全文获取类型
收费全文 | 165篇 |
免费 | 3篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 2篇 |
地球物理 | 4篇 |
地质学 | 151篇 |
海洋学 | 2篇 |
天文学 | 4篇 |
自然地理 | 3篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 12篇 |
2013年 | 11篇 |
2012年 | 17篇 |
2011年 | 13篇 |
2010年 | 12篇 |
2009年 | 12篇 |
2008年 | 14篇 |
2007年 | 10篇 |
2006年 | 18篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1921年 | 1篇 |
1919年 | 1篇 |
1918年 | 2篇 |
1917年 | 1篇 |
1916年 | 4篇 |
1915年 | 1篇 |
1914年 | 3篇 |
1913年 | 4篇 |
1912年 | 5篇 |
1911年 | 3篇 |
1910年 | 1篇 |
排序方式: 共有168条查询结果,搜索用时 15 毫秒
1.
Low multipath antennas for GNSS-based attitude determination systems applied to high-altitude platforms 总被引:1,自引:1,他引:0
Luigi Boccia Pasquale Pace Giandomenico Amendola Giuseppe Di Massa 《GPS Solutions》2008,12(3):163-171
High-altitude platforms (HAPs) are a flexible and attractive technology for providing innovative wireless services. These
aerial platforms can be successfully employed for mobile or broadband communications and for disaster monitoring or response.
However, one of the open issues is whether HAP stations can provide reliable services without temporal outages owing to stratospheric
winds that can cause positional and attitude instabilities thus affecting the communication system operation. To counteract
this issue, one possible solution is to use reconfigurable antennas whose pointing direction can be adjusted depending on
the platform spatial orientation. However, this would require real-time three-axial attitude data. As a possible solution,
this paper will review the potential of GNSS-based attitude determination systems with reference to HAP stations. In particular,
it will be shown how the use of a particular class of low multipath and lightweight antennas can provide a high degree of
accuracy without altering the avionic ballast. 相似文献
2.
3.
Yu. V. Plotkina E. B. Sal’nikova A. B. Kotov M. D. Tolkachev M. R. Pavlov 《Petrology》2006,14(2):201-208
The paper reports results obtained by the complex studying of zircon crystals from rocks of various genesis. Zircon is one of the minerals most often used as geochronometers. It also provides genetic information on superimposed processes that is “recorded” in the external and internal morphology of its crystals. This mineral is thoroughly examined to select its unaltered crystals for U-Pb dating by the single-grain method. Zircon grains are selected with the use of optical and electron microscopy and cathodoluminescence. This publication presents the first results obtained by examining zircon by computer microtomography (μCT) and the results of the studying of the external and internal structure by conventional techniques ([optical microscopy and SEM (SE and CL)]. The paper demonstrates the advantages of the application of the μCT techniques to the selection of targets for U-Pb zircon dating: there is no need for the special preparation of the samples and no material is destructed. However, this technique may be not informative enough if the zircon contains inherited core whose density does not differ from the density of the surrounding mineral. 相似文献
4.
A. M. Larin E. B. Sal’nikova A. B. Kotov L. B. Makar’ev S. Z. Yakovleva V. P. Kovach 《Stratigraphy and Geological Correlation》2006,14(5):463-474
Early Proterozoic granitoids are of a limited occurrence in the Baikal fold area being confined here exclusively to an arcuate belt delineating the outer contour of Baikalides, where rocks of the Early Precambrian basement are exposed. Geochronological and geochemical study of the Kevakta granite massif and Nichatka complex showed that their origin was related with different stages of geological evolution of the Baikal fold area that progressed in diverse geodynamic environments. The Nichatka complex of syncollision granites was emplaced 1908 ± 5 Ma ago, when the Aldan-Olekma microplate collided with the Nechera terrane. Granites of the Kevakta massif (1846 ± 8 Ma) belong to the South Siberian postcollision magmatic belt that developed since ~1.9 Ga during successive accretion of microplates, continental blocks and island arcs to the Siberian craton. In age and other characteristics, these granites sharply differ from granitoids of the Chuya complex they have been formerly attributed to. Accordingly, it is suggested to divide the former association of granitoids into the Chuya complex proper of diorite-granodiorite association ~2.02 Ga old (Neymark et al., 1998) with geochemical characteristics of island-arc granitoids and the Chuya-Kodar complex of postcollision S-type granitoids 1.85 Ga old. The Early Proterozoic evolution of the Baikal fold area and junction zone with Aldan shield lasted about 170 m.y. that is comparable with development periods of analogous structures in other regions of the world. 相似文献
5.
Dr. S. von Bubnoff Sal Rüger C. Gagel Wcks Rudolf Hundt 《International Journal of Earth Sciences》1921,11(5-6):267-274
Ohne Zusammenfassung 相似文献
6.
7.
8.
9.
V. N. Golubev I. V. Chernyshev A. B. Kotov E. B. Sal’nikova Yu. V. Golzman E. D. Bairova S. Z. Yakovleva 《Geology of Ore Deposits》2010,52(6):496-513
An isotopic geochronological study of Russia’s largest Strel’tsovka uranium district has been carried out. Polychronous granite
generation, which determined the structure of the pre-Mesozoic basement, had important implications for the formation of volcanotectonic
structural elements bearing economic uranium mineralization. The study of U-Pb, Rb-Sr, and Sm-Nd isotopic systems of whole-rock
samples and minerals of granitic rocks allowed us to estimate the deportment of these systems in spatially conjugated granite-forming
and hydrothermal processes differing in age and gave grounds for revising the age of granites pertaining to the Urulyungui
Complex and refining the age of the Unda Complex. 相似文献
10.
Glukhov A. N. Kotov A. B. Priymenko V. V. Sal’nikova E. B. Ivanova A. A. Plotkina Yu. V. Fedoseenko A. M. 《Geotectonics》2022,56(2):178-190
Geotectonics - In our study we analyzed the composition of granitoid rocks within the Kongo magmatic zone of the Omolon median mass. The studied calc-alkaline granitoids cut through the Early... 相似文献