全文获取类型
收费全文 | 15577篇 |
免费 | 1360篇 |
国内免费 | 1731篇 |
专业分类
测绘学 | 2894篇 |
大气科学 | 1473篇 |
地球物理 | 2743篇 |
地质学 | 3201篇 |
海洋学 | 1584篇 |
天文学 | 197篇 |
综合类 | 1058篇 |
自然地理 | 5518篇 |
出版年
2024年 | 58篇 |
2023年 | 131篇 |
2022年 | 609篇 |
2021年 | 694篇 |
2020年 | 712篇 |
2019年 | 802篇 |
2018年 | 611篇 |
2017年 | 801篇 |
2016年 | 788篇 |
2015年 | 802篇 |
2014年 | 847篇 |
2013年 | 1241篇 |
2012年 | 891篇 |
2011年 | 878篇 |
2010年 | 655篇 |
2009年 | 790篇 |
2008年 | 832篇 |
2007年 | 909篇 |
2006年 | 837篇 |
2005年 | 719篇 |
2004年 | 653篇 |
2003年 | 533篇 |
2002年 | 470篇 |
2001年 | 369篇 |
2000年 | 348篇 |
1999年 | 276篇 |
1998年 | 252篇 |
1997年 | 230篇 |
1996年 | 182篇 |
1995年 | 122篇 |
1994年 | 93篇 |
1993年 | 88篇 |
1992年 | 91篇 |
1991年 | 48篇 |
1990年 | 50篇 |
1989年 | 42篇 |
1988年 | 40篇 |
1987年 | 30篇 |
1986年 | 23篇 |
1985年 | 39篇 |
1984年 | 25篇 |
1983年 | 15篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1971年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
Seasonal and Spatial Variations of Iceberg Drift off Dronning Maud Land, Antarctica, Detected by Satellite Scatterometers 总被引:1,自引:0,他引:1
Shigeru Aoki 《Journal of Oceanography》2003,59(5):629-635
Seasonal and spatial variations of iceberg drift were studied using continuous satellite scatterometer images off Dronning
Maud Land, East Antarctica. Generally, iceberg drift speed showed a westward increase to the Greenwich Meridian. Seasonal
variations of the drift speed were high in autumn—early winter and low in spring, and their magnitudes also increased westward.
Seasonal variations of the drift speed were significantly correlated with variations of sea levels at Syowa and Mawson Stations,
and hence qualitatively consistent with geostrophic current variations. Thus, the scatterometer data are demonstrated to be
useful in monitoring iceberg trajectory and oceanic current variations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
63.
青岛市大气污染时间序列分析预报方法研究 总被引:5,自引:0,他引:5
根据青岛市大气污染监测资料 ,采用时间序列分析方法 ,建立多种预报模型 ,有原序列周期外延法、均生函数周期外延法、均生函数逐步回归法以及自回归预报法等 ,最后提出一种综合预报模型。连续预报试验表明 ,综合预报模型优于任何个别预报模型 ,有较好的预报能力。利用马尔可夫概型对污染状态 (轻、中、重 )进行了分级预报试验 ,也获得良好的效果。 相似文献
64.
65.
Using meteorological data of field observation in 1990 - 2000, especially polar orbit high-resolution NOAA satellite cloud maps received from the Antarctic expedition vessel since 1997, the formation and development of the Prydz Bay cyclone are studied in this paper. Some new viewpoints are suggested such as: when surround-polar cyclone enters the Prydz Bay, it can also intensify and develop in summer; cyclone can also develop in the easterlies in this bay. These view points revise old uncom-plete view point that the Prydz Bay is a burial ground of cyclone, and also further consummate formation-development theory of surround-cyclone in the Antarctic westerlies and cyclone in the Antarctic easterlies. In this paper, the mechanism of ice-air-sea interaction in the Prydz Bay is studied, and the physical process of cyclone formation-development is explained. By use of wholly dynamic transportation method, an energy exchange case of a cyclone, which explosively developed after entering the Prydz Bay, is calcu 相似文献
66.
67.
68.
High-resolution underway temperature and conductivity measurements collected by R/V Knorr during winter and spring 2003 are used to characterize errors associated with spatial aliasing in the northern and central Adriatic Sea. During winter, 99th percentile temperature, salinity and density errors were 0.62 °C, 0.25 and 0.12 kg/m3 (0.25 °C, 0.10 and 0.05 kg/m3) for sampling at 10 km (5 km) horizontal resolution, respectively. The corresponding values in spring were 1.31 °C, 0.50 and 0.40 kg/m3 (0.93 °C, 0.25 and 0.22 kg/m3) for the 10 km (5 km) sample spacing, respectively. The largest errors were associated with energetic regions over the shallow, western Adriatic, in front of the Po River mouth and off the tip of the Istrian peninsula. The deeper eastern basin exhibited smaller errors. The variability of errors in time and space reflected the variability of small-scale density features, characterized by wavelengths as small as 2 km in winter and 1 km in spring and being more pronounced in the western and northern parts of the Adriatic. As these results indicate that errors associated with undersampling can be considerable, they should be taken into account while planning future CTD measurements in the region. 相似文献
69.
Based on Hong‘s theory, previous random models, and a generalized expression suitable for FIT calculation, the interaction between irregular waves and vertical walls is numerically simulated. The results of simulation demonstrate that the wave energy changes with the incidence angle and the distance from the wall. Particularly, the Mach effect and the combined wave spectrum characteristics are analyzed in detail, which are significant in both theory and practice. 相似文献
70.