全文获取类型
收费全文 | 97篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 17篇 |
地球物理 | 22篇 |
地质学 | 26篇 |
海洋学 | 9篇 |
天文学 | 17篇 |
自然地理 | 9篇 |
出版年
2022年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 9篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 2篇 |
2008年 | 3篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1966年 | 2篇 |
1938年 | 1篇 |
排序方式: 共有102条查询结果,搜索用时 15 毫秒
1.
P. G. Jonker G. Nelemans Z. Wang A. K. H. Kong D. Chakrabarty M. Garcia P. J. Groot M. van der Klis T. Kerr B. Mobasher M. Sullivan T. Augusteijn B. W. Stappers P. Challis R. P. Kirshner J. Hjorth A. Delsanti 《Monthly notices of the Royal Astronomical Society》2003,344(1):201-206
We have obtained optical and near-infrared images of the field of the accreting millisecond X-ray pulsar XTE J1751−305. There are no stars in the 0.7-arcsec error circle (0.7 arcsec is the overall uncertainty arising from tying the optical and X-ray images and from the intrinsic uncertainty in the Chandra X-ray astrometric solution). We derive limiting magnitudes for the counterpart of R > 23.1, I > 21.6, Z > 20.6, J > 19.6 and K > 19.2 . We compare these upper limits with the magnitudes one would expect for simple models for the possible donor stars and the accretion disc subject to the reddening observed in X-rays for XTE J1751−305 and when put at the distance of the Galactic Centre (8.5 kpc). We conclude that our non-detection does not constrain any of the models for the accretion disc or possible donor stars. Deep, near-infrared images obtained during quiescence will, however, constrain possible models for the donor stars in this ultracompact system. 相似文献
2.
3.
4.
Compositional profiles of a series of garnets, extracted from a pelitic schist occurring in the Moinian rocks of Northern Sutherland, have been established. The profiles are complex and do not conform to a simple fractionation model. A model to explain them is suggested. 相似文献
5.
Activated charcoal chromatography was used to isolate dissolved organic matter from a series of water samples collected in Narragansett Bay, Rhode Island, during 1975–1976. The range of dissolved organic carbon values in the samples was 1.46–3.75 mg OC/1. A relatively constant amount of organic carbon was isolated giving overall recoveries of 23 to 63% (mean of 45%). The isolated organic matter was characterized by spectrophotometric measurements, stable carbon isotope determinations, and copper solubilizing capacities. In general, the isolated material displayed considerable constancy in terms of the parameters measured. However, several chemical variations were detected that were probably related to the introduction of organic matter from diatom blooms and terrigenous runoff. 相似文献
6.
7.
F. M. Kerr A. Gouveia R. W. Lee P. K. Patel O. Renner S. J. Rose H. A. Scott J. S. Wark 《Astrophysics and Space Science》2005,298(1-2):171-176
An astrophysically relevant experiment is compared to the output of a multidimensional radiation transfer code in which populations
and radiation are self-consistently treated. Experimental Al Ly α spectra obtained with a very high-resolution spectrometer
are presented as quantitative evidence of dot plasma non-planar expansion. Analysis of these spectra using the code is performed,
in particular examining the effects of velocity gradients in directions other than that of the primary expansion. These calculations
are found to be in good agreement with the experimental results. Usage of the Ly α doublet as a planarity diagnostic is discussed. 相似文献
8.
Dissolved organic matter was isolated from coastal and open-ocean surface waters having a wide range of biological productivities, and from seawater of intermediate depths. Approximately 50% of the organic matter was recovered by the use of activated-charcoal chromatography. The organic matter isolated from different types of water masses exhibited varying spectroscopic characteristics, and stable carbon-isotope compositions. The ability of the isolated organic matter to interact with copper ions also varied, but over a relatively narrow range which was not exceeded by more than a factor of two by similarly isolated terrigenous organic matter. 相似文献
9.
We evaluated the prevalence of partial migration, coexisting resident and migratory life history types, within six white perch
(Morone americana) populations in sub-estuaries (Upper Bay, and Potomac, Choptank, Nanticoke, James, and York Rivers) of the Chesapeake Bay.
Otolith stable isotope (δ18O) values were used to resolve fish habitat use along an estuarine salinity gradient and define resident or migratory behavior.
The majority of adults within Upper Bay and Potomac River populations were resident, whereas individuals from the Choptank,
Nanticoke, James, and York Rivers were predominantly migratory. Beyond population differences, large interannual variability
in life history types was observed, likely due to differences in estuarine conditions that influence growth rate of individuals
(e.g., temperature, zooplankton density). Because we observed partial migration in all study populations, we suggest that
this trait is characteristic of this species, permitting plastic responses to variation in the estuarine environment. 相似文献
10.
C.A. Mériaux J.A. Mansour L.N. Moresi R.C. Kerr D.A. May 《Physics of the Earth and Planetary Interiors》2011,184(1-2):63-79
The rise of an initially horizontal, buoyant cylinder of fluid through a denser fluid at low Reynolds number is used to look at the ascent of strongly tilted mantle plumes through the mantle. Such ascents are characterized by (1) the growth of instabilities and (2) the development of a thermal wake downstream. Three-dimensional numerical experiments were carried out to examine these features. An hybrid particle-in-cell finite element method was used to look at the rise of non-diffusing cylinders and, a standard finite element method was used to look at the diffusing case. First the experiments show that the timescale of the fastest growing instability vary with the Rayleigh number and the viscosity ratio. In particular the growth rate decreases as the Rayleigh number decreases, in agreement with our analysis of the laboratory experiments of Kerr et al. (2008). Second the experiments show that the length of the thermal wake increases with the Rayleigh number but the change in viscosity has almost no influence on the wake length. Applied to strongly tilted mantle plumes we conclude that such plumes cannot be unstable given the plume timescales. We also discuss the application of this conclusion to weakly tilted plumes. Besides, this study allows to predict that mantle plumes are unlikely to have developed a significant thermal wake by the time they reach the surface. Finally, the resolution that is required to allow for the growth of mantle plume tails by combined diffusion and thermal entrainment is shown to represent a challenge for the large scale mantle convection simulations. 相似文献