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991.
Research on vulnerability and adaptation in social-ecological systems (SES) has largely centered on climate change and associated biophysical stressors. Key implications of this are twofold. First, there has been limited engagement with the impacts of social drivers of change on communities and linked SES. Second, the focus on climate effects often assumes slower drivers of change and fails to differentiate the implications of change occurring at different timescales. This has resulted in a body of SES scholarship that is under-theorized in terms of how communities experience and respond to fast versus slow change. Yet, social and economic processes at global scales increasingly emerge as ‘shocks’ for local systems, driving rapid and often surprising forms of change distinct from and yet interacting with the impacts of slow, ongoing ‘trends’. This research seeks to understand the nature and impacts of social shocks as opposed to or in concert with trends through the lens of a qualitative case study of a coastal community in Mexico, where demand from international seafood markets has spurred rapid development of a sea cucumber fishery. Specifically, we examined what different social-ecological changes are being experienced by the community, how the impacts of the sea cucumber fishery are distinct from and interacting with slower ongoing trends and how these processes are affecting system vulnerability, adaptations and adaptive capacity. We begin by proposing a novel framework for conceptualizing impacts on social systems, as comprised of structures, functions, and feedbacks. Our results illustrate how the rapid-onset of this fishery has driven dramatic changes in the community. New challenges such as the ‘gold-rush-style’ arrival of new actors, money, and livelihoods, the rapid over-exploitation of fish stocks, and increases in poaching and armed violence have emerged, exacerbating pressures from ongoing trends in immigration, overfishing and tourism development. We argue that there is a need to better understand and differentiate the social and ecological implications of shocks, which present novel challenges for the vulnerability and adaptive capacity of communities and the sustainability of marine ecosystems.  相似文献   
992.
Dissolved Organic Carbon (DOC) is an important component in the global carbon cycle. It also plays an important role in influencing the coastal ocean biogeochemical (BGC) cycles and light environment. Studies focussing on DOC dynamics in coastal waters are data constrained due to the high costs associated with in situ water sampling campaigns. Satellite optical remote sensing has the potential to provide continuous, cost-effective DOC estimates. In this study we used a bio-optics dataset collected in turbid coastal waters of Moreton Bay (MB), Australia, during 2011 to develop a remote sensing algorithm to estimate DOC. This dataset includes data from flood and non-flood conditions. In MB, DOC concentration varied over a wide range (20–520 μM C) and had a good correlation (R2 = 0.78) with absorption due to coloured dissolved organic matter (CDOM) and remote sensing reflectance. Using this data set we developed an empirical algorithm to derive DOC concentrations from the ratio of Rrs(412)/Rrs(488) and tested it with independent datasets. In this study, we demonstrate the ability to estimate DOC using remotely sensed optical observations in turbid coastal waters.  相似文献   
993.
一个简单的二维线性模式用于考查近海海洋对过境热带风暴的动力响应过程中的底坡度和底摩擦效应。选择了自东向西和向西后转向的两个模式风暴路径。数值试验结果表明,海底坡度与风暴引起的水位波动、风暴中心后部的尾流以及路径右侧后方面的涡旋密切相关。而底摩察是阻尼风暴潮和风暴流持续增长的重要因子。结果还表明,近海对风暴的强响应偏向于风暴轨迹的右侧,这与Chang和Anthes(1978)对深海响应的研究结论是一  相似文献   
994.
The saturation of calcite and aragonite in the Arctic Ocean   总被引:1,自引:0,他引:1  
We report on the chemical saturation of CaCO3 in the waters of the Arctic Ocean calculated from total alkalinity (AT) and total dissolved inorganic carbon (CT). Data based on four different expeditions are presented: International Arctic Ocean Expedition (IAOE-91), Arctic Ocean Section 94 (AOS94), Polarstern Arctic '96 expedition (ACSYS 96), and Joint Ocean Ice Study 97 (JOIS 97). The results show a lysocline at around 3500 m for aragonite and that most of the Arctic Ocean sea floor lies above the lysocline for calcite. The only anomaly is the low degree of saturation at the shelf break depth in the Canadian Basin seen in the sections of the AOS94 and JOIS 97 cruises, correlated with nutrient maxima and very low O2 concentration, suggesting decomposition of organic matter. The insignificant variability in degree of saturation between the deep waters of the different basins in the Arctic Ocean indicates a very low sedimentation/remineralisation of organic soft matter.  相似文献   
995.
D.-S. Jeng  B.R. Seymour   《Ocean Engineering》2005,32(16):1747-1916
In this paper, the phenomenon of ocean waves propagating over a beach with variable water depth is re-examined. Based on the assumption of shallow water, a linearised shallow water equation is solved with an arbitrary beach profile. These irregular beach profiles form a set of partial differential equation with variable coefficient as the governing equation, which is the main obstacle in obtaining analytical solutions. In this paper, two families of beach profile are used as examples. A parametric study is conducted to investigate the influence of the beach profiles on the water surface elevation (η) and velocities (u).  相似文献   
996.
Johann  Hohenegger 《Marine Ecology》1994,15(3-4):291-334
Abstract. Living, symbiont-bearing, larger foraminiferids restricted to the photic zone incorporate mechanisms blocking solar radiation and water current transportation. They can be divided in two groups according to their wall structure: 1, Families with opaque test walls, reducing light penetration: Peneroplids inhabit shallow-water environments from the intertidal ( Peneroplis in large numbers) down to 40 m ( Dendritina , preferring sandy substrates). Soritids are restricted to subtidal environments with less water turbulence and range from the reef moat down to 60 m. Amphisorus and Marginopora are common down to 30 m, whereas Parasorites is restricted to deeper parts of the reef slope. Alveolinella can be found in the upper 40 m of the reef slope. 2. Families with hyaline test walls, adjusted for light penetration: amphisteginids inhabit the whole photic zone, demonstrating a correlation of test flattening with increasing depth. Calcarinids cling with their spines to firm substrates such as algal thalli or macroids. Baculogypsina is restricted to high energetic regions on the reef flat. Calcarina inhabits similar environments, extending its distribution range within fore reefs down to 80 m. Baculogypsinoides is a dominant calcarinid genus from 30 to 70 m depth. Within nummulitids, Heterostegina prefers hard substrates on the reef slope, while Assilina (= Operculina ) is frequent in deeper parts and is independent of substrates. Sandy bottoms from 30 to 60 m are inhabited by the last living representative of the genus Nummulites, N. venosus . The giant foraminifer Cycloclypeus , with test sizes up to 7 cm, is restricted to fore reef areas below 50 m down to the base of the photic zone.  相似文献   
997.
This study investigated the distribution of Molgolaimus species (Nematoda) at different hierarchical spatial scales and observed the turnover of species along bathymetrical transects and among transects in two separate geographical regions. Samples from six transects (200–2000 m) from the Southern Oceans (SO) and four bathymetric transects (50–2000 m) from the Western Indian Ocean (WIO) were compared. Of the 30 species recorded, only one was common to both regions. WIO had higher local species richness than the SO. In both regions, the local scale was the greatest contributor to the total species richness. In the SO, there was no difference between species turnover at the different spatial scales, however, in the WIO, the turnover along bathymetrical transects was higher than among separated transects. For the particular genus studied, the evidence suggests that the study area in WIO has more widespread species and was better sampled, while the SO has many restricted species and it is most probably characterized by different biogeographical provinces. At the ocean scale (i.e. WIO versus SO), evolutionary histories may have strongly influenced nematodes species composition, while at local and regional scales, ecological processes are probably promoting species co‐existence and speciation. The high co‐existence of certain species at local scale is partially explained by species preference for different sediment layers.  相似文献   
998.
对COADS资料中1950-1992年太平洋4°×8°方区的海水表层温度及海面气温、气压、风速序列数据,进行了时间序列分析。分析结果表明:太平洋海表气温和水温年上升率分别为0.0063℃·a(-1)和0.0026℃·a(-1)。两者的变化趋势在赤道太平洋都有一个年上升率高值区;而在东海以北的西北太平洋广大海区,都有一个年下降率的低值区。西太平洋海面气压呈上升趋势,东太平洋则相反。气温和水温的升降区域分布特征与风速分量增强和减弱的变化趋势有关。文章还指出,中国和日本沿岸今后几十年海平面变化趋势的预测模式,应以太平洋或全球海平面上升趋势的预测为基础,加上本海区海平面的局地变化订正。  相似文献   
999.
近几年来,我们对山东近岸34个海岛和一些海湾进行了综合性调查,本文主要根据这些调查的实测资料.在综合分析整理的基础上.获得了山东近岸水域浮植物的现存量(叶绿素 a)为0.91mg/m~2,初级生产力水平为310.2mg/(m~2·d),基本接近温带海洋近岸水域标准;其分布特征是以莱州湾、渤海海峡、千里岩海区为最高,宫家岛、鸭岛海区为最低;季节变化显著,主要显示双峰型特征.根据初级生产力的测定结果,我们对山东近岸水域潜在的各级生物生产力做出了初步估算,旨在为山东近岸水域开展海水增养殖,合理开发海洋资源提供科学依据.  相似文献   
1000.
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