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991.
一个从基于位置相关服务而收集的零星位置点中获取连续车辆轨迹的方法(英文) 总被引:1,自引:1,他引:0
The paper proposes an economical and fast algorithm for deriving trajectories from sporadic tracking points collected in location-based
services (LBS). Although many traffic studies or applications can benefit from the derived trajectories, the sporadic tracking
points are always implicitly overlooked by most of existing map-matching algorithms. The algorithm proposed in this paper
finds network paths or trajectories traveled by vehicles through augmenting GPS data with odometer data. An odometer can provide
data of traveled distance which are compared with the lengths of candidate network paths in order to find the most approximate
network path approaching the trajectory of a vehicle. Tracking points are classified into anchor points and non-anchor points.
The former are used to divide trajectories, and the latter screen candidate network paths. An elliptic selection zone and
a reduction process are applied to the selection of possible road segments composing candidate network paths. A brute-force
searching algorithm is developed to find candidate network paths and calculate their lengths. A two-step screening process
is designed to select the final result from candidate network paths. Finally, a series of experiments are conducted to validate
the proposed algorithm.
Supported by the National Natural Science Foundation of China (No.40701142), the Scientific Research Starting Foundation for
Returned Overseas Chinese Scholars, Ministry of Education, China. 相似文献
992.
993.
A simplified yaw-attitude model for eclipsing GPS satellites 总被引:11,自引:2,他引:9
J. Kouba 《GPS Solutions》2009,13(1):1-12
A simplified yaw-attitude modeling, consistent with Bar-Sever (1996), has been implemented and tested in the NRCan PPP software.
For Block IIR GPS satellite it is possible to model yaw-attitude control during eclipsing periods by using the constant hardware
yaw rate of 0.20°/s. The Block IIR satellites maintain the nominal yaw attitude even during a shadow crossing (Y. E. Bar-Sever,
private communication, 2007), except for the noon and shadow midnight turn maneuvers, both of which can be modeled and last
up to 15 min. Thus, for Block IIR satellites it is possible to maintain continuous satellite clock estimation even during
eclipsing periods. For the Block II/IIA satellites, it is possible to model satisfactorily the noon turns and also shadow
crossing, thanks to the permanent positive yaw bias of 0.5°, implemented in November 1995. However, in order to model the
Block II/IIA shadow crossings, satellite specific yaw rates should be used, either solved for or averaged yaw-rate solutions.
These yaw rates as estimated by the Jet Propulsion Laboratory (JPL) can differ significantly from the nominal hardware values.
The Block II/IIA post-shadow recovery periods, which last about 30 min, should be considered uncertain and cannot be properly
modeled. Data from post-shadow recovery periods should, therefore, not be used in precise global GPS analyses (Bar-Sever 1996). For high-precision applications, it is essential that users implement a yaw-attitude model, which is consistent with the
generation of the satellite clocks. Initial testing and analyses, based on the IGS and AC Final orbits and clocks have revealed
that during eclipsing periods, significant inconsistencies in yaw-attitude modeling still exist amongst the IGS Analyses Centers,
which contribute to the errors of the IGS Final clock combinations. 相似文献
994.
995.
996.
简要介绍了GPS生产过程中局域范围的坐标转换常用模型、重合点选择以及对约束平差精度进行分析,根据约束平差精度要求选择重合点、转换模型和方法,对GPS相对定位测量数据处理中的约束平差、坐标转换模型及重舍点选择对约束平差精度的影响进行系统分析,以统计图表方式进行系统研究,从GPS应用中探讨约束平差的方法。 相似文献
997.
GDCORS在某区像控测量中的应用 总被引:1,自引:0,他引:1
论述了应用GDCORS中网络RTK技术在某区像控点测量的实践。重点介绍了CORS技术的原理以及像控点采集的整个生产作业流程。通过实践结果分析得出:CORS技术完全可以满足像控点测量的精度要求,并且与常规导线测量、RTK测量等方法相比具有很大的优越性,在进行大面积测绘、快速测量中具有非常广泛的应用前景。 相似文献
998.
GPS起算数据兼容性分析 总被引:1,自引:0,他引:1
随着GPS技术的不断成熟,在各种控制网建设中的应用越来越多,若起算数据存在粗差或部分点间相对精度较低时,约束平差后的GPS网点成果精度会急剧下降.达不到预定要求.为此,在GPS控制网约束平差前必须对约束的起算点进行兼容性分析和处理,以达到预期的等级要求.以辽宁工程技术大学校园GPS控制网为实例,应用几种兼容性分析方法,得出了有益结论. 相似文献
999.
��ά����ɨ�����ֱ���Զ���ȡ�㷨�о� 总被引:1,自引:1,他引:0
???????????????д???????????????????????????????????н??????????????????Щ?????????????????????????д?????????????????????Ч????????????????????????е??????????????RANSAC????????????н???????????????????Ч???????????????н????????????????????????????????????????????????????????????????????????????????????? 相似文献
1000.
本文首先利用像片与点云融合建模的技术方法,提出了面向对象的精细化建模思路,从数据采集、数据处理及模型生产3个阶段对某一景观小品进行了实践与探索。然后通过对比分析,得出不同类别传感器所获取的数据在模型成果中的优缺点。最后利用点云与像片融合建模的技术,解决了实景模型几何结构粗糙、纹理差的问题,为小尺度规划工作提供了可参考的基础数据。 相似文献