全文获取类型
收费全文 | 2151篇 |
免费 | 175篇 |
国内免费 | 353篇 |
专业分类
测绘学 | 190篇 |
大气科学 | 164篇 |
地球物理 | 163篇 |
地质学 | 922篇 |
海洋学 | 127篇 |
天文学 | 919篇 |
综合类 | 75篇 |
自然地理 | 119篇 |
出版年
2024年 | 5篇 |
2023年 | 14篇 |
2022年 | 31篇 |
2021年 | 14篇 |
2020年 | 18篇 |
2019年 | 33篇 |
2018年 | 20篇 |
2017年 | 23篇 |
2016年 | 40篇 |
2015年 | 45篇 |
2014年 | 113篇 |
2013年 | 85篇 |
2012年 | 151篇 |
2011年 | 58篇 |
2010年 | 92篇 |
2009年 | 140篇 |
2008年 | 163篇 |
2007年 | 174篇 |
2006年 | 203篇 |
2005年 | 211篇 |
2004年 | 128篇 |
2003年 | 153篇 |
2002年 | 144篇 |
2001年 | 118篇 |
2000年 | 67篇 |
1999年 | 105篇 |
1998年 | 41篇 |
1997年 | 37篇 |
1996年 | 47篇 |
1995年 | 39篇 |
1994年 | 31篇 |
1993年 | 45篇 |
1992年 | 31篇 |
1991年 | 20篇 |
1990年 | 12篇 |
1989年 | 8篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 8篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有2679条查询结果,搜索用时 31 毫秒
61.
62.
63.
64.
Wenguang Yang Hongbo Zheng Ke Wang Xin Xie Guocheng Chen Xi Mei 《Frontiers of Earth Science》2008,2(2):170-176
Sediments with high sedimentation rate at site MD05-2905 in the Northeastern slope of the South China Sea provide unique materials
for a high-resolution study on the paleoenvironment. Based on precise dating of AMS 14C, grain size analysis of terrigenous debris at core MD05-2905 was conducted after organic matter, biological carbonate and
biogenic opal were removed. The results show that 15.5–63.5 μm coarse grain size ingredients may indicate East Asian winter
monsoon changes and that 2–9 μm fine grain size ingredients may be used as a proxy of evolution of the East Asian summer monsoon.
The results of grain size analysis, which suggest East Asian monsoon intensity, reveal that a winter monsoon dominated the
glacial regime and a summer monsoon dominated the Holocene regime. It was also shown that the summer monsoon increased gradually,
experienced several abrupt changes and reached a culmination in the early Holocene (11200–8500 a B.P.) since 36 ka. Controlled
by precession periodicity, it may be related with the amount of solar radiation at the highest stage, which needs further
study.
__________
Translated from Advances in Earth Science, 2007, 22(10): 1012–1018 [译自: 地球科学进展] 相似文献
65.
临港新城地质特征及其对新城规划与建设的影响分析 总被引:2,自引:1,他引:1
结合临港新城三维地质调查所取得的成果,分析了该城区地质特征及对新城建设的影响,为新城规划建设提供科学依据和服务。 相似文献
66.
67.
Strength and stability of frictional sliding of gabbro gouge at elevated temperatures 总被引:7,自引:1,他引:7
To investigate the strength of frictional sliding and stability of mafic lower crust, we conducted experiments on oven-dried gabbro gouge of 1 mm thick sandwiched between country rock pieces (with gouge inclined 35° to the sample axis) at slip rates of 1.22 × 10− 3 mm/s and 1.22 × 10− 4 mm/s and elevated temperatures up to 615 °C. Special attention has been paid to whether transition from velocity weakening to velocity strengthening occurs due to the elevation of temperature.Two series of experiments were conducted with normal stresses of 200 MPa and 300 MPa, respectively. For both normal stresses, the friction strengths are comparable at least up to 510 °C, with no significant weakening effect of increasing temperature. Comparison of our results with Byerlee's rule on a strike slip fault with a specific temperature profile in the Zhangbei region of North China shows that the strength given by experiments are around that given by Byerlee's rule and a little greater in the high temperature range.At 200 MPa normal stress, the steady-state rate dependence a − b shows only positive values, probably still in the “run-in” process where velocity strengthening is a common feature. With a normal stress of 300 MPa, the values of steady-state rate dependence decreases systematically with increasing temperature, and stick-slip occurred at 615 °C. Considering the limited displacement, limited normal stress applied and the effect of normal stress for the temperatures above 420 °C, it is inferred here that velocity weakening may be the typical behaviour at higher normal stress for temperature above 420 °C and at least up to 615 °C, which covers most of the temperature range in the lower crust of geologically stable continental interior. For a dry mafic lower crust in cool continental interiors where frictional sliding prevails over plastic flow, unstable slip nucleation may occur to generate earthquakes. 相似文献
68.
69.
对河北省昌黎县闫庄铁矿床的磁铁石英岩型铁矿石261件样品进行了光谱反射率测量,并与其铁含量进行了相关关系研究,目
的是对钻孔岩芯编录的新方法即高光谱岩芯编录在此类矿床中的可行性进行分析。研究结果表明,铁矿石反射率较低,一般为5%~20%
,铁离子的吸收峰主要表现在400~1 100 nm范围内,铁矿石中铁含量与850~900 nm的反射率均值呈现显著指数负相关关系,为高光谱
岩芯编录在此类矿床中的可行性提供了理论依据和技术途径。 相似文献
70.