全文获取类型
收费全文 | 104篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 8篇 |
大气科学 | 1篇 |
地球物理 | 20篇 |
地质学 | 36篇 |
海洋学 | 30篇 |
天文学 | 2篇 |
综合类 | 4篇 |
自然地理 | 8篇 |
出版年
2022年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2010年 | 9篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 16篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有109条查询结果,搜索用时 954 毫秒
1.
2.
Yoichi Fukuda Toshihiro Higashi Shuzo Takemoto Maiko Abe Sjafra Dwipa Dendi Surya Kusuma Achmad Andan Koichiro Doi Yuichi Imanishi Giuseppe Arduino 《Journal of Geodynamics》2004,38(3-5):489
For the purposes of the calibration of the superconducting gravimeter (SG) in Bandung and the establishment of the absolute gravity (AG) points, we carried out AG measurements for the first time in Indonesia in November 2002. The measurements in Bandung were conducted between November 15th and 20th by means of a FG5 (#210), and 14,520 effective drops were obtained. The gravity value newly determined at the AG point in Bandung is 977976701.2 μgal (1 μgal = 10−8 ms−2) and the scale factor for the SG is −52.22 μgal/V. We also established another AG point in Yogyakarta near Merapi volcano and carried out AG measurements in Yogyakarta between November 22nd and 26th. The gravity value determined for this station is 978203093.5 μgal. 相似文献
3.
Dissolution of water in magmas significantly affects phase relations and physical properties. To shed new light on the this issue, we have applied 1H and 29Si nuclear magnetic resonance (NMR) spectroscopic techniques to hydrous silicate glasses (quenched melts) in the CaO-MgO-SiO2 (CMS), Na2O-SiO2, Na2O-CaO-SiO2 and Li2O-SiO2 systems. We have also carried out ab initio molecular orbital calculations on representative clusters to gain insight into the experimental results.The most prominent result is the identification of a major peak at ∼1.1 to 1.7 ppm in the 1H MAS NMR spectra for all the hydrous CMS glasses. On the basis of experimental NMR data for crystalline phases and ab initio calculation results, this peak can be unambiguously attributed to (Ca,Mg)OH groups. Such OH groups, like free oxygens, are only linked to metal cations, but not part of the silicate network, and are thus referred to as free hydroxyls in the paper. This represents the first direct evidence for a substantial proportion (∼13∼29%) of the dissolved water as free hydroxyl groups in quenched hydrous silicate melts. We have found that free hydroxyls are favored by (1) more depolymerized melts and (2) network-modifying cations of higher field strength (Z/R2: Z: charge, R: cation-oxygen bond length) in the order Mg > Ca > Na. Their formation is expected to cause an increase in the melt polymerization, contrary to the effect of SiOH formation. The 29Si MAS NMR results are consistent with such an interpretation. This water dissolution mechanism could be particularly important for ultramafic and mafic magmas.The 1H MAS NMR spectra for glasses of all the studied compositions contain peaks in the 4 to 17 ppm region, attributable to SiOH of a range of strength of hydrogen bonding and molecular H2O. The relative population of SiOH with strong hydrogen bonding grows with decreasing field strength of the network-modifying cations. Ab initio calculations confirmed that this trend largely reflects hydrogen bonding with nonbridging oxygens. 相似文献
4.
Abstract. For the purpose of development of methane hydrate, occurring in the deep marine subsurface, as a resource, the most important issue is to understand the methane hydrate system (generation, migration and accumulation) as well as to delineate the methane hydrate reservoir properties. We have applied the Amplitude Versus Offset (AVO) analysis to the seismic data acquired in the Nankai Trough, offshore Japan, in order to confirm the occurrence of gas just below the methane hydrate-bearing zone, assuming that gas will show a so-called Class-3 AVO response. Knowledge of the amount and occurrence of gas in the sediment below methane hydrate-bearing zone is one of the keys to understand the methane hydrate system.
We have utilized the qualitative analysis of AVO methodology to delineate how gas is located below the BSR, which is thought to be the reflection event from the interface between the methane hydrate-bearing zone and the underlying gas-bearing zone. In the region of MITI Nankai Trough Well PSW-3, we observe two BSRs separated by 25 ms. After AVO modeling using well data, we applied AVO attribute analysis and attribute crossplot analysis to the seismic data. Finally we applied an offset-amplitude analysis to CMP gather data at specific locations to confirm the results of AVO attribute analysis. The AVO analysis shows that there is very little gas located in the underlying sediment below methane hydrate-bearing zone. This result supports the fact that we could not obtain any clear evidence of gas occurrence just below the methane hydrate-bearing zone in the Nankai Trough well drilling. 相似文献
We have utilized the qualitative analysis of AVO methodology to delineate how gas is located below the BSR, which is thought to be the reflection event from the interface between the methane hydrate-bearing zone and the underlying gas-bearing zone. In the region of MITI Nankai Trough Well PSW-3, we observe two BSRs separated by 25 ms. After AVO modeling using well data, we applied AVO attribute analysis and attribute crossplot analysis to the seismic data. Finally we applied an offset-amplitude analysis to CMP gather data at specific locations to confirm the results of AVO attribute analysis. The AVO analysis shows that there is very little gas located in the underlying sediment below methane hydrate-bearing zone. This result supports the fact that we could not obtain any clear evidence of gas occurrence just below the methane hydrate-bearing zone in the Nankai Trough well drilling. 相似文献
5.
Abstract. The MITI Nankai Trough wells were drilled offshore Japan in the Tokai area in 1999 and 2000. The occurrence of methane hydrate was confirmed by various indicators in the borehole logs and from core data. These findings have a large impact on potential future Japanese energy resources and other related-scientific interests.
We first tried to find the methane hydrate-bearing zones using interval velocities derived from NMO velocity analysis. However, this analysis produced poor resolution. To achieve a more detailed delineation of the gas hydrate- and gas-bearing zones, we executed a seismic impedance inversion calibrated by the logs from two of the MITI Nankai Trough wells. Although these two wells are only about 90 m apart, we were able to produce an impedance section with fine detail by adopting a simple initial model and incorporating physical properties of the methane hydrate-bearing zones. The locations of the methane hydrate-bearing zones are readily apparent in the final section. 相似文献
We first tried to find the methane hydrate-bearing zones using interval velocities derived from NMO velocity analysis. However, this analysis produced poor resolution. To achieve a more detailed delineation of the gas hydrate- and gas-bearing zones, we executed a seismic impedance inversion calibrated by the logs from two of the MITI Nankai Trough wells. Although these two wells are only about 90 m apart, we were able to produce an impedance section with fine detail by adopting a simple initial model and incorporating physical properties of the methane hydrate-bearing zones. The locations of the methane hydrate-bearing zones are readily apparent in the final section. 相似文献
6.
7.
8.
Multiple Parameter Regularization: Numerical Solutions and Applications to the Determination of Geopotential from Precise Satellite Orbits 总被引:1,自引:0,他引:1
Kaula’s rule of thumb has been used in producing geopotential models from space geodetic measurements, including the most recent models from satellite gravity missions CHAMP. Although Xu and Rummel (Manuscr Geod 20 8–20, 1994b) suggested an alternative regularization method by introducing a number of regularization parameters, no numerical tests have ever been conducted. We have compared four methods of regularization for the determination of geopotential from precise orbits of COSMIC satellites through simulations, which include Kaula’s rule of thumb, one parameter regularization and its iterative version, and multiple parameter regularization. The simulation results show that the four methods can indeed produce good gravitational models from the precise orbits of centimetre level. The three regularization methods perform much better than Kaula’s rule of thumb by a factor of 6.4 on average beyond spherical harmonic degree 5 and by a factor of 10.2 for the spherical harmonic degrees from 8 to 14 in terms of degree variations of root mean squared errors. The maximum componentwise improvement in the root mean squared error can be up to a factor of 60. The simplest version of regularization by multiplying a positive scalar with a unit matrix is sufficient to better determine the geopotential model. Although multiple parameter regularization is theoretically attractive and can indeed eliminate unnecessary regularization for some of the harmonic coefficients, we found that it only improved its one parameter version marginally in this COSMIC example in terms of the mean squared error. 相似文献
9.
10.
White Spot Syndrome Virus (WSSV) was purified from hemolymph of infected shrimp. After nucleic acid extraction from the purified
virus particles, EcoR I-digested fragments of the WSSV genome were cloned; three of these fragments were used as non-radioactive
probes labeled with DIG-11-dUTP. The probes hybridized in situ, with sections located in the nuclei of all WSSV-infected tissues.
The virus was detected in the gill, stomach, epidermis, and connective tissue and so on, but not detected in healthy shrimp
tissues and epithelial cells of hepatopancreatic tubules of diseased shrimp.
This work was supported by SRF for ROCS, SEM and the National 863 Project (Grant 819-Q-08) and Project under major State Basic
Research Development Program (Grant G1999012002). 相似文献