全文获取类型
收费全文 | 134篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
大气科学 | 1篇 |
地球物理 | 2篇 |
地质学 | 10篇 |
天文学 | 129篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2013年 | 3篇 |
2012年 | 1篇 |
2011年 | 3篇 |
2010年 | 1篇 |
2009年 | 7篇 |
2008年 | 6篇 |
2007年 | 10篇 |
2006年 | 10篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 14篇 |
2002年 | 15篇 |
2001年 | 7篇 |
2000年 | 12篇 |
1999年 | 9篇 |
1998年 | 9篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有142条查询结果,搜索用时 578 毫秒
11.
The current study focuses on understanding key factors controlling geochemical export in eight diverse coastal watersheds at seasonal and annual time scales. Geochemical, atmospheric and hydrologic data across a range of hydro‐climatic regimes and varying land uses were investigated and relationships analysed. A hyperbolic dilution model was fitted for each watershed system to evaluate discharge–concentration relationships. Nitrate concentration effects were observed in watersheds exposed to high atmospheric deposition rates as well as agricultural watersheds, whereas urban watersheds showed nitrate dilution effects. Dilution patterns were observed for calcium, magnesium and sulfate for almost all watersheds. Seasonal loads for almost all constituents were noted to be mainly driven by hydrologic seasonality, but are also dependent on inputs (atmospheric deposition and land use sources). Understanding the primary controls on hydro‐chemical interactions is critical for developing and refining predictive water quality models, especially in coastal watersheds where sensitive downstream ecosystems act as receiving waters for upstream pollutant loads. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
12.
13.
14.
C.S. Jeffery R.L.C. Starling P.W. Hill D. Pollacco 《Astrophysics and Space Science》2002,279(1-2):115-122
Speculative connections have been made between Sakurai's Object andother hydrogen-deficient stars, principally the RCB stars and [WC]central stars of planetary nebulae. RCBs have also been postulated as the precursors of extreme helium stars (EHes). The question arises to whether Sakurai's Object will evolve down the [WC]-PG1159 evolution track, or the RCB-EHe-HesdO track. From a number of IUE observations, we have measured thesecular contraction rates and pulsation masses of several EHes. These are inconsistent with the predicted contraction rates for helium-shell burning giants produced by a final helium-shell flash (the [WC]-PG1159 track). Although there may be some similarities between Sakurai's Object and some RCBs, if the RCB-EHe conection is valid then these must be superficial rather than structural. 相似文献
15.
Z. G. Zhang S. Svanberg P. Palmeri P. Quinet E. Biémont 《Monthly notices of the Royal Astronomical Society》2002,334(1):1-10
The lifetimes of three short-lived levels belonging to the 4f9 6p configuration and of two long-lived levels of the 4f9 5d configuration of Dy iii have been measured for the first time using time-resolved laser-induced fluorescence techniques. They are in good agreement with theoretical values calculated within the framework of a pseudo-relativistic configuration interaction approximation. Using the experimental lifetimes and the theoretical branching fractions, a first set of transition probabilities of astrophysical interest has been obtained for Dy iii . 相似文献
16.
The search of roAp stars at Mt. Dushak-Erekdag Observatory was started in 1992 using the 0.8 m Odessa telescope equipped with
a two-star high-speed photometer. We have observed more than a dozen stars so far and discovered HD 99563 as roAp star while
BD+8087 is suspected to have rapid oscillations. Negative results of our observations for the search of rapid oscillations
in four stars in NGC 752 are also discussed. 相似文献
17.
V. Urpin 《Astronomische Nachrichten》2015,336(3):266-270
The stars of the middle main sequence often have spot‐like chemical structures at their surfaces. We consider the diffusion process caused by electric currents that can lead to the formation of such chemical spots. Diffusion is considered using the partial momentum equations derived by the Chapman‐Enskog method. We argue that diffusion caused by electric currents can substantially change the surface chemistry of stars and form spotted chemical structures even in a relatively weak magnetic field. The considered mechanism can be responsible for a formation of element spots in Hg‐Mn and Ap‐stars. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
18.
19.
20.
Hideyuki Saio 《Monthly notices of the Royal Astronomical Society》2005,360(3):1022-1032
This paper presents the results of a non-adiabatic analysis for axisymmetric non-radial pulsations including the effect of a dipole magnetic field. Convection is assumed to be suppressed in the stellar envelope, and the diffusion approximation is used to radiative transport. As in a previous adiabatic analysis, the eigenfunctions are expanded in a series of spherical harmonics. The analysis is applied to a 1.9-M⊙ , main-sequence model (log T eff = 3.913) . The presence of a magnetic field always stabilizes low-order acoustic modes. All the low-order modes of the model that are excited by the κ-mechanism in the He ii ionization zone in the absence of a magnetic field are found to be stabilized if the polar strength of the dipole magnetic field is larger than about 1 kG. For high-order p modes, on the other hand, distorted dipole and quadrupole modes excited by the κ-mechanism in the H ionization zone remain overstable, even in the presence of a strong magnetic field. It is found, however, that all the distorted radial high-order modes are stabilized by the effect of the magnetic field. Thus, our non-adiabatic analysis suggests that distorted dipole modes and distorted quadrupole modes are most likely excited in rapidly oscillating Ap stars. The latitudinal amplitude dependence is found to be in reasonable agreement with the observationally determined one for HR 3831. Finally, the expected amplitude of magnetic perturbations at the surface is found to be very small. 相似文献