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61.
地壳流体对地震活动的影响与控制作用 总被引:2,自引:0,他引:2
地壳中普遍存在着流体,不仅在地壳动力过程中发挥重要作用,而且也极有可能在地震孕育与发生过程中起着不为人知的重要作用。这样的认识,越来越得到地质学家与地球物理学者们的认可。本文概括介绍了地壳流体对地震活动的空间分布、震源深度与强震活动周期的影响与控制作用,并提出了地壳硬夹层孕震与流体促震的假设。最后还介绍了通过流体控制地震活动并实现减轻地震灾害的思想。 相似文献
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Long term variability in the surface winds over the marginal seas of China is examined with a dominant-mode singular value decomposition method. Both interannual and interdecadal patterns are found to be seasonally and spatially dependent, with reanalyses and satellite remote sensing data yielding highly consistent results. The study reveals that summer monsoon winds over the East China Sea experienced an interdecadal weakening in the late 1960s and began a persistent recovery in 2005. The study also shows gradual weakening of the winter monsoon in the southern South China Sea by more than 2m/s since the 1960s, with corroboration from coastal climate stations in Borneo. This phenomenon has not been reported in previous monsoon studies. 相似文献
64.
Amir Shah Ruddin Md Shah Mashhor Mansor Shahrul Anuar Mohd Shah Che Salmah Mohd Rawi Abu Hassan Ahmad Ibrahim Jaafar 《湿地科学》2008,6(1):34-44
A survey was carried out at the largest rice cultivation area in Peninsular Malaysia,the Muda rice agroecosystem.The main objective of this study was to document the overall biodiversity associated with this unique agroecosystem by using a combination of sampling techniques in order to record different groups of fauna and flora.The total number of biota recorded and identified from the rice field ecosystem during the study period consisted of 46 species of zooplankton,81 species of aquatic insects,5 species of rodents,7 species of bats,87 species of birds,11 species of fishes and 58 species of weeds.A long-term study should be carried out as more species are expected to be recorded when more of the Muda rice agroecosystem area has been sampled to obtain sufficient information on the Muda rice agrobiodiversity. 相似文献
65.
南秦岭旬阳盆地的钠长岩此前被认为是热水沉积或热液交代作用的产物。本文对南秦岭旬阳盆地东端黄石板地区侵入于下志留统梅子亚组浅变质岩中的钠长岩体进行了地球化学和锆石U-Pb LA-ICP-MS年代学研究,结果表明钠长岩具有富钠贫钾、铝不饱和、亏损大离子亲石元素K和Rb、高场强元素(Nb、Ta、Th、Hf)显著富集的地球化学特点,主体属于钙碱性系列岩石,反映幔源成因的特征。钠长岩中获得最年轻的锆石U-Pb年龄为364~376Ma,该年龄代表岩体的形成年龄,反映晚泥盆世时南秦岭旬阳盆地处于强烈的伸展构造环境。此项研究结果表明,在旬阳盆地的志留系中,岩浆成因与热水沉积成因的钠长岩可能是共存的。黄石板岩浆成因钠长岩岩体中含有大量前寒武纪和早古生代的捕获锆石,在捕获锆石中测得迄今为止在研究区及其邻区获得的最古老的锆石U-Pb年龄(3291Ma)。这些捕获锆石的测年数据说明,研究区所在的南秦岭地区可能从古太古代开始就与扬子地块具有明显的亲缘性。 相似文献
66.
<正>Objective Shandong Province is divided into two parts by the Tan–Lu fault zone:the western part(Luxi)and the eastern part(Jiaodong).Large-scale volcanic activity occurred during the Late Mesozoic in Shandong Province,eastern China(Fig.1b),and was controlled by the Tan–Lu fault zone and its secondary faults.Mesozoic volcanic rocks in Shandong Province mainly occur within the Cretaceous Qingshan 相似文献
67.
Razarul Naim Roslan Mohamed Rozali Othman Xan Xue Yan Che Abd Rahim Mohamed 《Marine pollution bulletin》2010,60(9):1584-5700
A study was done to determine the concentrations of surfactants on the sea-surface microlayer and in atmospheric aerosols in several coastal areas around the Malaysian peninsula. The concentrations of surfactants from the sea-surface microlayer (collected using rotation drum) and from aerosols (collected using HVS) were analyzed as methylene blue active substances and disulphine blue active substances through the colorimetric method using a UV-vis spectrophotometer. The results of this study showed that the average concentrations of surfactants in the sea-surface microlayer ranged between undetected and 0.36 ± 0.34 μmol L−1 for MBAS and between 0.11 ± 0.02 and 0.21 ± 0.13 μmol L−1 for DBAS. The contribution of surfactants from the sea-surface microlayer to the composition of surfactants in atmospheric aerosols appears to be very minimal and more dominant in fine mode aerosols. 相似文献
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A streamfunction EOF method is applied to a time series of hydrographic sections in the Southern Ocean south of Australia to study water mass variations. Results show that there are large thermohaline variations north of the Subantarctic Front (SAF) at 300–1500 dbar level, indicating upwelling and downwelling of the Antarctic Intermediate Water (AAIW) along isopycnal surfaces. Based on the latest altimeter product, Absolute Dynamic Topography, a mechanism due to frontal wave propagation is proposed to explain this phenomenon, and an index for frontal waves is defined. When the frontal wave is in positive (negative) phase, the SAF flows northeastward (southeastward) with the fresh AAIW downwelling (upwelling). Such mesoscale processes greatly enhance cross-frontal exchanges of water masses. Spectral analysis shows that frontal waves in the Southern Ocean south of Australia are dominated by a period of about 130 days with a phase speed of 4 cm/s and a wavelength of 450 km. 相似文献
70.
AbstractA semi-distributed hydrological model and reservoir optimization algorithm are used to evaluate the potential impacts of climate change on existing and proposed reservoirs in the Sonora River Basin, Mexico. Inter-annual climatic variability, a bimodal precipitation regime and climate change uncertainties present challenges to water resource management in the region. Hydrological assessments are conducted for three meteorological products during a historical period and a future climate change scenario. Historical (1990–2000) and future (2031–2040) projections were derived from a mesoscale model forced with boundary conditions from a general circulation model under a high emissions scenario. The results reveal significantly higher precipitation, reservoir inflows, elevations and releases in the future relative to historical simulations. Furthermore, hydrological seasonality might be altered with a shift toward earlier water supply during the North American monsoon. The proposed infrastructure would have a limited ability to ameliorate future conditions, with more benefits in a tributary with lower flood hazard. These projections of the impacts of climate change and its interaction with infrastructure should be of interest to water resources managers in arid and semi-arid regions.
Editor D. Koutsoyiannis 相似文献