全文获取类型
收费全文 | 116篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 5篇 |
大气科学 | 10篇 |
地球物理 | 26篇 |
地质学 | 49篇 |
海洋学 | 1篇 |
天文学 | 25篇 |
综合类 | 1篇 |
自然地理 | 7篇 |
出版年
2022年 | 4篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 4篇 |
2012年 | 3篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 6篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1940年 | 1篇 |
1934年 | 2篇 |
排序方式: 共有124条查询结果,搜索用时 109 毫秒
41.
Diele Fasma Luiso Ilenia Marangi Carmela Martiradonna Angela Woźniak Edyta 《Computational Geosciences》2022,26(5):1345-1366
Computational Geosciences - The SOC change index, defined as the normalized difference between the actual Soil Organic Carbon and the value assumed at an initial reference year, is here tailored to... 相似文献
42.
Tomáš Pačes 《Geochimica et cosmochimica acta》1975,39(4):541-544
If the temperature of ground water is below 75°C and the partial pressure of CO2 in the aquifer is above 10?4 atm, a chemical steady-state between water and felsic rocks (rather than chemical equilibrium) may be maintained. The temperature of water in the aquifer may be estimated using a modified form of the Na-K-Ca geothermometer from, . where the departure of the steady-state from equilibrium, , is a function of : . 相似文献
43.
44.
45.
Diana Kjurkchieva Dragomir Marchev Waldemar Ogloza 《Astrophysics and Space Science》1998,262(1):53-74
BVRI photometry of SS Cyg from the end of 1996 and the beginning of 1997 is presented. The star underwent an eruption around December 11. The amplitude of which was slightly bigger than those of observed earlier eruptions. We saw some indication of the future outburst in the decreasing of brightness in all colours by about 0.4 mag during the last two weeks before the event. The emission of the system moved strongly to the shorter wavelengths at outburst. Our multicolour data confirm the existence of a light variability with the orbital (spectroscopic) period at quiescence. Moreover we found for the first time that this variability exists also at outburst but its amplitude is 3–5 times smaller. Whereas the amplitudes of the orbital variability at quiescence decrease to the longer wavelengths, they increase at outburst to the longer wavelengths. The orbital folded curve at quiescence has two-wave shape and was fitted well by the different visibility of two diametrical opposite hot spots (210000 K) with angular size 100 on the magnetic poles of the white dwarf. An analogy between the two basic states of the U Gem-star SS Cyg, the polar AM Her and Z Cam-star RX And was found. 相似文献
46.
Krzysztof Goździewski 《Celestial Mechanics and Dynamical Astronomy》1998,70(1):41-58
In this paper we consider the problem of motion of an infinitesimal point mass in the gravity field of an uniformly rotating
dumb-bell. The aim of our study is to investigate Liapunov stability of Lagrangian libration points of this problem. We analyze
the stability of libration points in the whole range of parameters ω, μ of the problem. In particular, we consider all resonance
cases when the order of resonance is not greater than five.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
47.
In the Russian school, the total normalized gradient method belongs to the most wide-spread of direct interpretation methods for potential field data. This method was also used and partly developed by many experts from abroad. The main advantage of the total normalized gradient method is its relative independence of parameters such as the expected differential density of interpreted structures. The method is built from a construction of a specially transformed field (total normalized gradient) on a section crossing the potential field sources. The special properties of this transformed field allow it to be used to detect the source positions. From the 1960s, the mathematical basis of the method underwent enormous development and several modifications of the method have been elaborated. The total normalized gradient operator itself represents a relatively complicated, non-linear band-pass filter in the spectral domain. The properties of this operator can be handled by means of several parameters that act to separate the information about field sources at different depth levels. In this contribution, we describe the development of the method from its very beginning (based mostly on qualitative interpretation of simple total normalized gradient sections) through to more recent numerical improvements to the method. These improvements include the quasi-singular points method, which refines the filter properties of the total normalized gradient operator and defines an objective criteria (so called criterion ‘α’ and ‘Г') for the definition of source depths in the section. We end by describing possibilities for further development of the method in the future. 相似文献
48.
Ahmed Melegy Igor Slaninka Tomas Pa?es Stanislav Rapant 《Environmental Earth Sciences》2011,64(2):549-555
Inputs of As to a small catchment due to chemical weathering of bedrock, mechanical weathering of bedrock, and atmospheric
precipitation were 71.53, 23.98 and 0.02 g ha−1 year−1, respectively. The output fluxes of As due to mechanical erosion of soil, biological uptake, stream discharge, and groundwater
flow were 6.32, 4.77, 0.37 and 0.02 g ha−1 year−1, respectively. The results indicate that arsenic accumulates in soil and regolith with a very high rate. This is attributed
to the selective weathering and erosion with respect to arsenic and fixation of arsenic in the secondary solids produced by
weathering. The output fluxes of As in stream and groundwater in Vydrica catchment in Slovak Republic (0.39 g ha−1 year−1) based on muscovite–biotite granites and granodiorites were much lower compared to catchments in a gold district in the Czech
Republic. These results may be ascribed to the low levels of arsenic pollution measured in Vydrica catchment. The arsenic
fluxes were estimated by calculation of mechanical and chemical weathering rates of the bedrocks in Vydrica catchment from
mass balance data on sodium and silica. The justification of the steady state of Na and Si is that neither of the elements
is appreciably accumulated in plants and in exchangeable pool of ions in soil. 相似文献
49.
Diana Kjurkchieva Dragomir Marchev Waldemar Ogloza 《Astrophysics and Space Science》1997,250(2):261-269
The cataclysmic star RX And was observed in the states standstill and quiescence. They differed not only in the light level but in the type of variations around this level. The standstill observed by us turned out quite near to the maximum light and its duration was unusually long. The energy distribution of RX And at the standstill seemed similar to the spectrum of an accretion disk. Two variabilities with periods 3 h 43 min and 1 h 26 min were found at the standstill but only the second of them was present at quiescence too. The star did not show light variability with the spectroscopic period. We tried to interpret some of the results by the supposition that the Z Cam-stars are an intermediate subtype of the cataclysmic stars evolving from UX UMa-subtype to U Gem-subtype and that probably RX And presents a pattern of Z Cam-star that is very near to the U Gem-subtype. 相似文献
50.
Comparison between the distribution of PGE in black shales from the Bohemian Massif (CSFR) and other black shale occurrences 总被引:3,自引:0,他引:3
J. Pašava 《Mineralium Deposita》1991,26(2):99-103
Selected metal-rich and normal black shales of the Bohemian Massif have been analysed for PGE * and the results have been compared with other anoxic sediments of the world. It has been discussed and partly proved that these rocks may represent an important and promising source of platinoids. 相似文献