全文获取类型
收费全文 | 471篇 |
免费 | 20篇 |
国内免费 | 30篇 |
专业分类
测绘学 | 207篇 |
大气科学 | 18篇 |
地球物理 | 20篇 |
地质学 | 82篇 |
海洋学 | 48篇 |
天文学 | 61篇 |
综合类 | 38篇 |
自然地理 | 47篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 16篇 |
2021年 | 19篇 |
2020年 | 34篇 |
2019年 | 26篇 |
2018年 | 9篇 |
2017年 | 25篇 |
2016年 | 11篇 |
2015年 | 17篇 |
2014年 | 22篇 |
2013年 | 45篇 |
2012年 | 27篇 |
2011年 | 20篇 |
2010年 | 17篇 |
2009年 | 20篇 |
2008年 | 26篇 |
2007年 | 24篇 |
2006年 | 23篇 |
2005年 | 22篇 |
2004年 | 21篇 |
2003年 | 18篇 |
2002年 | 12篇 |
2001年 | 12篇 |
2000年 | 15篇 |
1999年 | 10篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有521条查询结果,搜索用时 78 毫秒
231.
滑坡危险性评价是滑坡灾害防治的重要前提和基础,简单高效的评价方式是其中的一个研究重点。本文以四川安县作为研究区域,基于ArcGIS中的分析功能,引入可视化的建模工具Modelbuilder,以模型的方式演示和运行整个滑坡危险性评价过程,得到了滑坡危险性的分级图,并进行对比分析。实验结果表明,利用可视化建模方式完成复杂地区的滑坡危险性评价,能够简化操作流程,节约时间和精力。 相似文献
232.
M. Scardia J.-L. Prieur L. Pansecchi R. W. Argyle M. Sala M. Ghigo L. Koechlin E. Aristidi 《Monthly notices of the Royal Astronomical Society》2006,367(3):1170-1180
We present relative astrometric measurements of visual binaries taken during the second semester of 2004 with the Pupil Interferometry Speckle camera and Coronagraph (PISCO) at the 1-m Zeiss telescope of the Brera Astronomical Observatory, in Merate, Italy. We performed 207 new observations of 194 objects with angular separations in the range 0.1–4.0 arcsec and an accuracy better than ∼0.01 arcsec. Our sample contains orbital couples as well as binaries whose motion is still uncertain. Our purpose is to improve the accuracy of the orbits and constrain the masses of the components.
Those measurements show that the orbit of ADS 15115 needs to be revised; we propose a new orbit for this object. 相似文献
Those measurements show that the orbit of ADS 15115 needs to be revised; we propose a new orbit for this object. 相似文献
233.
B. Novakovic 《中国天文和天体物理学报》2007,7(3):415-420
We present the orbits of ten visual binary stars: WDS 01015 6922, WDS 01424– 0645, WDS 01461 6349, WDS 04374–0951, WDS 04478 5318, WDS 05255–0033, WDS 05491 6248, WDS 06404 4058, WDS 07479–1212, and WDS 18384 0850. We have also determined their masses, dynamical parallaxes and ephemerides. 相似文献
234.
S. K. Leggett Peter H. Hauschildt F. Allard T. R. Geballe E. Baron 《Monthly notices of the Royal Astronomical Society》2002,332(1):78-90
We present 0.9–2.5 μm spectroscopy with R ∼800 and 1.12–1.22 μm spectroscopy with R ∼5800 for the M dwarfs Gl 229A and LHS 102A, and for the L dwarf LHS 102B. We also report IZJHKL ' photometry for both components of the LHS 102 system, and L ' photometry for Gl 229A. The data are combined with previously published spectroscopy and photometry to produce flux distributions for each component of the kinematically old disc M/L dwarf binary system LHS 102 and the kinematically young disc M/T dwarf binary system Gliese 229. The data are analysed using synthetic spectra generated by the latest 'AMES-dusty' and 'AMES-cond' models by Allard & Hauschildt. Although the models are not able to reproduce the overall slope of the infrared flux distribution of the L dwarf, most likely because of the treatment of dust in the photosphere, the data for the M dwarfs and the T dwarf are well matched. We find that the Gl 229 system is metal-poor despite having kinematics of the young disc, and that the LHS 102 system has solar metallicity. The observed luminosities and derived temperatures and gravities are consistent with evolutionary model predictions if the Gl 229 system is very young (age∼30 Myr) with masses (A,B) of (0.38,≳0.007) M⊙ , and the LHS 102 system is older, aged 1–10 Gyr with masses (A,B) of (0.19,0.07) M⊙ . 相似文献
235.
利用2017年10月26日—2018年3月14日期间,乌鲁木齐机场跑道视程≤600 m时跑道25方向大气透射仪和前向散射仪的跑道视程数据,以及跑道25方向大气透射仪和中间段大气透射仪跑道视程数据进行对比分析,得到以下结论:(1)大气透射仪的跑道视程数据大于等于前向散射仪的跑道视程数据的比例为96%,跑道视程≤400 m时,两种设备相互替代性较好;(2)相比于黑夜,白天情况下前向散射仪的跑道视程数据更接近25方向大气透射仪的跑道视程数据;(3)相比于跑道中间段大气透射仪,跑道25方向前向散射仪跑道视程数据更接近25方向的大气透射仪跑道视程数据。 相似文献
236.
237.
R. & R. Griffin 《Journal of Astrophysics and Astronomy》1989,10(4):433-438
π Aquilae is a visual double star whose angular separation of 1 ”.4 is so small that the system has been regarded as a composite-spectrum
binary. However, by taking advantage of the excellence of the site and optics of the Mount Wilson 100-inch telescope, we have
been able to obtain spectra of each component separately; the spectral types are about G8 III and A2V 相似文献
238.
渗流场与斜坡稳定性的耦合分析是揭示灌溉诱发型黄土滑坡机理的重要途径,也是后续开展基于水位的滑坡灾害风险控制的基础.在综合分析研究区地质结构和水文地质条件的基础上,以调查、钻探、测量、三维激光扫描和监测资料为依据,联合应用Visual Modflow和FLAC3D数值模拟软件,开展潜水渗流场与斜坡稳定性的耦合分析,模型计算结果与监测及野外调查结果吻合较好,潜水渗流场的演化对斜坡稳定性具有控制作用,随着潜水位的升高,台塬周边不稳定区域逐年增加,1990、2000和2010年焦家崖头附近最大位移值分别为0.85、1.19和1.80m. 相似文献
239.
We present relative astrometry and differential photometry measurements for a sample of nearby southern orbital binaries making use of the technique of Adaptive Optics. The observations were made in December 2000, with the ADONIS camera mounted at the 3.6‐m ESO telescope from La Silla Observatory, equipped with the broad‐band near‐infrared filters (J ‐, H ‐, K ‐passbands). Our sample contains stars which do not fit very well the empirical mean mass‐luminosity relation (according to our previous study), but for which accurate parallaxes (determined by the Hipparcos satellite) and high‐quality orbits were available thanks to many previous efforts. We derived accurate positions and J, H, K magnitudes of the individual components of those binaries. The individual stellar components have near‐infrared colour indices well grouped in those plots and are comparable to standard single stars. The data reduction procedure used for deriving those results is described in detail. It is based on a least‐squares fit of Moffat‐Lorentz profiles in direct imaging for well‐resolved systems and on Fourier analysis for very close pairs. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
240.
遥感技术已成为快速、准确监测土地利用变化的重要手段,国情普查是一项利国利民的大工程,遥感影像解译在整个工程中占有相当大的比例.通过即定时间的影像数据,结合测绘专业知识判读影像内容,总结两种影像解译的特点.结合实际工程情况和影像特点,介绍两种解译方法在地理国情普查中的应用. 相似文献