鲤鱼神经垂体的超微结构研究     

贾翠红  车轶  李世美  张志南 《中国海洋大学学报(自然科学版)》1997,(3)

经电子显微镜观察，提出鲤鱼（Ｃｙｐｉｎｕｓｃａｒｐｉｏ）神经垂体（ｎｅｕｒｏｈｙｐｏｐｈｙｓｉｓ）由有髓神经分泌纤维和三种无髓神经分泌纤维（Ａ．Ｂ．Ｃ）以及垂体细胞和毛细血管组成。神经分泌纤维与垂体细胞之间存在着突触联系，神经分泌纤维之间只有细胞间连接（桥粒）。在神经垂体组织中还存在Ⅰ型和Ⅱ型两种结构与功能不同的垂体细胞，另外在血管间道内观察到了很少见的特殊空泡结构  相似文献   

Vertical distribution and source identification of polycyclic aromatic hydrocarbons in anoxic sediment cores of Chini Lake, Malaysia: Perylene as indicator of land plant-derived hydrocarbons   总被引：3，自引：0，他引：3  

Alireza Riyahi Bakhtiari  Mohamad Pauzi Zakaria  Mohammad Ismail Yaziz  Mohamad Nordin Hj Lajis  Xinhui Bi  Mohamad Che Abd Rahim 《Applied Geochemistry》2009,24(9):1777-1787

Four anoxic sediment cores were collected from Chini Lake, Malaysia in order to investigate the variability of polycyclic aromatic hydrocarbon (PAH) and perylene concentrations. The study also determined significant differences of perylene concentrations in different sediment layers. Total PAH concentrations ranged from 248 to 8098 ng g⁻¹ in the samples. Diagnostic PAH ratios such as methylphenanthrenes/phenanthrene (MP/P), phenanthrene/anthracene (P/A) and fluoranthene/(fluoranthene + pyrene) (Fl/(Fl + Py) revealed a dominance of pyrogenic influences and partial petrogenic inputs to the top sediment layers. Perylene concentrations were high in the top layers (<12 cm) and increased with increasing depth. There is a significant positive correlation (r = 0.705, p = 0.01) between perylene concentrations and TOC. Analysis of variance (ANOVA) and LSD revealed significant differences (p < 0.05) in TOC-normalized perylene concentrations between the upper (<12 cm) and bottom layers (>12 cm). The average perylene concentrations accounted for 26–50% (0–12 cm) and 50–77% (12–36 cm) of pentacyclic-aromatic hydrocarbon isomers (PAI) present whereas it made up 10–34% (0–12 cm) and 46–66% (12–36 cm) of the total PAH. The average pyrene concentrations decreased with increasing depth and accounted for 62% (0–3 cm), 20–23% (3–12 cm) and 3–1.4% (12–36 cm) of perylene present. The results of hierarchical cluster analysis based on these ratios suggested different input sources for the top and bottom layers. It is concluded that the activity of termites on woody plants produced perylene which is supplied to the lake by run-off from the heavy and frequent rains in this Asian tropical climate. In addition, there was also in situ formation of perylene in the bottom layers due to diagenetic processes.  相似文献   

矿物磁性特征在金矿床形成及成矿预测中的作用   总被引：3，自引：1，他引：2  

孙忠实  车迎房  郑培玺  甘云  杨惠心 《地质科学》2005,40(1):32-39

金矿床形成和成矿预测一直为国内外学者所关注。随绿岩带金矿、暗色岩易富金及赤铁矿总含有大粒金等不断地被发现,指示矿物磁性对金矿床形成有一定的控制作用。1)金粒级的大小与磁体间作用力的强弱呈正比,磁力的大小与两磁体间距离的平方呈反比,这正、反比规律进一步解析绿岩带富金机理和强、弱磁性岩石富金条件的差别。2)电流在金、黄铁矿和磁黄铁矿等附近每一点都能产生磁化场(H场)和磁通密度(B场),H场和B场的大小与不同成矿介质具有一定的正比例关系,按此比例可追踪含矿流体形成过程和富金条件。3)根据矿物磁性特征,建立了矿物磁力晕、矿物磁性矢量等找矿标志。4)除温度和压力等因素外,矿物磁性特征应视为金矿床形成和预测主要条件之一。  相似文献   

论地震预测(报)现状及基础研究问题     

车用太  刘成龙  鱼金子 《国际地震动态》2005,(12):19-23

我国的地震预报研究取得了重要进展,在防震减灾事业中目前仍然起着决定性的作用,然而预测（报）的能力仍然较低,对大量的地震仍作不出成功的预测（报）。要显著提高地震预测能力,需要加强基础研究。这种研究应从地震预测（报）能力的现状出发,重点应放在地震前兆异常的成因类别与属性、机理与可靠性等“原始”问题的研究上,而不是回避这些基础问题而去研究那些靠不住的“上层建筑”问题。  相似文献   

玉树地震序列重新定位及其地震构造研究   总被引：3，自引：0，他引：3  

朱艾斓  徐锡伟  于贵华  张晓清  陈桂华  任烨 《地学前缘》2012,19(4):8-14

对玉树地震序列自2010年4月11日至9月15日由台网记录到的1 832个地震采用双差地震定位法进行重新定位,获得了1 670个地震重新定位的震源参数。重新定位后的震源深度主要分布在15 km以内。重新定位后的Ms 7.1级主震发生在无地表破裂段,余震活动向两侧破裂扩展。余震沿地表破裂带基本呈线性分布,剖面上显示为近垂直的结构面,在北西端无地表破裂出露处,出现近垂直于断裂方向较宽的北东向地震密集带。震源机制解显示的主压应力方向斜交地表破裂带,地表破裂与震源破裂都表现为纯左旋走滑的错动性质,而在北西端主压应力方向偏转为近垂直于断裂带的方向,此处较宽的北东向地震密集带可能由近东西与南北两个方向的共轭破裂所组成。余震的后期活动与发展并不局限于主震形成的破裂带内,更多的受局部应力调整被触发而产生新的破裂。  相似文献   

汶川地震后关于地震预测问题的再思考   总被引：8，自引：2，他引：6  

车用太  刘成龙 《国际地震动态》2008,(10)

汶川地震预测失败之后,笔者仍然坚持认为,地震是可以预测的,但存在多方面的困难,从根本上来说,需要等待地球科学的突破性发展与地学探测技术的革命性进步,但当前经过进一步完善现有的观测技术,加强异常动态的调查与落实,重建地震宏观异常监视系统,完全有可能进一步提高地震预测的成功率,尽最大可能减轻地震灾害,防止汶川地震这样的惨痛历史重现.  相似文献   

Seismic performance evaluation of a 34‐story steel building retrofitted with response modification elements     

Yuan‐Tao Weng  Keh‐Chyuan Tsai  Pei‐Ching Chen  Chung‐Che Chou  Ya‐Ran Chan  Sheng‐Jhih Jhuang  Yung‐Yu Wang 《地震工程与结构动力学》2009,38(6):759-781

The original structural design of this case study consisted of five basement floors and a 34‐story hotel tower in Kaohsiung, Taiwan. The construction started in 1993, and the erection of the entire steel frame and the pouring of concrete slabs up to the 26th floor were completed before 1996. However, construction of the original hotel was subsequently suspended for 10 years. Recently, this building has been retrofitted for residential purposes. Buckling restrained braces (BRBs) and eccentrically braced frames were incorporated into the seismic design of the new residential tower. This paper presents the seismic resisting structural system, seismic design criteria, full‐scale test results of one BRB member and the as‐built welded moment connections. Test results confirm that the two side web‐plate stiffening details can effectively improve the rotational capacity of welded moment connection. The paper also discusses the analytical models for simulating the experimental responses of the BRB members and the welded moment connections. Nonlinear response history analyses (NLRHA) indicate that the inelastic deformational demands of the original and the redesigned structures induced by the maximum considered earthquakes are less than those found in the seismic building codes or laboratory tests. This paper also proposes a ground motion scaling method considering multi‐mode effects for NLRHA of the example building. It is shown that the proposed scaling method worked well in reducing the scatter in estimated peak seismic demands. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Phosphorus retention and release by sediments in the eutrophic Mai Po Marshes, Hong Kong   总被引：5，自引：0，他引：5  

Lai DY  Lam KC 《Marine pollution bulletin》2008,57(6-12):349-356

This study examined the phosphorus retention and release characteristics of sediments in the eutrophic Mai Po Marshes in Hong Kong. Results of chemical fractionation show that the sum of inorganic P pools exceeded 50% of the total sediment P content, with the redox-sensitive iron-bound P (Fe(OOH) approximately P) being the dominant P fraction. Given the considerable average Fe(OOH) approximately P concentration of 912 microg g(-1), Mai Po sediments demonstrated a great potential to release bioavailable P under low sediment redox potentials. This was further supported by the high mean anaerobic P flux of 31.8 mg m(-2)d(-1) recorded in Mai Po sediment cores, indicating the role of bottom sediments as a net P source. Although sediments in Mai Po had appreciable Langmuir adsorption maxima (1642-3582 mg kg(-1)), the high zero equilibrium P concentrations (0.02-0.51 mg L(-1)) obtained suggest that sediment sorption processes would contribute to sustaining the eutrophic conditions in overlying water column even with a further reduction in external P load. Concerted efforts should be made to reduce internal loading of P, especially under reducing conditions, to complement the implementation of zero discharge policy for Deep Bay for effective eutrophication abatement and long-term water quality improvement in the Mai Po Marshes.  相似文献   

板内强震的中地壳硬夹层孕震与流体促震假设   总被引：29，自引：2，他引：27       下载免费PDF全文

车用太  刘五洲  鱼金子  王基华 《地震学报》2000,22(1):93-101

以国内外地壳流体及其与强震活动关系的最新研究结果为基础,进行了多方面的探索与论证,提出板内强震的中地壳硬夹层孕震与流体促震（BEH-PEF）的假设．该假设的要点是地壳中存在上下两大流体活动系统,其间发育有中地壳硬夹层,该层是地壳应力积累并孕育地震的层．当其中某些部位积累的应力达到屈服强度时,则进入微破裂-膨胀（扩容）阶段并形成震源体．被扩容的震源体在真空吸泵作用下,由下层流体系统把流体吸渗到其内,在震源体内引起剪切力增强与抗剪力减弱的两个过程同步发展,并最终因剪切力达到抗剪力导致震源体的破裂而发生地震．   相似文献   

地下水地表水联合模拟的解析单元法理论及应用     

易立新  王广才 《工程地质学报》2000,8(3):337-340

本文介绍了解析单元法的基本理论及适用条件 ,并运用该方法 (GFL OW1软件 )计算了某水库蓄水过程中库首结晶岩区风化裂隙水渗流场变化 ,取得良好效果.  相似文献