全文获取类型
收费全文 | 352篇 |
免费 | 55篇 |
国内免费 | 47篇 |
专业分类
测绘学 | 63篇 |
大气科学 | 40篇 |
地球物理 | 87篇 |
地质学 | 170篇 |
海洋学 | 33篇 |
天文学 | 9篇 |
综合类 | 22篇 |
自然地理 | 30篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 13篇 |
2021年 | 20篇 |
2020年 | 18篇 |
2019年 | 20篇 |
2018年 | 19篇 |
2017年 | 27篇 |
2016年 | 21篇 |
2015年 | 18篇 |
2014年 | 22篇 |
2013年 | 12篇 |
2012年 | 20篇 |
2011年 | 13篇 |
2010年 | 17篇 |
2009年 | 17篇 |
2008年 | 16篇 |
2007年 | 19篇 |
2006年 | 13篇 |
2005年 | 13篇 |
2004年 | 6篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 16篇 |
1998年 | 14篇 |
1997年 | 24篇 |
1996年 | 12篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有454条查询结果,搜索用时 281 毫秒
81.
库车坳陷充填有厚约4000~5000 m(局部最大厚度可达6000 m)的中生界陆相地层。地面特征和地震资料表明,库车坳陷北部地区中生界与下伏强烈变形、变质的古生界呈角度不整合接触,南部地区中生界与下伏寒武系-奥陶系呈平行不整合或微角度不整合接触。按照地层厚度趋势推测的中生界在山前地带有强烈的剥蚀,沉积厚度轴线位于南天山晚古生代造山楔之上,显示库车坳陷中生代盆地是上叠在塔里木克拉通北部边缘隆起和南天山晚古生代造山楔过渡带上的拗陷盆地。三叠纪-侏罗纪沉降-沉积中心向后陆(造山带)迁移,早白垩世向前陆迁移,且盆地同沉积期区域规模的断裂活动不明显,据此推测晚古生代造山作用后的岩石圈热作用及地壳均衡作用是中生代盆地沉降的主控动力学因素。 相似文献
82.
83.
Adjoint free four-dimensional variational data assimilation for a storm surge model of the German North Sea 总被引:1,自引:1,他引:0
Xiangyang Zheng Roberto Mayerle Qianguo Xing José Manuel Fernández Jaramillo 《Ocean Dynamics》2016,66(8):1037-1050
In this paper, a data assimilation scheme based on the adjoint free Four-Dimensional Variational(4DVar) method is applied to an existing storm surge model of the German North Sea. To avoid the need of an adjoint model, an ensemble-like method to explicitly represent the linear tangent equation is adopted. Results of twin experiments have shown that the method is able to recover the contaminated low dimension model parameters to their true values. The data assimilation scheme was applied to a severe storm surge event which occurred in the North Sea in December 5, 2013. By adjusting wind drag coefficient, the predictive ability of the model increased significantly. Preliminary experiments have shown that an increase in the predictive ability is attained by narrowing the data assimilation time window. 相似文献
84.
以大通河流域为研究区域,利用1985年和2005年土地利用数据,结合SWAT分布式水文模型定量评估了流域土地利用/覆被变化的水文效应。结果表明:1985-2005年大通河流域的土地利用变化主要表现为草地向耕地、居工地转变,草地所占比例由46.7%骤降至20.9%,而耕地面积由1985年的1065.8km2增加到2005年的3243km2;相较于1985年的土地利用情景,2005年土地利用情景下的模拟的多年平均径流增加了1.92×108m3,由于上中下游主要的土地利用/覆被变化不同,导致流域径流变化增加程度由西北至东南逐渐增大;大通河流域年径流的增加主要表现为汛期径流增加,讯期月平均径流增幅达到了0.40×108m3·mon-1;非汛期径流则呈不明显减小趋势,平均降幅为0.024×108m3·mon-1。合理规划大通河流域土地利用方式,提高水源区涵养能力,对流域水资源可持续发展具有重要意义。 相似文献
85.
86.
87.
G. Yu. Ivanyuk Yu. A. Korchak Ya. A. Pakhomovsky Yu. P. Men’shikov V. N. Yakovenchuk 《Geology of Ore Deposits》2012,54(7):575-579
Ulvöspinel is a typical accessory mineral of xenoliths of volcanic and volcanosedimentary rocks in alkaline syenites of the Khibiny and Lovozero plutons. Ulvöspinel forms homogeneous Cr- and V-rich grains in slightly altered olivine basalts, basaltic tuffs, and tuffites and is enriched in Mn and Si in the course of contact-metasomatic alteration of these rocks. The strongly reduced conditions of contact metamorphism controlled by ascending flows of hydrocarbon gases and hydrogen sulfide gave rise to the subsolidus decomposition of primary ulvöspinel and Ti-high magnetite with the formation of ilmenite lamellae and then, with decreasing redox potential, of the second-generation latticed ulvöspinel lamellae. 相似文献
88.
Evidence for Century-Timescale Acceleration in Mean Sea Levels and for Recent Changes in Extreme Sea Levels 总被引:2,自引:0,他引:2
Two of the most important topics in Sea Level Science are addressed in this paper. One is concerned with the evidence for the apparent acceleration in the rate of global sea level change between the nineteenth and twentieth centuries and, thereby, with the question of whether the twentieth century sea level rise was a consequence of an accelerated climate change of anthropogenic origin. An acceleration is indeed observed in both tide gauge and saltmarsh data at different locations around the world, yielding quadratic coefficients ??c?? of order 0.005 mm/year2, and with the most rapid changes of rate of sea level rise occurring around the end of the nineteenth century. The second topic refers to whether there is evidence that extreme sea levels have increased in recent decades at rates significantly different from those in mean levels. Recent results, which suggest that at most locations rates of change of extreme and mean sea levels are comparable, are presented. In addition, a short review is given of recent work on extreme sea levels by other authors. This body of work, which is focused primarily on Europe and the Mediterranean, also tends to support mean and extreme sea levels changing at similar rates at most locations. 相似文献
89.
90.