全文获取类型
收费全文 | 47292篇 |
免费 | 1264篇 |
国内免费 | 1049篇 |
专业分类
测绘学 | 1158篇 |
大气科学 | 3303篇 |
地球物理 | 9515篇 |
地质学 | 17911篇 |
海洋学 | 4541篇 |
天文学 | 9783篇 |
综合类 | 303篇 |
自然地理 | 3091篇 |
出版年
2022年 | 1033篇 |
2021年 | 1465篇 |
2020年 | 1395篇 |
2019年 | 1461篇 |
2018年 | 1363篇 |
2017年 | 1161篇 |
2016年 | 1169篇 |
2015年 | 832篇 |
2014年 | 1105篇 |
2013年 | 2080篇 |
2012年 | 1458篇 |
2011年 | 2054篇 |
2010年 | 1811篇 |
2009年 | 2335篇 |
2008年 | 1872篇 |
2007年 | 1925篇 |
2006年 | 1886篇 |
2005年 | 1368篇 |
2004年 | 1412篇 |
2003年 | 1390篇 |
2002年 | 1362篇 |
2001年 | 1117篇 |
2000年 | 1011篇 |
1999年 | 850篇 |
1998年 | 926篇 |
1997年 | 914篇 |
1996年 | 625篇 |
1995年 | 615篇 |
1994年 | 569篇 |
1993年 | 472篇 |
1992年 | 492篇 |
1991年 | 469篇 |
1990年 | 516篇 |
1989年 | 438篇 |
1988年 | 413篇 |
1987年 | 484篇 |
1986年 | 464篇 |
1985年 | 498篇 |
1984年 | 600篇 |
1983年 | 537篇 |
1982年 | 495篇 |
1981年 | 455篇 |
1980年 | 453篇 |
1979年 | 382篇 |
1978年 | 381篇 |
1977年 | 373篇 |
1976年 | 329篇 |
1975年 | 331篇 |
1974年 | 386篇 |
1973年 | 399篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
61.
Spiridonov E. A. Vinogradova O. Yu. 《Izvestiya Atmospheric and Oceanic Physics》2019,55(11):1814-1819
Izvestiya, Atmospheric and Oceanic Physics - A method for calculating of the Earth’s surface displacements due to atmospheric loading effect is presented. The load displacements are... 相似文献
62.
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
63.
Stable water isotopes δ18O and δ2H are used to investigate precipitation trends and storm dynamics to advance knowledge of precipitation patterns in a warming world. Herein, δ18O and δ2H were used to determine the relationship between extratropical cyclonic precipitation and local meteoric water lines (LMWLs) in the eastern Ohio Valley and the eastern United States. Precipitation volume weighted and unweighted central Ohio LMWLs, created with samples collected during 2012–2018, showed that temperature had the greatest effect on precipitation isotopic composition. HYSPLIT back trajectory modelling showed that precipitation was primarily derived from a mid-continental moisture source. Remnants of major hurricanes were collected as extratropical precipitation during the 2012–2018 sampling period in central Ohio. Extratropical precipitation samples were not significantly different from the samples that created the central Ohio LMWL. Six additional LMWLs were derived from United States Geological Survey (USGS) Atmospheric Integrated Research Monitoring Network (AIRMoN) samples collected in Pennsylvania, Delaware, Tennessee, Vermont, New Hampshire, and Oxford, Ohio. Meteoric water lines describing published samples from Superstorm Sandy, plotted with these AIRMoN LMWLs, showed isotopic composition of Superstorm Sandy precipitation was commonly more depleted than the average isotopic composition at the mid-latitude locations. Meteoric water lines describing the Superstorm Sandy precipitation were not significantly different in slope from LMWLs generated within 300 km of the USGS AIRMoN site. This finding, which was observed across the eastern Ohio Valley and eastern United States, demonstrated a consistent precipitation δ2H–δ18O relationship for extratropical cyclonic and non-cyclonic events. This work also facilitates the analysis of storm development based on the relationship between extratropical event signature and the LMWL. Analysis of extratropical precipitation in relation to LMWLs along storm tracks allows for stronger development of precipitation models and understanding of which climatic and atmospheric factors determine the isotopic composition of precipitation. 相似文献
64.
Astronomy Letters - The reduction of all the available photometry for the Cepheid CE Pup has allowed its $$O-C$$ diagram spanning a time interval of 128 years to be constructed. This has made it... 相似文献
65.
Astrophysics - A general catalog of active galactic nuclei (AGN) has been created from identified optical sources of X-ray data from the Hamburg-ROSAT Catalog (HRC) and the Byurakan-Hamburg ROSAT... 相似文献
66.
Solar System Research - The discovery of the first interstellar comet 2I/Borisov confirmed the astronomers’ speculation that the passage through the solar system of relatively large objects... 相似文献
67.
Pavlenko E. P. Sosnovskii A. A. Antonyuk K. A. Antonyuk O. I. Pit’ N. V. Kokhirova G. I. Rakhmatullaeva F. J. Baklanov A. V. 《Astrophysics》2021,64(3):293-305
Astrophysics - Photometric studies of the type SU UMa dwarf nova NY Her were made during 2017 and 2020 at the Crimean Astrophysical Observatory and at the Sanglokh Observatory over a total of 77... 相似文献
68.
Astrophysics - We used modified holographic Ricci dark energy to find anisotropic LRS Bianchi type I cosmological model in five-dimensions based on Lyra geometry. The exact solutions of the... 相似文献
69.
Stuart J. Robbins Wesley A. Watters John E. Chappelow Veronica J. Bray Ingrid J. Daubar Robert A. Craddock Ross A. Beyer Margaret Landis Lillian R. Ostrach Livio Tornabene Jamie D. Riggs Brian P. Weaver 《Meteoritics & planetary science》2018,53(4):583-637
One important, almost ubiquitous, tool for understanding the surfaces of solid bodies throughout the solar system is the study of impact craters. While measuring a distribution of crater diameters and locations is an important tool for a wide variety of studies, so too is measuring a crater's “depth.” Depth can inform numerous studies including the strength of a surface and modification rates in the local environment. There is, however, no standard data set, definition, or technique to perform this data-gathering task, and the abundance of different definitions of “depth” and methods for estimating that quantity can lead to misunderstandings in and of the literature. In this review, we describe a wide variety of data sets and methods to analyze those data sets that have been, are currently, or could be used to derive different types of crater depth measurements. We also recommend certain nomenclature in doing so to help standardize practice in the field. We present a review section of all crater depths that have been published on different solar system bodies which shows how the field has evolved through time and how some common assumptions might not be wholly accurate. We conclude with several recommendations for researchers which could help different data sets to be more easily understood and compared. 相似文献
70.
We describe a partial filament eruption on 11 December 2011 that demonstrates that the inclusion of mass is an important next step for understanding solar eruptions. Observations from the Solar Terrestrial Relations Observatory-Behind (STEREO-B) and the Solar Dynamics Observatory (SDO) spacecraft were used to remove line-of-sight projection effects in filament motion and correlate the effect of plasma dynamics with the evolution of the filament height. Flux cancellation and nearby flux emergence are shown to have played a role in increasing the height of the filament prior to eruption. The two viewpoints allow the quantitative estimation of a large mass-unloading, the subsequent radial expansion, and the eruption of the filament to be investigated. A 1.8 to 4.1 lower-limit ratio between gravitational and magnetic-tension forces was found. We therefore conclude that following the loss-of-equilibrium of the flux-rope, the radial expansion of the flux-rope was restrained by the filamentary material until 70% of the mass had evacuated the structure through mass-unloading. 相似文献