全文获取类型
收费全文 | 430篇 |
免费 | 42篇 |
国内免费 | 27篇 |
专业分类
测绘学 | 138篇 |
大气科学 | 5篇 |
地球物理 | 73篇 |
地质学 | 15篇 |
海洋学 | 184篇 |
天文学 | 10篇 |
综合类 | 47篇 |
自然地理 | 27篇 |
出版年
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 11篇 |
2019年 | 14篇 |
2018年 | 6篇 |
2017年 | 17篇 |
2016年 | 16篇 |
2015年 | 34篇 |
2014年 | 20篇 |
2013年 | 65篇 |
2012年 | 16篇 |
2011年 | 10篇 |
2010年 | 15篇 |
2009年 | 16篇 |
2008年 | 27篇 |
2007年 | 29篇 |
2006年 | 19篇 |
2005年 | 19篇 |
2004年 | 32篇 |
2003年 | 27篇 |
2002年 | 8篇 |
2001年 | 20篇 |
2000年 | 11篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有499条查询结果,搜索用时 15 毫秒
51.
Mesoscale surface circulation and variability of Southern Indian Ocean derived by combining satellite altimetry and drifter observations 总被引:1,自引:1,他引:0
BENNY N. Peter SHENBAKAVALLI Ranjan MAZLAN Hashim MOHD Nadzri Re MOHD Razali Mahmud 《海洋学报(英文版)》2015,34(9):12-22
High resoultion Eulerian mean velocity field has been derived by combining the satellite tracked surface drifter data with satellite altimetry and ocean surface winds. The drifter data used in this study includes Argos and surface drifter data from Global Drifter Program. Maps of Sea Level Anomaly(MSLA) weekly files with a resolution of(1/3)° in both Latitude and Longitude for the period 1993–2012 have been used. The Ekman current is computed using ocean surface mean wind fields from scatterometers onboard ERS 1/2,Quikscat and ASCAT. The derived mean velocity field exhibits the broad flow of Antarctic Circumpolar Current with speeds up to 0.6 m/s.Anomalous field is quite significant in the western part between 20° and 40°E and in the eastern part between 80°E and 100°E with velocity anomaly up to 0.3 m/s. The estimated mean flow pattern well agrees with the dynamic topography derived from in-situ observations. Also,the derived velocity field is consistent with the in-situ ADCP current measurements. Eddy kinetic energy illustrates an increasing trend during 1993–2008 and is in phase coherence with the Southern Annular Mode by three month lag. Periodic modulations are found in the eddy kinetic energy due the low frequency Antarctic Circumpolar Wave propagation. 相似文献
52.
CryoSat-2卫星海冰区域波形识别及海冰干舷高确定 总被引:1,自引:0,他引:1
利用40%阈值法对CryoSat-2卫星波形数据进行重跟踪,将波形特征参数和海冰浓度相结合,对海冰和Lead(浮冰之间的开阔水域)进行有效识别。利用沿轨前后搜索算法计算海冰干舷高,并引用AWI结果,绘制2011~2013年北冰洋多年冰区域和一年冰区域平均海冰干舷高变化趋势图。比较本文结果与AWI结果的各年同期数据,验证本文结果的可靠性。 相似文献
53.
针对多源星载激光测高数据监测湖泊水位变化问题,该文选取2003—2009年ICESat/GLAH14全球地表高程数据、2018年10月—2019年8月的ICESat-2/ATL13全球内陆水体高程数据,提取丹江口水库多期水位变化数据,最后利用水位站实测水位对其准确度进行了验证,并分析了丹江口水库年度水位变化规律。结果表明,丹江口水库水位呈现明显的季节性变化,每年11月达到较高水位,3月降至较低水位;由ICESat/GLAH14数据估算水库水位的精度为16 cm,ICESat-2/ATL13数据集估算水库水位的精度达到10 cm。因此,ICESat-2/ATL13数据用于内陆水体水位变化监测具有很高的可行性。 相似文献
54.
《Polar Science》2014,8(1):10-23
This study compares the common harmonic constants of the O1, K1, P1, Q1, M2, S2, N2, and K2 tidal constituents from eight global and four regional tide models with harmonic constants from satellite altimeter and tide gauge data for the northern region of the Antarctic Peninsula (58°S–66°S, 53°W–66°W). To obtain a more representative comparison, the study area was divided into three zones with different physical characteristics but similar maximum tidal amplitude variations: Zone I (north of 62°S), Zone II (south of 62°S and west of the Antarctic Peninsula), and Zone III (between 62°S and 64.3°S, and east of 58.5°W). Root sum square (RSS) values are less than or equal to 3.0, 4.2, and 8.4 cm for zones I, II, and III, respectively. No single model shows superior performance in all zones. Because there are insufficient satellite altimetry observations in the vicinity of Matienzo Base (64.9761°S, 60.0683°W), this station was analyzed separately and presents the greatest values of both root mean square misfit and RSS. The maximum, minimum, and average amplitude values of the constituents that follow in importance after the eight common tidal constituents, and which have amplitudes greater than 1 cm, are also analyzed. 相似文献
55.
56.
利用苏门答腊附近海域T/P、Jason-1测高卫星近20年的海面高连续观测资料,分别计算了该区域(80°E~105°E,5°S~20°N)在2004年苏门答腊大地震前后的海面高变化趋势,并与该区域对应时间段GRACE重力卫星反演的地表质量迁移结果进行比较。研究结果表明,由卫星测高观测资料估算的震区地震前后海平面趋势的变化与卫星重力反演结果基本一致。由于卫星测高沿轨观测具有高精度、高时空分辨率的特性,卫星测高资料估算的海平面趋势变化可以更为准确地反映震区海平面变化的局部特征。还对该区域震后形变特征进行了初步分析。 相似文献
57.
????2004??2008???ICESat???????????????GLA12???????????????????????????????????????仯????????????????????????????????????仯??????????????????????????????3 m??????????????????????仯????????????????????????????????? 相似文献
58.
基于卫星高度计的北极海冰厚度变化研究 总被引:5,自引:3,他引:2
A modified algorithm taking into account the first year(FY) and multiyear(MY) ice densities is used to derive a sea ice thickness from freeboard measurements acquired by satellite altimetry ICESat(2003–2008). Estimates agree with various independent in situ measurements within 0.21 m. Both the fall and winter campaigns see a dramatic extent retreat of thicker MY ice that survives at least one summer melting season. There were strong seasonal and interannual variabilities with regard to the mean thickness. Seasonal increases of 0.53 m for FY the ice and 0.29 m for the MY ice between the autumn and the winter ICESat campaigns, roughly 4–5 month separation, were found. Interannually, the significant MY ice thickness declines over the consecutive four ICESat winter campaigns(2005–2008) leads to a pronounced thickness drop of 0.8 m in MY sea ice zones. No clear trend was identified from the averaged thickness of thinner, FY ice that emerges in autumn and winter and melts in summer. Uncertainty estimates for our calculated thickness, caused by the standard deviations of multiple input parameters including freeboard, ice density, snow density, snow depth, show large errors more than 0.5 m in thicker MY ice zones and relatively small standard deviations under 0.5 m elsewhere. Moreover, a sensitivity analysis is implemented to determine the separate impact on the thickness estimate in the dependence of an individual input variable as mentioned above. The results show systematic bias of the estimated ice thickness appears to be mainly caused by the variations of freeboard as well as the ice density whereas the snow density and depth brings about relatively insignificant errors. 相似文献
59.
A laser altimeter, making 4000 measurements per second, was used to measure channel and gully morphology. The laser measurements provide quick, accurate and readily obtained data on the cross-section and morphology of channels and gullies in relation to the adjacent landscape. Although ground based techniques can be used to make these measurements, using a laser altimeter mounted in an aircraft allows data to be collected faster, with greater density and detail, and in areas with limited access for ground surveys. The laser altimeter data are valuable for measuring channel and gully cross-sections and roughness in relation to the surrounding landscape, for assessing soil loss from gullies and channels, and for providing input to the understanding of gully and channel dynamics in the landscape. 相似文献
60.