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871.
Investigation of changes in characteristics of hydrological time series by Bayesian methods 总被引:1,自引:0,他引:1
A. Ramachandra Rao Wahju Tirtotjondro 《Stochastic Environmental Research and Risk Assessment (SERRA)》1996,10(4):295-317
A review of literature reveals the inadequacy of Intervention analysis and spectrum based methods to adequately quantify changes in hydrologic times series. A Bayesian method is used to investigate the statistical significance of observed changes in hydrologic times series and the results are reported herein. The Bayesian method is superior to the previous methods. 相似文献
872.
V. V. L. N. Sarma G. Murali Krishna B. Hema Malini K. Nageswara Rao 《Journal of the Indian Society of Remote Sensing》2001,29(1-2):85-91
Interpretation of multi-date satellite imagery has revealed changes in land use/land cover pattern in the Godavari deltaic region during the past 26 years. The area under intensive agriculture has increased from 1459 to 3500 km2 and the extent of wetland from 368 to 648 km2 during the period 1973-1999, while the seasonal fallow has decreased by 2321 km2. Analysis of the climatic data of 1970-1998 from different stations covering the entire 5100 km2 area of the delta indicated that the day time temperatures have decreased by 0.2° C to 0.7° C, while the night time temperatures have increased by 0.5° C to 0.6° C during the past three decades. At the same time the rainfall has increased by about 75 to 479 mm. These trends in the climatic parameters arc attributed to the increased vegetation cover and wetland extent in the Godavari deltaic region. 相似文献
873.
论长英质隐爆角砾岩的气热流体溶浸成矿机制——以赣南6722铀矿床为例 总被引:6,自引:1,他引:6
通过对6722铀矿床地质-地球化学特征及长英质隐爆角砾岩和围岩超微构造研究,结合U,Th等元素溶浸实验结果,得出“隐爆气热流体溶浸成矿富集机制”;来自深部的富含挥发组分(H2O、F、CO2等)的高热安粗岩浆,在早白垩世末(107Ma)沿富城花岗岩体西部蚀变带发育的火山机构中发生隐爆作用,致使围岩发生强烈脆性变形,生成长英质隐爆角砾岩带和震裂花岗岩带;压力、温度降低导致安粗岩浆中挥发组分逸出形成气热流进入稳隐爆裂隙中,并将蚀变花岗岩中的活动性成矿元素(U)浸出转移;成矿物质在物理化学条件(p,t,Eh,pH,化学组分等)急剧变化的部位(长英质隐爆角砾岩及碎裂花岗岩)沉淀富集。 相似文献
874.
875.
Boby Mathew B. M. Pathan K. N. Iyer D. R. K. Rao 《Journal of Earth System Science》1991,100(4):331-340
Using simultaneous long-term observations of ionospheric scintillation at equator and anomaly crest region in the same longitude
(Indian) zone comparative features of scintillation occurrence are brought out. The salient features are: (a) predominantly
pre-midnight occurrence of scintillation at equator during winter and equinox seasons, (b) increase of pre-midnight scintillation
occurrence with solar activity (c) shifting of occurrence peak during summer from post-midnight in low to pre-midnight in
high solar activity periods (d) similarity of scintillation behaviour at these locations during winter and equinoxes but dissimilarity
during summer. The solar activity response and magnetic effects indicate that the scintillations at the anomaly crest region
in winter and equinox, particularly during high solar activity periods, are of equatorial origin while the summer events may
be of local or mid-latitude origin. 相似文献
876.
Preliminary analysis of seismograms recorded by a wide band high dynamic range digital seismograph installed under a collaborative
research programme between IPG, Paris and NGRI, Hyderabad, indicates that the crust and upper mantle structure below the Indian
continent are characterized by high velocity up to a depth of 500 km. Both the group and phase velocities in the period range
of 100–350s are found to be faster by 3–4% and 1–3% respectively compared with global models such as the preliminary reference
earth model. 相似文献
877.
An analytical method based on Penny-Taylor model has been modified and applied for the estimation of the final cavity radius
for contained peaceful nuclear explosions. The calculated cavity radii for some nuclear explosions in granite, alluvium and
sandstone rocks are in good agreement with measured values. 相似文献
878.
Detectable ionization effects in the ionosphericD-region from individual, strong and steady x-ray sources such as Sco X-1 and transient x-ray sources such as Cet X-2 have been reported by us and many others previously based on the field strength and phase variations of the VLF data. As a follow up to these investigations, we have examined the integrated effects of many of the known x-ray sources discovered by UHURU, ANS, Ariel V and SAS-3 satellites, in order to understand the totality of their effects. These effects are examined in the present paper for 0° and +38° geographic latitudes corresponding to midnight conditions and for different times of the year. Such effects are compared, in turn, with those of the known steady sources responsible forD-region ionization such as Lyman-alpha and galactic cosmic radiations. The results are presented as profiles of electron production rates as a function of height. Our study leads to the conclusion that there should be detectable annual variations of the electron density which are pronounced around May-August. Further, the results of the computations on electron production rates corresponding to the spectacular x-ray nova A0620-00 are also included in the present paper. 相似文献
879.
The evolution and structure of the steady state of an idealized nocturnal drainage flow over a large uniformly-sloping surface are studied using a nonstationary model with a height-dependent eddy diffusivity profile and a specified surface cooling rate. The predicted mean velocity and temperature profiles are compared with Prandtl's stationary analytical solutions based on the assumption of a constant eddy diffusivity in the drainage layer. The effects of important physical parameters, such as the slope angle, surface cooling, atmospheric stability, and surface roughness, on the steady drainage flow are investigated.Affiliated with Oak Ridge Associated Universities (ORAU). 相似文献
880.