全文获取类型
收费全文 | 801篇 |
免费 | 277篇 |
国内免费 | 393篇 |
学科分类
地球科学 | 1471篇 |
出版年
2024年 | 2篇 |
2023年 | 10篇 |
2022年 | 23篇 |
2021年 | 32篇 |
2020年 | 44篇 |
2019年 | 60篇 |
2018年 | 41篇 |
2017年 | 44篇 |
2016年 | 55篇 |
2015年 | 44篇 |
2014年 | 70篇 |
2013年 | 83篇 |
2012年 | 70篇 |
2011年 | 76篇 |
2010年 | 65篇 |
2009年 | 59篇 |
2008年 | 71篇 |
2007年 | 84篇 |
2006年 | 68篇 |
2005年 | 59篇 |
2004年 | 65篇 |
2003年 | 38篇 |
2002年 | 43篇 |
2001年 | 43篇 |
2000年 | 30篇 |
1999年 | 40篇 |
1998年 | 31篇 |
1997年 | 20篇 |
1996年 | 24篇 |
1995年 | 19篇 |
1994年 | 18篇 |
1993年 | 11篇 |
1992年 | 12篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有1471条查询结果,搜索用时 15 毫秒
1.
1 INTRODUCTIONGlobal change research involves much geo-objectsand geo-process, such as climate and environmentalchange, substance and energy cycling, land-use/land-cover change (LUCC), interactivity between human and nature, etc.. So it need cooperation frommany research communities including international research programs groups such as IGBP (InternationalGeosphere-Biosphere Programme IPCC (Intergovemmental Panel on Climate Change), IHDP (InternationalHuman Dimension Program o… 相似文献
2.
3.
作者研究三维变系数抛物方程 Douglas交替方向隐格式的稳定性和收敛性。采用 H1能量估计方法 ,证明格式按离散 H1范数是绝对稳定的 ,并且收敛阶为 O(Δ t2 + h2 ) 相似文献
4.
南黄海表层沉积物天然湿容重和含水量的分布及其与粒度之间的关系 总被引:2,自引:0,他引:2
本文论述了南黄海表层沉积物天然湿容重和含水量的分布,并利用回归分析的方法讨论了容重和含水量与粒度之间的关系。结果表明,容重和含水量与粘土粒级相关性最好,容重与粘土粒级含量(相似文献
5.
6.
7.
王树林 《中国海洋大学学报(自然科学版)》1995,(Z1)
以现代高速摄影技术和图像分析以及数据处理方法,针对高效振动磨机中弹性散体工质(如钢棒、球体等)的振动力学进行了深入的探讨和分析,为研究散体动力学和振动超细粉碎过程中的能量分布和传递规律以及能量与物质的相互转换机理奠定了基础,也为相关学科的发展提供了一种可以借鉴的方法。 相似文献
8.
Presented here is a compact explicit difference scheme of high accuracy for solving the extended Boussinesq equations.For time discretization,a three-stage explicit Runge-Kutta method with TVD property is used at predicting stage,a cubic spline function is adopted at correcting stage,which made the time discretization accuracy up to fourth order;For spatial discretization,a three-point explicit compact difference scheme with arbitrary order accuracy is employed.The extended Boussinesq equations derived by Beji and Nadaoka are solved by the proposed scheme.The numerical results agree well with the experimental data.At the same time,the comparisons of the two numerical results between the present scheme and low accuracy difference method are made,which further show the necessity of using high accuracy scheme to solve the extended Boussinesq equations.As a valid sample,the wave propagation on the rectangular step is formulated by the present scheme,the modelled results are in better agreement with the experimental data than those of Kittitanasuan. 相似文献
9.
The Princeton Ocean Model with realistic bottom topography has been used to investigate the summer temperature decrease in
the past 25 years in Fukuoka Bay. The vertical mixing of the model is expressed by a scheme that effectively includes the
influences of interannual variations of tidal currents and wind. The results show that the historical temperature decrease
in summer has been caused by tidal currents and wind weakening in the past 25 years in Fukuoka Bay. The weakening of tidal
currents and wind gives rise to weakening of the vertical mixing, and to enhancement of the estuarine circulation in the bay.
The enhancement of the estuarine circulation activates the inflow of open-ocean water toward Fukuoka Bay. Coastal water in
summer has therefore tended to be colder and more saline in the past 25 years. This interannual variation in coastal waters
is called “open-oceanization” in this study. On the basis of the numerical model, it is anticipated that the temperature will
decrease by 0.2°C in the next 25 years in Fukuoka Bay if the tide and wind weaken persistently as in the present bay. 相似文献
10.