全文获取类型
收费全文 | 95837篇 |
免费 | 1531篇 |
国内免费 | 799篇 |
专业分类
测绘学 | 2623篇 |
大气科学 | 7360篇 |
地球物理 | 19819篇 |
地质学 | 31902篇 |
海洋学 | 8272篇 |
天文学 | 21705篇 |
综合类 | 236篇 |
自然地理 | 6250篇 |
出版年
2021年 | 620篇 |
2020年 | 769篇 |
2019年 | 883篇 |
2018年 | 1745篇 |
2017年 | 1673篇 |
2016年 | 2294篇 |
2015年 | 1501篇 |
2014年 | 2275篇 |
2013年 | 4675篇 |
2012年 | 2406篇 |
2011年 | 3438篇 |
2010年 | 3046篇 |
2009年 | 4306篇 |
2008年 | 3847篇 |
2007年 | 3623篇 |
2006年 | 3621篇 |
2005年 | 2931篇 |
2004年 | 3016篇 |
2003年 | 2827篇 |
2002年 | 2775篇 |
2001年 | 2480篇 |
2000年 | 2390篇 |
1999年 | 2083篇 |
1998年 | 2047篇 |
1997年 | 2057篇 |
1996年 | 1750篇 |
1995年 | 1667篇 |
1994年 | 1497篇 |
1993年 | 1383篇 |
1992年 | 1275篇 |
1991年 | 1158篇 |
1990年 | 1320篇 |
1989年 | 1206篇 |
1988年 | 1061篇 |
1987年 | 1274篇 |
1986年 | 1135篇 |
1985年 | 1385篇 |
1984年 | 1655篇 |
1983年 | 1503篇 |
1982年 | 1423篇 |
1981年 | 1341篇 |
1980年 | 1162篇 |
1979年 | 1133篇 |
1978年 | 1194篇 |
1977年 | 1067篇 |
1976年 | 1000篇 |
1975年 | 949篇 |
1974年 | 939篇 |
1973年 | 983篇 |
1972年 | 637篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
The first data on the chemical composition of dispersed matter from sedimentary traps are reported. The suspended components of sedimentary matter (amorphous silica, organic matter, carbonates, and lithogenic material, as well as Fe, Mn, and minor elements) are considered. As a result, it is shown that the intraannual variability in vertical fluxes of sedimentary matter is characterized by a seasonal increase in spring and autumn. The high fluxes of the components of sedimentary matter on the northern and southern slopes of the Derbent Basin in winter are explained by precipitation of material from the nepheloid layer that forms over the contour current. 相似文献
992.
The atmospheric disturbances caused by the first rocket launch from the Vostochnyi Cosmodrome on April 28, 2016, were registered 10–24 min after the launch using the signals of the GPS/GLONASS global navigation satellite systems. The analysis of the spatial distribution of the disturbances allowed the conclusion that the launch vehicle moved northwest from the cosmodrome, which corresponds to a trajectory of the satellite movement to the orbit with an inclination of 98º. 相似文献
993.
994.
Potential of river bank filtration (RBF) in Egypt 总被引:1,自引:0,他引:1
995.
996.
Fokin P. A. Zakrevskaya E. Yu. Sahakyan L. G. Grigoryan T. E. 《Lithology and Mineral Resources》2021,56(5):438-459
Lithology and Mineral Resources - Nummulite facies are known to be a good indicator of Eocene shallow-water paleoenvironments. Nummulitic limestones are widespread in the Lower Eocene of... 相似文献
997.
Astronomy Reports - An algorithm has been developed for finding the global minimum of a multidimensional error function by fitting model spectral maps into observed ones. Principal component... 相似文献
998.
We propose, as a testable hypothesis, a basin-scale approach for interpreting the abundance of in situ produced cosmogenic isotopes, an approach which considers explicitly both the isotope and sediment flux through a drainage basin. Unlike most existing models, which are appropriate for evaluating in situproduced cosmogenic isotope abundance at discrete points on Earth's surface, our model is designed for interpreting isotope abundance in sediment. Because sediment is a mixture of materials, in favourable cases derived from throughout a drainage basin, we suggest that measured isotope abundances may reflect spatially averaged rates of erosion. We investigate the assumptions and behaviour of our model and conclude that it could provide geomorphologists with a relatively simple means by which to constrain the rate of landscape evolution if a basin is in isotopic steady state and if sampled sediments are well mixed. 相似文献
999.
1000.