全文获取类型
收费全文 | 1519篇 |
免费 | 475篇 |
国内免费 | 541篇 |
专业分类
测绘学 | 19篇 |
大气科学 | 637篇 |
地球物理 | 667篇 |
地质学 | 625篇 |
海洋学 | 205篇 |
天文学 | 145篇 |
综合类 | 54篇 |
自然地理 | 183篇 |
出版年
2024年 | 6篇 |
2023年 | 35篇 |
2022年 | 43篇 |
2021年 | 43篇 |
2020年 | 77篇 |
2019年 | 97篇 |
2018年 | 63篇 |
2017年 | 68篇 |
2016年 | 78篇 |
2015年 | 78篇 |
2014年 | 104篇 |
2013年 | 131篇 |
2012年 | 72篇 |
2011年 | 114篇 |
2010年 | 66篇 |
2009年 | 108篇 |
2008年 | 108篇 |
2007年 | 134篇 |
2006年 | 113篇 |
2005年 | 116篇 |
2004年 | 86篇 |
2003年 | 96篇 |
2002年 | 83篇 |
2001年 | 65篇 |
2000年 | 87篇 |
1999年 | 71篇 |
1998年 | 65篇 |
1997年 | 52篇 |
1996年 | 57篇 |
1995年 | 33篇 |
1994年 | 44篇 |
1993年 | 33篇 |
1992年 | 23篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 17篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1954年 | 3篇 |
排序方式: 共有2535条查询结果,搜索用时 15 毫秒
51.
These last 10 years, numerical models of mantle convection have emphasized the role of the 670 km endothermic phase change in generating avalanches that trigger catastrophic mass transfers between upper and lower mantle. On the other hand, scientists have emphasized the concomitance of large-scale worldwide geophysical and tectonic events, which could find their deep thermal roots in the huge mass transfers induced by the avalanches. In particular, the paleontological records show two periods of length of day (l.o.d.) shortening between 420 and 360, and 200 and 80 Myr BP. This last event is synchronous with a strong true polar wander and a global warming of the upper mantle. In order to study the potential effects of the avalanche on the main component of the Earth’s rotation, the Liouville equation has been solved and the l.o.d. evolution has been calculated from the perturbations of the inertia tensor. The results show that the inertia tensor of the Earth’s is mainly sensitive to the global transfers through the 670 km discontinuity. The l.o.d. perturbations will be synchronous with the global thermal effects of the avalanche. These theoretical results allow proposing a self-consistent physical mechanism to explain periods of the Earth’s rotation acceleration. Within this context, the l.o.d. shortening during the Cenozoic and Cretaceous brings one more clue to the possible participation of a mantle avalanche in generating the concomitant large scale events which have occurred during this very particular period of the Earth’s history. 相似文献
52.
MODIFIED MASS FLUX CUMULUS CONVECTIVE PARAMETERIZATION SCHEME AND ITS SIMULATION EXPERIMENT—PART Ⅰ:MASS FLUX SCHEME AND ITS SIMULATION OF THE 1991 FLOOD EVENT* 下载免费PDF全文
Based on the existing cumulus convective parameterization schemes,a mass flux scheme (MFS) for cumulus convective parameterization has been successfully developed by reference to the work of Chen et al. (1996).The MFS is a comprehensive scheme.In MFS,not only the importance of the large-scale moisture convergence is taken into account,but also it includes the cumulus updrafts and downdrafts,cumulus-induced subsidence in the environmental air.entrainment,detrainment and evaporation.The interaction between the cumulus and the environment is described by using a one-dimensional bulk model.At the same time the scheme includes the penetrative and shallow convections.The MFS has been successfully incorporated into the regional climate model RegCM2 developed by NCAR.The new model has been applied to simulate summer monsoon characteristics and their variations of heavy rainfall process in the Changjiang-Huaihe River Basins for three months from May to July 1991.The results show that the new model can successfully simulate this rainfall prolonged process.By comparising the model outputs of RegCM2.using the Kuo scheme and the MFS.it is found that the MFS is better in simulating the surface temperature,rainfall position and amount,and rainfall duration. 相似文献
53.
在中国大陆科学钻探孔区 (江苏省东海县南部 )进行了系统的地球物理调查 ,包括二维地震测网和专门的地震剖面 ,大地电磁法和位场方法等 .地震调查表明 ,在超高压变质岩出露区上地壳充满了反射体 ,包括倾斜反射体与上拱的反射弧 .本文介绍大陆科学钻探先行研究中地震调查的成果 .根据大陆科学钻探预先导孔的岩芯和测井资料、井旁VSP和数值模拟结果证实 ,高波速的榴辉岩体、破碎断裂带和大型韧性剪切带都可引起倾斜的地震反射 ,而上拱的弧形反射体则是由近似直立的榴辉岩体和其中的破碎带的综合反映 .由于地壳深部广泛分布着经受变质的岩石 ,上述研究结果对标定地壳中的反射地震信号具有一定意义 相似文献
54.
55.
56.
57.
58.
A comparison of subgrid-scale models for large-eddy simulations of convection in the Earth's core 总被引:2,自引:1,他引:2
Bruce A. Buffett 《Geophysical Journal International》2003,153(3):753-765
59.
60.
A. K. Mitra M. Das Gupta R. K. Paliwal S. V. Singh 《Journal of Earth System Science》2003,112(2):223-232
A daily rainfall dataset and the corresponding rainfall maps have been produced by objective analysis of rainfall data. The
satellite estimate of rainfall and the raingauge values are merged to form the final analysis. Associated with epochs of monsoon
these rainfall maps are able to show the rainfall activities over India and the Bay of Bengal region during the BOBMEX period.
The intra-seasonal variations of rainfall during BOBMEX are also seen using these data. This dataset over the oceanic region
compares well with other available popular datasets like GPCP and CMAP. Over land this dataset brings out the features of
monsoon in more detail due to the availability of more local raingauge stations. 相似文献