全文获取类型
收费全文 | 3516篇 |
免费 | 323篇 |
国内免费 | 396篇 |
专业分类
测绘学 | 24篇 |
大气科学 | 289篇 |
地球物理 | 1085篇 |
地质学 | 338篇 |
海洋学 | 1064篇 |
天文学 | 693篇 |
综合类 | 72篇 |
自然地理 | 670篇 |
出版年
2024年 | 10篇 |
2023年 | 24篇 |
2022年 | 39篇 |
2021年 | 31篇 |
2020年 | 52篇 |
2019年 | 89篇 |
2018年 | 63篇 |
2017年 | 75篇 |
2016年 | 73篇 |
2015年 | 84篇 |
2014年 | 103篇 |
2013年 | 190篇 |
2012年 | 54篇 |
2011年 | 121篇 |
2010年 | 118篇 |
2009年 | 214篇 |
2008年 | 261篇 |
2007年 | 309篇 |
2006年 | 233篇 |
2005年 | 179篇 |
2004年 | 193篇 |
2003年 | 211篇 |
2002年 | 175篇 |
2001年 | 125篇 |
2000年 | 147篇 |
1999年 | 165篇 |
1998年 | 152篇 |
1997年 | 75篇 |
1996年 | 104篇 |
1995年 | 77篇 |
1994年 | 73篇 |
1993年 | 69篇 |
1992年 | 60篇 |
1991年 | 55篇 |
1990年 | 48篇 |
1989年 | 40篇 |
1988年 | 26篇 |
1987年 | 27篇 |
1986年 | 18篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 19篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1954年 | 4篇 |
排序方式: 共有4235条查询结果,搜索用时 15 毫秒
141.
Delineation of detailed mantle structure frequently requires the separation of source signature and structural response from seismograms recorded at teleseismic distances. This deconvolution problem can be posed in a log-spectral domain where the operation of time-domain convolution is reduced to an additive form. The introduction of multiple events recorded at many stations leads to a system of consistency equations that must be honoured by both the source time functions and the impulse responses associated with propagation paths between sources and receivers. The system is inherently singular, and stabilization is accomplished through the supply of an initial estimate of the source time function. Although alternative choices exist, an effective estimate is derived from the eigenimage associated with the largest eigenvalue in a singular-value decomposition of the suite of aligned seismograms corresponding to a given event. The relation of the deconvolution scheme to simultaneous least-squares deconvolution is examined. Application of the methodology to broadband teleseismic P waveforms recorded on the Canadian National Seismograph Network demonstrates the retrieval of effective Green's functions including secondary phases associated with upper-mantle structure. 相似文献
142.
J. L. Mateos O. Novaro T. H. Seligman J. Flores 《Geophysical Journal International》1997,129(1):212-214
We show that most of the arguments in the above paper are either incorrect or irrelevant to the point the authors are trying to make. We show that their results have no bearing on the model proposed by our group, as they claim. They discuss the seismic response of a valley with a 2-D trapezoidal cross-section in a vertical plane, whereas we dealt with a closed basin with a 2-D cross-section but of arbitrary geometry and in the horizontal plane. Even more significantly, the width of the valley they use is much smaller than the wavelength of the horizontal P waves that can resonate, thereby precluding any possibility of them being trapped. Therefore, their arguments do not clarify the issue posed in the title of their article. 相似文献
143.
144.
145.
146.
Reinterpretation of the RRISP-77 Iceland shear-wave profiles 总被引:1,自引:0,他引:1
147.
148.
149.
150.