CT定位用于眼面部异物诊断治疗

本文报告２６例由于外力作用致使眼面部广泛异物存留。临床应用Ｘ线的归咎常见漏诊及定位困难，因此采取ＣＴ定位达到异物诊断治疗目的。     

基于岩石物理模型的页岩孔隙结构反演及横波速度预测

准确预测储层的等效孔隙纵横比对页岩储层岩石物理建模及横波速度预测具有重要意义。为分析页岩储层孔隙纵横比及预测横波速度,提出了基于岩石物理模型的页岩孔隙纵横比反演及横波速度预测方法。本文首先通过岩石物理模型建立岩石的纵、横波速度与孔隙纵横比、孔隙度和矿物组分等参数之间的定量关系,寻找最佳孔隙纵横比;然后通过使理论预测与实际测量的纵波速度之间误差达到最小的方式反演孔隙纵横比,并以此为约束预测横波速度。实际测井数据反演结果表明,龙马溪组页岩地层的孔隙纵横比稳定,而围岩的孔隙纵横比变化范围较大;说明与围岩相比,页岩的孔隙结构更为稳定。同时,预测得到的页岩横波速度与实测横波速度的误差较小,另外对于缺少矿物组分资料的页岩层段,用平均矿物组分预测得到的横波速度误差仍较小;说明与矿物组分相比,龙马溪组页岩的纵、横波速度对孔隙纵横比参数更敏感。综上所述,利用该方法可预测到较为准确的等效孔隙纵横比和横波速度。     

珠江三角洲晚第四纪沉积特征

本文主要研究珠江三角洲的第四纪地层;晚更新世玉木亚间冰期、全新世中期(大西洋期)海侵阶段的地貌景观及珠江三角洲晚第四纪以来的沉积形成过程。     

浙江长兴二叠系和三叠系界限地层的碳同位素

研究海相碳酸盐岩的碳和氧同位素已有三十多年,积累了数千个数据,其目的在于研究古海洋碳和氧同位素的演变。在此期间,一部分研究者认为,海相碳酸盐岩的δ¹³C值在0±2范围内变化,未表现出与地质时代相关的变化趋势(Clayton和Degens,1959;Degens和Epstein,1962;Keith和Weber,1964;Galimov,1965;Becker和Clayton,1972;Schidlowski等,1975)。但是,另一些学者,如Jeffery等(1955),Baertschi(1975),Compston(1960),Weber(1967),Garrels和Parry(1974)却认为,海相碳酸盐岩的δ¹³C值随地质时代而有规律地变化。     

Optimizing layout of pumping well in irrigation district for groundwater sustainable use in northwest China

Optimizing layout of pumping well plays a vital role in curbing the groundwater level decline. A novel optimization model is presented in this study. First, the optimal well number is obtained by taking into account factors of local economy and environment based on nonlinear programming model. Then, the well spatial layout assessment model is attained based on information entropy weight and technique for order preference by similarity to ideal solution (TOPSIS). After that, the relative closeness to positive ideal solution of alternative (c_i) on the rationality of well spatial layout in cultivated land is calculated, and a set of alternatives are ranked according to the descending order of c_i. Finally, the well optimization layout is obtained by combining the optimal well number with well spatial layout assessment result based on the GIS data of pumping wells. As a case study, this method was applied in Yongchang Irrigation District of Shiyang River Basin, the arid region of northwest China. Results show that under the conditions of sustainable use of water resources, the irrigation district needed 724 wells for irrigation, with a decrease of 31.0% when compared with the existing number of wells. The wells with low flow rate and operating efficiency distributed in high density where groundwater is over‐exploitation were recommended to be closed. This well optimization layout method is expected to play a significant role in helping make plans for exploiting groundwater at more sustainable level, curbing the groundwater level decline trend, and improving the local ecological environment. Copyright © 2015 John Wiley & Sons, Ltd.     

沙漠化:从圈层耦合到全球变化

从沙漠化概念提出伊始 ,沙漠化成因机理的研究就一直成为学术界关注的焦点。沙漠化过程究竟有多少是由自然因素所致 ,多少是由人类活动所为 ,诸因素与沙漠化之间有何内在关系 ,沙尘天气发生发展过程及其诱因等 ,当属地球系统科学应解决的难题。文章从全球变化的角度 ,将沙漠系统视作一种类生命的非线性动力系统 ,指出沙漠化源于地球表层系统各圈层之间复杂的相关与耦合作用 :气候变化是控制沙漠进退的首要因素 ;陆表水持续亏损则是导致干旱、半干旱地区沙漠化发展的直接原因 ;岩石圈构造运动塑造了不同的地形地貌单元 ,奠定了沙漠分布的地理格局 ;人类的不当活动和气候变化引起的生物生产力的衰退及土地覆盖的破坏 ,造成了现代沙漠化的快速扩张。     

冀北侏罗系上统火山岩中宇宙尘的发现及其地质意义

在冀北丰宁、沽源、赤城一带的上侏罗统火山岩中发现有不同形态的铁质及玻璃质微球粒。经电镜扫描及外貌结构构造的鉴定，显示有熔融、碰撞、逸气、旋纹、冷疑、收缩等特征；经电子探针及Ｘ射线粉晶衍射分析，认为是宇宙尘。对其进行研究不仅有重要的地质意义，而且有找矿意义。     

GD—DTPA脊髓造影磁共振扫描技术应用的研究

本文目的,通过将ＧＤ－ＤＴＰＡ直接注入蛛网膜下腔后进行脊髓造影ＭＲ扫描,探索一种新的ＭＲ检查方法,材料方法：对１１例患者进行ＧＤ－ＤＴＰＡ蛛网膜腔直接注射脊髓造影前后ＭＲ扫描,保持扫描序列不变。造影剂量为０．５～１．０ｍｌ,结果：所有患者脊髓造影后即刻扫描显示脑脊液信号反转,Ｔ１Ｗ高信号。Ｔ２Ｗ低信与,结论：小剂量ＧＤ－ＤＴＰＡ直接蛛网膜注射脊髓造影ＭＲ扫描是一种安全可靠的检查方法。对观察脑脊液动     

The role of anthropogenic activities in karst spring discharge volatility

The traditional hydrological time series methods tend to focus on the mean of whichever variable is analysed but neglect its time‐varying variance (i.e. assuming the variance remains constant). The variances of hydrological time series vary with time under anthropogenic influence. There is evidence that extensive well drilling and groundwater pumping can intercept groundwater run‐off and consequently induce spring discharge volatility or variance varying with time (i.e. heteroskedasticity). To investigate the time‐varying variance or heteroskedasticity of spring discharge, this paper presents a seasonal autoregressive integrated moving average with general autoregressive conditional heteroskedasticity (SARIMA‐GARCH) model, whose the SARIMA model is used to estimate the mean of hydrological time series, and the GARCH model estimates its time‐varying variance. The SARIMA‐GARCH model was then applied to the Xin'an Springs Basin, China, where extensive groundwater development has occurred since 1978 (e.g. the average annual groundwater pumping rates were less than 0.20 m³/s in the 1970s, reached 1.20 m³/s at the end of the 1980s, surpassed 2.0 m³/s in the 1990s and exceeded 3.0 m³/s by 2007). To identify whether human activities or natural stressors caused the heteroskedasticity of Xin'an Springs discharge, we segmented the spring discharge sequence into two periods: a predevelopment stage (i.e. 1956–1977) and a developed stage (i.e. 1978–2012), and set up the SARIMA‐GARCH model for the two stages, respectively. By comparing the models, we detected the role of human activities in spring discharge volatility. The results showed that human activities caused the heteroskedasticity of the Xin'an Spring discharge. The predicted Xin'an Springs discharge by the SARIMA‐GARCH model showed that the mean monthly spring discharge is predicted to continue to decline to 0.93 m³/s in 2013, 0.67 m³/s in 2014 and 0.73 m³/s in 2015. Copyright © 2014 John Wiley & Sons, Ltd.     

山西省落家河铜矿地质特征及矿床成因浅析

落家河矿田位于中条三叉裂谷南东支的落家河构造剥蚀天窗内,该区域位于线性构造和弧形构造的交叉部位,是成矿有利部位.落家河矿区赋矿岩性为新太古界绛县群宋家山组绿泥片岩和变细碧岩.宋家山组一套钠质中基—中酸性火山凝灰岩夹正常沉积钙质副变质岩组成.经变质后的绿片岩层是主要找矿层位,特别是该岩层沿走向或倾向变化大和膨胀部位.硅化...