植物护理效应研究综述

植物护理效应是指护理植物在其自身冠幅下辅助目标植物生长发育的现象.近年来,植物护理效应被应用于世界范围内多数的退化生态系统的修复与重建.文章综述了当前植物护理效应的主流研究内容主要为护理植物的确定、影响其效应的因素、形成其效应的原因与机理以及护理、竞争及胁迫梯度假说,归纳了样方调查、种子萌发实验、幼苗栽植实验等研究方法,总结了其与生态位、系统发育、全球变化等相关生态学概念的关系,指出未来对植物护理效应的研究不应仅仅局限于中观尺度上,在微观尺度上(目标植物对护理效应的生态适应性的激素效应与分子机制)和宏观尺     

西安FDI市场计量分级与对策建议

近十年来,西安吸引外国直接投资（FDI）的力度大大增强,投资来源地增多且数额逐年上升,FDI在区域经济中的作用日益凸显。本文应用动态偏离—份额分析法（DSSA）对西安FDI来源地进行了实证分析,结果表明,不同来源地的FDI在西安的竞争力呈现出差异状态。文章根据分析结果将来源地划分为成熟、崛起、兴旺、停滞四个市场,并基于此为今后西安从不同地区吸引FDI提出了针对性的对策建议。     

柴家庄金矿成矿模式及找矿方向探讨

柴家庄金矿位于西秦岭褶皱系北秦岭加里东褶皱带李子园—吊把子金矿带上,赋存于柴家庄二长花岗岩体外接触带的丹凤群地层中,严格受NE向及NNW向断裂控制。矿床形成经历了火山沉积期、区域变质期、构造热液成矿期及岩浆热液成矿期4个阶段,属沉积变质—岩浆期后热液叠加改造的变质热液金矿床。岩体外接触带0～2km范围内的NE向、NNW向断裂构造带是找矿的最佳方向。     

大兴安岭南端红山子盆地流纹岩的成因:元素和Sr-Nd-Pb同位素制约

红山子晚侏罗世早期火山盆地位于西拉木伦河-长春缝合带以南、康宝-围场-赤峰-开原断裂带以北的辽源地块,其中赋存铀钼矿床的流纹岩为肉红色流纹岩和灰白色流纹岩。为了查明流纹岩的物质来源和形成的构造背景,本文分析了流纹岩的主量元素、微量元素、稀土元素和Sr-Nd-Pb同位素组成。分析结果显示：流纹岩具有高SiO₂、K₂O和Fe₂O₃/FeO值,低Al₂O₃、CaO和MgO的特征,肉红色流纹岩比灰白色流纹岩的SiO₂含量略低、（K₂O+Na₂O）含量高和Fe₂O₃/FeO值略高;肉红色流纹岩和灰白色流纹岩均有较高的稀土含量,明显富集轻稀土,显著亏损铕;高场强元素Nb、Ta、Zr、Hf、Ce、Y、Ga和大离子亲石元素Rb、Th、U的含量较高,但大离子亲石元素Ba、Sr的含量低且变化较大,具有A₁型流纹岩、低Sr-Ba流纹岩和板内拉张构造流纹岩的微量元素特征;具有较小的（⁸⁷Sr/⁸⁶Sr）_i、较高的ε_Nd（t）、较年轻的T_DM2和较低的（²⁰⁶Pb/²⁰⁴Pb）_i、（²⁰⁷Pb/²⁰⁴Pb）_i、（²⁰⁸Pb/²⁰⁴Pb）_i,指示流纹岩是源于EMⅠ富集地幔的中元古代年轻下地壳部分熔融的产物,并在岩浆过程中经历了结晶分异。肉红色流纹岩和灰白色流纹岩的差异可能与年轻下地壳物质的成分差异有关。     

云南省昵博铜镍多金属矿床地质特征及找矿前景分析

昵博铜镍多金属矿床位于哀牢山地体、红河裂陷槽、屏边西畴山弧构造交汇派生的多条数百千米长北西向深大断裂收敛区,有利于铜镍矿成矿岩体的产出.矿区铜镍矿（化）体产于元古宇瑶山群第一段灰紫色混合岩化石榴夕线黑云片岩夹混合质夕线黑云片麻岩中,两矿（化）体露头均具较强的糜棱岩化,矿（化）体产于糜棱岩化带中.通过综合研究矿床地质特征,提出矿体与层间构造、叠加构造密切相关.对矿区内发现的两个矿化程度较高的露头进行勘查,分析了矿床的找矿前景,并指出了下一步勘查方向和合理的勘查手段.     

辽西地区玛瑙矿床成矿地质特征及找矿方向

辽西地区玛瑙矿发育在晚中生代断陷盆地内中基性火山岩建造中,主要产于白垩系义县组中基性火山岩气孔构造和断裂破碎带中,受围岩岩性控制明显.该地区找矿勘查的重要方向就是围绕义县期中基性火山岩且气孔和破碎带发育的地段.     

中国二氧化碳地质储存目标靶区筛选技术方法

在沉积盆地三级构造单元CO₂地质储存潜力与适宜性评价得出的“适宜CO₂地质储存”区域的基础上,借鉴国外已有的选址流程和方法,结合我国的地质条件和技术方法水平,提出了深部咸水层CO₂地质储存目标靶区筛选评价指标体系,包括安全性、储存规模、场地地面环境条件和经济适宜性四大评价指标层以及44个具体评价指标,并将层次分析法和多因子逐层叠加法等评价方法应用于目标靶区筛选。通过鄂尔多斯盆地和河套盆地3处典型目标靶区适宜性评价的实例,证明了该评价指标体系在目标靶区筛选过程中具有较好的可操作性和推广应用价值。     

RCS analysis in the detection of a generic missile target with sea clutter background

The detection of a missile target in heavy sea clutter is a significantly challenging problem due to the clutter effects. In this paper, the radar cross sections (RCS) of a pre-assumed generic missile model is computed with multilevel fast multi-pole algorithm (MLFMA), while the RCS of ocean surface is computed by a more reduced form of the fractional Weierstrass scattering model proposed here. At last, the computed RCS of missile model is compared with that of sea surface, and then the comparisons of missile-to-ocean RCS ratios of different incident angles, incident frequencies, and polarization patterns are also presented. The discussion and comparisons of RCS of the missile and ocean surface can help us to plan and design a radar system in the application of detection of a missile target or other analogous weaker targets in the strong sea clutter background.     

路基坡脚积水对多年冻土路基稳定性的影响研究进展

多年冻土路基的稳定性很大程度上取决于其下伏多年冻土层的热稳定性. 当融雪、降雨或人为等外界因素形成的路基坡脚积水持续一段时间后,这些积水可能通过入渗对流换热、热边界侵蚀、补给冻胀水分等方式加剧或诱发多年冻土路基热稳定性的下降和丧失. 通过回顾国内外相关文献,从影响多年冻土路基稳定性的因素、积水对路基活动层冻融过程中水分迁移的影响、热融湖塘类积水对冻土路基的热影响、降雨和融雪积水入渗对冻土路基的热影响等方面,归纳总结了坡脚积水对多年冻土路基影响方面的研究进展;在此基础上,提出了对此问题进一步深入的研究展望和探讨.     

Evaluation of displacement coefficient method for seismically retrofitted buildings with various ductility capacities

This research study is aimed at evaluating the accuracy of the displacement coefficient method (DCM) of FEMA 440 and associated nonlinear static procedure (NLSP) for actual buildings with soft story mechanism and various ductility capacities. The DCM and associated NLSP are evaluated using two existing seismically vulnerable buildings with soft story mechanism. The buildings are first retrofitted using a ductile steel‐brace‐link system to represent those with good ductility capacity and then retrofitted with RC squat infill shear panels (SISPs) to represent those with relatively poor ductility capacity. The evaluation of the DCM of FEMA 440 and associated NLSP is then performed by comparing the roof displacements (target displacements), maximum interstory drifts, and maximum plastic hinge rotations of the original and retrofitted buildings obtained from NLSP (at the target displacement level of DCM) with those obtained from nonlinear response history (NRH) analyses for three different seismic performance levels. It is observed that the DCM, and hence, the NLSP fail to accurately predict the NRH analyses results mainly due to uncertainties in the coefficient C₁ of the DCM in the short period range, the inability of the DCM to capture the failure of structural members beyond a certain lateral displacement or plastic rotation limit and associated soft story mechanism. Copyright © 2013 John Wiley & Sons, Ltd.