全文获取类型
| 收费全文 | 2134篇 |
| 免费 | 690篇 |
| 国内免费 | 364篇 |
专业分类
| 测绘学 | 150篇 |
| 大气科学 | 78篇 |
| 地球物理 | 312篇 |
| 地质学 | 1380篇 |
| 海洋学 | 199篇 |
| 天文学 | 721篇 |
| 综合类 | 116篇 |
| 自然地理 | 232篇 |
出版年
| 2024年 | 7篇 |
| 2023年 | 18篇 |
| 2022年 | 65篇 |
| 2021年 | 76篇 |
| 2020年 | 68篇 |
| 2019年 | 106篇 |
| 2018年 | 85篇 |
| 2017年 | 101篇 |
| 2016年 | 96篇 |
| 2015年 | 99篇 |
| 2014年 | 118篇 |
| 2013年 | 159篇 |
| 2012年 | 120篇 |
| 2011年 | 135篇 |
| 2010年 | 149篇 |
| 2009年 | 205篇 |
| 2008年 | 134篇 |
| 2007年 | 167篇 |
| 2006年 | 191篇 |
| 2005年 | 151篇 |
| 2004年 | 140篇 |
| 2003年 | 133篇 |
| 2002年 | 93篇 |
| 2001年 | 89篇 |
| 2000年 | 93篇 |
| 1999年 | 96篇 |
| 1998年 | 56篇 |
| 1997年 | 44篇 |
| 1996年 | 31篇 |
| 1995年 | 38篇 |
| 1994年 | 40篇 |
| 1993年 | 17篇 |
| 1992年 | 20篇 |
| 1991年 | 8篇 |
| 1990年 | 13篇 |
| 1989年 | 3篇 |
| 1988年 | 7篇 |
| 1987年 | 3篇 |
| 1986年 | 3篇 |
| 1985年 | 4篇 |
| 1984年 | 2篇 |
| 1983年 | 1篇 |
| 1982年 | 1篇 |
| 1981年 | 1篇 |
| 1979年 | 2篇 |
排序方式： 共有3188条查询结果，搜索用时 218 毫秒
21.
22.
23.
24.
25.
Li Yucheng He Ming Professor Dalian University of Technology Dalian Former master student Dalian University of Technology Dalian 《中国海洋工程》1994,(3)
-Based on the extended Morison Equation and model tests, the in-line forces on small square cylinders caused by waves (regular and irregular) and currents are analyzed in detail in this paper. The hydrodynamic coefficient CD and Cu related to KC number and the effect of direction of wave incidence are also given, which can be used in engineering practice. 相似文献
26.
小直径组合桩的波浪力实验分析 总被引：2，自引：1，他引：2
本文给出小直径孤立桩、两个桩和2×2个桩的波浪作用力实验结果。在波浪水槽中以0°,45°,90°三个波浪方向测量了各桩所受的纵向力和横向力,文中讨论了组合桩之间的干扰效应,给出了干扰系数随KC数和桩距的变化。 相似文献
27.
本文提出在小偏心受压构件正截面强度计算中，取消弯曲抗压强度ｆｃｍ（Ｒｗ），采用轴心抗压强度ｆｃ，这与构件的实际破坏形态相符。对小偏心受压构件正截面强度计算提出了设计建议。特别是对工程上大量应用的矩形截面对称配筋小偏压构件提示了简捷的设计方法，与以往的近似计算方法相比具有物理概念明确，精度高，方法简捷的特点。 相似文献
28.
29.
Spatio-temporal variability of small copepods (especially Oithona plumifera) in shallow nearshore waters off the south coast of South Africa 总被引：1，自引：0，他引：1
Francesca Porri Christopher D. McQuaid William P. Froneman 《Estuarine, Coastal and Shelf Science》2007,72(4):711-720
Although small copepods are one of the main dietary sources for many commercially important fish, their role in the pelagic trophic dynamics has traditionally been underestimated due to the methodology commonly used in plankton sampling. Temporal variation in abundance of adults and nauplii of small copepods (particularly Oithona plumifera) in nearshore waters on the south coast of South Africa was investigated fortnightly over 14 months at site (km) and location (100 m) scales. Sampling was within <500 m of the shore, where depth was ca. 10 m, using vertical hauls of an 80-μm mesh plankton net from 1 m above the seabed to the surface. Twenty-seven adult copepod taxa were recorded, but Oithona spp. was consistently the most abundant. Taxon richness was 7–19 on each sampling occasion. There was strong temporal variation (Oithona varied between 0 and 2300 m−3), but much of this was short-term variability (e.g. between consecutive sampling sessions), with no seasonality or other long-term discernable patterns. There were periods of consistently low numbers, but very high numbers often followed samples with low abundances. Nor was there spatial structure at the location scale, though numbers differed between sites. Despite considerable variability at the location scale within sites, Kenton consistently showed higher densities than High Rocks. Separate analyses, with Bonferroni adjustment, showed that this difference was significant on eight out of 21 occasions for Oithona, six for other pelagic copepods and three for nauplii. This suggests that hydrodynamics favour aggregation of plankton at Kenton. A high degree of short-term variability, with a tendency for aggregation of small zooplankton at certain sites has implications for both pelagic processes and food-web links between the benthic and pelagic environments. 相似文献
30.