Variation of P-Wave Velocity before the Bear Valley, California, Earthquake of 24 February 1972

Residuals for P-wave traveltimes at a seismnograph station near Bear Valley, California, for small, precisely located local earthquakes at distances of 20 to 70 kilometers show a sharp increase of nearly 0.3 second about 2 months before a magnitude 5.0 earthquake that occurred within a few kilometers of the station. This indicates that velocity changes observed elsewhere premonitory to earthquakes, possibly related to dilatancy, occur along the central section of the San Andreas fault system.     

全息干涉法中刚体位移的利用

用全息干涉法测定物体变形时,总会遇到物体承载时产生微小的刚体运动。本文探讨了这部分刚体运动的利用,变弊为益的处理方法,并用实例说明方法的实施,最后用图象处理得出实验结果。     

Crustal Spreading in Southern California: The Imperial Valley and the Gulf of California formed by the rifting apart of a continental plate

The current excitement among geologists and geophysicists stemming from the "new global tectonics" has led to a widespread, speculative reinterpretation of continental geology. The Gulf of California and its continuation into the Imperial Valley provide an excellent opportunity for studying the border zone between the North American and Pacific plates, and an interface of continental and oceanic tectonics. The Salton trough, the landward extension of the gulf, is a broad structural depression, comparable in size with the deeper marine basins of the southern part of the gulf, but here partially filled with sediments deposited by the Colorado River.     

Earthquake Swarm Along the San Andreas Fault near Palmdale, Southern California, 1976 to 1977

Between November 1976 and November 1977 a swarm of small earthquakes (local magnitude 相似文献   

Coseismic and Postseismic Fault Slip for the 17 August 1999, M = 7.5, Izmit, Turkey Earthquake

We use Global Positioning System (GPS) observations and elastic half-space models to estimate the distribution of coseismic and postseismic slip along the Izmit earthquake rupture. Our results indicate that large coseismic slip (reaching 5.7 meters) is confined to the upper 10 kilometers of the crust, correlates with structurally distinct fault segments, and is relatively low near the hypocenter. Continued surface deformation during the first 75 days after the earthquake indicates an aseismic fault slip of as much as 0.43 meters on and below the coseismic rupture. These observations are consistent with a transition from unstable (episodic large earthquakes) to stable (fault creep) sliding at the base of the seismogenic zone.     

Subatomic Features on the Silicon (111)-(7x7) Surface Observed by Atomic Force Microscopy

The atomic force microscope images surfaces by sensing the forces between a sharp tip and a sample. If the tip-sample interaction is dominated by short-range forces due to the formation of covalent bonds, the image of an individual atom should reflect the angular symmetry of the interaction. Here, we report on a distinct substructure in the images of individual adatoms on silicon (111)-(7x7), two crescents with a spherical envelope. The crescents are interpreted as images of two atomic orbitals of the front atom of the tip. Key for the observation of these subatomic features is a force-detection scheme with superior noise performance and enhanced sensitivity to short-range forces.     

农业部部党组成员于永维同志参加《农业科技发展纲要》发布座谈会的讲话

同志们: 国务院召开全国农业科技大会和颁布<农业科技发展纲要>,把农业科技工作放在空前的高度,体现了党中央、国务院对农业科技事业的关怀和重视.<纲要>的颁布,为我国农业科技发展勾画了蓝图,标志着我国农业开始进入依靠科技加速发展的新时期,是实施"科教兴农"战略的更高阶段,在农业科技进步史上具有重要意义.<纲要>立足新阶段农业科技发展的形势,更加突出了农业科技进步与创新的地位和作用,明确了新阶段农业科技工作的方针、原则、目标和任务,提出了"十五"期间"十大科技行动",并提出了农业科技机构、服务体系的改革方向,是全面指导今后十年农业科技工作的纲领性文件,必将对加快农业科技进步与创新,推进农业科技革命,促进农业生产力的跨越式发展产生极大的推动作用和深远影响.     

汶川地震堰塞湖旅游开发研究

地震堰塞湖是指由于强烈地震诱发河道两侧山体发生块体运动,以滑坡、崩塌、泥石流等形式堆积的大量固体物质形成的土石堤坝横向堵塞河道,上游壅水而形成的湖泊。汶川地震后形成了132个堰塞湖,地震堰塞湖在对区域安全及环境造成了巨大危害的同时,也蕴藏了丰富的旅游资源。将地震堰塞湖开发成为旅游景区是国内外常见的堰塞湖利用方式之一。针对地震堰塞湖的安全性特点,浅析了旅游开发中存在的安全问题和旅游问题,并提出了相应的对策。     

黄河源区生态景观的无人机观测与无人机技术升级研究

应用国产神龙260电动直升型无人机和数码摄像机,在DJI飞控技术和高空数字影像采集技术的支持下,对青海省贵南县境内的沙漠地貌、四川省唐克县境内的九曲黄河第一湾和青海省泽库县境内的草场分别进行了超低空航空观测,获得了黄河源区沙丘形态、沙草生态交错带、黄河沙洲、草场钙化壳的初步观测结果,为深入研究和解决黄河源区面临的地貌学和生态学问题开辟了新的技术途径。结合无人机在青藏高原的飞行实践,讨论了神龙260型无人机应用于高原对地观测领域的局限并指出了升级方向,为进一步发展高原地区的无人机对地观测技术奠定了工作基础。     

地震对涉农企业合作关系管理的影响探析——基于汶川地震重灾区36户涉农企业的调查

汶川地震后,灾区涉农企业环境发生巨大变化,震前的企业合作关系受到影响,合作绩效随之降低。通过对重灾区都江堰市、彭州市、崇州市、什邡市、绵竹市和汉源县等6个地震（重）灾区市（县）的36家涉农企业进行随机抽样调查和典型调查,取得相关数据资料来研究分析企业灾后合作受到影响的具体状况,并在该基础上提出灾后如何优化企业合作关系的思路,以期能够为相关企业在重建过程中提供参考。     

地震成因环境污染及其防治对策探讨——以汶川8.0级特大地震为例

通过深入分析震后灾区环境污染状况,提出了相应的环境污染防治对策.     

Ice Movement of Valley Glaciers Flowing into the Ross Ice Shelf, Antarctica

Seven glaciers from 9 to 26 kilometers in width move 0.3 to 2.3 meters per day. Byrd Glacier is the fastest moving of the known valley glaciers in Antarctica.     

High-Resolution Spectroscopy of the Earth's Free Oscillations, Knowing the Earthquake Source Mechanism

A new method for identification of normal modes of oscillation of the earth yielded unambiguous determinations of many overtones never before identified. This method consists of the superposition of spectra observed at many stations over the earth, after a correction for the phase determined from the known earthquake source mechanism.     

Simultaneous Determination of Hexoestrol,Diethylstilbestrol, Estrone and 17-Beta-estradiol in Feed by Gas Chromatography-mass Spectrometry

A method was developed for the simultaneous determination of four kinds of estrogens(hexoestrol, diethylstilbestrol, estrone, and 17-beta-estradiol) in feed by gas chromatography-mass spectrometry(GC-MS). After the sample was extracted by ethyl ether and cleaned-up on HLB phase extraction column, four kinds of estrogens were derived and quantified in gas chromatographymass spectrometry. The results showed that the linear detectable ranged from 2.5 ng·mL~(-1) to 250 ng·mL~(-1) for hexoestrol and from 5 ng·mL~(-1) to 500 ng·mL~(-1) for three other estrogens with the correlation coefficients(R~2) were no less than 0.990. The recoveries were in the range of 76.34%-96.33% and the relative standard deviation was no more than 22.7%. The limits of quantitation(LOQ) for all analytics were between 10 ug·kg~(-1) and 20 ug·kg~(-1).The method was accurate and sensitive and could meet the actual requirements for the analyses of feed samples.