全文获取类型
| 收费全文 | 161篇 |
| 免费 | 31篇 |
| 国内免费 | 49篇 |
专业分类
| 测绘学 | 7篇 |
| 大气科学 | 11篇 |
| 地球物理 | 17篇 |
| 地质学 | 49篇 |
| 海洋学 | 137篇 |
| 天文学 | 1篇 |
| 综合类 | 14篇 |
| 自然地理 | 5篇 |
出版年
| 2024年 | 2篇 |
| 2023年 | 7篇 |
| 2022年 | 14篇 |
| 2021年 | 23篇 |
| 2020年 | 27篇 |
| 2019年 | 20篇 |
| 2018年 | 19篇 |
| 2017年 | 13篇 |
| 2016年 | 7篇 |
| 2015年 | 6篇 |
| 2014年 | 24篇 |
| 2013年 | 11篇 |
| 2012年 | 15篇 |
| 2011年 | 10篇 |
| 2010年 | 9篇 |
| 2009年 | 5篇 |
| 2008年 | 3篇 |
| 2007年 | 6篇 |
| 2006年 | 6篇 |
| 2005年 | 3篇 |
| 2004年 | 2篇 |
| 2003年 | 1篇 |
| 2002年 | 2篇 |
| 2001年 | 2篇 |
| 1999年 | 2篇 |
| 1997年 | 1篇 |
| 1986年 | 1篇 |
排序方式： 共有241条查询结果，搜索用时 187 毫秒
61.
南海上层海洋热力结构年代际变化的研究,是海气相互作用与变化研究的热点之一,对南海区域及更大范围的气候异常的研究和南海海洋环流年际变化的研究都具有重要意义。本文采用多套海温、流场和海气界面通量资料,基于热平衡方程和统计分析方法,分析了南海上层热含量的年代际变化,研究了南海上层热含量影响因子的变化特征,比较了混合层及混合层以下热含量变化的异同,进而探讨了影响因子在混合层及混合层以下的不同作用;利用区域积分海温方程后得到的热量收支方程,诊断南海内区不同海域的热收支方程中的各项,发现了不同海域在影响热收支的物理过程方面存在差异。结果表明:南海混合层的热含量的变化主要受海气界面热通量的影响,夹卷效应在热含量的变化中也有接近1/3的贡献。在整个上层400m的热含量变化中,平流效应占据了主导地位。 相似文献
62.
应用WOA13季节平均数据和BELLHOP模型,在季节、声源频率、声源深度和掠射角等因素确定的情况下,分析北大西洋冬季(1-3月)声道轴深度、最小声速值、表层声速值的分布,通过仿真计算研究选用位置点5 m深度声源的声传播规律:反转深度随纬度升高而降低,低纬度海岭东西两侧差别不大,15°N以北为西侧大于东侧。55°N以南海区可形成汇聚区波导,海岭西侧的汇聚区跨度大于海岭东侧,有混合层时还存在一定强度的表面波导,汇聚区处5 m、100 m和250 m接收深度上的传播损失差异较小,增益为7～19 dB,55°N以北海区则为有焦散结构的表面波导。以北大西洋35°N为界,以南以汇聚区波导探测有利,以北以表面波导探测有利。 相似文献
63.
Wang Jiliang Wu Shiguo Zhao Luanxiao Wang Weiwei Wei Jiangong Sun Jin 《Marine Geophysical Researches》2019,40(4):655-664
Marine Geophysical Research - Shear-wave velocity is essential in various seismic exploration applications, including seismic modeling, amplitude variation with offset analysis, multicomponent... 相似文献
64.
Dai Jie Tang Hongzhi Li Xuegong Santini Claire-Lise Cui Wenpeng Liu Na Qi Xiaoqing Cui Xuehua Grossi Alain Notareschi Philippe Zhang Wei-Jia Wu Long-Fei 《中国海洋湖沼学报》2021,39(1):297-305
Journal of Oceanology and Limnology - Resazurin (RZ) is a weakly fluorescent blue dye and can be reduced irreversibly to highly fluorescent pink resorufin (RF) that is reduced reversibly to... 相似文献
65.
珊瑚与虫黄藻的共生是珊瑚礁生态系统最基本的生态特征,虫黄藻光合作用效率直接决定着珊瑚的健康状况。本研究对海南三亚鹿回头珊瑚礁礁坪上5种典型珊瑚(澄黄滨珊瑚Porites lutea、丛生盔形珊瑚Galaxea fascicularis、标准蜂巢珊瑚Favia speciosa、多弯角蜂巢珊瑚Goniastrea favulus和伞房鹿角珊瑚Acropora corymbosa)共生藻的实际光量子产量ΦPSⅡ进行了连续5日的现场监测,并同时监测了该海域的7种环境参数(温度、盐度、溶解氧、pH、海水中二氧化碳分压pCO2、辐射和潮位),旨在探索鹿回头海域珊瑚共生虫黄藻光合作用的日变化规律及其调控因素。结果表明,珊瑚共生虫黄藻光合作用效率和各环境参数都存在明显的日变化,但共生藻光合作用效率主要受光合有效辐射强度(photosynthetic active radiation,PAR)所调控,其次是温度和潮位变化。澄黄滨珊瑚的共生藻光合作用最易受到环境因素的影响。 相似文献
66.
Most of the basins developed in the continental core of SE Asia (Sundaland) evolved since the Late Cretaceous in a manner that may be correlated to the conditions of the subduction in the Sunda Trench. By the end of Mesozoic times Sundaland was an elevated area composed of granite and metamorphic basement on the rims; which suffered collapse and incipient extension, whereas the central part was stable. This promontory was surrounded by a large subduction zone, except in the north and was a free boundary in the Early Cenozoic. Starting from the Palaeogene and following fractures initiated during the India Eurasia collision, rifting began along large faults (mostly N–S and NNW–SSE strike-slip), which crosscut the whole region. The basins remained in a continental fluvio-lacustrine or shallow marine environment for a long time and some are marked by extremely stretched crust (Phu Khanh, Natuna, N. Makassar) or even reached the ocean floor spreading stage (Celebes, Flores). Western Sundaland was a combination of basin opening and strike-slip transpressional deformation. The configuration suggests a free boundary particularly to the east (trench pull associated with the Proto-South China Sea subduction; Java–Sulawesi trench subduction rollback). In the Early Miocene, Australian blocks reached the Sunda subduction zone and imposed local shortening in the south and southeast, whereas the western part was free from compression after the Indian continent had moved away to the north. This suggests an important coupling of the Sunda Plate with the Indo-Australian Plate both to SE and NW, possibly further west rollback had ceased in the Java–Sumatra subduction zone, and compressional stress was being transferred northwards across the plate boundary. The internal compression is expressed to the south by shortening which is transmitted as far as the Malay basin. In the Late Miocene, most of the Sunda Plate was under compression, except the tectonically isolated Andaman Sea and the Damar basins. In the Pliocene, collision north of Australia propagated toward the north and west causing subduction reversal and compression in the short-lived Damar Basin. Docking of the Philippine Plate confined the eastern side of Sundaland and created local compression and uplift such as in NW Borneo, Palawan and Taiwan. Transpressional deformation created extensive folding, strike-slip faulting and uplift of the Central Basin and Arakan Yoma in Myanmar. Minor inversion affected many Thailand rift basins. All the other basins record subsidence. The uplift is responsible for gravity tectonics where thick sediments were accumulated (Sarawak, NE Luconia, Bangladesh wedge). 相似文献
67.
We assess the results of a number of deep seismic soundings performed in China over the last few decades, and study the variations in crustal structure in 18 tectonic units comprised of three platforms and 15 fold systems. Thickness data on 344 Mesozoic–Cenozoic sedimentary basins, as well as data on Moho depth are collected in order to discuss the relationship between the thickness of the basins and the average thickness of the consolidated crust in each tectonic unit. The degree of mirror-image symmetry between Mesozoic–Cenozoic sedimentary basins and the uplifting topmost parts of the mantle is herein analyzed using deep geophysical data on sedimentary basins. By applying standard methods of least-squares analysis to both datasets, we have obtained both the average thickness of the consolidated crust and the mirror-image symmetry factor for every platform and tectonic fold system, thereby allowing us to explore the correlation between the depths of the bottom of the sedimentary basins and the top of the uplifting mantle. The thickness of the consolidated crust in China is found to be between 20 and 63 km, following a pattern of gradual thickening from east to west. Expressed in terms of spatial seismicity and the concentration of seismic energy, and according to the sharing-out of earthquake hypocenters in the top 80 km of the earth, the rheology of the area does not appear to suit the widely accepted “jelly–sandwich” model for the continents, which does not seem to be entirely valid in China. The findings on the mirror-image symmetry factor show that this parameter varies mainly in the range ? 0.5 to ? 1.8 compared with each other tectonic unit. Most of the tectonic systems in China appear to be isostatically compensated. Tibet is an exception, in that the symmetry factor is positive for the Gangdise–Nyainqentanglha (1.0) and Himalayan (0.1) fold systems, implying that these tectonic zones are far from being in the isostatic equilibrium of the other regions. We have also analyzed the zoning characteristics through the logarithmic relationship ln R = ln (h/|a|), using the average thickness of the consolidated crust and the absolute value of the symmetry factor. The key finding is that regardless of geographical location, all the values of R = h/|a| for those sedimentary basins in which oil/gas reservoirs have to date been found, fall into the narrow range of values between 19.38 and 37.40. There is some appeal in a possible relationship involving the ratio of crustal thickness to symmetry factor, more so when the results obtained appear to suggest a prognostic tool for exploratory practice in relation to oil/gas reservoirs. 相似文献
68.
69.
Since turbidity current was reported in the 19th century, its flow dynamics, depositional processes and products have drawn much attention of geoscience community. In the last decades, with the help of rapid development of geophysical technology in deep-water areas, superficial bedforms formed by turbidity currents like cyclic steps have been widely documented on the seafloor, and they have been interpreted to be closely related to turbidite facies defined by the Bouma sequence. However, there is still a lack of direct observation on turbidity currents due to difficulties in the design and deployment of flow-measuring instruments under the sea. Such difficulties also result in much uncertainties in the explanations for the formation of bedforms and related flow processes. This paper summarized and discussed current research status of turbidity-currents classification, the formation and evolution of bedforms. Examples of supercritical-bedform studies using various methods such as experiments, numerical simulation, bathymetric data and seismic data, were shown in this paper. As one of main supercritical flow bedforms, cyclic steps were described in detail in this paper, including its formation, evolution and relationship with Bouma sequence. The variations in initial bed morphology and hydrodynamic parameters are responsible for the changes in the shapes of bedforms. Turbidites formed under different hydrodynamic conditions correspond to different units of Bouma sequence. Not all turbidity events can form a complete Bouma sequence. Therefore, traditional Bouma sequence cannot be applied to all turbidite studies. A more complete turbidite facies model must be established through studies from modern deep-sea sediments, outcrops, physical and numerical simulations. Additionally, turbidity currents and related supercritical bedforms are receiving more and more attention. They are important components of understanding the dynamic evolution of deep-water continental slope. The study of cyclic steps and other bedforms related to turbidity currents not only helps to characterize flow dynamics, but also provides a theoretical basis for the research of turbidite reservoirs. Finally, we proposed future research directions of turbidity currents and their related supercritical bedforms. 相似文献
70.
The biologically mediated weathering of the ocean crust has received increasing attention in recent decades, but the rates and the possible mechanism of elemental release during microbe–basalt interactions occurring below the seafloor have not been studied in detail. In this study, we established an experimental weathering study of seafloor natural basaltic glass comparing the effect of microbial activity (Pseudomonas fluorescens) in P-rich and P-poor media with parallel controls containing either nonviable cells or organic acid. The changes in the chemical parameters, including pH, bacterial densities, and ion concentrations (Ca, Mg, Si, Mn, Al, Fe, and P) in the solution, were examined during the different batch experiments. The results showed that the pH decreased from 7.0 to 3.5 and the bacterial density increased from 105 to 108 cells/ml during the first 120 h, and the cell numbers remained constant at 108 cells/ml and the pH increased from 3.5 to 6 between 120 h and 864 h in the P-bearing reactors containing bacteria. In contrast, during all the experimental time, the pH remained close to neutral condition in the abiotic control systems and the dissolution rates increased markedly with a decrease in pH and became minimal at near-neutral pH in P-bearing reactors containing bacteria, where Ca, Si, and Mg release rates were 2- to 4-fold higher than those obtained in chemical systems and biotic P-limited systems. Furthermore, the surfaces of the natural volcanic glass from the biotic systems were colonized by bacteria. Simultaneously, the etch pits were observed by Scanning Electron Microscope, which further indicate that the bacteria may promote the mineral dissolution for energy gain. Some elements (e.g., Fe, Mn, and Al) releasing from natural volcanic glass are likely an important source of the elemental budget in the ocean, and thus the element release and its possible mechanism conducted in this experimental study have potential implications on the biogeochemical cycling process in the Mid-Oceanic Ridge setting. 相似文献