全文获取类型
收费全文 | 3002篇 |
免费 | 410篇 |
国内免费 | 419篇 |
专业分类
测绘学 | 1290篇 |
大气科学 | 283篇 |
地球物理 | 568篇 |
地质学 | 824篇 |
海洋学 | 351篇 |
天文学 | 84篇 |
综合类 | 291篇 |
自然地理 | 140篇 |
出版年
2024年 | 10篇 |
2023年 | 35篇 |
2022年 | 129篇 |
2021年 | 161篇 |
2020年 | 169篇 |
2019年 | 210篇 |
2018年 | 136篇 |
2017年 | 206篇 |
2016年 | 148篇 |
2015年 | 183篇 |
2014年 | 204篇 |
2013年 | 254篇 |
2012年 | 268篇 |
2011年 | 217篇 |
2010年 | 119篇 |
2009年 | 173篇 |
2008年 | 153篇 |
2007年 | 183篇 |
2006年 | 147篇 |
2005年 | 135篇 |
2004年 | 102篇 |
2003年 | 116篇 |
2002年 | 58篇 |
2001年 | 54篇 |
2000年 | 45篇 |
1999年 | 40篇 |
1998年 | 27篇 |
1997年 | 40篇 |
1996年 | 20篇 |
1995年 | 22篇 |
1994年 | 13篇 |
1993年 | 13篇 |
1992年 | 5篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1984年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1971年 | 1篇 |
1954年 | 2篇 |
排序方式: 共有3831条查询结果,搜索用时 375 毫秒
961.
珠江口红树林湿地演变与现状的遥感分析 总被引:1,自引:0,他引:1
1 Introduction Half of the mangrove wetlands in China are situated in Guangdong province (Wang and Chen, 1998). The province used to have various types of wild mangrove forests along its coastal areas. The rapid expansion of urban areas and the fast deve… 相似文献
962.
963.
Some unfavorable geological conditions can affect the construction of tunnels.In order to evaluate the damage degree of tunnel construction and determine the surrounding rock grade and stability of the tunnel,the authors used high-density resistivity method to detect the surrounding rocks of Shimodong tunnel in Xicheng Town of Helong City.The underground resistivity structures of the entrance,exit and middle parts of the tunnel are obtained.Through analysis,it is found that there are no bedrock faults near the tunnel,although some joints and fissures are developed in some locations,which are characterized by low-resistivity anomalies.The tunnel structures are stable overall,favorable for safe and efficient construction.The study also proves the good application effect of the high-density resistivity method in tunnel safety detection. 相似文献
964.
965.
Shiran Havivi Doron Amir Ilan Schvartzman Yitzhak August Shimrit Maman Stanley R. Rotman Dan G. Blumberg 《地球表面变化过程与地形》2018,43(6):1229-1240
It is generally held that subtle changes in sandy environments are very difficult to detect in imagery. Nonetheless, this study demonstrates how synthetic aperture radar (SAR) interferometric decorrelation can be used to identify changes in individual sand dunes. The use of coherence maps over time facilitates the analysis of dune dynamics, both temporally and spatially. The Ashdod‐Nizzanim coastal dunes, along the southern coastal plain of Israel, were chosen as an illustrative example of the analysis of dune dynamics. High‐resolution TerraSAR‐X (TSX) radar images covering the entire research area were acquired for the period February to July 2012, together with meteorology data (wind and rain) for the area. The coherence results enabled the stability of individual dunes to be described as a function of time. It was found that the dune crests were more stable than the windward slopes and that the degree of stability was dependent on the distance of the dune from the sea. The results of this study show the potential of using interferometric synthetic aperture radar (InSAR) decorrelation for aeolian studies, even in areas characterized by low coherence. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
966.
967.
分析2015年8月—2018年7月满洲里地震台FHDZ-M15地磁总场与分量组合观测系统记录的地磁秒采样观测数据(剔除磁暴与磁扰时间段),发现台站地磁秒采样数据资料所受干扰主要呈阶跃和尖峰形态,通过测量测区地磁场水平梯度,排查周边环境,并对设备和线路进行漏电检测,认为:阶跃形态干扰主要由高压直流输电和车辆停放引起;经逐项排查对UPS加热及输电线路漏电检测,仪器室温度过低和输电线路漏电均造成高频毛刺尖峰形态干扰,对UPS加热处理,干扰状态得到改善,但Z、F分量干扰仍在.受满洲里气候条件等因素限制,未能在2019年完成输电线路更换,当前无法确定干扰是否为输电线路漏电所致,后续将采取相应措施予以确认. 相似文献
968.
Information Detection of Seismic Debris Flow by UAV High-resolution Image Based on Transfer Learning
A large number of debris flow disasters (called Seismic debris flows) would occur after an earthquake, which can cause a great amount of damage. UAV low-altitude remote sensing technology has become a means of quickly obtaining disaster information as it has the advantage of convenience and timeliness, but the spectral information of the image is so scarce, making it difficult to accurately detect the information of earthquake debris flow disasters. Based on the above problems, a seismic debris flow detection method based on transfer learning (TL) mechanism is proposed. On the basis of the constructed seismic debris flow disaster database, the features acquired from the training of the convolutional neural network (CNN) are transferred to the disaster information detection of the seismic debris flow. The automatic detection of earthquake debris flow disaster information is then completed, and the results of object-oriented seismic debris flow disaster information detection are compared and analyzed with the detection results supported by transfer learning. 相似文献
969.
以河北测震台网记录的连续波形数据为基础,采用模板匹配滤波方法,检测2017年9月4日—6日河北临城震群遗漏地震。利用波形互相关扫描,检测到19次被测震台网常规分析遗漏的地震,震级范围为M_(L )0.0—1.2,并标定新检测地震事件的P波和S波到时,估计其震中位置及震级。通过地震精定位和最大地震震源机制解,认为此次临城地震序列的主要发震构造应为近EW向活动断层。 相似文献
970.
对集宁2017年4月1日-5月31日地电阻率原始观测数据曲线常规分析发现,NS、EW测道数值差异明显,采用电测深曲线进行对比分析,发现2测道电阻率数值基本一致。在同场范围内,地电阻率与电测深曲线应同步变化。对集宁地电阻率布极区、观测环境、观测系统、装置系统进行系列检查、测试,发现NS测道导线线芯与导线铠导通,导线铠与避雷箱箱体接触导致线路漏电,造成数值出现误差。通过对外线路以及电极引线等进行优化改造,集宁地电阻率观测数据恢复正常。 相似文献