面向21世纪的地质找矿方向     

杨文智 《河南国土资源》1999,(3)

21世纪地质找矿既是地质技术问题,又是当代地质经济问题。为保障人类资源可持续利用,拓宽地质找矿的空间,不断增长科技含量,提高地质找矿效益,是面向21世纪的地质找矿方向。  相似文献   

不同典型年“引江济巢”工程对巢湖水质的影响     

易雨君  郭玉明  刘泓汐 《湖泊科学》2022,34(6):1901-1911

“引江济巢”作为引江济淮的起始段工程,承担着改善巢湖水质的重要任务,调水路线的选取对水质改善效果有关键影响.本文基于MIKE21模型构建了巢湖水动力水质模型,分别模拟了丰水年、平水年和枯水年情景下巢湖流场和总氮、总磷浓度时空分布特征,以及不同调水路线在各典型年对巢湖水质的影响.结果显示巢湖流场和水质分布有明显的空间差异性,受入湖负荷和流量影响,巢湖在丰水年水质较差,整体来说东湖区水质优于西湖区.相比其他年份,丰水年调水对湖区水质的改善作用最明显;不同调水路线中,自白石天河入流相较兆河入流对巢湖,尤其是西湖区水质改善明显.  相似文献   

ATMOSPHERIC SCIENCES IN THE 21ST CENTURY—IN MEMORY OF THE 70TH ANNIVERSARY OF THE FOUNDING OF THE CHINESE METEOROLOGICAL SOCIETY          下载免费PDF全文

Zhou Xiuji 《Acta Meteorologica Sinica》1995,9(3):368-372

On the basis of the development of society,economy,sciences and technologies in the 21st centu-ry,a possible new leap is analysed and outlined in the systems and concepts of the atmospheric sound-ing,prediction,services and modification.It is indicated that the atmospheric sciences should be aclosely integrated component and actively play the leading role in the global system sciences.  相似文献   

天然气——21世纪的能源   总被引：2，自引：1，他引：1  

史斗 《地球科学进展》1998,13(3):251-260

天然气是一种生态型能源或理想的城市能源。综述了世纪之交的全球天然气工业发展状况,包括储量的增长、输气管道的延长、液化天然气厂的发展和天然气利用技术的进步。介绍了有关国家的天然气利用法规和政策。预测了21世纪全世界天然气供需趋势。论述了为什么说天然气是21世纪的能源。指出了当前和未来全球天然气工业面临的挑战。  相似文献   

面向21世纪的我国区域经济地理学科理论体系建设   总被引：15，自引：0，他引：15  

陈才  刘曙光 《地理科学》1998,18(5):393-400

通过分析影响我国区域经济地理学理论发展的因素,探讨了区域经济地理学科的研究对象,理论主线,主要分支理论以及学科理论框架等理论建设问题。文章提出劳动地域分工理论和经济地域运动理论同为学科理论基础;阐述了经济地域条件与要素的区别与联系;强调经济地域结构－功能研究与经济地域类型分析评价;在已有经济地域系统类型基础上提出地缘经济地域系统。在学科建设的原则中强调学科间交叉渗透与自主发展并重,指出本学科与区域  相似文献   

Millisecond pulsars     

D. C. Backer 《Journal of Astrophysics and Astronomy》1984,5(3):187-207

In 1982 we discovered a pulsar with the phenomenal rotation rate of 642 Hz, 20 times faster than the spin rate of the Crab pulsar. The absence of supernova debris in the vicinity of the pulsar at any wavelength indicates an age of the neutron star greater than 10⁵ yr. The miniscule spindown rate of 1.1 × 10^-19 confirms the old age and indicates a surface magnetic field of 10⁹ G. A second millisecond pulsar was discovered by Boriakoff, Buccheri & Fauci (1983) in a 120-day orbit. These fast pulsars may have been spun-up by mass transfer in a close binary evolutionary stage. Arrival-time observations of the 642-Hz pulsar display remarkably low residuals over the first 14 months. The stability implied by these observations, 3 × 10^-14, suggests that millisecond pulsars will provide the most accurate basis for terrestrial dynamical time. If so, the pulsar data will lead to improvements in the planetary ephemeris and to new searches for light-year scale gravitational waves. Many new searches for fast pulsars are under way since previous sky surveys excluded pulsars with spins above 60 Hz.  相似文献   

Tilt Observations in the Normal Mode Frequency Band at the Geodynamic Observatory Cueva de los Verdes,Lanzarote     

A. V.?KalininaEmail author  V. A.?Volkov  A. V.?Gorbatikov  J.?Arnoso  R.?Vieira  M.?Benavent 《Pure and Applied Geophysics》2004,161(7):1597-1611

We have conducted observations with the aid of a seismo-tiltmeter station, which is based on the Ostrovsky pendulum and installed at the Geodynamic Observatory Cueva de los Verdes at Lanzarote Island since 1995. In this station the signal is separated into two frequency bands – tidal tilts (from 0 to 5 mHz) and ground oscillations in the frequency range of free Earths normal modes (from 0.2 to 5 mHz). The later band, called accelerometer channel, has additional amplification. We analyzed the background records in the frequency range of Earths free oscillations from August 2000 to September 2001, as well as, Earths normal modes after strong earthquakes. We found several distinctive persistent peaks in the spectra of background oscillations. Both amplitudes of distinguished peaks and noises have seasonal variations. We found that spectra of background oscillations are different in the frequency interval between 1.4 and 2.5 mHz for North- South and East-West components.  相似文献   

豫西煤田构造煤反射率及其与古构造应力场的关系     

谢洪波  徐亚富  康继武 《煤田地质与勘探》2008,36(4)

为研究构造应力对煤反射率的影响,以豫西煤田不同构造区的构造煤和原生结构煤为对象,采用定向标本及反射率测定的方法作对比研究,发现构造煤的反射率比原生结构煤的反射率普遍偏高。根据反射率与构造应力的关系,求得各构造区的古构造应力场,通过与聚煤期后多次构造运动的主应力方向进行对比,可推知:影响嵩箕区二1煤变形和镜煤反射率的主要构造,是在前期断裂基础上喜山早期掀斜运动诱发的重力滑动构造,而影响崤熊区的则为燕山晚期的逆冲推覆作用。  相似文献   

Advection-diffusion models establishment of water-pollution accident in middle and lower reaches of Hanjiang river          下载免费PDF全文

WANG Qing-gai  ZHAO Xiao-hong  WU Wen-jun  YANG Mu-shui  MA Qiang  LIU Kun 《水科学进展》2008,19(4)

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Terminus recession,proglacial lake expansion and 21st century calving retreat of Tasman Glacier,New Zealand     

Robert C. Dykes  Martin S. Brook 《New Zealand geographer》2010,66(3):203-217

The Tasman Glacier is the largest glacier in New Zealand. Although 20th century warming caused down-wastage, it remained at its Little Ice Age terminus until the late 20th century. Since then, rapid calving retreat (U_r) has occurred, allowing a large (5.96 × 10⁶ m²) proglacial lake to form (maximum depth ∼240 m). From sequential satellite image analysis and echo sounding of Tasman Lake, we document (U_r) from 2000 to 2008. U_r varies temporally, with mean U_r of 54 m/a from 2000 to 2006 and a mean U_r of 144 m/a from 2007 to 2008. Consistent with global data sets, calving rate appears closely associated with lake depth at the calving terminus.  相似文献