犯诊断准确率为86.7%;无需使用造影剂能直接显示肺门及纵隔区大血管的受累与否、诊断准确率为83.3%;对肺门及纵隔淋巴结转移诊断准确率为90%,敏感性为91.3%,特异性为85.7%;与手术病理分期结果比较,MRI 对肺癌分期准确率为80%。故认为 MRI 是对肺癌分期癌一种准确的无创性新方法。 相似文献
922.
This paper introduces how the ratioR of the characteristic stiffness of rock samplevs. the stiffness of testing machines would influence the rupturing process and the acoustic emission (AE) on the part of the
tested rock samples. Result of the experiment shows: WhenR>0.20, the rock sample would rupture abruptly; whereas whenR<0.20, the rock samples would rupture slowly. When the samples rupture abruptly, the time-dependent variation of the AE rate
takes such a pattern:peak value—stable low values—rises to the maximum value (concentration)—drops back to the minimum value
(quiescence)—(rises again)—ruptures. Moreover, smallerR-value tends to be associated with longer quiescence and vice versa. WhenR>1.50, no pre-failure quiescence is detected. When the rock samples rupture slowly, the variation pattern of the AE rate (after
the stress has increased to more than 50% of the rupturing stress) is as the following:stable low (or high) values—rises (or
drops) to its maximum (or minimum) values and then continues for some time—ruptures.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 223–233, 1991.
This study is supported by the Chinese Joint Seismological Science Foundation. 相似文献
923.
We have made a data collection and analysis system for recording microcracks in rock to study the three dimensional pattern
of fracture and the dynamic properties of rock during pressurization. This system, with 8 channel data detection, records
in real-time, from the initial microcracks to the final vibration waveform excited by the master fracture. The detected data
are recorded digitally at the hard disk of an IBM computer (or 286, 386 personal computer) as well as transmitted to disk.
The sampling rate for each channel is 10 MHz.
Collecting every acoustic emission events in the loaded rock sample with 8 channels by this system, mathematically modelling
the AE event travel time, and taking the coordinates of the AE event hypocenter and the three components of P wave velocity
as unknown parameters, we set up a set of residual equations for joint inversion, so that the three dimensional localization
of AE event hypocenters can be completed under variable velocities, which will lay foundations for the research on rock fracture
clearly.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismological Sinica,13, 489–495, 1991.
The design and development of the system, and the experiments are sponsored by the Chinese Joint Seismological Science Foundation. 相似文献
924.
925.
Jiangchuan Ni Yuntai Chen Ming Wang Mingxi Wu Jiayu Zhou Peide Wang Francis T. Wu 《地震学报(英文版)》1992,5(3):459-467
Based on the three component accelerograms, recorded at near-field distance by a temporary seismic network consisting of digital
cassette tape recording accelerographs, the focal mechanisms of three aftershocks of the April 18, 1985, Luquan, Yunnan Province,
China, earthquake ofM
S=6.1, are calculated using seismic moment tensor inversion technique. The phases of direct P, S and converted SP waves in
the displacement seismograms, produced by twice integrations of the observed accelerograms, are identified via forward calculation
using Green’s functions for homogeneous semi-infinite elastic medium, and used in the inversion. The results of inversion
show that a better fit of synthetic to the observed seismograms of direct as well as converted phases can be achieved if appropriate
weighting functions are used in solving the over definite linear equations. While these aftershocks are of different magnitudes
(M
L=4.8, 3.2 and 3.5, respectively) and hypocentral locations, their focal mechanisms are very similar and consistent with that
of the main shock. This feature demonstrates the intrinsic correlation between the occurrence of aftershocks and the seismogenic
fault of main shock. Our experimentations show that using the near field accelerogram obtained from the digital seismic network
with appropriate azimuthal coverage on the focal sphere, with the aid of even simple medium model, not only the shear dislocation
source, but also the isotropic part and CLVD (compensated linear vector dipole) can be retrieved by the technique of moment
tensor inversion.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 412–419, 1991.
This work is supported by the Chinese Joint Seismological Sciences Foundation and the Western Yunnan Earthquake Prediction
Test Site (WYEPTS), State Seismological Bureau. 相似文献
926.
常宁县汤市硼矿属接触交代—热液型矿床。区内沉积岩和花岗岩磁性微弱或无磁性,与硼矿密切相关的矽卡岩及硼矿石中磁铁矿含量较高。大理岩型硼矿石磁化率168×10~(-1)nT,矽卡岩型硼矿石磁化率29033×10~(-1)nT。已知半边街矿段△T等值线形态反映出矿体产状,并与矿体投影形态一致。用△T高精度磁测寻找埋深大、磁性弱的隐伏内生硼矿是有效的方法之一。从已有磁测资料分析,预测该地区瓦盏洲一新屋山、周家屋场一带可作为硼矿找矿靶区。 相似文献
927.
高压喷射注浆技术是近年发展起来的一种基础处理新技术,它是利用高压载能介质将软弱土体冲切破碎后注入固结浆液在原位混合凝固,达到强化地基的目的。该技术多用于深层软土地基加固,建造堤坝防渗帷幕及高强度的防渗挡土墙等。本文就这项新技术及其机具设备与安装、施工程序、应用前景作了概括介绍。 相似文献
928.
929.
930.
闽东沿海构造带—东海陆架西缘断裂、钓鱼岛隆起带(台湾—宍道褶皱带)以及帛琉—九州洋脊在中生代期间先后经历了自转换断层向俯冲系统的转变,这种转变构成了中国东南及毗邻海区独特的大陆增生方式,它表明特提斯和古太平洋的演化对这一地区的中、新生代构造格局起着重要的制约作用。 相似文献