全文获取类型
收费全文 | 62431篇 |
免费 | 460篇 |
国内免费 | 1185篇 |
专业分类
测绘学 | 2122篇 |
大气科学 | 3838篇 |
地球物理 | 11710篇 |
地质学 | 26495篇 |
海洋学 | 4677篇 |
天文学 | 10548篇 |
综合类 | 2301篇 |
自然地理 | 2385篇 |
出版年
2022年 | 521篇 |
2021年 | 756篇 |
2020年 | 808篇 |
2019年 | 872篇 |
2018年 | 6409篇 |
2017年 | 5527篇 |
2016年 | 4261篇 |
2015年 | 920篇 |
2014年 | 1614篇 |
2013年 | 2183篇 |
2012年 | 2708篇 |
2011年 | 4614篇 |
2010年 | 3878篇 |
2009年 | 4329篇 |
2008年 | 3682篇 |
2007年 | 4370篇 |
2006年 | 1850篇 |
2005年 | 1152篇 |
2004年 | 1239篇 |
2003年 | 1210篇 |
2002年 | 1002篇 |
2001年 | 823篇 |
2000年 | 692篇 |
1999年 | 437篇 |
1998年 | 464篇 |
1997年 | 491篇 |
1996年 | 345篇 |
1995年 | 361篇 |
1994年 | 337篇 |
1993年 | 282篇 |
1992年 | 287篇 |
1991年 | 293篇 |
1990年 | 338篇 |
1989年 | 273篇 |
1988年 | 260篇 |
1987年 | 263篇 |
1986年 | 194篇 |
1985年 | 303篇 |
1984年 | 307篇 |
1983年 | 295篇 |
1982年 | 275篇 |
1981年 | 269篇 |
1980年 | 284篇 |
1979年 | 204篇 |
1978年 | 242篇 |
1977年 | 204篇 |
1976年 | 184篇 |
1975年 | 184篇 |
1974年 | 171篇 |
1973年 | 206篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
981.
Summary The morphology of the Wadati-Benioff zone in the region of Southern Kuriles and Hokkaido, based on the distribution of 4015 earthquake foci, verified the existence of an intermediate depth aseismic gap and its relation to active andesitic volcanism. A paleosubduction zone activated by an intermediate depth collision with the active subduction zone was found and described.
u Wadati-Benioff amu uu - u a¶rt;, aa a an¶rt;uu 4015 a mu, nm¶rt;ua mau n¶rt; au u amu a¶rt;um au. a a¶rt;a u nuaa a na¶rt;uu, amuuuaa nmu mu amu ¶rt;uu.相似文献
982.
Human activity is an important agent defining the contemporary hydrologic cycle. We have documented the potential impacts of impoundment, land use change and climate change on the Zambezi River system in southern Africa and found that they can be substantial. A full analysis requires construction and parameterization of a simulation for the entire catchment. This paper develops a strategy for implementing catchment-scale models of the major hydrologic processes operating within the basin. A coherent data set for calibrating the models has also been assembled. The algorithms consist of a Water Balance (WBM) and a Water Transport (WTM) operating at 1/2o spatial scale and at monthly timesteps. These models transform complex patterns of regional climatology into estimates of soil water, evapotranspiration, runoff, and discharge through rivers of various size. The models are dependent on the characteristics of the terrestrial surface, principally soil texture and land cover. A simulated river network is also required. Additional tabular data sets are essential for model testing and calibration. These include subcatchment areas; observed river discharge at selected points; flooding, storage and loss characteristics of major wetlands; floodwave translation; and, volume, surface area, withdrawal and evaporative losses from impoundments. An important design consideration for the numerous impoundments in the Zambezi requires an understanding of the seasonal variation in discharge, in particular how it might respond to climate and land use change. The research strategy offered here lays a framework for addressing such issues. Although the primary focus of this work is hydrologic, we discuss how the model can be extended to consider constituent transport and biogeochemical cycling issues at the continental scale. 相似文献
983.
984.
D. V. Ellis 《Marine pollution bulletin》1983,14(12):437-438
985.
986.
Uranium has been measured by homogenized fission track analysis in 34 samples of 22 achondrites. Potassium has been determined in aliquots of eleven of these. The results, combined with previous Al data, are not compatible with achondrite formation from chondritic material by previously suggested fractional melting or metal-sulfide segregation processes. 相似文献
987.
Water Resources - A new method was used for experimental simulation of the sorption–desorption transformation of microelement composition of the adsorbed complex of solid substances of river... 相似文献
988.
Izvestiya, Physics of the Solid Earth - Abstract—In their paper published in Izvestiya, Physics of the Solid Earth, G.A. Sobolev et al. (2020) discussed the results of their study. Firstly,... 相似文献
989.
L’Her Alexandre Reinert Markus Prants Sergey Carton Xavier Morvan Mathieu 《Ocean Dynamics》2021,71(5):601-612
Ocean Dynamics - The Eastern Kamchatka Current (EKC) is the western boundary current of the North Pacific subpolar gyre. Southeast of the Kamchatka Peninsula lies a large anticyclonic eddy, the... 相似文献
990.
This article describes geological and geophysical studies of an underground nuclear explosion area in one of the boreholes at the Semipalatinsk test site in Kazakhstan. During these studies, the typical elements of mechanical impact of the underground explosion on the host medium—fracturing of rock, spall zones, faults, cracks, etc., were observed. This information supplements to the database of underground nuclear explosion phenomenology and can be applied in fulfilling on-site inspection tasks under the Comprehensive Nuclear-Test-Ban Treaty. 相似文献