全文获取类型
收费全文 | 87篇 |
免费 | 6篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 22篇 |
大气科学 | 13篇 |
地球物理 | 4篇 |
地质学 | 13篇 |
海洋学 | 35篇 |
综合类 | 10篇 |
自然地理 | 1篇 |
出版年
2024年 | 2篇 |
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 6篇 |
2012年 | 7篇 |
2011年 | 4篇 |
2010年 | 2篇 |
2009年 | 7篇 |
2008年 | 11篇 |
2007年 | 4篇 |
2006年 | 3篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1999年 | 7篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有98条查询结果,搜索用时 15 毫秒
21.
22.
In the supervised classification process of remotely sensed imagery, the quantity of samples is one of the important factors affecting the accuracy of the image classification as well as the keys used to evaluate the image classification. In general, the samples are acquired on the basis of prior knowledge, experience and higher resolution images. With the same size of samples and the same sampling model, several sets of training sample data can be obtained. In such sets, which set reflects perfect spectral characteristics and ensure the accuracy of the classification can be known only after the accuracy of the classification has been assessed. So, before classification, it would be a meaningful research to measure and assess the quality of samples for guiding and optimizing the consequent classification process. Then, based on the rough set, a new measuring index for the sample quality is proposed. The experiment data is the Landsat TM imagery of the Chinese Yellow River Delta on August 8th, 1999. The experiment compares the Bhattacharrya distance matrices and purity index zl and △x based on rough set theory of 5 sample data and also analyzes its effect on sample quality. 相似文献
23.
24.
25.
26.
ZhangZhenfei HuGuangdao YangMingguo LiuXing WangZhenlmi LiWenhui ZhangXiaobing HeLi 《中国地质大学学报(英文版)》2003,14(3):257-260
Field data of outcrop spectrums provide important basis for modeling of hyper-spectral remote sensing aiming at mineral prospecting. We make an approach to the application of rough set theory in spectral discriminiation of rocks. We build a decision table with an adequate number of samples (out-crops) of known rock type (the universe), of which the conditional atributes are discretized “area spectrum absorption indexes“ (ASAI) corresponding to wavelength intervals, and the decision atribute is rock type. We search to obtain the exhaustive set of reducts of the table, each of which will serve as a variable number of deduction rules. Suppose we have n (usually a very big number) rules in total and there are m types of rocks in our universe, for any unknown sample, we judge its rock type by each of those rules. An unknown sample may be recognized as a different type by different rules because it is out-side our universe, and we accept the most frequent judgment result and ignore the other m-1 types of results. Our ASAI is an improvement upon the traditional spectrum absorption index (SAI), better applicable to field spectrums: given a spectrum curve and a wavelength interval, we take the average reflectance within the interval as a base line and let ASAI=αbelow/(αabove αbelow), where αbelow and αabove stand for total areas, bounded by the curve, the base line and the borders of the intervalbelow and above the base line respectively. With the equipments of FieldSpectr Fr (made by ASD Co., US), we collected data from Baiya gold deposit, Yunnan, and applied the above method to discriminate altered rocks as an experiment. The results show satisfactory performance of the method. 相似文献
27.
本文介绍了一种用于车辆导航系统的红外线遥控键盘原理与设计,详细介绍了遥控键盘的编码原理、利用单片机进行解码的方法、相关软件的设计思路以及系统通过PS/2口和计算机之间的通信方法。 相似文献
28.
数字摄像能见度仪器系统(DPVS)是完全仿照人工目测能见度的方法测量能见度的,比传统的透射式、散射式能见度仪更具客观性。为了说明DPVS在硬件方面的工作原理,从该仪器系统的控制电路原理、电路详细构成、元器件的选配、电路设计思路以及系统在实际运行中出现的一些问题和解决方法等方面做了详细介绍。同时还对控制电路中应用的单片机的部分软件做了简要介绍。 相似文献
29.
30.