Paleomagnetism of the earliest Cretaceous to early late Cretaceous sandstones, Khorat Group, Northeast Thailand: Implications for tectonic plate movement of the Indochina block

A total of 400 samples (33 sites) were collected from the earliest Cretaceous to early Late Cretaceous sandstones of the Khorat Group in the Indochina block for paleomagnetic study to unravel the tectonic evolution of the region. The sites were adopted from 3 traverses located in the northern edge of the Khorat Plateau, northeastern Thailand. Results indicate that almost all the sandstones exhibit similar magnetic values with an average declination (D) = 31.7°, inclination (I) = 30.3°, λ = 59.7°,  = 190.9°, K = 54.4, and A₉₅ = 3.7 at reference point 17°30′N and 103°30′E. The calculated paleolatitude points are inferred to deviate from the present latitude point by 1.2 ± 2.3°. Only the lowermost part of the Cretaceous sandstones can pass a positive fold test at 95% confidence level. The relationship between the virtual geomagnetic poles (VGPs) of Cretaceous rocks of the Indochina plate in Thailand and those of the South China plate advocate that there is a major displacement of Indochina along the northwest-trending Red River and associated faults by about 950 ± 150 km with a 16.0–17.0° clockwise rotation relative to the South China plate during earliest Cretaceous times. Paleomagnetic results of the early Late Cretaceous Indochina plate point to a 20–25° clockwise rotation relative to the present occurring since very Late Cretaceous (65 Myrs)–Early Neogene times which may be due to the collision between India and Asia.     

新一代天气雷达三维数字组网软件系统设计与实现

天气雷达三维格点组网基数据具有多方面的应用价值,而且,新一代天气雷达观测资料目前基本上都可以实时传输到区域中心,为充分发挥雷达网的作用,基于近期相关具有实用性的研究成果,在国内首次研制了新一代天气雷达三维数字组网软件系统.系统以后台数据处理为核心,辅以简便的控制界面,多线程编程技术提高了系统数据处理的效率,模块化的多线程管理便于扩展新算法模块,混合语言编程技术缩短了科研成果业务化应用的周期.系统可在微机上运行,进行高时空分辨率的区域雷达三维数字组网以及二次产品生成.     

牙鲆、石鲽和川鲽的线粒体16S rRNA基因片段的序列比较研究

以相应引物对牙鲆(Paralichthysolivaceus)和石鲽(K.areiusbicoloratus)的线粒体16SrRNA基因片段进行了PCR扩增,PCR产物经T载体连接之后进行了克隆、测序,均得到了590bp的碱基序列,并将其与GenBank中牙鲆线粒体全序列相应片段和川鲽(Platichthysflesus)相应片段进行比较,结果表明,川鲽和石鲽序列差异很小(核苷酸差异数为7,同源性为98.8%);而牙鲆与川鲽和石鲽的序列差异明显(核苷酸差异数为90～93,同源性约为84%),且大多数核苷酸变异位点集中在序列中部大约200bp的区域.     

盆地流体动力学演化及其成矿效应——以广东富湾-长坑银金矿床为例

文章以广东富湾－长坑层控银金矿床为实例，基于各阶段盆地中温度场，压力场和流动场的动力学演化过程与成矿效应的研究，发现盆地流体转变为成矿流体具有漫长的演化与更迭历程；构造演化和盆地的沉积充填特征，不仅直接影响着流体在盆地中的流动样式，而且直接影响着成矿物质空间存在形式的变化以及“流体－岩石”体系中各要素间的再分配。流体的大规模活动及大型矿床的形成与大幅度的构造运动，沉积作用，岩浆活动，火山活动等宏观地球动力作用有关，盆地边缘沟通深部的垂向断裂与浅部不整合面－侧向断裂交汇地段是成矿物质堆积的最佳场所。     

优化采样策略下长江口潮间带大型底栖生物物种丰富度的估算

在异质性潮间带湿地中通过野外采样估算大型底栖动物物种丰富度,面临的挑战是统计上精确性的要求与实际采样难度之间的矛盾。为了解决这个问题,本研究通过对采样策略整个过程的三个主要部分进行优化设计（优化采样方法、确定最少采样效力、探索最佳的采样间距）,以期在中国长江河口典型的潮间带湿地中获得一个优化、有效和实用的大型底栖动物采样策略。本研究选取了横断面采样方法,并根据典型栖息地类型（潮滩、潮沟、盐沼植被）进行分层优化采样,这种类型的采样也称为横断面分层抽样。最少采样效力和最佳的采样间距由两个数学方法确定：蒙特·卡洛模拟和物种累积曲线。结果表明,根据典型栖息地类型优化的横断面分层采样,在大为减少采样效力和劳动力的情况下,还能采集样地81%物种,优化效果明显。同时,还分别确定了三类栖息地的最佳采样间隔和最小采样效力：在盐沼植被中,采样效力需要超过1.8 m2,最佳采样间隔为10 m;在潮滩中,最小采样效力2 m2,最佳采样间隔为10 m;在潮沟中,采样效力为3 m2,间隔为1 m。不同栖息地类型之间最小采样效力和最佳采样间隔的差异可能受到优势物种的迁移范围和栖息地的物理差异（例如潮汐水文、底泥、植被覆盖）的影响。本研究所采用的优化采样策略在平衡采样效力的情况下,为大型底栖动物丰富度估算提供良好的精度。此外,在河口湿地进行大型底栖动物调查之时,本研究的结论能提供采样策略参考。本研究所采用的采样策略设计注重采样的三个关键部分,具有良好的采样效果,可作为栖息地管理或生态系统评估的野外实地采样指南。     

中型医院CT室实施质量管理原则初探

本文应用我国推广普及型ＣＴ（ＣＴＭＡＸ－Ⅱ），根据世界卫生组织（ＷＨＯ）提出的ＱＡ、ＱＣ体系的原则，制定我院ＣＴ室十个扫描技术规范和ＣＴ诊断技术规范等，和ＣＴ日常维护（ＰＭ）规程和ＣＴ图像考贝后处理等３个规程．     

Dew variability in three habitats of a sand dune transect in a desert oasis ecotone,Northwestern China

Dew, as a supplementary water source, may have an important ecological role in arid and semi‐arid regions. During August and September of 2007 and 2008, measurements were taken to investigate the dew accumulation and evaporation patterns in the very early morning hours, in three different habitats (dunetop, footslope, and interdune lowland) of a fixed sand dune in Northwest China. Dew quantities were measured using the cloth‐plate method. The results indicated that there was a positive correlation between dew amounts and relative humidity, but a negative correlation between dew amounts and mean temperature. Clear mornings were characterized by higher dew amounts and longer dew duration, whereas less dew was recorded during cloudy and especially windy mornings. Dew continued to condense even after sunrise, although a shorter warming time after dawn is also of vital importance in dew formation. The higher average maximum dew quantities (0.06 mm) and longer average dew duration (2.3 h) occurred in the interdune lowland; the lower and shorter average dew amounts (0.048 mm) and duration (1.9 h) were obtained at the dune top. The footslope habitat exhibited intermediate values. Clearly, the differences in dew deposition can be partially attributed to the distinguishing characteristics of the microhabitats. The present study highlighted the impacts of these characteristics on near‐ground dew condensation accumulation and evaporation in a fixed sand dune and may facilitate evaluation of the role of dew in arid and semi‐arid environments. Copyright © 2012 John Wiley & Sons, Ltd.     

论经典平差模型的几何统一

为了更直观、深入地理解参数平差与条件平差的本质区别并找出它们的内在联系,在参数平差、条件平差、具有参数的条件平差、附有限制条件的条件平差和具有条件的参数平差模型中引入线性泛函,构建其统一的几何模型,从几何角度统一经典平差模型.     

土-地铁隧道动力相互作用的大型振动台试验——试验结果分析

在进行土-地铁隧道动力相互作用的大型振动台模型试验中,分别测出了模型地基的加速度反应、隧道结构的加速度反应、结构的侧向土压力反应和隧道结构的应变反应。本文首先对模型体系的加速度反应实测值进行整理,分析了模型地基的边界模拟效果、模型地基和隧道结构的加速度反应规律。其次,对模型隧道结构的应变实测结果进行了分析,给出了地铁区间隧道在水平向地震动作用下横截面的应变分布规律,分析了模型箱侧壁与地基土以及隧道结构与土体接触面上的动土压力实测结果及其反应的规律。最后,对试验中模型土的液化现象、地震裂缝和地下结构上浮等震害现象进行了描述。     

宽频带海底地震仪的研制

为填补我国海洋地震监测和海洋地震研究的空白,获得对海洋地震多发区域的监测能力,特此进行宽频带海底地震仪的研制.本文详细介绍了宽频带海底地震仪的设计目标、基本工作原理、组成结构及性能技术指标和研制过程.此外,还介绍了宽频带海底地震仪在中国南海东北部海域应用实例的实验结果,展示了宽频带海底地震仪在3000m海底所记录到的数据资料.