能谱CT诊断腹部多发病灶同源性的初步研究     

杨伟洪  沈新平  潘娜  向先俊  胡小红 《CT理论与应用研究》2013,(3):395-400

目的:探讨CT能谱成像在诊断腹部多发病灶同源性中的价值。材料和方法:收集10例经手术病理或随访观察证实的腹部多发病灶患者资料,回顾性分析患者多发病灶,包括肝脏、胃、肾上腺及腹腔淋巴结转移病灶的CT能谱图像。多发病灶的感兴趣区按照直径5mm的圆形选取,用能谱后处理工具行多发病灶的能量衰减曲线、直方图、散点图分析,将三个图像的吻合情况分成基本吻合,部分吻合,不吻合三种情况,比较多发病灶能谱图像的吻合情况,总结规律,对腹部多发病灶的同源性作出评价。结果:发现腹部恶性肿瘤原发灶与多发转移灶的能量衰减曲线、直方图图像基本吻合,散点图部分吻合,提示原发灶和转移灶同源。多发良性病灶如血管瘤、能谱图像也基本吻合,可帮助诊断病灶的同源性。结论:初步判断能谱CT可作为诊断腹部多发病灶同源性的有效工具。  相似文献   

Recent glitches detected in the Crab pulsar     

Jingbo Wang  Na Wang  Hao Tong  Jianping Yuan 《Astrophysics and Space Science》2012,340(2):307-315

From 2000 to 2010, monitoring of radio emission from the Crab pulsar at Xinjiang Observatory detected a total of nine glitches. The occurrence of glitches appears to be a random process as described by previous researches. A persistent change in pulse frequency and pulse frequency derivative after each glitch was found. There is no obvious correlation between glitch sizes and the time since last glitch. For these glitches Δν _p and D[(n)\dot]_p\Delta\dot{\nu}_{p} span two orders of magnitude. The pulsar suffered the largest frequency jump ever seen on MJD 53067.1. The size of the glitch is ∼6.8×10⁻⁶ Hz, ∼3.5 times that of the glitch occurred in 1989 glitch, with a very large permanent changes in frequency and pulse frequency derivative and followed by a decay with time constant ∼21 days. The braking index presents significant changes. We attribute this variation to a varying particle wind strength which may be caused by glitch activities. We discuss the properties of detected glitches in Crab pulsar and compare them with glitches in the Vela pulsar.  相似文献   

Research on Ensemble Pulsar Time Based on Observed Data     

Ding Chen  Xing-zhi Zhu  Na Wang 《Chinese Astronomy and Astrophysics》2012

The applications of pulsar timing to several important aspects are introduced and a skeletal definition of the pulsar time scale is given. By taking advantage of the observational timing data of millisecond pulsars obtained at the Parkes Astronomical Observatory, Australia, the ensemble pulsar time based on 4 millisecond pulsars is built up, the comparison of its stability σz, with that of the atomic time is made, and finally a few of important factors which affect the ensemble pulsar time, as well as their influences on the pulsar timing accuracy and application are analyzed.  相似文献   

Physical parameters of some close binaries: ET Boo,V1123 Tau,V1191 Cyg,V1073 Cyg and V357 Peg     

F. Ekmekçi  A. Elmaslı  M. Yılmaz  T. Kılıçoğlu  T. Tanrıverdi  Ö. Baştürk  H.V. Şenavcı  Ş. Çalışkan  B. Albayrak  S.O. Selam 《New Astronomy》2012,17(7):603-609

With the aim of providing new and up-to-date absolute parameters of some close binary systems, new BVR CCD photometry was carried out at the Ankara University Observatory (AUG) for five eclipsing binaries, ET Boo, V1123 Tau, V1191 Cyg, V1073 Cyg and V357 Peg between April, 2007 and October, 2008. In this paper, we present the orbital solutions for these systems obtained by simultaneous light and radial velocity curve analyses. Extensive orbital solution and absolute parameters for ET Boo system were given for the first time through this study. According to the analyses, ET Boo is a detached binary while the parameters of four remaining systems are consistent with the nature of contact binaries. The evolutionary status of the components of these systems are also discussed by referring to their absolute parameters found in this study.  相似文献   

Ground water radon anomalies in Bodrum Peninsula          下载免费PDF全文

Öztürk Ülküm  Caner Taşköprü  Mutlu İçhedef  Müslim Murat Saç  Mehmet N. Kumru 《地学学报》2018,30(2):152-161

Bodrum Peninsula is located between Hellenic Trench in the west and Gökova Fault Zone in the east which is affected by hundreds of earthquakes every year. Because of its active environment is allowed to monitor tracers/precursors continuously to analyse natural processes. This study focused on the determination of ground water radon (²²²Rn) concentrations in the Bodrum Peninsula in terms of seismic activities. Radon levels of ten ground water wells were measured periodically throughout the peninsula and these wells were divided into two groups according to the number of earthquakes they are exposed. Radon variations in second group stations are fairly significant as a result of high number of earthquakes. In these stations, radon continuously increased before the seismic storm and then decreased step by step. The results indicated that radon variations in ground waters of Bodrum Peninsula can be a good indicator for seismic storms instead of one specific event.  相似文献   

Improvement of a simplified process‐based model for estimating transpiration under water‐limited conditions     

Na Liu  Thomas N. Buckley  Xinguang He  Xinping Zhang  Cicheng Zhang  Zidong Luo  Hailong Wang  Nasrin Sterling  Huade Guan 《水文研究》2019,33(12):1670-1685

Plant transpiration depends on environmental conditions, and soil water availability is its primary control under water deficit conditions. In this study, we improve a simplified process‐based model (hereafter “BTA”) by including soil water potential (ψ_soil) to explicitly represent the dependence of plant transpiration on root‐zone moisture conditions. The improved model is denoted as the BTA‐ψ model. We assessed the performance of the BTA and BTA‐ψ models in a subtropical monsoon climate and a Mediterranean climate with different levels of water stress. The BTA model performed reasonably in estimating daily and hourly transpiration under sufficient water conditions, but it failed during dry periods. Overall, the BTA‐ψ model provided a significant improvement for estimating transpiration under a wide range of soil moisture conditions. Although both models could estimate transpiration (sap flow) at night, BTA‐ψ was superior to BTA in this regard. Species differences in the calibrated parameters of both models were consistent with leaf‐level photosynthetic measurements on each species, as expected given the physiological basis of these parameters. With a simplified representation of physiological regulation and reasonable performance across a range of soil moisture conditions, the BTA‐ψ model provides a useful alternative to purely empirical models for modelling transpiration.  相似文献   

Establishment and Characterization of a New Cell Line from the Kidney of Spotted Halibut Verasper variegates   总被引：1，自引：0，他引：1  

WANG Xianli  CHEN Songlin  SHA Zhenxia  FAN Tingjun  WANG Na 《青岛海洋大学学报(英文版)》2010,(2):162-168

  相似文献   

武汉市轨道交通运行对地磁观测的影响   总被引：1，自引：0，他引：1  

罗俊秋  李德前  贺玉方  孙伶俐  邓娜  杨艳芳 《大地测量与地球动力学》2010,30(Z1)

对武汉市轨道交通一号线附近进行了地磁干扰测试,测试结果表明轨道交通的运行对周边地磁观测产生了干扰,干扰距离为10km左右,其干扰主要来自轨道泄露电流产生的磁场和输电线路产生的磁场。  相似文献   

抛物线形沙丘的形态与演变的研究进展   总被引：3，自引：3，他引：0  

闫娜  哈斯  刘怀泉  李双全 《中国沙漠》2010,30(4):801-807

抛物线形沙丘是一种重要的风积地貌类型,其形态及演变与气候变化密切相关,同时受到人类活动的影响,对其研究有助于理解全球变暖背景下的地貌响应和土地沙漠化正逆过程。本研究从沙丘形态类型、分布、成因、影响因素、动力过程及演变等几个方面回顾了近50 a来国内外对抛物线形沙丘的研究进展,并提出了未来的研究方向。  相似文献   

辽宁春玉米出苗期水分胁迫试验初探   总被引：8，自引：1，他引：7       下载免费PDF全文

赵先丽  张玉书  纪瑞鹏  冯锐  张淑杰  米娜  蔡福  王宏博 《气象与环境学报》2010,26(4):35-39

以丹玉39为试验材料,采用盆栽实验方法,研究辽宁春玉米25%、35%、45%、55%、65%、75%、85%、95%共8种供水处理条件下的玉米出苗率及玉米根系和叶片对水分胁迫的响应,旨在探索辽宁春玉米播种和出苗期间水分胁迫对玉米出苗及生长发育的影响,分析不同水分胁迫对其影响的程度。结果表明：玉米出苗率在中度到重度干旱条件下(<45%),为不能播种指标;在轻度干旱条件下(55%),为非经济播种指标;在适宜土壤水分条件下(65%—75%),为适宜播种指标;在85%左右时也为适宜播种指标;在偏湿条件下(95%),为可播种指标。玉米出苗期间,水分胁迫对玉米植株和根系的生长发育有较大影响,对根系影响比对植株的影响更显著。  相似文献