全文获取类型
收费全文 | 53999篇 |
免费 | 5956篇 |
国内免费 | 8425篇 |
专业分类
测绘学 | 2929篇 |
大气科学 | 8842篇 |
地球物理 | 11985篇 |
地质学 | 27032篇 |
海洋学 | 4677篇 |
天文学 | 3105篇 |
综合类 | 5083篇 |
自然地理 | 4727篇 |
出版年
2024年 | 169篇 |
2023年 | 629篇 |
2022年 | 1433篇 |
2021年 | 1710篇 |
2020年 | 1431篇 |
2019年 | 1546篇 |
2018年 | 6001篇 |
2017年 | 5227篇 |
2016年 | 4076篇 |
2015年 | 1683篇 |
2014年 | 2039篇 |
2013年 | 1753篇 |
2012年 | 2595篇 |
2011年 | 4232篇 |
2010年 | 3658篇 |
2009年 | 3917篇 |
2008年 | 3246篇 |
2007年 | 3662篇 |
2006年 | 1326篇 |
2005年 | 1314篇 |
2004年 | 1260篇 |
2003年 | 1254篇 |
2002年 | 1165篇 |
2001年 | 901篇 |
2000年 | 1108篇 |
1999年 | 1515篇 |
1998年 | 1268篇 |
1997年 | 1321篇 |
1996年 | 1110篇 |
1995年 | 1022篇 |
1994年 | 922篇 |
1993年 | 792篇 |
1992年 | 645篇 |
1991年 | 468篇 |
1990年 | 325篇 |
1989年 | 354篇 |
1988年 | 295篇 |
1987年 | 202篇 |
1986年 | 165篇 |
1985年 | 123篇 |
1984年 | 104篇 |
1983年 | 79篇 |
1982年 | 76篇 |
1981年 | 75篇 |
1980年 | 69篇 |
1979年 | 32篇 |
1978年 | 16篇 |
1977年 | 7篇 |
1976年 | 12篇 |
1958年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
王平 《地球科学与环境学报》1995,(1)
陕西镇巴火焰溪剖面位于大巴山西段,临近川陕交界、交通便利。那里晚泥盆世地层出露完好,层序清楚,化石丰富。本文就该剖面法门阶牙形刺动物群、泥盆系石炭系的界线进行了研讨,建立了该区法门阶的两个浅水相牙形刺生物组合带。 相似文献
92.
本文提出了二维不同类型叠加变形的有限应变分解方法。只要测定有限应变及能代表各期主应变面的面理或剪切指向,就可以计算出各期构造应变。 相似文献
93.
Lateral extrusion along the Altyn Tagh Fault,Qilian Shan (NE Tibet): insight from a 3D crustal budget 下载免费PDF全文
Feng Cheng Marc Jolivet Guillaume Dupont‐Nivet Lin Wang Xiangjiang Yu Zhaojie Guo 《地学学报》2015,27(6):416-425
The lithospheric strike‐slip Altyn Tagh Fault has accommodated hundreds of kilometres of displacement between the Qaidam and Tarim blocks since its Eocene reactivation. However, the way the deformation is accommodated in the Qilian Shan and further east remains uncertain. Based on 360 km of north‐eastward migration of the relatively rigid Qaidam block along the Altyn Tagh Fault and 3D isovolumetric balancing of the crustal deformation within the Altyn Tagh Fault–Qilian Shan system, we demonstrate that 250 ± 28 km (43.8–49.4%) of N20E directed crustal shortening and an additional ~250–370 km of eastward motion of the Qilian Shan crust must be accounted for by strike‐slip faulting in the Qilian Shan and crustal thickening in the Qinling area, as well as by extension in the adjoining North China block graben systems. 相似文献
94.
Wang Xiaoqing Gao MengtanCenter for Analysis Prediction SSB Beijing China Institute of Geophysics SSB Beijing China 《中国地震研究》1996,(2)
This paper offers an approach to the relative confidence level of medium- and long-term earthquake prediction methods by use of the analytical hierarchy process (AHP). We construct the criterion judgment matrices according to the results of an expert questionnaire known as the Delphi scheme. From the matrices we can obtain a scale for the relative preference or priority weight of each factor. The quantitative weights might be applied to make synthetic prediction of earthquake risk areas in the northern part of the North China seismic region. 相似文献
95.
辽宁省“十五”数字化地磁数据分析系统 总被引:1,自引:0,他引:1
依据台站“十五”数字化地磁工作需求,结合地磁学科组运行管理的相关技术要求,研发辽宁省“十五”数字化地磁数据分析系统.该软件采用IDL作为开发语言,Oracle 10g数据库管理数据,主要包含用户管理模块、日志管理模块和数据管理模块3部分,具备数据实时处理、快速成像、操作简便、安全稳定等特点,可以有效解决目前台站地磁数据... 相似文献
96.
University of Maryland, College Park 相似文献
97.
煤层冲刷带预测方法评述 总被引:2,自引:0,他引:2
介绍了沉积分析法、矿井物探法以及地质统计法三种煤层冲刷带预测方法.实例证明,根据煤矿生产的具体情况,选择一种或综合运用几种方法,能较好地预测冲刷带的位置和范围. 相似文献
98.
Development of the ideas about the equilibrium between freshwater and saline water has received considerable attention in the literature, but little has been written so far about the earliest scientific works about well salinization. Based on a review of the literature from the second half of the 19th century and the early 20th century, this historical note explores how insights into groundwater abstraction and saltwater intrusion developed, and examples of the earliest field studies are provided. Fundamental research was driven by the need for increasing water supply, but the progress of science did not lead to sustainable management practices everywhere. Research outcomes were shared between scientists of different countries, marking the beginning of coastal hydrogeology as a scientific specialization in the first decade of the 20th century. 相似文献
99.
A reasonable warmer winter index (IWWI) in the framework of the three equiprobability categories (i.e. warmer, normal and colder categories) is proposed based on the winter temperature data observed at 565 stations in China during 1956-2005, where IWWI is defined as the ratio of the station number of warmer category over the total number of stations. The results suggest that the trend of IWWI was consistent with that of the winter temperature on decadal time scale, and their rates of change were 10%/10 a and 0.4 ℃/10 a, respectively. It is found that only 13 warmer winter events in total were detected by IWWI over the past 50 years, and 85% of them occurred after 1986. 相似文献
100.