全文获取类型
收费全文 | 16799篇 |
免费 | 2798篇 |
国内免费 | 2721篇 |
专业分类
测绘学 | 4819篇 |
大气科学 | 662篇 |
地球物理 | 1623篇 |
地质学 | 10590篇 |
海洋学 | 1430篇 |
天文学 | 105篇 |
综合类 | 1584篇 |
自然地理 | 1505篇 |
出版年
2024年 | 46篇 |
2023年 | 190篇 |
2022年 | 694篇 |
2021年 | 858篇 |
2020年 | 808篇 |
2019年 | 723篇 |
2018年 | 559篇 |
2017年 | 798篇 |
2016年 | 833篇 |
2015年 | 902篇 |
2014年 | 1191篇 |
2013年 | 1118篇 |
2012年 | 1133篇 |
2011年 | 1110篇 |
2010年 | 977篇 |
2009年 | 1035篇 |
2008年 | 1021篇 |
2007年 | 1175篇 |
2006年 | 1022篇 |
2005年 | 890篇 |
2004年 | 838篇 |
2003年 | 683篇 |
2002年 | 584篇 |
2001年 | 519篇 |
2000年 | 421篇 |
1999年 | 411篇 |
1998年 | 371篇 |
1997年 | 332篇 |
1996年 | 246篇 |
1995年 | 197篇 |
1994年 | 141篇 |
1993年 | 110篇 |
1992年 | 118篇 |
1991年 | 76篇 |
1990年 | 49篇 |
1989年 | 41篇 |
1988年 | 15篇 |
1987年 | 21篇 |
1986年 | 19篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1972年 | 1篇 |
1954年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
71.
You Yuming Hou Min Senior Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing Assistant Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing 《中国海洋工程》1992,(3)
- The data of landsat TM of multi-temporal for Lingdingyang Estuary, Pearl River in China is firstly used with suspended sediment concentration of field measurement to establish a correlative model equation. After the ratio processing of TM data and atmospheric correction, the images of suspended sediment concentration of different temporals are exported from the image processing systems AREIS II and III. These images express the characteristics of suspended sediment distribution, the mode of sediment transport and the extent of dispersion under the actions of tidal current and wind condition of different seasons. 相似文献
72.
73.
本文概述了建国以来我国海洋地质调查与研究工作取得的丰硕成果。论述区域地质调查在海洋地质基础工作和未来海洋开发中的战略意义,介绍了国内外海洋区域地质调查的现状,对开展这项调查的可行性条件,以及进行1/100万海洋区域地质调查的项目内容、技术方法和提交成果等提出了设想和建议。 相似文献
74.
75.
76.
77.
该文报道碱厂废水随浓度变化的光谱实验。分析碱厂废水的光谱特征 ,并与相同浓度的海水悬浮泥沙水体的光谱进行比较 ;确定该废水特征波长为 50 1.3nm。根据光谱实验结果 ,结合当前已有的水色传感器的资料 ,选择两个卫星传感器波段 :Sea WIFS第四频道 (497.2~ 52 1.6 nm)和TM第二频道 (518.9~ 6 0 0 .2 nm) ;利用数字对 (R,c) ,建立了反射率与该污染水体浓度间的相关模式。为遥感技术大面积、快速地监测碱厂废水污染水体提供理论依据。 相似文献
78.
Ocean Color Satellite Imagery and Shipboard Measurements of Chlorophyll a and Suspended Particulate Matter Distribution in the East China Sea 总被引:1,自引:0,他引:1
Satellite-derived ocean color data of Coastal Zone Color Scanner (CZCS) on board the Nimbus-7 and Ocean Color and Temperature Scanner (OCTS) on board the Advanced Earth Observing Satellite (ADEOS) are jointly used with historical in situ data to examine seasonal and spatial distributions of chlorophyll a (Chl-a) and suspended particulate matter (SPM) concentrations in the East China Sea. Ocean color imagery showed that Chl-a concentrations on the continental shelf were higher than those of the Kuroshio area throughout the year. Satellite-derived Chl-a concentrations are generally in good accordance with historical in situ values during spring through autumn (although no shipboard in situ measurement was conducted at nearshore areas). In contrast, ocean color imagery in winter indicated high Chl-a concentrations (4–10 mg m–3) on the continental shelf where bottom depth was less than 50 m when surface water was turbid (2–72 g m–3 of SPM at surface), while historical in situ values were usually less than 1 mg m–3. This suggests that resuspended bottom sediment due to wind-driven mixing and winter cooling is responsible for the noticeable overestimation of satellite-derived Chl-a concentrations. The algorithm for ocean color needs to be improved urgently for turbid water. 相似文献
79.
80.
Scientific sea-floor dredging is currently used in marine geology primarily by the hard-rock community interested in the recovery of basement rock samples from the unsedimented deep ocean floor. The technique has generally been eclipsed by ocean drilling for recovery of sedimentary rocks, because of perceived uncertainties in the location of sampling and in the representativeness of recovered material. This contribution reviews dredging equipment currently in use by marine geological institutions and refers to pinger attachments that allow precise information on the behaviour of the dredge to be telemetered back to the ship. We argue that improvements in ship navigation and transponder navigation at the seafloor, when used in conjunction with surface and/or deeply towed sidescan and swathemapping surveys, now allow for considerably less uncertainty on the location of dredge sampling. Refined sorting criteria for dredge hauls are now also available. Recent comparisons of regional sample recovery by ocean drilling and by dredge sampling indicate that the dredge hauls can usefully supplement the drilling data in the construction of sedimentary and tectonic histories of seafloor areas. 相似文献