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981.
982.
High resolution sediment physical properties, measured on gravity and piston cores collected during cruises to Lake Winnipeg, include bulk density, acoustic velocity, magnetic susceptibility, shear strength and colour reflectance. The high resolution data are used here to construct complete stratigraphic (composite) sections of Lake Winnipeg sediments from a series of individual, discontinuous cores for the North and South Basins. These composite sections are used to evaluate basin-wide glacial and post-glacial depositional histories and to compare the northern and southern basin histories. In addition, these sections provide a baseline depth reference for interpretation of the biostratigraphy, paleomagnetic record and rock magnetic stratigraphy. Some of the data (density and shear strength) are also be used to estimate sediment stress history for the two major lithostratigraphic units and their variations across the basin. 相似文献
983.
土壤风蚀中有关土壤性质因子的研究历史与动向 总被引:10,自引:1,他引:9
国外土壤风蚀中有关土壤性质因子的研究历史可分为四个阶段:第一,定性描述阶段;第二,定量实验研究阶段;第三,运用综合因子建立和完善“通用风蚀方程式”阶段;第四,土壤风蚀土壤亚模型和预测系统的建立和动态研究阶段。国内对土壤风蚀的研究起步较晚,对于不同土类的土壤物理化学性质对风蚀的影响尚没有作深入研究。其历史大致可分为二个阶段:第一,野外观测研究;第二,风蚀的半定量实验研究。目前正由半定量向定量化、标准化、国际化以及动态研究方向发展。 相似文献
984.
Micro-fine disseminated gold deposits are hosted in the Triassic Baipeng Formation (argillaceous siltstone and arenaceous mudstone)in the Youjiang Rift,South China.Physical properties(grain size,specific surface,porosity and permeability)of the host rocks are studied with respect to ore-fluid cirulation,water-rock reaction and the effective volume from which ore-components could be extracted.On this basis,it is considered that the ore-fluid and oremetals were extracted mainly from the strata and hydrothermal solutions,tending to move to wards low-energy sites,depositing their gold in fault zones at the margins of the basin and in the circle fracture systems around underwater uplifts.The gold deposits resulted from the deepcirculation of hydrothermal solutions,Probably aided by multi-stage superimposition The quantites of ore-fluid necessary to form the deposits were estimated. 相似文献
985.
煤系岩石工程地质性质指标变异性研究 总被引:2,自引:0,他引:2
对山东金山矿区3煤覆岩及底板工程地质性质类型的物理力学性质指标的变异性进行了研究,用K-S法进行的概率分布类型拟合检验表明,各指标基本服从正态分布;另外,还对煤系岩石物理力学性质指标的关联性及各向异性特征进行了初步分析,为煤矿工程地质可靠度研究提供了依据。 相似文献
986.
Dejun LI Chuanfeng ZHAO Peiren LI Cao Liu Dianli GONG Siyao LIU Zhengteng YUAN Yingying CHEN 《大气科学进展》2022,39(12):2040-2055
This study investigates the cloud macro- and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in Shandong province on 21 May 2018, based on the observations from the aircraft, the Suomi National Polar-Orbiting Partnership (NPP) satellite, and the high-resolution Himawari-8 (H8) satellite. The aircraft observations show that convection was deeper and radar echoes were significantly enhanced with higher tops in response to seeding in the convective region. This is linked with the conversion of supercooled liquid droplets to ice crystals with released latent heat, resulting in strengthened updrafts, enhanced radar echoes, higher cloud tops, and more and larger precipitation particles. In contrast, in the stratiform cloud region, after the Silver Iodide (AgI) seeding, the radar echoes become significantly weaker at heights close to the seeding layer, with the echo tops lowered by 1.4–1.7 km. In addition, a hollow structure appears at the height of 6.2–7.8 km with a depth of about 1.6 km and a diameter of about 5.5 km, and features such as icing seeding tracks appear. These suggest that the transformation between droplets and ice particles was accelerated by the seeding in the stratiform part. The NPP and H8 satellites also show that convective activity was stronger in the convective region after seeding; while in the stratiform region, a cloud seeding track with a width of 1–3 km appears 10 km downstream of the seeding layer 15 minutes after the AgI seeding, which moves along the wind direction as width increases. 相似文献
987.
利用2010—2020年黑龙江省龙凤山区域大气本底站气溶胶光学特性长期观测资料, 分析并探讨了背景地区气溶胶光学厚度、波长指数、单次散射反照率、粒子体积谱分布以及气溶胶直接辐射强迫效应的变化特征。结果表明: 龙凤山区域气溶胶光学厚度最高值出现在7月, 平均值为0.67;最小值出现在12月、1月和2月, 平均值分别为0.17、0.02和0.18;气溶胶光学厚度在17时达到最高值为0.39。气溶胶波长指数在4—5月最低, 平均值分别为1.20和1.21;12月最高, 平均值为1.74;波长指数在12时达到峰值, 为1.44。单次散射反照率最低值分别出现在4月、8月和10月, 平均值分别为0.84、0.82和0.84;气溶胶单次散射反照率在12时出现峰值, 为0.95。龙凤山区域春季气溶胶粗粒子体积分数最高值出现在5月, 为0.04 μm3·μm-2, 有效半径为3.85 μm; 夏季气溶胶细粒子体积分数最高值出现在7月, 为0.06 μm3·μm-2, 有效半径为0.19 μm; 秋冬季龙凤山背景地区气溶胶细粒子和粗粒子体积分数均进一步减小。龙凤山区域地面和大气层顶气溶胶直接辐射强迫最高值均出现在7月, 分别为-94.44 W·m-2和-22.33 W·m-2。 相似文献
988.
Clay-bearing Upper Pliocene red clastics and Quaternary alluvial deposits occupy the Ankara basin. The clayey levels of the Upper Pliocene deposits, referred to as Ankara clay, is considered as a source for compacted clay liners due to their low coefficients of permeability and widespread distributions throughout Ankara. This study investigates the geological, geotechnical and mineralogical properties of the founding clayey soils at two sites of the Ankara region. The geotechnical index properties along with the hydraulic conductivities of the clayey soil samples collected from these sites were determined. A mathematical relation between the clay mineralogical content and hydraulic conductivity was established. The results of this investigation show that, from a geotechnical point of view, Ankara clay may be regarded as a highly suitable material for a compacted clay landfill liner given that its mineralogical compatibility with leachate is confirmed. 相似文献
989.
Slake durability study of shaly rock and its predictions 总被引:2,自引:0,他引:2
More than 35% of the earths crust is comprised of clay-bearing rocks, characterized by a wide variation in engineering properties and their resistance to short term weathering by wetting and drying phenomenon. The resistance to short-term weathering can be determined by slake durability index test. There are various methods to determine the slake durability indices of weak rock. The effect of acidity of water (slaking fluid) on slake durability index of shale in the laboratory is investigated. These methods are cumbersome and time consuming but they can provide valuable information on lithology, durability and weather ability of rock. Fuzzy set theory, Fuzzy logic and Artificial Neural Networks (ANN) techniques seem very well suited for typical complex geotechnical problems. In conjunction with statistics and conventional mathematical methods, a hybrid method can be developed that may prove a step forward in modeling geotechnical problems. During this investigation a model was developed and compared with two other models i.e., Neuro-fuzzy systems (combination of fuzzy and artificial neural network systems) and artificial neural network system, for the prediction of slake durability index of shaly rock to evaluate the performance of its prediction capability. 相似文献
990.
Electronic and optical properties of Fe, Zn and Pb sulfides 总被引:1,自引:0,他引:1
Ab initio quantum-chemical calculations of the spatial and electronic structures of sphalerite (ZnS), pyrite (FeS2) and galena (PbS), using the density functional theory (DFT) local density approximation (LDA) and generalized gradient approximation (GGA), the Hartree–Fock (HF) method and the hybrid functional B3LYP, have been carried out. For galena, the DFT LDA and GGA functionals provided the best estimate of the band gap, from within –0.1 eV to +0.4 eV of the measured value. B3LYP and RHF gave rise to errors of +1.3 and +5.4 eV, respectively. The unit cell parameter error varied from between –1.1% and +2.3% for all the functionals examined. For sphalerite the B3LYP functional provided the best estimate of the band gap (error +0.3 eV). The unit cell parameter error varied between –2.1% and +2.0% for the various DFT functionals and B3LYP. RHF gave rise to an error of +3.8%. For FeS2, the DFT-GGA approach provides the best results for both the unit cell and the band gap. This may be due to mutual cancellation of the crystal field splitting and band separation force, which are of equal but opposite magnitudes. The calculated density of states (DOS) for the conduction band is used to interpret the experimental features of the S 1s XANES (X-ray absorption near-edge structure) spectra obtained using synchrotron radiation. Because of the l = ±1 selection rule for electron excitation, the S K-edge XANES spectra represent a transition of the S 1s electron to conduction band S p-like orbitals. The near-edge region, up to 15 eV past the edge is approximated well by the DOS. Individual peaks in the DOS correlate with peaks in the XANES spectra. In addition, the imaginary part of the dielectric function, which reflects the transitions from occupied to unoccupied levels, is used to model the near-edge region of the XANES, using the DFT-GGA formalism. Individual peaks in the XANES spectrum are moderately well resolved using the dielectric function, especially for ZnS and FeS2, while the DOS for the conduction band is more successful in predicting the shape of the XANES spectra for all three minerals. 相似文献