全文获取类型
收费全文 | 46517篇 |
免费 | 830篇 |
国内免费 | 386篇 |
专业分类
测绘学 | 938篇 |
大气科学 | 2942篇 |
地球物理 | 8982篇 |
地质学 | 17438篇 |
海洋学 | 4496篇 |
天文学 | 9978篇 |
综合类 | 145篇 |
自然地理 | 2814篇 |
出版年
2022年 | 913篇 |
2021年 | 1334篇 |
2020年 | 1298篇 |
2019年 | 1385篇 |
2018年 | 1400篇 |
2017年 | 1244篇 |
2016年 | 1162篇 |
2015年 | 684篇 |
2014年 | 1067篇 |
2013年 | 1978篇 |
2012年 | 1273篇 |
2011年 | 1826篇 |
2010年 | 1610篇 |
2009年 | 2017篇 |
2008年 | 1732篇 |
2007年 | 1809篇 |
2006年 | 1655篇 |
2005年 | 1115篇 |
2004年 | 1269篇 |
2003年 | 1397篇 |
2002年 | 1300篇 |
2001年 | 1108篇 |
2000年 | 945篇 |
1999年 | 856篇 |
1998年 | 877篇 |
1997年 | 933篇 |
1996年 | 609篇 |
1995年 | 593篇 |
1994年 | 560篇 |
1993年 | 477篇 |
1992年 | 464篇 |
1991年 | 481篇 |
1990年 | 480篇 |
1989年 | 448篇 |
1988年 | 418篇 |
1987年 | 438篇 |
1986年 | 515篇 |
1985年 | 547篇 |
1984年 | 589篇 |
1983年 | 602篇 |
1982年 | 508篇 |
1981年 | 494篇 |
1980年 | 458篇 |
1979年 | 417篇 |
1978年 | 394篇 |
1977年 | 401篇 |
1976年 | 350篇 |
1975年 | 372篇 |
1974年 | 409篇 |
1973年 | 408篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Geomagnetism and Aeronomy - Diurnal variations in the statistical characteristics of the day-to-day variability in the electron number density NmF2 of the ionospheric F2 layer maximum is studied... 相似文献
2.
Geomagnetism and Aeronomy - The results of a study of the geoelectric section of the upper layers of the Earth at observation sites in Yakutia via vertical electrical sounding and surface impedance... 相似文献
3.
Astronomy Letters - The emission from the Crab nebula exhibits a significant gamma-ray variability. In this paper we have analyzed this variability in terms of periodicity. Using the pulsar... 相似文献
4.
Astrophysics - We study the modulation of galactic cosmic rays due to magnetic clouds observed during solar cycles 23 and 24 (1996-2018). We utilize solar wind plasma and field data together with... 相似文献
5.
Geomagnetism and Aeronomy - Additional horizontal traces of ground reflections were observed in a studied series of high-latitude, Kp sounding ionograms from the Interkosmos-19 satellite. The... 相似文献
6.
Kim I. S. Krusanova N. L. Popov V. V. Osokin A. R. Mironova I. V. 《Geomagnetism and Aeronomy》2020,60(4):441-445
Geomagnetism and Aeronomy - The color of the coronal continuum was determined from observations in order to search for manifestations of coronal expansion. A brief review of studies determining the... 相似文献
7.
Oparin I. D. Charikov Yu. E. Ovchinnikova E. P. Shabalin A. N. 《Geomagnetism and Aeronomy》2020,60(7):889-895
Geomagnetism and Aeronomy - We study the electron energy spectra of two powerful solar flares SOL2003-10-28T 1106:16 (GOES class X17.2) and SOL2002-07-23T 0018:16 (X4.8) analyzing the HXR and... 相似文献
8.
Application of surface-wave tomography to mineral exploration: a case study from Siilinjärvi,Finland
Federico Da Col Myrto Papadopoulou Emilia Koivisto Łukasz Sito Mikko Savolainen Laura Valentina Socco 《Geophysical Prospecting》2020,68(1):254-269
In order to assess the feasibility and validity of surface-wave tomography as a tool for mineral exploration, we present an active seismic three-dimensional case study from the Siilinjärvi mine in Eastern Finland. The aim of the survey is to identify the formation carrying the mineralization in an area south of the main pit, which will be mined in the future. Before acquiring the data, we performed an accurate survey design to maximize data coverage and minimize the time for deployment and recollection of the equipment. We extract path-averaged Rayleigh-wave phase-velocity dispersion curves by means of a two-station method. We invert them using a computationally efficient tomographic code which does not require the computation of phase-velocity maps and inverts directly for one-dimensional S-wave velocity models. The retrieved velocities are in good agreement with the data from a borehole in the vicinity, and the pseudo three–dimensional S-wave velocity volume allows us to identify the geological contact between the formation hosting most of the mineralization and the surrounding rock. We conclude that the proposed method is a valid tool, given the small amount of equipment used and the acceptable amount of time required to process the data. 相似文献
9.
Water Resources - An array of data collected in the Institute of Limnology, Russian Academy of Sciences, in the course of studies aimed to evaluate the total water surface areas has been used to... 相似文献
10.
Water Resources - The relationships between various hydrological and morphometric characteristics of branch channels in the backwater zone are analyzed in the case of the Chilia channel system in... 相似文献