全文获取类型
收费全文 | 5327篇 |
免费 | 1077篇 |
国内免费 | 1356篇 |
专业分类
测绘学 | 496篇 |
大气科学 | 1078篇 |
地球物理 | 1526篇 |
地质学 | 2639篇 |
海洋学 | 678篇 |
天文学 | 162篇 |
综合类 | 557篇 |
自然地理 | 624篇 |
出版年
2024年 | 43篇 |
2023年 | 119篇 |
2022年 | 290篇 |
2021年 | 367篇 |
2020年 | 247篇 |
2019年 | 285篇 |
2018年 | 293篇 |
2017年 | 315篇 |
2016年 | 334篇 |
2015年 | 286篇 |
2014年 | 315篇 |
2013年 | 313篇 |
2012年 | 288篇 |
2011年 | 291篇 |
2010年 | 259篇 |
2009年 | 297篇 |
2008年 | 297篇 |
2007年 | 252篇 |
2006年 | 176篇 |
2005年 | 151篇 |
2004年 | 165篇 |
2003年 | 210篇 |
2002年 | 233篇 |
2001年 | 197篇 |
2000年 | 206篇 |
1999年 | 240篇 |
1998年 | 157篇 |
1997年 | 178篇 |
1996年 | 179篇 |
1995年 | 145篇 |
1994年 | 115篇 |
1993年 | 104篇 |
1992年 | 82篇 |
1991年 | 64篇 |
1990年 | 64篇 |
1989年 | 48篇 |
1988年 | 35篇 |
1987年 | 23篇 |
1986年 | 18篇 |
1985年 | 15篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1962年 | 4篇 |
1958年 | 4篇 |
1957年 | 4篇 |
排序方式: 共有7760条查询结果,搜索用时 15 毫秒
81.
82.
建筑物变形观测是监视建筑物在各种应力作用下是否安全的重要手段,观测成果也是验证设计理论和检验施工质量的重要的资料.本文介绍了利用近景摄影测量技术观测建筑变形的基本思想,与传统的变形观测方法相比,它具有效率高、质量好、劳动强度低、野外工作量少等显著优点. 相似文献
83.
分析了几种常用的对流层延迟改正模型和对流层延迟的影响因素,在软件LGO和Pinnacle中运用不同对流层改正模型,对外业GPS测量得到的数据进行基线解算,比较不同对流层模型解算后的基线各分量,并得出一些有益的结论。 相似文献
84.
Zhanfeng Shen Jiancheng Luo Wei Wu Xiaodong Hu 《Journal of the Indian Society of Remote Sensing》2012,40(3):357-370
Object-oriented remotely sensed images processing method has been accepted by more and more experts of remote sensing. To advance the efficiency of data processing, parallel image computing is a good choice since large volumes of data need be analyzed efficiently and rapidly. This paper presents the information extraction method based on per-parcel extraction of high-resolution remotely sensed image; to extract efficiently different information from remotely sensed image, this paper gives the research idea of image rough-classification based on large-scale and subtle-segmentation based on small-scale; to improve the efficiency of image processing, we adapt parallel computing method to solve this problem by presenting an new data-partition method. At last this paper gives the implementation of the research idea based on Message Passing Interface (MPI) and analyzes our experimental system efficiency, and the results show that the new methods can improve the efficiency of high-resolution remotely sensed image data processing efficiently and have a good application. 相似文献
85.
我国地质分析综述论文统计 总被引:2,自引:0,他引:2
作者检索了地质分析专业刊物《岩矿测试》、《地质实验室》全部论文以及国内相关期刊近30年来的文献.统计分析了地质分析综述性文献在各有关期刊的分布及特点,为了解和评价国内地质分析文献的基本状况提供了有益信息。 相似文献
86.
87.
88.
Weiwei Song Wenting Yi Yidong Lou Chuang Shi Yibin Yao Yanyan Liu Yong Mao Yu Xiang 《GPS Solutions》2014,18(3):323-333
GLONASS carrier phase and pseudorange observations suffer from inter-channel biases (ICBs) because of frequency division multiple access (FDMA). Therefore, we analyze the effect of GLONASS pseudorange inter-channel biases on the GLONASS clock corrections. Different Analysis Centers (AC) eliminate the impact of GLONASS pseudorange ICBs in different ways. This leads to significant differences in the satellite and AC-specific offsets in the GLONASS clock corrections. Satellite and AC-specific offset differences are strongly correlated with frequency. Furthermore, the GLONASS pseudorange ICBs also leads to day-boundary jumps in the GLONASS clock corrections for the same analysis center between adjacent days. This in turn will influence the accuracy of the combined GPS/GLONASS precise point positioning (PPP) at the day-boundary. To solve these problems, a GNSS clock correction combination method based on the Kalman filter is proposed. During the combination, the AC-specific offsets and the satellite and AC-specific offsets can be estimated. The test results show the feasibility and effectiveness of the proposed clock combination method. The combined clock corrections can effectively weaken the influence of clock day-boundary jumps on combined GPS/GLONASS kinematic PPP. Furthermore, these combined clock corrections can improve the accuracy of the combined GPS/GLONASS static PPP single-day solutions when compared to the accuracy of each analysis center alone. 相似文献
89.
This paper presents a conceptual data model, the STA-model, for handling spatial, temporal and attribute aspects of objects in GIS. The model is developed on the basis of object-oriented modeling approach. This model includes two major parts: (a) modeling the signal objects by STA-object elements, and (b) modeling relationships between STA-objects. As an example, the STA-model is applied for modeling land cover change data with spatial, temporal and attribute components. 相似文献
90.
Xiaodong Zhang Ho Jin Kim Clinton Streeter David A. Claypool Ramesh Sivanpillai Santhosh Seelan 《国际地球制图》2013,28(7):537-551
Precision agriculture often relies on high-resolution imagery to delineate the variability within a field. Airborne Environmental Research Observational Camera (AEROCam) was designed to meet the needs of agriculture producers, ranchers, and researchers, who require high-resolution imagery in a near real-time environment for rapid decision support. AEROCam was developed and operated through a unique collaboration between several departments at the University of North Dakota, including the Upper Midwest Aerospace Consortium (UMAC), the School of Engineering and Mines, and flight operations at the John D. Odegard School of Aerospace Sciences. AEROCam consists of a Redlake MS4100 area-scan multi-spectral digital camera that features a 1920 × 1080 CCD array (7.4-μm detector) with 8-bit quantization. When operated at ~2 km above ground level, multispectral images with four bands in the visible and near infrared have a ground sample distance of 1 m with a horizontal extent of just over 1.6 km. Depending on the applications, flying at different altitudes can adjust the spatial resolution from 0.25 to 2 m. Rigorous spectral and radiometric calibrations allow AEROCam to be used in a variety of applications, qualitative and quantitative. Equipped with an inertial measurement unit (IMU) system, the images acquired can be geo-referenced automatically and delivered to end users near real time through our Digital Northern Great Plains system (DNGP). The images are also available to zone mapping application for precision farming (ZoneMAP), an online decision support tool for creating management zones from remote sensing imagery and data from other sources. Operational since 2004, AEROCam has flown over 250 sorties and delivered over 150,000 images to the users in the Northern Great Plains region, resulting in numerous applications in precision agriculture and resource management. 相似文献