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961.
962.
可降水量资料反演及在暴雨数值模拟中的初步应用 总被引:4,自引:2,他引:4
通过同化可降水资料改善模式初始湿度场从而提高暴雨模拟与预报效果。首先应用适时回归方法反演大气可降水量资料,然后以1998年6月18—19日暴雨模拟为例,采用变分同化方法研究了可降水量资料在暴雨数值模拟中的作用。数值模拟结果表明:1)MM5模式中同化可降水量资料后,对于雨带位置的模拟效果起到很大的改善;亦可改进暴雨降水强度的模拟效果,改进程度与降水参数化方案有关。2)同化可降水量资料后,明显改善初始湿度场,在一定程度上缓解旋转加强(spin up)问题,从而有效地提高降水模拟效果。3)降水模拟对参数化方案的选取同样敏感,改进初始湿度场的同时应该选择相应的降水参数化方案。 相似文献
963.
A semi‐active fuzzy control strategy for seismic response reduction using a magnetorheological (MR) damper is presented. When a control method based on fuzzy set theory for a structure with a MR damper is used for vibration reduction of a structure, it has an inherent robustness, and easiness to treat the uncertainties of input data from the ground motion and structural vibration sensors, and the ability to handle the non‐linear behavior of the structure because there is no longer the need for an exact mathematical model of the structure. For a clipped‐optimal control algorithm, the command voltage of a MR damper is set at either zero or the maximum level. However, a semi‐active fuzzy control system has benefit to produce the required voltage to be input to the damper so that a desirable damper force can be produced and thus decrease the control force to reduce the structural response. Moreover, the proposed control strategy is fail‐safe in that the bounded‐input, bounded‐output stability of the controlled structure is guaranteed. The results of the numerical simulations show that the proposed semi‐active control system consisting of a fuzzy controller and a MR damper can be beneficial in reducing seismic responses of structures. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
964.
当代摄影测量与遥感技术的迅速发展,已经步入大数据时代,如何对获得的海量数字影像的辐射质量进行评价是一个值得重视的问题。本文从信息量、清晰度、灰度分布3个方面选择了10个评价指标作为影像特征,利用支持向量机监督学习的方法对以资源三号为例的遥感影像的辐射质量进行评价及结果分析。试验结果表明,本文方法得到的评价结果与人工评价结果较为一致,准确度较高,并且自动化程度高,可应用于遥感影像的辐射质量评价。 相似文献
965.
This study is based on a series of numerical modeling experiments to understand the tidal circulation in the Kangjin Bay (KB).
The tidal circulation in the KB is mostly controlled by the inflow from two channels, Noryang and Daebang which introduce
the open ocean water into the northern part of the KB with relatively strong tidal current, while in the southern part of
the KB, shallowest region of the entire study area, weak tidal current prevails. The model prediction of the sea level agrees
with observed records at skill scores exceeding 90 % in terms of the four major tidal constituents (M2, S2, K1, O1). However,
the skill scores for the tidal current show relatively lower values of 87, 99, 59, 23 for the semi-major axes of the constituents,
respectively. The tidal ellipse parameters in the KB are such that the semi-major axes of the ellipse for M2 range from 1.7
to 38.5 cm/s and those for S2 range from 0.5 to 14.4 cm/s. The orientations of the major-axes show parallel with the local
isobath. The eccentricity values at various grid points of ellipses for M2 and S2 are very low with 0.2 and 0.06 on the average,
respectively illustrating that the tidal current in the KB is strongly recti-linear. The magnitude of the tidal residual current
speed in the KB is on the order of a few cm/s and its distribution pattern is very complex. One of the most prominent features
is found to be the counter-clockwise eddy recirculation cell at the mouth of the Daebang Channel. 相似文献
966.
Recent sediment accumulation and origin of shelf mud deposits in the Yellow and East China Seas 总被引:3,自引:0,他引:3
Modern (last 100 yr) accumulation rates of shelf mud deposits in the Yellow and East China Seas were investigated using the distribution of excess 210Pb (210Pbex) in sediment core samples. Compilation and merger of new and previously published data helped clarify sediment accumulation in these seas. The estimated accumulation rates, together with data of suspended sediment concentrations, provided findings on the sediment budget, origin, and transport pathway of the mud deposits. The overall accumulation distribution in the Yellow and East China Sea shelf revealed a general, cross-shelf decreasing trend along the sediment dispersal system away from the rivers, except for the South Sea (SSM) and southeastern Yellow Sea (SEYSM) mud patches found along the Korean coast. Notably, 210Pbex activity profiles within the SSM and the SEYSM yielded a relatively high accumulation rate of 2-5 mm/yr, implying a sedimentation rate of 4-15 × 107 tons per year in this coastal zone. Such an annual accumulation rate is about one order of magnitude greater than the total sediment discharge (6-20 × 106 tons/yr) from Korean rivers, suggesting an additional offshore source. The distribution pattern of the well-defined suspended plume clearly showed the possible transport and exchange of fine-grained sediments between the ECS shelf and the coastal area of Korea, especially during winter. Such a high accumulation in Korean coastal areas is attributable to the sediments supplied from the mud deposit of the ECS (i.e., SWCIM), with origins in Chinese rivers. Therefore, the Korean coastal area may be an important sink for some of Chinese river sediments being transported from the south by the Yellow Sea Warm Current. 相似文献
967.
Jin Yeong Kim Il Su Choi Joo Il Kim Seok Gwan Choi Young Yull Chun 《Ocean Science Journal》2007,42(1):41-48
We investigated the temperature and salinity effects on the major fish species in the wintering grounds based on trawl surveys
and oceanographic observations in the southwestern waters of Korea during March-early April in 2002-2003. The influence area
of warm Kuroshio water was limited to the southwestern area of Korea in 2003 with a range of 7.7-16.3°C, 32.54-34.70 of salinity,
wider than that of 2002. The number of fish species and density of major fish species in 2003 were higher than in 2002. Geographical
estimation showed high proportions of species number and catches in the areas around Jeju Islands, southwestern waters and
the southeastern coast of Korea. Five species; silver pomfret (Pampus echinogaster), hairtail (Trichiurus lepturus), anchovy (Engraulis japonicus), small yellow croaker (Larimichthys polyactis) and yellow goosefish (Lophius litulon) were most abundant, composing above 60% of the total catch in 2002 and 2003. More than 50% of catch in the major fish species
were mostly distributed in the range of 9.5-11.0°C of temperature and 33.1-33.9 of salinity. Non-parametric estimation for
the major species showed the 1st mode around 10°C and the 2nd mode at 8-9°C in 2002 and 11-14°C in 2003. A m o n g major fish
species, hairtail was principally composed of juveniles, and larger individuals were caught in southeastern waters. These
results are considered to be helpful for the areabased fishery management strategy for the wintering grounds of the Yellow
Sea and coastal waters of Korea. 相似文献
968.
B.H. Choi 《Progress in Oceanography》1986,17(3-4)
Two typhoon surges generated during July–August 1978 are investigated numerically with the use of a vertically-integrated finite-difference model of the Yellow Sea and the East China Sea. The hindcast scheme involves processing pressure data from weather charts to provide the necessary meteorological forcing to a sea model that computes the response in terms of water levels and currents. Computed residuals are compared with hourly records from selected tide gauges (Inchon, Kunsan, Mokpo, Jeju and Yeosu) along the coast of Korea. Some of the preliminary results are presented and discussed. 相似文献
969.
ThreeSynechococcus strains were isolated from seawater near the Ieodo Ocean Research Station (IORS), and their 16S rDNA genes and the internal
transcribed spacer (ITS) between the 16S and 23S rRNA genes were sequenced to investigate their phylogenetic relationships.
Phylogenetic trees based on the 16S rDNA and ITS sequences showed that they clustered in the main MC-ASynechococcus group (subcluster 5.1), but formed branches differentiating them from the described clades. As the IORS is located in an
area affected by diverse water masses, highSynechococcus diversity is expected in the area. Therefore, the IORS might be a good site to study the diversity, physiology, and distribution
of theSynechococcus group. Key words —Synechococcus, Phylogeney, 16S rRNA, ITS gene, Ieodo 相似文献
970.
A coupled ice-ocean isopycnal numerical model of the Southern Ocean is established tostudy the circulation and its seasonal variability in the region around the Kerguelen Plateau. An analysis of the simulated results shows significant stripe-like structure and non-zonal feature of the Antarctic Cir-cumpolar Current (ACC) in this region. ACC begins to bifurcate and to turn its direction before meeting the plateau. The southernmost branch of ACC is near to the Antarctic coast and displays its strong interaction with the westward Antarctic Slope Current. The northern branch of ACC has a tendency of annual variations while the southern one varies in a semiannual cycle. The variation phases of both branches are coincident with that of the wind stress in this region. 相似文献