全文获取类型
收费全文 | 1498篇 |
免费 | 265篇 |
国内免费 | 362篇 |
专业分类
测绘学 | 132篇 |
大气科学 | 215篇 |
地球物理 | 399篇 |
地质学 | 153篇 |
海洋学 | 894篇 |
天文学 | 27篇 |
综合类 | 199篇 |
自然地理 | 106篇 |
出版年
2024年 | 11篇 |
2023年 | 19篇 |
2022年 | 50篇 |
2021年 | 63篇 |
2020年 | 73篇 |
2019年 | 96篇 |
2018年 | 61篇 |
2017年 | 60篇 |
2016年 | 59篇 |
2015年 | 81篇 |
2014年 | 58篇 |
2013年 | 104篇 |
2012年 | 89篇 |
2011年 | 98篇 |
2010年 | 75篇 |
2009年 | 79篇 |
2008年 | 80篇 |
2007年 | 105篇 |
2006年 | 85篇 |
2005年 | 95篇 |
2004年 | 85篇 |
2003年 | 77篇 |
2002年 | 55篇 |
2001年 | 49篇 |
2000年 | 61篇 |
1999年 | 54篇 |
1998年 | 34篇 |
1997年 | 42篇 |
1996年 | 30篇 |
1995年 | 35篇 |
1994年 | 44篇 |
1993年 | 31篇 |
1992年 | 24篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
排序方式: 共有2125条查询结果,搜索用时 15 毫秒
31.
32.
报道了黄骅沿海赤潮发生的过程和形成赤潮的生物种类及造成的危害,并对赤潮成因作了初步分析。 相似文献
33.
A New Methodology for Incorporating Tide Gauge Data in Sea Surface Topography Models 总被引:1,自引:0,他引:1
As part of the Vertical Offshore Reference Frames (VORF) project sponsored by the U. K. Hydrographic Office, a new model for Sea Surface Topography (SST) around the British Isles has been developed. For offshore areas (greater than 30 km from the coast), this model is largely derived from satellite altimetry. However, its accuracy and level of detail have been enhanced in coastal areas by the inclusion of not only the 60 PSMSL tide gauges with long-term records around the coasts of the United Kingdom and Ireland but also some 385 gauges established at different epochs and for different observation spans by the U. K. Admiralty. All tide gauge data were brought into a common reference frame by a combination of datum models and direct GPS observations, but a more significant challenge was to bring all short-term sea level observations to an unbiased value at a common epoch. This was achieved through developing a spatial-temporal correlation model for the variations in mean sea level around the British Isles, which in turn meant that gauges with long-term observation spans could be used as control points to improve the accuracy of Admiralty gauges. It is demonstrated that the latter can contribute point observations of mean sea level (MSL) with a precision of 0.078 m. A combination of least squares collocation and interpolation was developed to merge the coastal point and offshore gridded data sets, with particular algorithms having to be developed for different configurations of coastal topology. The resulting model of sea surface topography is shown to present a smooth transition from inshore coastal areas to offshore zones. Further benefits of the techniques developed include an enhanced methodology for detecting datum discontinuities at permanent tide gauges. 相似文献
34.
In recent years, the red tide erupted frequently, and caused a great economic loss. At present, most literatures emphasize the academic research on the growth mechanism of red tide alga. In order to find out the characters of red tide in detail and improve the precision of forecast, this paper gives some new approaches to dealing with the red tide. By the extreme values, we deal with the red tide frequency analysis and get the estimation of T-times red tide level U (T) , which is the level once the consistence of red tide alga exceeds on the average in a period of T times. 相似文献
35.
近海水域有机物污染,引起海水富营养化,是形成赤潮的主要原因。赤潮不仅给渔业生产、海水养殖业带来重大损失,而且破坏了海洋环境,危及人民的健康。近年来,我国沿海赤潮时有发生,应加强对有发生赤潮潜在危险海区的经常性观测和监测;切实控制沿海工业和生活污水的任意排放;科学、合理地开发利用海洋资源;推广科学养殖技术,防止海水养殖自身污染;大力开展有关赤潮科学的研究,特别是赤潮的防治方法和技术研究,避免或减少赤潮造成的危害 相似文献
36.
长江口羽状锋海区浮游植物的生态研究:—昼夜分布动态 总被引:5,自引:0,他引:5
本文对长江口羽状锋海区浮游植物的昼夜变动进行了初步研究,结果表明,浮游植物数量的昼夜变化明显,潮汐作用是影响数量昼夜分布变化的主导因素,同时也与该地区浮游植物的水平分布有着密切的联系。 相似文献
37.
38.
青岛地区的台风暴潮与潮灾 总被引:3,自引:0,他引:3
本文分析了青岛沿海地区的台风暴潮灾害状况,给出了潮位与海浪的联合作用对灾的影响关系式,提出了今后风暴潮预报的思路。 相似文献
39.
Biochemical mechanism of forming the red tide is discussed in this paper.The existence of a large number of nitrates and phosphates in the eutrophic water is the prerequisite of explosive increase of algae and the forming of red tide.Reduction of eutrophication is an important approach to preventing the red tide.The method of deep treatment of the waste water and its denitrification and dephosphorization are introduced,and a new opinion on the red tide formation and fundamental prevention is put forward. 相似文献
40.