全文获取类型
收费全文 | 12451篇 |
免费 | 129篇 |
国内免费 | 76篇 |
专业分类
测绘学 | 255篇 |
大气科学 | 781篇 |
地球物理 | 2405篇 |
地质学 | 4852篇 |
海洋学 | 1254篇 |
天文学 | 2568篇 |
综合类 | 50篇 |
自然地理 | 491篇 |
出版年
2022年 | 154篇 |
2021年 | 221篇 |
2020年 | 216篇 |
2019年 | 245篇 |
2018年 | 554篇 |
2017年 | 453篇 |
2016年 | 510篇 |
2015年 | 212篇 |
2014年 | 450篇 |
2013年 | 659篇 |
2012年 | 488篇 |
2011年 | 601篇 |
2010年 | 597篇 |
2009年 | 693篇 |
2008年 | 618篇 |
2007年 | 600篇 |
2006年 | 520篇 |
2005年 | 346篇 |
2004年 | 330篇 |
2003年 | 294篇 |
2002年 | 290篇 |
2001年 | 254篇 |
2000年 | 261篇 |
1999年 | 177篇 |
1998年 | 192篇 |
1997年 | 173篇 |
1996年 | 120篇 |
1995年 | 134篇 |
1994年 | 121篇 |
1993年 | 98篇 |
1992年 | 76篇 |
1991年 | 100篇 |
1990年 | 101篇 |
1989年 | 72篇 |
1988年 | 82篇 |
1987年 | 100篇 |
1986年 | 80篇 |
1985年 | 108篇 |
1984年 | 96篇 |
1983年 | 105篇 |
1982年 | 86篇 |
1981年 | 83篇 |
1980年 | 98篇 |
1979年 | 90篇 |
1978年 | 91篇 |
1977年 | 79篇 |
1976年 | 61篇 |
1975年 | 65篇 |
1974年 | 76篇 |
1973年 | 66篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Astronomy Letters - Techniques for solving the problem of constructing a Stäckel model by generalizing the potential from the equatorial plane to the entire space are considered. The initial... 相似文献
102.
Astronomy Letters - The primordial $${}^{4}$$ He abundance (Y $${}_{p}$$ ) is one of the key characteristics of Primordial Nucleosynthesis processes that occurred in the first minutes after the Big... 相似文献
103.
Solar System Research - The possibility of determining the thermophysical characteristics of the lunar soil by a penetrating probe when using solar heat as a heater is considered. The effectiveness... 相似文献
104.
Joseph B. Lambert Suzanne C. Johnson George O. Poinar James S. Frye 《Geoarchaeology》1993,8(2):141-155
The carbon-13 nuclear magnetic resonance spectra of fossil resins from New Zealand and Australia have been compared with those of modern and semifossilized materials. The great majority of the fossilized samples have strong spectral similarities to modern Agathis resins and to North American fossil resins, which have been attributed to Agathis. The Agathis-related spectra are different from those of modern Hymenaea and Araucaria. A small subgroup of Late Cretaceous resins from Australia and Papua New Guinea appears to derive from a different botanical source and shows strong resemblances to Claiborne amber from Arkansas. The spectral resonances of the exomethylene carbons degrade over time and on average provide an approximate measure of the geological age of Agathis-related fossil resins. © 1993 John Wiley & Sons, Inc. 相似文献
105.
Solar System Research - The paper is dedicated to the study of dust vortices on the Earth and Mars. The hydrodynamic similarity of convective vortices is considered, and the similarity criteria are... 相似文献
106.
Mikhailov E. F. Ivanova O. A. Nebosko E. Yu. Vlasenko S. S. Ryshkevich T. I. 《Izvestiya Atmospheric and Oceanic Physics》2019,55(4):357-364
Izvestiya, Atmospheric and Oceanic Physics - Bioparticles constitute a significant fraction of atmospheric aerosol. Their size range varies from nanometers (macromolecules) to hundreds of... 相似文献
107.
O. I. Podymov 《Oceanology》2008,48(5):656-663
A problem-oriented database (PODB) was developed for the statistical analysis of the hydrochemical characteristics of the redox layer of the Black Sea. The paper describes the features of the PODB, including the algorithm of interpolation and the location of the levels of the appearance and disappearance of hydrochemical parameters (the so-called onset levels) based on Akima’s spline. The application of the PODB allowed us to obtain a series of biogeochemical estimates, in particular, (1) to reveal the constancy of the vertical gradients of the hydrochemical parameters at selected density levels; (2) to calculate the seasonal variability of the degree of manifestation of the phosphate minimum in the near-shore and open sea areas; and (3) to calculate the interannual variability of the level of the disappearance of the hydrogen sulfide, ammonium, total manganese, and methane, as well as the oxygen content in the cold intermediate layer, and to find out their relations with the climatic variations. 相似文献
108.
109.
Aref M.O.AL-JABALI Abdo S.AL-MAQTARY Hussein AL-AKHALI Mohammed HAZAEA Fadel AL-AGHBARI 《东北亚地学研究》2009,(1)
According to topography of Yemen,most areas and villages are located at obligated crest,toe of mountain and under cliffs.Therefore Al-Huwayshah consisting of Tawilah sandstone group is characterized by steep slope reach to 90° in some areas.This area is affected by strong tectonic movements and faults that occurred during the geological epochs.This effect enhances to find out fractures and joints as well as the rocks become brittle and ready to slide depending on the position of area.And there are some frac... 相似文献
110.
A field work has been carried out to identify the occurrence of oil and oil products pollution in mangrove sediment from Red Sea of Yemen. The concentration of total petroleum hydrocarbons is from 700ng/g at Kamaran Island station to 400 ng/g at Al-Hodiedah station, and the total organic carbon (TOC) in samples ranges from 0. 07% at Dhubab station to 0. 03% at Kamaran Island station. This pollution is as a result of localized oil pollution and/or heavy ship traffic in the Red Sea and Gulf of Aden. 相似文献