全文获取类型
收费全文 | 193篇 |
免费 | 4篇 |
国内免费 | 9篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 8篇 |
地球物理 | 46篇 |
地质学 | 68篇 |
海洋学 | 17篇 |
天文学 | 46篇 |
综合类 | 7篇 |
自然地理 | 11篇 |
出版年
2021年 | 1篇 |
2020年 | 4篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 5篇 |
2012年 | 8篇 |
2011年 | 13篇 |
2010年 | 13篇 |
2009年 | 21篇 |
2008年 | 11篇 |
2007年 | 13篇 |
2006年 | 10篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 12篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有206条查询结果,搜索用时 15 毫秒
71.
72.
73.
Marina G. Persova Yuri G. Soloveichik Georgy M. Trigubovich Denis V. Vagin Petr A. Domnikov 《Geophysical Prospecting》2014,62(5):1193-1201
A large closed wire loop is generally used in field experiments for testing airborne electrical exploration equipment. Thus, methods are required for the precise calculation of an electromagnetic response in the presence of a closed wire loop. We develop a fast and precise scheme for calculating the transient response for such a closed loop laid out at the surface of a horizontally layered conductive ground. Our scheme is based on the relationship between the magnetic flux flowing through a closed loop and the current induced in it. The developed scheme is compared with 2D and 3D finite‐element modelling for several positions of an airborne electromagnetic system flying over a closed loop. We also study the coupling effect between the current flowing in the closed loop and the current flowing in the horizontally layered conductive medium. The result shows that for the central position of the transmitter, the difference between axisymmetrical finite‐element modelling and our scheme is less than 1%. Moreover, for the non‐coaxial transmitter–receiver–loop system, the solution obtained by our scheme is in good agreement with full 3D finite‐element modelling, and our total simulation time is substantially lower: 1 minute versus 120 hours. 相似文献
74.
Shigetoshi Sugahara Rosmeri Porfirio da Rocha Rita Yuri Ynoue Reinaldo Bomfim da Silveira 《Theoretical and Applied Climatology》2012,107(3-4):361-374
This work assessed homogeneity of the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG) weather station climate series, using various statistical techniques. The record from this target station is one of the longest in Brazil, having commenced in 1933 with observations of precipitation, and temperatures and other variables later in 1936. Thus, it is one of the few stations in Brazil with enough data for long-term climate variability and climate change studies. There is, however, a possibility that its data may have been contaminated by some artifacts over time. Admittedly, there was an intervention on the observations in 1958, with the replacement of instruments, for which the size of impact has not been yet evaluated. The station transformed in the course of time from rural to urban, and this may also have influenced homogeneity of the observations and makes the station less representative for climate studies over larger spatial scales. Homogeneity of the target station was assessed applying both absolute, or single station tests, and tests relatively to regional climate, in annual scale, regarding daily precipitation, relative humidity, maximum (TMax), minimum (TMin), and wet bulb temperatures. Among these quantities, only precipitation does not exhibit any inhomogeneity. A clear signal of change of instruments in 1958 was detected in the TMax and relative humidity data, the latter certainly because of its strong dependence on temperature. This signal is not very clear in TMin, but it presents non-climatic discontinuities around 1953 and around 1970. A significant homogeneity break is found around 1990 for TMax and wet bulb temperature. The discontinuities detected after 1958 may have been caused by urbanization, as the observed warming trend in the station is considerably greater than that corresponding to regional climate. 相似文献
75.
Secondary calcite residing in open cavities in the unsaturated zone of Yucca Mountain has long been interpreted as the result of downward infiltration of meteoric water through open fractures. In order to obtain information on the isotopic composition (δD and δ18O) of the mineral-forming water we studied fluid inclusions from this calcite. Water was extracted from inclusions by heated crushing and the δD values were measured using a continuous-flow isotope-ratio mass spectrometry method. The δ18O values were calculated from the δ18O values of the host calcite assuming isotopic equilibrium at the temperature of formation determined by fluid-inclusion microthermometry.The δD values measured in all samples range between ? 110 and ? 90‰, similar to Holocene meteoric water. Coupled δ18O–δD values plot significantly, 2 to 8‰, to the right of the meteoric water line. Among the various processes operating at the topographic surface and/or in the unsaturated zone only two processes, evaporation and water–rock exchange, could alter the isotope composition of percolating water. Our analysis indicates, however, that none of these processes could produce the observed large positive δ18O-shifts. The latter require isotopic interaction between mineral-forming fluid and host rock at elevated temperature (>100 °C), which is only possible in the deep-seated hydrothermal environment. The stable isotope data are difficult to reconcile with a meteoric origin of the water from which the secondary minerals at Yucca Mountain precipitated; instead they point to the deep-seated provenance of the mineral-forming waters and their introduction into the unsaturated zone from below, i.e. a hypogene origin. 相似文献
76.
77.
Kuh Kim Young-Gyu Kim Yang-Ki Cho Masaki Takematsu Yuri Volkov 《Journal of Oceanography》1999,55(2):103-109
Analysis of CTD data from four CREAMS expeditions carried out in summers of 1993–1996 produces distinct T-S relationships
for the western and eastern Japan Basin, the Ulleung Basin and the Yamato Basin. T-S characteristics are mainly determined
by salinity as it changes its horizontal pattern in three layers, which are divided by isotherms of 5°C and 1°C; upper warm
water, intermediate water and deep cold water. Upper warm water is most saline in the Ulleung Basin and the Yamato Basin.
Salinity of intermediate water is the highest in the eastern Japan Basin. Deep cold water has the highest salinity in the
Japan Basin. T-S curves in the western Japan Basin are characterized by a salinity jump around 1.2–1.4°C in the T-S plane,
which was previously found off the east coast of Korea associated with the East Sea Intermediate Water (Cho and Kim, 1994).
T-S curves for the Japan Basin undergo a large year-to-year variation for water warmer than 0.6°C, which occupies upper 400
m. It is postulated that the year-to-year variation in the Japan Basin is caused by convective overturning in winter.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
78.
Yuri A. Bazlov Viktor F. Galazin Boris L. Kaplan Valery G. Maksimov Vladimir P. Rogozin 《GPS Solutions》1999,3(1):13-16
The 29th Research Institute recently published its latest transformation parameters for WGS and PZ 90. Because these tranformation
parameter estimates were derived from stations located within Russia, variance-covariance propagation was carried out to study
the benefits of a better global distribution of stations. An example that includes two stations in North America is presented.
The transformation improves significantly. ? 1999 John Wiley & Sons, Inc. 相似文献
79.
80.