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991.
992.
宁芜中生代火山杂岩覆盖面积约1200km~2,累计厚度1920m左右,分五组,经筛选得出各组的标准岩石共22块,分别从矿物学特征和岩石化学判据上建立了区分各火山岩组的判别模型。在此基础上,用“标准岩石-阶段成图法”测制的岩性图、相图和组图,能较准确地反映出古火山岩地喷构造特征。 相似文献
993.
Electric resistance and emissions of hydrogen and radon isotopes of concrete (which is somewhat similar to fault-zone materials) under increasing uniaxial compression were continuously monitored to check whether they show any pre- and post-failure changes that may correspond to similar changes reported for earthquakes. The results show that all these parameters generally begin to increase when the applied stresses reach 20% to 90% of the corresponding failure stresses, probably due to the occurrence and growth of dilatant microcracks in the specimens. The prefailure changes have different patterns for different specimens, probably because of differences in spatial and temporal distributions of the microcracks. The resistance shows large co-failure increases, and the gas emissions show large post-failure increases. The post-failure increase of radon persists longer and stays at a higher level than that of hydrogen, suggesting a difference in the emission mechanisms for these two kinds of gases. The H2 increase may be mainly due to chemical reaction at the crack surfaces while they are fresh, whereas the Rn increases may be mainly the result of the increased emanation area of such surfaces. The results suggest that monitoring of resistivity and gas emissions may be useful for predicting earthquakes and failures of concrete structures. 相似文献
994.
大地电磁测深结果受表层构造横向不均匀性的影响,其视电阻率曲线会发生畸变。为了分析表层构造横向不均匀性对测深曲线的影响,本文采用有限单元方法对几种野外常见的表层横向不均匀构造进行了模拟计算。研究结果表明,表层构造的横向不均匀性对于测深曲线的影响是严重的 相似文献
995.
The nature of horizontal anomalies and anomalous current systems in the region of the southern Indian peninsula is theoretically
calculated with the aid of a thin sheet algorithm for northward and westward polarizations of a uniform inducing magnetic
Held of period 20 min. The numerical model of the geoelectric structure is the one devised by Agarwal and Weaver (1989). The
model results indicate the correspondence between the general features of the computed horizontal anomalies and the observed
anomalies both at temporary array stations and at two permanent magnetic observatories (ANN and TRD). On the basis of model
estimates of apparent resistivity and phase it is suggested that a one-dimensional interpretation of the sub-surface conductivity
structure is valid near two of the array stations, whereas at all other coastal and inland stations, two-or three-dimensional
interpretations of magnetotelluric (MT) data are required. 相似文献
996.
V. C. Thakur 《Journal of Earth System Science》1990,99(2):169-185
The Indus Tsangpo suture zone in Ladakh lies between the Phanerozoic sequence of the Zanskar Zone of Tethys Himalaya in the
south and Karakoram zone in the north. The five palaeotectonic regimes recognized in the suture zone are: The Indus palaeosubduction
complex, the Ladakh magmatic arc, the Indus arc-trench gap sedimentation, the Shyok backarc and the Post-collision molasse
sedimentation. The Ladakh magmatic arc, comprising intrusives of the Ladakh plutonic complex and extrusives of the Dras, Luzarmu
and Khardung formations, owes its origin to the subduction of the Indian oceanic plate underneath the Tibet-Karakoram block.
The Indus Formation, lower Cretaceous to middle Eocene in age, was laid down in a basin between the magmatic arc and the subduction
complex. The Shergol and Zildat ophiolitic melange belts exhibit green-schist and blue-schist facies metamorphism and show
structural geometry and deformation history dissimilar to that of the underlying and overlying formations. The melange belts
and the flysch sediments of the Nindam Formation represent a palaeosubduction complex. The Shyok suture zone consists of tectonic
slices of metamorphics of the Pangong Tso Crystallines, Cretaceous to lower Eocene volcanics and sedimentaries, together with
ultramafic and gabbro bodies and molasse sediments. This petrotectonic assemblage is interpreted as representing a back-are
basin. Post-collision molasse sedimentaries are continental deposits of Neogene age, and they occur with depositional contact
transgressing the lithological and structural boundaries. Two metamorphic belts, the Tso Morari crystalline complex and the
Pangong Tso Crystallines, flank to the south and north respectively of the Indus suture zone in Eastern Ladakh. Three generations
of fold structures and associated penetrative (and linear) structures, showing a similar deformation history of both the metamorphic
belts, are developed. The shortening structures developed as a result of collision during the postmiddle Eocene time. 相似文献
997.
The magnetic method is the oldest and one of the most widely used geophysical techniques for exploring the earth’s subsurface.
It is a relatively easy and inexpensive tool to employ, being applicable to a wide variety of subsurface exploration problems
involving horizontal magnetic property variations occurring from near the base of the crust to within the uppermost meter
of soil. Successful applications of the magnetic method require an in-depth understanding of its basic principles and careful
field work, data reduction, and interpretation. Commonly, interpretations are limited to qualitative approaches which simply
map the spatial location of anomalous subsurface conditions, but under favourable circumstances the technological status of
the method will permit more quantitative interpretations involving specification of the nature of the anomalous sources. No
other geophysical method provides critical input to such a wide variety of problems. However, seldom does the magnetic method
provide the complete answer to an investigation problem. As a result, it is generally used in concert with other geophysical
and geological data to limit its interpretational ambiguities. 相似文献
998.
曹庄片麻杂岩包括35亿年的表壳岩及三个不同时期的复期正片麻岩。水厂片麻杂岩包括水厂表壳岩及侵入其中的淡花岗岩和紫苏花岗岩,后者年龄为26.5亿年。 相似文献
999.
1000.
煤电阻率与其瓦斯含量关系的实验研究 总被引:1,自引:0,他引:1
煤体中的瓦斯含量能显著影响煤的电阻率,本文利用高精度电阻测试实验装置,在连续吸附/解吸与等体积吸附/解吸条件下,对煤样的电阻率随瓦斯含量的变化规律进行测定。研究结果表明:煤样在连续吸附/解吸与等体积吸附/解吸条件下,电阻率随着瓦斯吸附量增大先逐渐减小,后趋于平稳;等体积吸附(静态吸附)时电阻率改变较连续吸附(动态吸附)明显,且等体积解吸结束时,煤体电阻率距离原始值较远;在瓦斯解吸过程中,煤体电阻率随煤中瓦斯含量增大呈线性减小。研究结果为利用煤体电阻率与瓦斯含量的线性关系预测矿井瓦斯含量提供了理论依据,对指导现场的瓦斯含量测量具有重要意义。 相似文献