全文获取类型
收费全文 | 590篇 |
免费 | 30篇 |
专业分类
测绘学 | 22篇 |
大气科学 | 19篇 |
地球物理 | 166篇 |
地质学 | 204篇 |
海洋学 | 23篇 |
天文学 | 160篇 |
综合类 | 4篇 |
自然地理 | 22篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 6篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 27篇 |
2017年 | 27篇 |
2016年 | 39篇 |
2015年 | 32篇 |
2014年 | 34篇 |
2013年 | 27篇 |
2012年 | 30篇 |
2011年 | 25篇 |
2010年 | 26篇 |
2009年 | 34篇 |
2008年 | 28篇 |
2007年 | 30篇 |
2006年 | 24篇 |
2005年 | 20篇 |
2004年 | 12篇 |
2003年 | 13篇 |
2002年 | 19篇 |
2001年 | 6篇 |
2000年 | 13篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 9篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有620条查询结果,搜索用时 15 毫秒
81.
82.
83.
We discuss Arp's hypothesis that the HII regions are more numerous and more conspicuous on the side of a galaxy facing its companion. Arp's hypothesis seems not to be true if we add to Hodge's sets of galaxies only the most probably tidally-interacting cases. 相似文献
84.
85.
It is shown that the non-keplerian character of the rotation of the ring of gas particles in a close binary system gives too large an amplitude of the radial velocity curve if this amplitude is determined from the positions of the emission lines of the ring. 相似文献
86.
A. I. Reshetnikov A. V. Zinchenko S. V. Yagovkina I. L. Karol V. E. Lagun N. N. Paramonova 《Russian Meteorology and Hydrology》2009,34(3):171-179
Methane emitted into the atmosphere from sources located in the Urengoi natural gas field is estimated from direct methane concentration measurements in the atmospheric boundary layer and modeling. The results of direct profile measurements in the summer-fall season of 2003 are generalized versus the data from the previous field studies and background monitoring of greenhouse gases in the northern polar region. The use of models for calculating the intensity of emission from sources located in the field area together with a set of methane concentration measurements at three altitudes allowed the authors to develop a method of verification of emission from a specific source, a deposit. The method estimates the emission both from part of the field area and from the whole field with an irregular distribution of the intensity of sources across the deposit area. 相似文献
87.
In this paper we consider the buying/selling prices of carbon dioxide (CO2) emission permits in trading models with uncertainty. Permission prices, although usually omitted from standard models, may significantly influence the trading market. We thus undertook to construct a more realistic trade model and to compare it with the standard one. To do this, we introduced several important changes to the standard model, namely, (1) a new optimized quality function; and (2) transactions with price negotiations between regions. We also enhanced the model using methods described in the literature to allow it to deal with reported emissions uncertainty. Additionally, we used an original method of simulating this kind of market based on a specialized evolutionary algorithm (EA). 相似文献
88.
J. Skowron . Wyrzykowski S. Mao M. Jaroszyski 《Monthly notices of the Royal Astronomical Society》2009,393(3):999-1009
Microlensing events are usually selected among single-peaked non-repeating light curves in order to avoid confusion with variable stars. However, a microlensing event may exhibit a second microlensing brightening episode when the source or/and the lens is a binary system. A careful analysis of these repeating events provides an independent way to study the statistics of wide binary stars and to detect extrasolar planets. Previous theoretical studies predicted that 0.5–2 per cent of events should repeat due to wide binary lenses. We present a systematic search for such events in about 4000 light curves of microlensing candidates detected by the Optical Gravitational Lensing Experiment (OGLE) towards the Galactic bulge from 1992 to 2007. The search reveals a total of 19 repeating candidates, with six clearly due to a wide binary lens. As a by-product, we find that 64 events (∼2 per cent of the total OGLE-III sample) have been misclassified as microlensing; these misclassified events are mostly nova or other types of eruptive stars. The number and importance of repeating events will increase considerably when the next-generation wide-field microlensing experiments become fully operational in the future. 相似文献
89.
90.
Zofia Majewska Grażyna Ceglarska-Stefańska Stanisław Majewski Jerzy Ziętek 《International Journal of Coal Geology》2009,77(1-2):90-102
There is still no clear understanding of the specific interactions between coal and gas molecules. In this context sorption–desorption studies of methane and carbon dioxide, both in a single gas environment and gas mixtures, are of fundamental interest. This paper presents the results of unique simultaneous measurements of sorption kinetics, volumetric strain and acoustic emission (AE) on three tetragonal coal samples subjected to sorption of carbon dioxide and methane mixtures. The coal was a high volatile bituminous C coal taken from the Budryk mine in the Upper Silesia Basin, Poland. Three different gas mixtures were used in the sorption tests, with dominant CO2, with dominant CH4 and a 50/50 mixture.The experimental set-up was designed specially for this study. It consisted of three individual units working together: (i) a unit for gas sorption experiments using a volumetric method, (ii) an AE apparatus for detecting, recording and analysing AE, and (iii) a strain meter for measuring strains induced in the coal sample by gas sorption/desorption. All measurements were computer aided.The experiments indicated that the coal tested showed preferential sorption of CH4 at 2.6 MPa pressure and exhibited comparable affinities for CH4 and CO2 at higher pressures (4.0 MPa). The results of chromatographic analysis of the gas released on desorption suggested that the desorption of methane from the coal was favoured. The relationship between the volumetric strain and the amount of sorbed gas was found to be non-linear. These results were contrary to common opinions on the coal behaviour. Furthermore, it appeared that the swelling/shrinkage of coal was clearly influenced by the network of fractures. Besides, the AE and strain characteristics suggested common sources of sorption induced AE and strain.The present results may have implications for the sequestration of carbon dioxide in coal seams and enhanced coalbed methane recovery (ECBM). 相似文献