农业生态地质调查工作方法浅谈          下载免费PDF全文

王从祥  杨斌  张尚坤  刘书才  易辉 《山东国土资源》2002,18(5):41-43

农业生态地质调查涉及到与农业生态相关的诸多地学方面 ,其主要包括地貌、地质结构及土壤、地球化学及工业发展对农业生态地质环境的影响。在调查工作中主要借鉴于地质学、农学的基本工作方法 ,如农业地质填图、剖面测量、样品采集 ,以及资料收集与综合整理、综合研究、编绘各类农业地质图件等。  相似文献   

A new formulation of the Type Ia supernova rate and its consequences on galactic chemical evolution     

F. Matteucci  N. Panagia  A. Pipino  F. Mannucci  S. Recchi  M. Della Valle 《Monthly notices of the Royal Astronomical Society》2006,372(1):265-275

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Absolute spectrophotometry and photometric evolution of Nova Scuti 2005 N.1 (≡ V476 Sct)     

U. Munari  A. Henden  G. Pojmanski  S. Dallaporta  A. Siviero  H. Navasardyan 《Monthly notices of the Royal Astronomical Society》2006,369(4):1755-1759

Our CCD photometry of Nova Scuti 2005 N.1 shows it to be a fast nova, characterized by   t ₂= 15  and   t ₃= 28d  , affected by an   E ( B − V ) ∼ 1.9  mag reddening, appearing at a position     (±0.04 arcsec)     (±0.09 arcsec, J2000) and peaking at   V ∼ 11.1  mag on ∼September 28.1 ut . Absolute spectrophotometry places it within the Fe  ii class. The profile of emission lines is characterized by a double peak with a velocity separation of 690 km s⁻¹ and a width at half intensity of 1200 km s⁻¹. The distance to the nova is  4 ± 1 kpc  , and its height above the Galactic plane is   z = 80 ± 20  pc. The highly crowded field affects a possible identification of the progenitor, whose pre-outburst magnitude should, however, have been  22 < V < 25  mag, thus below the limit of photographic surveys. A deep   B V R _C I _C  photometric sequence is provided to support continued observations of the advanced decline phases.  相似文献   

Statistical analysis of undetected point sources in cosmic microwave background maps     

F. Argüeso  J. L. Sanz  R. B. Barreiro  D. Herranz  J. González-Nuevo 《Monthly notices of the Royal Astronomical Society》2006,373(1):311-320

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Cosmological parameters from cosmic microwave background measurements and the final 2dF Galaxy Redshift Survey power spectrum   总被引：1，自引：0，他引：1  

Ariel G. Sánchez  C. M. Baugh  W. J. Percival  J. A. Peacock  N. D. Padilla  S. Cole  C. S. Frenk  P. Norberg 《Monthly notices of the Royal Astronomical Society》2006,366(1):189-207

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Weak lensing in the second post-Newtonian approximation: gravitomagnetic potentials and the integrated Sachs–Wolfe effect     

B. M. Schäfer  M. Bartelmann 《Monthly notices of the Royal Astronomical Society》2006,369(1):425-440

Dark matter currents in the large-scale structure give rise to gravitomagnetic terms in the metric, which affect the light propagation. Corrections to the weak-lensing power spectrum due to these gravitomagnetic potentials are evaluated by perturbation theory. A connection between gravitomagnetic lensing and the integrated Sachs–Wolfe (iSW) effect is drawn, which can be described by a line-of-sight integration over the divergence of the gravitomagnetic vector potential. This allows the power spectrum of the iSW-effect to be derived within the framework of the same formalism as derived for gravitomagnetic lensing and reduces the iSW-effect to a second-order lensing phenomenon. The three-dimensional power spectra are projected by means of a generalized Limber-equation to yield the angular power spectra. Gravitomagnetic corrections to the weak-lensing spectrum are negligible at currently accessible scales, and cosmic-variance considerations suggest that the detection of the iSW-effect's contribution to the cosmic microwave background angular power spectrum is too small to be detectable at multipoles probed by the Planck satellite.  相似文献   

Site evaluation and RFI spectrum measurements in Portugal at the frequency range 0.408–10 GHz for a GEM polarized galactic radio emission experiment     

Rui Fonseca  Domingos Barbosa  Luis Cupido  Ana Mouro  Dinis M. dos Santos  George F. Smoot  Camilo Tello 《New Astronomy》2006,11(8):551-556

We probed for radio frequency interference (RFI) at three potential galactic emission mapping experiment (GEM) sites in Portugal using custom made omnidirectional disconic antennas and directional pyramidal horn antennas. For the installation of a 10-m dish dedicated to the mapping of polarized galactic emission foreground planned for 2005–2007 in the 5–10 GHz band, the three sites chosen as suitable to host the antenna were surveyed for local radio pollution in the frequency range 0.01–10 GHz. Tests were done to look for radio broadcasting and mobile phone emission lines in the radio spectrum. The results show one of the sites to be almost entirely RFI clean and showing good conditions to host the experiment.  相似文献   

全球巨震的天文背景     

胡辉  韩延本 《天文研究与技术》2006,3(1):77-84

分析了全球8．5M以上巨震的天文背景，分析结果表明，这些巨震大都发生在处于月亮轨道运动所对应的地震活跃期的地震带区，太阳活动的下降段与地球自转的加速期。这是就天文因素的长周期变化而言。对于天文因素的短周期变化，无论是对于地方时，地方恒星时与月相，都有集中发生在某一段时间的现象；对于地球自转的短周期变化更是比较明显，要么发生在其变化最快时期，要么发生在其变化的最慢时期。这一切都表明，这些地震的发生是受天文因素的影响的。天文因素是外界发震动力之一，长周期变化的天文因素可能是对地震的孕育、发展与发生起着调制作用，而短期变化的天文因素则是当其作用于远离平衡态的发震构造上时，引起系统的巨涨落，从而诱发地震。  相似文献   

New light on dark cosmos     

Enrique Gaztañaga †  Marc Manera  Tuomas Multamäki 《Monthly notices of the Royal Astronomical Society》2006,365(1):171-177

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PAPPA: Primordial anisotropy polarization pathfinder array     

A. Kogut  D.T. Chuss  D. Fixsen  G.F. Hinshaw  M. Limon  S.H. Moseley  N. Phillips  E. Sharp  E.J. Wollack  K. U-Yen  N. Cao  T. Stevenson  W. Hsieh  M. Devlin  S. Dicker  C. Semisch  K. Irwin 《New Astronomy Reviews》2006,50(11-12):1009

The primordial anisotropy polarization pathfinder array (PAPPA) is a balloon-based instrument to measure the polarization of the cosmic microwave background and search for the signal from gravity waves excited during an inflationary epoch in the early universe. PAPPA will survey a 20° × 20° patch at the North Celestial Pole using 32 pixels in 3 passbands centered at 89, 212, and 302 GHz. Each pixel uses MEMS switches in a superconducting microstrip transmission line to combine the phase modulation techniques used in radio astronomy with the sensitivity of transition-edge superconducting bolometers. Each switched circuit modulates the incident polarization on a single detector, allowing nearly instantaneous characterization of the Stokes I, Q, and U parameters. We describe the instrument design and status.  相似文献