全文获取类型
收费全文 | 567篇 |
免费 | 13篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 14篇 |
大气科学 | 50篇 |
地球物理 | 128篇 |
地质学 | 153篇 |
海洋学 | 70篇 |
天文学 | 126篇 |
综合类 | 4篇 |
自然地理 | 40篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 16篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 8篇 |
2016年 | 12篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 38篇 |
2012年 | 25篇 |
2011年 | 24篇 |
2010年 | 15篇 |
2009年 | 28篇 |
2008年 | 38篇 |
2007年 | 21篇 |
2006年 | 25篇 |
2005年 | 24篇 |
2004年 | 27篇 |
2003年 | 14篇 |
2002年 | 23篇 |
2001年 | 22篇 |
2000年 | 17篇 |
1999年 | 14篇 |
1998年 | 20篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1966年 | 2篇 |
排序方式: 共有585条查询结果,搜索用时 15 毫秒
581.
Certain factors influencing the incorporation, transport and release of fatty acids by clay minerals, calcite and marine sediments have been investigated.Salinity was found to be an important factor. The adsorption of heptadecanoic acid by bentonite clay at 4%. was nearly triple that at 0%.. However, from 4%. to 35%., only a minor adsorption increase occurred. This behavior is believed to be related to flocculation of the clay at the lower salinity range. The pH over the range of 6.0–8.5 has a small influence on fatty acid-clay association, depressing it somewhat as the basicity increases.When the temperature of the fatty acid solution was increased from 0°C to 50°C, a decrease in adsorption on to clay was found. This effect may be due to increased water solubility of the acid at higher temperatures, since solubility is very important in controlling the degree of fatty acid-mineral interaction. Furthermore, apparent solubilization of fatty acids by indigenous dissolved organic matter in sea water reduces adsorption on to clay minerals.Based upon the heat of adsorption of ?14.6 kcal/mole, fatty acids are physically bound to clay minerals by weak van der Waals forces and hydrogen bonds.Bentonite and kaolinite were found to be the most adsorptive minerals investigated, followed in order by illite, montmorillonite and calcite. Sediments from Narragansett Bay were found to lie between illite and montmorillonite in adsorptive capacity after indigenous sediment organic matter had been removed. Sediment organic matter reduced fatty acid uptake by a factor of 1.6. 相似文献
582.
A strange symbiosis: Seismic ray theory and Saturday touch football — Donald V. Helmberger as a graduate advisor
下载免费PDF全文
![点击此处可从《地震科学(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Terry C. Wallace 《地震科学(英文版)》2022,35(1):11-13
At the end of December of 1978 I was sitting in the office of Caltech Professor Don Helmberger,he was peering out his window towards the San Gabriel Mountains,s... 相似文献
583.
Chris Pearson Tanya Lim Chris North George Bendo Luca Conversi Darren Dowell Matt Griffin Terry Jin Nicolas Laporte Andreas Papageorgiou Bernhard Schulz Dave Shupe Anthony J. Smith Kevin Xu 《Experimental Astronomy》2014,37(2):175-194
The different algorithms appropriate for point source photometry on data from the SPIRE instrument on-board the Herschel Space Observatory, within the Herschel Interactive Processing Environment (HIPE) are compared. Point source photometry of a large ensemble of standard calibration stars and dark sky observations is carried out using the 4 major methods within HIPE: SUSSEXtractor, DAOphot, the SPIRE Timeline Fitter and simple Aperture Photometry. Colour corrections and effective beam areas as a function of the assumed source spectral index are also included to produce a large number of photometric measurements per individual target, in each of the 3 SPIRE bands (250, 350, 500μm), to examine both the accuracy and repeatability of each of the 4 algorithms. It is concluded that for flux densities down to the level of 30mJy that the SPIRE Timeline Fitter is the method of choice. However, at least in the 250 and 350μm bands, all 4 methods provide photometric repeatability better than a few percent down to at approximately 100mJy. The DAOphot method appears in many cases to have a systematic offset of ~8 % in all SPIRE bands which may be indicative of a sub-optimal aperture correction. In general, aperture photometry is the least reliable method, i.e. largest scatter between observations, especially in the longest wavelength band. At the faintest fluxes, <30mJy, SUSSEXtractor or DAOphot provide a better alternative to the Timeline Fitter. 相似文献
584.
The influence of solution complexation on the sorption of yttrium and the rare earth elements (YREEs) by amorphous ferric hydroxide was investigated at 25 °C over a range of pH (4.0-7.1) and carbonate concentrations . Distribution coefficients, defined as , where [MSi]T is the total concentration of sorbed YREE, MT is the total YREE concentration in solution, and [Si] is the concentration of amorphous ferric hydroxide, initially increased in magnitude with increasing carbonate concentration, and then decreased. The initial increase of is due to sorption of YREE carbonate complexes , in addition to sorption of free YREE ions (M3+). The subsequent decrease of , which is more extensive for the heavy REEs, is due to the increasing intensity of YREE solution complexation by carbonate ions. The competition for YREEs between solution complexation and surface complexation was modeled via the equation:
585.
Lumpkin Gregory R. Gieré Reto Williams C. Terry McGlinn Peter J. Payne Timothy E. 《Mineralogy and Petrology》2017,111(4):499-509
Mineralogy and Petrology - Tungsten-rich oxycalciobetafite occurs in complex Ti-rich hydrothermal veins emplaced within dolomite marble in the contact aureole of the Adamello batholith, northern... 相似文献