全文获取类型
收费全文 | 37016篇 |
免费 | 674篇 |
国内免费 | 449篇 |
专业分类
测绘学 | 893篇 |
大气科学 | 2541篇 |
地球物理 | 7775篇 |
地质学 | 13713篇 |
海洋学 | 3452篇 |
天文学 | 7180篇 |
综合类 | 106篇 |
自然地理 | 2479篇 |
出版年
2022年 | 906篇 |
2021年 | 1320篇 |
2020年 | 1248篇 |
2019年 | 1304篇 |
2018年 | 823篇 |
2017年 | 602篇 |
2016年 | 602篇 |
2015年 | 478篇 |
2014年 | 545篇 |
2013年 | 1470篇 |
2012年 | 679篇 |
2011年 | 1143篇 |
2010年 | 939篇 |
2009年 | 1287篇 |
2008年 | 1067篇 |
2007年 | 1048篇 |
2006年 | 1055篇 |
2005年 | 890篇 |
2004年 | 1093篇 |
2003年 | 1148篇 |
2002年 | 1147篇 |
2001年 | 915篇 |
2000年 | 866篇 |
1999年 | 799篇 |
1998年 | 805篇 |
1997年 | 857篇 |
1996年 | 519篇 |
1995年 | 515篇 |
1994年 | 518篇 |
1993年 | 450篇 |
1992年 | 436篇 |
1991年 | 399篇 |
1990年 | 434篇 |
1989年 | 373篇 |
1988年 | 395篇 |
1987年 | 427篇 |
1986年 | 435篇 |
1985年 | 546篇 |
1984年 | 581篇 |
1983年 | 601篇 |
1982年 | 445篇 |
1981年 | 469篇 |
1980年 | 460篇 |
1979年 | 404篇 |
1978年 | 423篇 |
1977年 | 373篇 |
1976年 | 384篇 |
1975年 | 369篇 |
1974年 | 454篇 |
1973年 | 408篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
The characteristic pattern of multiple colored layers in coastal stratified lakes in the process of separation from the White Sea 总被引:1,自引:1,他引:0
Krasnova Elena D. Matorin Dmitry N. Belevich Tatiana A. Efimova Ludmila E. Kharcheva Anastasiia V. Kokryatskaya Natalia M. Losyuk Galina N. Todorenko Daria A. Voronov Dmitry A. Patsaeva Svetlana V. 《中国海洋湖沼学报》2018,36(6):1962-1977
An unusual feature of the saline stratified lakes that were formed due to ongoing postglacial uplift on the White Sea coast is the presence of several differently colored thin layers in the zone with sharp gradients. Colored layers in five lakes at various stages of separation from the sea were investigated using optical microscopy, spectrophotometry, spectrofluorimetry, and photobiology. The upper greenish colored layer located in the aerobic strata of all lakes near the compensation depth of 1% light penetration contains green algae. In the chemocline, another layer, brightly green, red or pink, is dominated by mixotrophic flagellates. Despite the very low light intensities and the presence of H 2 S, active photosynthesis by these algae appears to be occurring, as indicated by high values of the maximum quantum yield of primary photochemistry, electron transport activity, photosynthetic activity of photosystem II, the fraction of active centers, and low values of heat dissipation. In the reduced zone of the chemocline, a dense green or brown suspension of anoxygenic phototrophs(green sulfur bacteria) is located. 相似文献
22.
23.
Izvestiya, Atmospheric and Oceanic Physics - The problem of atmospheric correction for shortwave channels of a multispectral low-resolution scanning radiometer onboard the Meteor-M No. 2 satellite... 相似文献
24.
Korzhenkov A. M. Gadzhiev M. S. Ovsyuchenko A. N. Lar’kov A. S. Rogozhin E. A. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(7):633-656
Izvestiya, Atmospheric and Oceanic Physics - As a result of studies conducted in the city of Derbent, it is established that its monumental fortification structures erected at the end of the 560s... 相似文献
25.
Yu Xinran Ahmadinia Masoud Shariatipour Seyed M. Lawton Don Osadetz Kirk Saeedfar Amin 《Natural Resources Research》2020,29(4):2735-2752
Natural Resources Research - Carbon capture and storage is part of Canada’s climate change action plan to reduce greenhouse gas emissions. The Containment and Monitoring Institute Field... 相似文献
26.
A Study on the Surface Wettability of Clastic Rocks with Potential Application for CO2 Storage Sites
Umar Bappah Adamu Gholami Raoof Raza Arshad Downey William Samuel Sarmadivaleh Mohammad Shah Afroz A. Nayak Prasanta 《Natural Resources Research》2020,29(3):2051-2061
Natural Resources Research - There have been many studies carried out in the past decades attempting to develop strategies for a safe injection of CO2 into storage sites without leakage and... 相似文献
27.
Natural Resources Research - Sand failure and production occurs when the formation stress exceeds the strength of the formation, which is derived majorly from the natural material that cements the... 相似文献
28.
Abstract— The possibility of volcanism on Mercury has been a topic of discussion since Mariner 10 returned images of half the planet's surface showing widespread plains material. These plains could be volcanic or lobate crater ejecta. An assessment of the mechanics of the ascent and eruption of magma shows that it is possible to have widespread volcanism, no volcanism on the surface whatsoever, or some range in between. It is difficult to distinguish between a lava flow and lobate crater ejecta based on morphology and morphometry. No definite volcanic features have been identified on Mercury. However, known lunar volcanic features cannot be identified in images with similar resolutions and viewing geometries as the Mariner 10 dataset. Examination of high‐resolution, low Sun angle Mariner 10 images reveals several features which are interpreted to be flow fronts; it is unclear if these are volcanic flows or ejecta flows. This analysis implies that a clear assessment of volcanism on Mercury must wait for better data. MESSENGER (MErcury: Surface, Space ENvironment, GEochemistry, Ranging) will take images with viewing geometries and resolutions appropriate for the identification of such features. 相似文献
29.
30.
青藏高原隆升的非线性动态有限元仿真研究 总被引:7,自引:4,他引:3
根据青藏高原的地质特征建立分析模型,采用3维动态有限元方法,在计算仿真板块速度场的基础上,计算在青藏高原的隆升过程中该地区地壳岩石的等效应力和位移随时间的变化,计算仿真得到的速度场与1998年GPS观测的速度场吻合良好;与过去一贯的假设相反,计算结果反映出地壳应力场不是静态的,而是此起彼伏,不断变化的,应力值最大且变化最剧烈的地区在克什米尔地区、鄂尔多斯地区和鲜水河-小江断裂带,与地震多发区域吻合。 相似文献