全文获取类型
收费全文 | 10639篇 |
免费 | 1969篇 |
国内免费 | 2864篇 |
专业分类
测绘学 | 960篇 |
大气科学 | 2266篇 |
地球物理 | 2492篇 |
地质学 | 5531篇 |
海洋学 | 1410篇 |
天文学 | 346篇 |
综合类 | 979篇 |
自然地理 | 1488篇 |
出版年
2024年 | 35篇 |
2023年 | 141篇 |
2022年 | 413篇 |
2021年 | 537篇 |
2020年 | 362篇 |
2019年 | 520篇 |
2018年 | 589篇 |
2017年 | 518篇 |
2016年 | 611篇 |
2015年 | 543篇 |
2014年 | 614篇 |
2013年 | 631篇 |
2012年 | 695篇 |
2011年 | 744篇 |
2010年 | 715篇 |
2009年 | 661篇 |
2008年 | 570篇 |
2007年 | 651篇 |
2006年 | 548篇 |
2005年 | 522篇 |
2004年 | 436篇 |
2003年 | 363篇 |
2002年 | 528篇 |
2001年 | 443篇 |
2000年 | 420篇 |
1999年 | 449篇 |
1998年 | 281篇 |
1997年 | 294篇 |
1996年 | 246篇 |
1995年 | 260篇 |
1994年 | 213篇 |
1993年 | 211篇 |
1992年 | 149篇 |
1991年 | 119篇 |
1990年 | 91篇 |
1989年 | 71篇 |
1988年 | 66篇 |
1987年 | 55篇 |
1986年 | 32篇 |
1985年 | 22篇 |
1984年 | 18篇 |
1983年 | 13篇 |
1982年 | 20篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1958年 | 15篇 |
1947年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
911.
Based on the long period surface wave data recorded by the China Digital Seismograph Network (CDSN), theQ
R
of fundamental mode Rayleigh wave with periods from 10 s to 146 s is determined for the eastern Sino-Korean paraplatform
in this paper. TheQ
β
models of the crust and upper mantle are respectively obtained for the 4 paths, with the aid of stochastic inverse method.
It shows that in the eastern Sino-Korean paraplatform, the average crustalQ
β
is about 200, and that there exists a weak attenuation layer in the middle crust (about 10–20 km deep) which is possibly
related to earthquake-prone layer. A strong attenuation layer (lowQ) of 70 km thick extensively exists in the uppermost mantle, with the buried depth about 80 km. The averageQ
R
of fundamental mode Rayleigh wave is between the value of stable tectonic region and that of active tectonic region, and
much close to the latter.
Contribution No. 96A0001, Institute of Geophysics, SSB, China.
Funded by the Chinese Joint Seismological Science Foundation. 相似文献
912.
Aseismio fault slip and block deformation in North China 总被引:1,自引:0,他引:1
Lanbo Liu Alan T. Linde I. Selwyn Sacks Shihai He 《Pure and Applied Geophysics》1996,146(3-4):717-740
In North China, the tectonic fault-block system enables us to use the Discontinuous Deformation Analysis (DDA) method to simulate the long-term cross-fault survey and other geodetic data related to aseismic tectonic deformation. By the simulation we have found that: (1) Slips on faults with different orientation are generally in agreement with the ENE-WSW tectonic stress field, but the slip pattern of faulting can vary from nearly orthogonal, to pure shear along the strike of the faults, this pattern cannot be explained by simple geometric relation between the strike of the fault and the direction of the tectonic shortening. This phenomenon has been observed at many sites of cross-fault geodetic surveys, and might be caused by the interactions between different blocks and faults. (2) According to the DDA model, if the average aseismic slip rate along major active faults is at the order of several tenths of millimeter per year as observed by the cross-fault geodetic surveys, the typical strain rate inside a block is at the order of 10–8 year–1 or less, so that the rate of 10–6 year–1, as reported by observations in smaller areas, cannot be the representative deformation rate in this region. (3) Between the slips caused by regional compression and block rotation, there is a possibility that the sense of slip caused by rigid body rotation in two adjacent blocks is opposite to the slip caused by the tectonic compression. But the magnitude of slip resulting from the tectonic compression is much larger than that due to the block rotation. Thus, in general, the slip pattern on faults as a whole agrees with the sense of tectonic compression in this region. That is to say, the slip caused by regional compression dominates the entire slip budget. (4) Based on (3), some observed slips in contradiction to ENE tectonic stress field may be caused by more localized sources, and have no tectonic significance. 相似文献
913.
依据地震危险性分析的思路,提出一种场地震害预测的方法。依此方法,给出山东地区50a超越概率为10%的震害预测略图 相似文献
914.
CHARACTERISTICS OF MESOSCALE FLOOD-MAKING TORRENTIAL RAIN SYSTEM SIMULATED BY HIGH RESOLUTION LIMITED AREA MODEL—NUMERICAL SIMULATION OF A HEAVY RAIN PROCESS DURING MEIYU SEASON IN 1991*
下载免费PDF全文
![点击此处可从《Acta Meteorologica Sinica》网站下载免费的PDF全文](/ch/ext_images/free.gif)
An experimental work on the transplant of high resolution limited area model(HIRLAM) isfirstly introduced into China.For the implementation,first of all is to adjust a new geographicalcoordination and to remove the instability caused by the Tibetan Plateau,the roof of the world.Then,we have applied this model to simulate a flood-making torrential rain process which occurredin the Changjiang-Huaihe River Valley in July 1991.That revealed the formation,development andmovement of a mesoseale heavy rain system which had made a disastrous flood event in the middleand lower reaches of Changjiang River Valley.The result encourages us to use the HIRLAM for the researches on the Meiyu belt,the salientfeature of precipitation of East Asia,and the numerical prediction of heavy rains in China. 相似文献
915.
本用标准偏差法和标度变换法,计算了云南省五个地震区带上1965-1995年间地震序列的自仿射分形的分维值D△t(地震时间间隔序列自仿射分形)DM-t(地震震级一时间序列自仿射分形)及自相似分形的分维值D0(地震时间分布自相似分形)得到了相应的时间变化曲线,DM-t~t,D△t~t和D0~t。通过相互比较发现,其中DM-t的随时间变化在中强地震前的反应最为敏感。 相似文献
916.
917.
918.
全新世内蒙古自然环境演变及其特点 总被引:9,自引:2,他引:9
根据内蒙古东、中、西部沙地、内陆湖、冰缘现象的发育与演变,讨论了全新世以来内蒙古环境演变过程,提出了对全新世中期沙漠化的形成环境、全新世环境演变特点及对现代环境影响的认识。 相似文献
919.
920.
水系的分形维数及其含义 总被引:66,自引:6,他引:66
在分述水系分维数的几个计算方法基础上,对两上试区采用地图照相缩小后扫描以及图象处理的方法提取河流信息,以计盒方法计算水系的分维数,并据此提出划以域地貌侵蚀发育阶段的方法。 相似文献