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1.
The coal seams in the Permian Taiyuan Formation and the Carboniferous Shanxi Formation are the primary reservoirs for the coalbed methane(CBM)in the Hancheng region in the Ordos Basin.In this paper,the origin and evolution of waters associated with CBM production were studied on the basis of water chemistry and isotopes including the chloride and iodine compositions,oxygen and hydrogen stable isotopes,and radioactive isotope ratio of129I/127I.The ratio of129I/127I of water was determined by accelerator mass spectrometry(AMS).The result shows that the formation water is of NaHCO3and NaCl types with the total dissolved solids(TDS)varying from 1532.29 mg/L to 7061.12 mg/L.The values of129I and I/Cl ratio indicate that the formation waters were diluted by meteoric water.The129I/127I ratios range from 6.6×10 13to 1459.5×10 13.The129I/127I ratios for most of the samples are between the129I/127I initial value and that of recent anthropogenic water.This age of the formation water samples,obtained through the129I decay curve method,ranges from 0 Ma to 18.5 Ma,suggesting that the waters from the Taiyuan Formation and the Shanxi Formation are very young.Two different origins of water are identified in the Hancheng region.One group is dominated by pre-anthropogenic meteoric water,and is characterized by129I/127I ratios lower than the initial value of 15×10 13andδD,δ18O values of waters below the Global Meteoric Water Line.The other group is characterized by129I/127I ratios in excess of 15×10 13,which has undergone variable degrees of dilution by recent anthropogenic water. 相似文献
2.
《Geophysical Prospecting》1965,13(1):136-137
Book reviewed in this article:
S. I. K uznetsov , M. V. I vanov and N. N. L yalikova , Introduction to Geological Microbiology
Organic Geochemistry , Editor I. A. B reger 相似文献
S. I. K uznetsov , M. V. I vanov and N. N. L yalikova , Introduction to Geological Microbiology
Organic Geochemistry , Editor I. A. B reger 相似文献
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4.
本文就地球电离层对行星际激波的动力学响应进行三维全球数值模拟研究．背景行星际磁场为螺旋场，南北分量为零；初始电离层由Ⅰ区场向电流和相应的晨昏电场所主导；行星际激波沿日地连线方向撞击地球．模拟结果表明，在激波的作用下，电离层Ⅰ区电流系统向子夜方向运动，在向阳侧相继出现与原Ⅰ区电流反向的异常场向电流对和同向的新生Ⅰ区电流对．该异常场向电流对在极盖区形成瞬间昏晨电场，尾随原Ⅰ区电流向夜侧方向漂移直至湮没．与此同时，新生的Ⅰ区电流不断增强并向夜侧和赤道方向延伸，最终取代原Ⅰ区电流，相应极盖区又恢复到原来的晨昏电场状态．这一响应过程和行星际激波强度有关：激波强度越强，新生的Ⅰ区场向电流也越强，它向赤道方向延伸的距离也越大，能到达的纬度也越低．上述结果在趋势上与观测到的输运对流涡旋和亚极光块的运动特征一致． 相似文献
5.
B. S. RATHOR 《Geophysical Prospecting》1978,26(3):550-561
Expressions for the I. P. activity coefficient for an inhomogeneous sphere with the conductivity increasing/decreasing from the core towards the periphery according to a power law have been derived. In certain geometrical situations of the electrode configurations a negative I. P. signal is obtained. The negative I. P. may be understood as due to modifications in the discharge current from the polarized medium during the discharge process. The results of the investigation may be useful for more accurate interpretation of I. P. anomalies due to isometric inhomogeneous bodies. 相似文献
6.
An auroral electron excitation model, combined with simple equilibrium neutral and ion chemistry models, is used to investigate the optical emission processes and height profiles of I(5577 Å) and I(7620 Å) in the 90 to 100 km altitude region. It is shown that the apparent discrepancies between ground-based and rocket-borne auroral observations of the I(7620 Å)/I(5577 Å) ratio are due to the extreme height variation of this intensity ratio in the 90 to 100 km region. 相似文献
7.
目的:探讨低剂量胸部CT（LDCT）原始数据迭代重建（SAFIRE）增强等级与不同类型（实性、部分实性及纯磨玻璃）肺小结节优化显示的对应关系。材料与方法:分析2020年9月至2021年1月行LDCT并符合肺小结节入组标准受试者101例105个肺小结节,依结节性质分为实性结节组（n=27）,部分实性结节组（n=37）和纯磨玻璃结节组（n=41）。采用单因素方差分析、卡方检验或Kruskal-Wallis H检验先分析组间一般资料,再以滤波反投影算法（FBP,B50f）为参照,比较SAFIRE I50f和I70f（分别1~5级）各模式下客观图像质量（噪声值、肺小结节CT值、SNR和CNR）和主观图像质量评分。结果:①三组在性别、身体质量指数和结节分布无显著差异,纯磨玻璃结节组年龄和结节长径均小于实性和部分实性结节组;② SAFIRE I50f 1~5和I70f-5图像噪声值均低于FBP B50f,其中SAFIRE I50f-5噪声值最低,不同模式下肺小结节CT值无显著差异,SAFIRE I50f-5肺小结节SNR和CNR均高于FBP B50f和其他SAFIRE模式;③ SAFIRE I50f 3~5实性和部分实性肺小结节图像质量主观评分高于FBP B50f和除I70f-5外SAFIRE其他模式,SAFIRE I50f-4纯磨玻璃肺小结节图像质量主观评分高于FBP B50f和除I50f-3、I50f-5外SAFIRE其他模式且组间评分无显著差异。结论:SAFIRE I50f-4在LDCT实性、部分实性和纯磨玻璃肺小结节图像质量客观、主观评价方面均表现良好且均衡,可适用于各类型肺小结节LDCT评价。 相似文献
8.
R. J. BROWN 《Geophysical Prospecting》1985,33(2):282-302
The Cole-Cole relaxation model has been found to provide good fits to multifrequency IP data and is derivable mathematically from a reasonable, albeit greatly simplified, physical model of conduction in porous rocks. However, the Cole-Cole model is used to represent the mutual impedance due to inductive or electromagnetic coupling on an empirical basis: this use has not been similarly justified by derivation from any simple physical representation of, say, a half-space, layered or uniform. A uniform conductive half-space can be represented as a simple subsurface loop with particular resistive and inductive properties. Based upon this, a mathematical expression for the mutual impedance between the two pairs of electrodes of a dipole-dipole array is derived and designated “model I”. It is seen that a degenerate case of model I is the Cole-Cole model with frequency exponent c= 1. Model I is thus more general than the Cole-Cole expression and must provide at least as good a fit to a set of field data. Provision for variation of c from unity could be made in model I equally well as for the Cole-Cole model although, at present, this would be a purely empirical alteration. Model I contains four parameters, one of which is, in effect, the resistivity of the half-space. Therefore only three parameters are involved in the model I expressions for normalized amplitude and for phase of the EM-coupling mutual impedance. Model I is compared with previously published “standard” values for two different dipole separations. Under particular constraints, model I is shown to provide better fits than the Cole-Cole model (with c= 1) over particular frequency ranges, specifically at very low frequencies and at moderately high frequencies where the model I phase curve follows the standard phase curve across the axis to positive values (negative coupling). 相似文献
9.
Desmond E.WALLING 《国际泥沙研究》2005,20(1)
It was a great honour and privilege to be elected President of WASER during the first Council meeting, held in Beijing last Saturday. I hope that I will be able to fulfil the expectations of those that elected me and I look forward to serving the Association and promoting its development. As a hydrologist/geomorphologist who started working in the field of erosion and sedimentation some 35 years ago, I have long appreciated the need for, and importance of, interaction with those with simi… 相似文献
10.
JACQUES BERTIN 《Geophysical Prospecting》1968,16(4):401-426
In the first part, the author, recalling the principle of d/c current measurements, shows by means of some examples, different experimental results relative to the induced polarization phenomenon. He presents the case of the negative induced polarization which can be explained by geometric effects. He gives some examples of saturation curves and discusses the problem of the linearity of the I.P. phenomenon. Then he shows some aspects which demonstrate that I.P. decay curves do not always conform to the general law. He concludes by showing the influence of the current electrodes, the position of which, relative to the polarizable bodies, may alter the shape of the I.P. anomalies. In the second part, the author presents different case histories of I.P. mineral surveys where I.P. is compared to other geophysical methods and drilling results. 相似文献
11.
Edward Garnero 《地震科学（英文版）》2022,35(1):29-33
I arrived at Caltech in June 1986,with interests in both mineral physics and seismology.I was excited to either study mineral physics with Professor Tom Ahrens,... 相似文献
12.
目的：探讨肺结核好发部位上周围型肺癌与结核瘤的CT征象及鉴别诊断依据。方法：搜集近6年来有结节或肿块发生在肺结核好发部位的陈旧性肺结核患者134例,其中合并周围型肺癌80例,继发结核瘤54例,所有病例均有完整CT影像资料,并均经病理证实。将周围型肺癌病例定为Ⅰ组,结核瘤病例定为Ⅱ组。再分别将结节或肿块与陈旧性肺结核灶不在同一肺段而孤立存在的,定为Ⅰa组（49例）和Ⅱa组（39例）;两者在同一肺段上混合存在的,定为Ⅰb组（31例）和Ⅱb组（15例）。回顾性分析各组的CT征象,对Ⅰ组和Ⅱ组数据组间及组内CT征象分别进行χ2检验并分析。结果：Ⅰ组患者中腺癌比例最高（61/80）。Ⅰ组与Ⅱ组病灶发生部位比较,差异无统计学意义（P〉0.05）。Ⅰa组与Ⅱa组对比,病灶大小≥3 cm、密度不均匀、空泡征、浅分叶征,强化≥20 Hu及不均匀强化以Ⅰa组多见（P〈0.05）;密度均匀、钙化、边缘清楚、强化〈20 Hu及环形强化以Ⅱa组多见（P〈0.05）。Ⅰb组与Ⅱb组对比,病灶大小≥3 cm、密度不均匀、强化≥20 Hu、不均匀强化及合并肺气肿以Ⅰb组多见（P〈0.05）;密度均匀及强化〈20 Hu以Ⅱb组多见（P〈0.05）。Ⅰa组与Ⅰb组对比,空洞及强化〈20 Hu以Ⅰa组多见（P〈0.05）;钙化、强化≥20 Hu、不均匀强化及合并肺气肿以Ⅰb组多见（P〈0.05）;Ⅱa组与Ⅱb组CT征象对比差异无统计学意义（P〉0.05）。结论：陈旧性肺结核患者合并周围型肺癌与继发结核瘤CT征象多有重叠,对各种CT征象综合分析是鉴别诊断的重要依据。 相似文献
13.
《Journal of Hydrology》2006,316(1-4):84-97
Dyes are important hydrological tracers. Many different dyes have been proposed as optimal tracers, but none of these dyes can be considered an ideal water tracer. Some dyes are toxic and most sorb to subsurface materials. The objective of this study was to find the molecular structure of an optimal water tracer. We used QSAR to screen a large number of hypothetical molecules, belonging to the class of triarylmethane dyes, in regard to their sorption characteristics to a sandy soil. The QSAR model was based on experimental sorption data obtained from four triarylmethane dyes: C.I. Food Blue 2 (C.I. 42090; Brilliant Blue FCF), C.I. Food Green 3 (C.I. 42053; FD&C Green No. 3), C.I. Acid Blue 7 (C.I. 42080; ORCOacid Blue A 150%), and C.I. Acid Green 9 (C.I. 42100; ORCOacid Fast Green B). Sorption characteristics of the dyes to the sandy soil were expressed with the Langmuir isotherm. Our premise was that dye sorption can be reduced by attachment of sulfonic acid (SO3) groups to the triarylmethane template. About 70 hypothetical dyes were created and QSAR were used to estimate sorption characteristics. The results indicated that both the position and the number of SO3 groups affected dye sorption. Sorption decreased with increasing number of SO3 groups attached to the molecule. Increasing the number of sulfonic acid groups also decreases the toxicity of the compounds. An optimal triarylmethane water tracer contains 4 to 6 SO3 groups. 相似文献
14.
Thallium (I) distribution in the Dubossari Reservoir of the Dniester River is studied. The method of inverse voltammetry is used to measure thallium (I) concentration in the water, bottom sediments, and some higher aquatic plants. In the central part of the reservoir, (where a large the Rezina-Rybnitsa Industrial Complex, producing cement and steel, is located), the concentration of thallium (I) in the investigated objects is maximum. The input of thallium (I) from the atmosphere and contaminated soil is assessed by means of measuring its concentration in Xanthoria parietina lichen and in the phytosuspension settled onto clasping-leaved pondweed (Potamogeton perfoliatus). 相似文献
15.
Variation in the concentrations of iodine-129 (129I, T1/2=15.7 Myr), a low-level radioactive component of nuclear fuel waste, is documented in surface waters and depth profiles collected during 2001 along a transect from the Norwegian Coastal Current to the North Pole. The surface waters near the Norwegian coast are found to have 20 times higher 129I concentration than the surface waters of the Arctic Ocean. The depth profiles of 129I taken in the Arctic Ocean reveal a sharp decline in the concentration to a depth of about 300-500 m followed by a weaker gradient extending down to the bottom. A twofold increase in the 129I concentration is observed in the upper 1000 m since 1996. Based on known estimates of marine transient time from the release sources (the nuclear reprocessing facilities at La Hague, France, and Sellafield, UK), a doubling in the 129I inventory of the top 1000 m of the Arctic Ocean is expected to occur between the years 2001 and 2006. As 129I of polar mixed layer and Atlantic layer of the Arctic Ocean is ventilated by the East Greenland Current into the Nordic Seas and North Atlantic Ocean, further dispersal and increase of the isotope concentration in these regions will be encountered in the near future. 相似文献
16.
Zhongwen Zhan 《地震科学（英文版）》2022,35(1):61-62
I joined Don Helmberger's group in the summer of 2008,after getting a Master's degree in China from Sidao Ni,another graduate student of Don's.I was very excite... 相似文献
17.
Lupei Zhu 《地震科学（英文版）》2022,35(1):40-43
When I received the shocking news on August 13,2020 that our beloved Don passed away,I was deeply saddened.The feeling was worsened by the COVID-19 pandemic tha... 相似文献
18.
Stephen P. Grand 《地震科学（英文版）》2022,35(1):14-16
I arrived at Caltech as a graduate student in the summer of 1979.With a BSc degree in physics,I knew little to nothing about seismology or geophysics.The Seismo... 相似文献
19.
Zi-Shun Li 《应用地球物理》2012,9(3):286-292
To avoid spatial aliasing problems in broad band high resolution seismic sections, I present a high density migration processing solution. I first analyze the spatial aliasing definition for stack and migration seismic sections and point out the differences between the two. We recognize that migration sections more often show spatial aliasing than stacked sections. Second, from wave propagation theory, I know that migration output is a new spatial sampling process and seismic prestack time migration can provide the high density sampling to prevent spatial aliasing on high resolution migration sections. Using a 2D seismic forward modeling analysis, I have found that seismic spatial aliasing noise can be eliminated by high density spatial sampling in prestack migration. In a 3D seismic data study for Daqing Oilfield in the Songliao Basin, I have also found that seismic sections obtained by high-density spatial sampling (10 × 10 m) in prestack migration have less spatial aliasing noise than those obtained by conventional low density spatial sampling (20 × 40 m) in prestack migration. 相似文献
20.
Some results of induced polarisation surveys carried out for the exploration of sulphide mineralisation in parts of Rajasthan and Gujarat, employing both frequency-domain and time-domain techniques, are presented. A few typical examples of I.P. results along with borehole sections and results of conventional geophysical surveys have been incorporated. Frequency-domain and time-domain I.P. data have been compared for selected areas.Borehole data pertaining to several areas investigated have corroborated the I.P. results fairly well. 相似文献