全文获取类型
收费全文 | 287篇 |
免费 | 37篇 |
国内免费 | 19篇 |
专业分类
测绘学 | 67篇 |
大气科学 | 20篇 |
地球物理 | 43篇 |
地质学 | 99篇 |
海洋学 | 38篇 |
天文学 | 5篇 |
综合类 | 39篇 |
自然地理 | 32篇 |
出版年
2024年 | 1篇 |
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 7篇 |
2017年 | 13篇 |
2016年 | 9篇 |
2015年 | 14篇 |
2014年 | 11篇 |
2013年 | 28篇 |
2012年 | 25篇 |
2011年 | 19篇 |
2010年 | 14篇 |
2009年 | 20篇 |
2008年 | 17篇 |
2007年 | 28篇 |
2006年 | 23篇 |
2005年 | 15篇 |
2004年 | 12篇 |
2003年 | 10篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有343条查询结果,搜索用时 46 毫秒
61.
62.
The basic properties to be dealt with, when considering initially the research needs related to the integration of remote sensing (RS) information into a geographic information system (GIS), are many-sided. The primary combination of remote sensing and GIS is mainly realized by the transforms of data structure. Because of its own limitations, there is an urgent need to investigate the integration of RS and GIS in higher levels. In this paper, we discuss the different types of combinations of RS with GIS, and propose that GIS data should be directly brought into image processing from the beginning. A tentative idea of how to use the method of granularity to study the common processing unit of RS and GIS is described. The example for the determination of granularity of spatial data processing related to run-length-code line is also given. 相似文献
63.
福建省地理信息公共服务平台数据应用服务模式探讨 总被引:1,自引:0,他引:1
介绍了福建省地理信息公共服务平台数据构成和应用服务,探讨了针对不同用户类型、不同网络环境下的平台数据共享应用服务模式,实现横纵向部门间数据服务的互联互通,为政府、企业和社会公众提供地理信息基础支撑。 相似文献
64.
本文对比了鞍本地区前寒武纪铅-锌-银矿区和铀矿区的硫化物矿石和花岗岩长石Pb同位素组成,分别用矿石铅二阶段普通铅法、铅构造模式图解和全岩铅同位素组成三阶段拟合法计算了年龄和全岩原始铀含量。结果表明,矿石铅和长石铅模式年龄约为2000 Ma,在铅构造模式图上投影于2000~1600 Ma间,花岗岩和辽河群全岩拟合年龄为2000~1800 Ma;铅同位素组成显示铅-锌-银来自早元古代辽河群地层,连山关地区明显为放射性成因Pb同位素组成,源于富铀花岗岩。连山关矿石铅年龄和全岩三阶段年龄与该区铀矿床沥青铀矿的年龄基本一致;花岗岩原始铀的得失计算表明,该地区不同地质体均经历了约2000~1800 Ma花岗岩重熔改造,花岗质岩石发生了铀的丢失,是连山关地区铀矿的主要来源。 相似文献
65.
Raju RAI ZHANG Yili LIU Linshan Paras Bikram SINGH Basanta PAUDEL Bipin Kumar ACHARYA Narendra Raj KHANAL 《资源与生态学报(英文版)》2022,13(2):173-185
Gandaki River Basin (GRB) is an important part of the central Himalayan region, which provides habitat for numerous wild species. However, climatic changes are making the habitat in this basin more vulnerable. This paper aims to assess the potential impacts of climate change on the spatial distributions of habitat changes for two vulnerable species, Himalayan black bear (Ursus thibetanus laniger) and common leopard (Panthera pardus fusca), using the maximum entropy (MaxEnt) species distribution model. Species occurrence locations were used along with several bioclimatic and topographic variables (elevation, slope and aspect) to fit the model and predict the potential distributions (current and future) of the species. The results show that the highly suitable area of Himalayan black bear within the GRB currently encompasses around 1642 km2 (5.01% area of the basin), which is predicted to increase by 51 km2 in the future (2050). Similarly, the habitat of common leopard is estimated as 3999 km2 (12.19% of the GRB area), which is likely to increase to 4806 km2 in 2050. Spatially, the habitat of Himalayan black bear is predicted to increase in the eastern part (Baseri, Tatopani and north from Bhainse) and to decrease in the eastern (Somdang, Chhekampar), western (Burtibang and Bobang) and northern (Sangboche, Manang, Chhekampar) parts of the study area. Similarly, the habitat of common leopard is projected to decrease particularly in the eastern, western and southern parts of the basin, although it is estimated to be extended in the southeastern (Bhainse), western (Harichaur and northern Sandhikhark) and north-western (Sangboche) parts of the basin. To determine the habitat impact, the environmental variables such as elevation, Bio 15 (precipitation seasonality) and Bio 16 (precipitation of wettest quarter) highly contribute to habitat change of Himalayan black bear; while Bio 13 (precipitation of wettest month) and Bio 15 are the main contributors for common leopard. Overall, this study predicted that the suitable habitat areas of both species are likely to be impacted by climate change at different altitudes in the future, and these are the areas that need more attention in order to protect these species. 相似文献
66.
67.
如何快速、精确地利用叠前深度偏移进行偏移速度分析是勘探地震学的一项重要研究内容,针对该问题,本文提出一种二阶精度广义非线性全局最优的偏移速度反演方法。我们将首先去掉速度模型修正量与成象深度差呈线性关系的假设,推导出具有二阶精度的速度模型修正量计算公式,使每一次迭代得到的速度模型尽可能地接近实际模型;然后采用广义非线性反演方法反演获得对所有道集的全局最优的速度模型修正量,不仅极大地加快了收敛速度,而且反演过程中陷入局部极小的可能性也减小了。理论模型和Marmousi模型的处理结果表明:本方法精度高、处理速度快,提高了偏移速度分析方法的实用性和对复杂构造成像的准确性。 相似文献
68.
GUAN Zequn 《地球空间信息科学学报》2000,3(4):16-19
The basic properties to be dealt with ,when considering initially the research needs related to the integration of remote sensing (RS) information into a geographic information system (GIS),are many-sided.The primary combination of remote sensing and GIS is mainly realized by the transforms of data structure .Because of its own limitations,there is an urgent need to investigate the integration of RS and GIS in higher levels.In this paper,we discuss the different types of combinations of RS with GIS,and propose that GIS data should be directly brought into image processing from the beginning.A tentative idea of how to use the method of granularity to study the common processing unit of RS and GIS is described.The example for the determination of granularity of spatial data processing related to run-length-code line is also given. 相似文献
69.
车贝雪夫多项式约简算法的研究 总被引:4,自引:0,他引:4
解释了车贝雪夫多项式化整计算通用算法中关于化整后的车贝雪夫多项式约简处理的技术原理,给出了一种可快速实现多项式约简处理的实用求算方法。 相似文献
70.
台湾连续GPS网主成分空间滤波分析 总被引:1,自引:0,他引:1
采用PCA方法提取台湾GPS区域网共模误差,进行空间滤波。结果表明,第1主成分在空间上表现出强烈的一致性,第2~5主成分在空间上呈现出局部响应的特点;滤波后残差时间序列的均方根(RMS)在N、E、U方向平均分别降低33%、31%、19%;滤波效果在水平方向好于垂直方向,东、西部存在明显的差异,这可能与台湾地区地形有关;幂律噪声振幅在N、E、U方向平均分别下降36%、43%、23%。 相似文献