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951.
Centroid Depth Versus Hypocentral Depth: Their Distribution and Depth/Mechanism Dependence 总被引:1,自引:0,他引:1
The Harvard Global CMT catalogue from 1977 to 1998 is analyzed to investigate the relation between the centroid depth and the hypocentral depth. It is observed that for shallow earthquakes, the hypocentral depth is systematically larger than the centroid depth, while for deep-focus earthquakes there is no statistically significant difference between the distributions of centroid and hypocentral depth. A detailed look at the result reveals that such a systematic difference is mainly from the contribution of thrust and normal earthquakes, while strike-slip earthquakes have no such regularity. It turns out that for shallow thrust and normal earthquakes, seismic rupture tends to initiate from the deeper part. 相似文献
952.
通过-工程实例指出,《建筑地基处理技术规范》JGJ79—9l地基承载力深度修正系数取1.0致使粗颗粒土在超过一定临界深度时地基处理是“无效”的,因而也是不合理的。 相似文献
953.
954.
The spatial and temporal variations in aerosols and precursor gases over oceanic regions have special importance in the estimation
of radiative forcing parameters and thereby in the refinement of general circulation models. Extensive observations of the
columnar aerosol optical depth (AOD), total column ozone (TCO) and precipitable water content (PWC) have been carried out
using the on-line, multi-band solar radiometers onboard ORV Sagar Kanya (Cruise # SK 147B) over Bay of Bengal during 11th–28th
August 1999. Aerosol optical and physical properties (optical depth and angstrom parameter) have been estimated at six wavelengths
covering from UV to NIR (380–1020 nm) while TCO and PWC have been determined using the UV band around 300 nm and NIR band
around 940 nm, respectively. Added, concurrent meteorological and satellite observations during this field phase of BOBMEX-99
have been utilized to investigate spectral-temporal variations of AOD, TCO and PWC in marine environment.
The results indicate lower AODs (around 0.4 at characteristic wavelength of 500 nm) and size distributions with abundance
of coarse-mode particles as compared to those aerosols of typical land origin. An interesting result that is found in the
present study is the significant reduction in AOD at all wavelengths from initial to later part of observation period due
to cloud-scavenging and rain-washout effects as well as signature of coastal aerosol loading. The clear-sky daytime diurnal
variation of TCO shows gradual increase during post-sunrise hours, broad maximum during afternoon hours and gradual decrease
during pre-sunset hours, which is considered to be due to photochemical reactions. The diurnal variation curve of PWC showed
maximum (~ 4 cm) during morning hours and gradual decrease (~ 3.5 cm) towards evening hours, which are found to be greater
as compared to typical values over land. Another interesting feature observed is that although the PWC values are very high,
there was no proportionate or appreciable enhancement in AOD—a feature that can be utilized to infer composition of aerosols
over the study region. 相似文献
955.
Antonio Jabaloy Jun-Carlos Balany Antonio Barnolas Jesús Galindo-Zaldívar F. Javier Hernndez-Molina Andrs Maldonado Jos-Miguel Martínez-Martínez Jos Rodríguez-Fernndez Carlos Sanz de Galdeano Luis Somoza Emma Suriach Jun Toms Vzquez 《Tectonophysics》2003,366(1-2):55-81
The lateral ending of the South Shetland Trench is analysed on the basis of swath bathymetry and multichannel seismic profiles in order to establish the tectonic and stratigraphic features of the transition from an northeastward active to a southwestward passive margin style. This trench is associated with a lithospheric-scale thrust accommodating the internal deformation in the Antarctic Plate and its lateral end represents the tip-line of this thrust. The evolutionary model deduced from the structures and the stratigraphic record includes a first stage with a compressional deformation, predating the end of the subduction in the southwestern part of the study area that produced reverse faults in the oceanic crust during the Tortonian. The second stage occurred during the Messinian and includes distributed compressional deformation around the tip-line of the basal detachment, originating a high at the base of the slope and the collapse of the now inactive accretionary prism of the passive margin. The initial subduction of the high at the base of the slope induced the deformation of the accretionary prism and the formation of another high in the shelf—the Shelf Transition High. The third stage, from the Early Pliocene to the present-day, includes the active compressional deformation of the shelf and the base-of-slope around the tip-line of the basal detachment, while extensional deformations are active in the outer swell of the trench. 相似文献
956.
957.
The atmospheric correction bands 7 and 8 (765nm and 865nm respectively) of the Indian Remote Sensing Satellite IRS P4-0CM
(Ocean Colour Monitor) can be used for deriving aerosol optical depth (AOD) over the oceans. A retrieval algorithm has been
developed which computes the AOD using band 7 data by treating the ocean surface as a dark background after removing the Rayleigh
path radiance in the sensor-detected radiances. This algorithm has been used to detect marine aerosol distributions at different
coastal and offshore locations around India.
A comparison between OCM derived AOD and the NOAA operational AOD shows a correlation ∼0.92 while that between OCM derived
AOD and the ground-based sun photometer measurements near the coast of Trivandrum shows a correlation of ∼0.90. 相似文献
958.
959.
利用GPS RTK等多源信号测算水库库容的应用研究 总被引:7,自引:0,他引:7
通过对某大型水库水下地形图绘制以及库容测算的成功试验,详细论述了基于GPSRTK配合测深仪绘制水库水下地形图库容测算的技术方案的可行性、工作流程和关键点。 相似文献
960.
过冷层状云中飞机播云有效区域的模拟研究 总被引:8,自引:2,他引:8
根据飞机人工增雨作业个例 ,利用层状云中催化剂输送扩散的三维时变模式 ,对过冷层状云中播云产生的有效区域、催化剂水平输送和扩散速率等进行了模拟研究。结果表明 :(1)飞机播云 4 5min线长 32 7km ,投影有效面积和有效体积在播云刚结束时 (5 0分 )达到极大 ,其值分别为 70 7km2 和 2 98.0km3 ,有效扩展宽度和厚度为 2 .5 1km和 0 .4 2km ;(2 )有效作用时段为 2 0~ 80min ,其间的投影有效面积平均值为 5 13.3km2 ,平均有效扩展宽度和厚度分别为 2 .4 1km和 0 .4 5km ;(3)在扩散作用下 ,投影有效面积和有效体积先随时间不断增加 ,达到极值后逐渐减小 ,播云结束 (5 5分 )后 ,云中的有效区域消失 ,其间的投影有效面积平均值为 389.7km2 ,平均有效扩展宽度和厚度分别为 2 .34km和 0 .4 4km ;(4)云中催化剂水平输送 1h的平均值达到 6 5km ,仅与风场有关。催化剂扩散速率 1h平均为 0 .82m/s,与风、温、湍流有关 ;(5 )在飞机增雨作业时 ,飞行方案的设计必须是严格科学的 ,以便进一步提高人工增雨的实效 相似文献