全文获取类型
收费全文 | 745篇 |
免费 | 53篇 |
国内免费 | 14篇 |
专业分类
测绘学 | 431篇 |
大气科学 | 21篇 |
地球物理 | 103篇 |
地质学 | 3篇 |
海洋学 | 33篇 |
天文学 | 5篇 |
综合类 | 209篇 |
自然地理 | 7篇 |
出版年
2024年 | 3篇 |
2023年 | 14篇 |
2022年 | 58篇 |
2021年 | 66篇 |
2020年 | 68篇 |
2019年 | 64篇 |
2018年 | 26篇 |
2017年 | 59篇 |
2016年 | 53篇 |
2015年 | 64篇 |
2014年 | 64篇 |
2013年 | 50篇 |
2012年 | 48篇 |
2011年 | 52篇 |
2010年 | 23篇 |
2009年 | 35篇 |
2008年 | 27篇 |
2007年 | 19篇 |
2006年 | 5篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1998年 | 1篇 |
1979年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有812条查询结果,搜索用时 15 毫秒
11.
Catherine Robin Shannon Nudds Phillip MacAulay André Godin Bodo De Lange Boom Jason Bartlett 《Marine Geodesy》2016,39(2):195-222
Since the advent of Global Navigation Satellite Systems, it has been possible to perform hydrographic survey reductions through the ellipsoid, which has the potential to simplify operations and improve bathymetric products. This technique requires a spatially continuous separation surface connecting chart datum (CD) to a geodetic ellipsoid. The Canadian Hydrographic Service (CHS), with support from the Canadian Geodetic Survey, has developed a new suite of such surfaces, termed Hydrographic Vertical Separations Surfaces, or HyVSEPs, for CD and seven tidal levels. They capture the spatial variability of the tidal datum and levels between tide gauges and offshore using semiempirical models coupling observations at tide stations with relative sea-level rise estimates, dynamic ocean model solutions, satellite altimetry, and a geoid model. HyVSEPs are available for all tidal waters of Canada, covering over seven million square kilometers of ocean and more than 200,000 kilometers of shoreline. This document provides an overview of the CHS's modeling approach, tools, methods, and procedures.
The HyVSEP for CD defines the new hydrographic datum for the tidal waters of Canada. HyVSEPs for other tidal levels are fundamental for coastal studies, climate change adaptation and the definition of the Canadian shoreline and offshore boundaries. HyVSEPs for inland waters are not discussed. 相似文献
12.
P. J. G. Teunissen 《Journal of Geodesy》2001,75(7-8):399-407
Carrier phase ambiguity resolution is the key to fast and high-precision GNSS (Global Navigation Satellite System) kinematic
positioning. Critical in the application of ambiguity resolution is the quality of the computed integer ambiguities. Unsuccessful
ambiguity resolution, when passed unnoticed, will too often lead to unacceptable errors in the positioning results. Very high
success rates are therefore required for ambiguity resolution to be reliable. Biases which are unaccounted for will lower
the success rate and thus increase the chance of unsuccessful ambiguity resolution. The performance of integer ambiguity estimation
in the presence of such biases is studied. Particular attention is given to integer rounding, integer bootstrapping and integer
least squares. Lower and upper bounds, as well as an exact and easy-to-compute formula for the bias-affected success rate,
are presented. These results will enable the evaluation of the bias robustness of ambiguity resolution.
Received: 28 September 2000 / Accepted: 29 March 2001 相似文献
13.
利用GNSS三维水汽层析技术全天候地获取高时空采样率的水汽垂直分布信息,已成为GNSS气象学中一大研究热点。当前,基于单一导航系统的传统层析方法存在观测数据利用率低、观测分布不均等不足。本文设计和实现了一种顾及边界入射信号的多模水汽层析方法,采用香港CORS网观测数据和无线电探空产品进行精度验证,并详细分析边界入射信号和多模层顶信号的引入对层析水汽结果的改善程度。结果表明:相较于传统GPS层析方法,本文采用的融合两类多模层顶信号和边界入射信号的新水汽层析方法,兼备边界入射信号和多模层顶信号的优点,可得到更高精度和更可靠的三维水汽信息。 相似文献
14.
大气加权平均温度(Tm)是全球导航卫星系统(GNSS)水汽监测的关键参数。针对中国区域地形起伏较大的特点,本文构建了顾及精细季节变化的Tm垂直递减率函数模型,在此基础上,利用2007—2014年的Global Geodetic Observing System(GGOS)atmosphere格网数据建立了中国区域的Tm格网新模型(简称为CTm模型)。以2015年GGOS格网数据和无线电探空资料为参考值,对CTm模型进行精度检验,并与常用的Bevis公式和GPT2w模型进行比较分析。结果表明:①以GGOS格网数据为参考值,CTm模型的年均偏差和均方根误差(RMS)分别为-0.52 K和3.28 K,相比于GPT2w-5和GPT2w-1模型,精度(RMS值)分别提高了27%和13%;②以探空数据为参考值,CTm模型的年均偏差和RMS误差分别为0.26 K和3.75 K,相对于GPT2w-5和GPT2w-1模型,精度分别提高了21%和16%,尤其在中国西部地区,CTm模型表现出更为显著的优势。此外,将CTm模型用于GNSS水汽计算,其引起的水汽计算RMS误差和相对误差分别为0.29 mm和1.36%。CTm模型不需要实测气象参数,因此,在中国区域的GNSS实时高精度水汽探测中具有重要的应用。 相似文献
15.
16.
F. Frappart N. Roussel R. Biancale J.J. Martinez Benjamin F. Mercier F. Perosanz 《Marine Geodesy》2015,38(3):219-232
This study presents the results of the 2013 Ibiza (Western Mediterranean) calibration campaign of Jason-2 and SARAL altimeters. It took place from 14 to 16 September 2013 and comprised two phases: the calibration of the GNSS (Global Navigation Satellite System) buoys to estimate the antenna height of each of them and the absolute calibration to estimate the altimeter bias (i.e., the difference of sea level measured by radar altimetry and GNSS). The first one was achieved in the Ibiza harbor at a close vicinity of the Ibiza tide gauge and the second one was performed at ~ 40 km at the northwest of Ibiza Island at a crossover point of Jason-2 and SARAL nominal groundtracks. Five buoys were used to delineate the crossover region and their measurements interpolated at the exact location of each overflight. The overflights occurred two consecutive days: 15 and 16 September 2013 for Jason-2 and SARAL, respectively. The GNSS data were processed using precise point positioning technique. The biases found are of (?0.1 ± 0.9) and (?3.1 ± 1.5) cm for Jason-2 and SARAL, respectively. 相似文献
17.
18.
???????????????????о??м????????????ε??????????????????????????????????????????????????????Э??????????????????????????б????????С??????????????????????????????????????????????о??????????????????????????????????????Σ?????б????????????? 相似文献
19.
????Windows????WinTrack????????GPS???????????????10 Hz??????1 Hz?л????????????????????????????????????ж?????????£?????????GPS????????????cm??????????????????????????????????????????????????????μ????????£???5 m???????????????????????С??1 mm?? 相似文献
20.
??????????λ???PANDA?????????纣????????2009??2011??2013??????3??GNSS?????????д????????????ITRF2008?μ???????????????з??????ó?????????????????仯????E???????32.16 mm/a????N???????-10.08 mm/a?????????????????????λ?????????????????????μ????????? 相似文献