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921.
基于BP模型和Ward法的北京市平谷区乡村地域功能评价与分区   总被引:13,自引:3,他引:10  
唐林楠  刘玉  潘瑜春  任艳敏 《地理科学》2016,36(10):1514-1521
构建乡村地域功能评价指标体系,借助BP神经网络模型揭示平谷区“生产-生活-生态”功能分异特征;运用Ward法划分功能区,服务于平谷区乡村转型发展和功能区布局。结果表明: 在多项功能综合作用下,平谷区基本形成了“平原地区生产功能较强、镇中心及周边村域生活功能明显、山地区以生态功能为主”的功能分布格局。 基于评价结果和空间属性,平谷区划分为西部平原生产区、东部山地生态生产区、中部平原城市生活区、中部近郊平原生活区、东部丘陵生态生活区和北部山地生态区。其中,西部平原生产区、中部平原城市生活区、北部山地生态区是平谷三生空间功能发展的优势区域,分布相对集中。按照“强功能重优化、中等功能重提升、弱功能重改善”的原则提升乡村地域功能,促进地区均衡发展。  相似文献   
922.
地图与地图学史研究有助于了解发展规律,探索学科发展方向。本文以中西方地图、地图学史为研究对象,依时间顺序提出中西方地图、地图学发展中的3次互补,结合历史史例予以说明;通过比较分析法,探索分析3次互补融合程度,结合学科前沿,对地图与地图学发展提出合理预测,推断第4次互补发生的可能。  相似文献   
923.
The article suggests Jobberns’ view of geopolitics ultimately rested on the work of British geographer Sir Halford Mackinder overlain by the writing of American political geographers. Jobberns’ geopolitical thinking was, however, also strongly informed by his being a Freemason. WWII, as the overshadowing external event of Jobberns’ early years at Canterbury, amplified his interest in geopolitics both as a way of understanding the world and, at a time when geography was not universally accepted as a university discipline, as a means of promoting to a wider public the utility of a geographical perspective on world affairs.  相似文献   
924.
Physical forcing plays a major role in determining biological processes in the ocean across the full spectrum of spatial and temporal scales. Variability of biological production in the Bay of Bengal (BoB) based on basin-scale and mesoscale physical processes is presented using hydrographic data collected during the peak summer monsoon in July–August, 2003. Three different and spatially varying physical processes were identified in the upper 300 m: (I) anticyclonic warm gyre offshore in the southern Bay; (II) a cyclonic eddy in the northern Bay; and (III) an upwelling region adjacent to the southern coast. In the warm gyre (>28.8 °C), the low salinity (33.5) surface waters contained low concentrations of nutrients. These warm surface waters extended below the euphotic zone, which resulted in an oligotrophic environment with low surface chlorophyll a (0.12 mg m−3), low surface primary production (2.55 mg C m−3 day−1) and low zooplankton biovolume (0.14 ml m−3). In the cyclonic eddy, the elevated isopycnals raised the nutricline upto the surface (NO3–N > 8.2 μM, PO4–P > 0.8 μM, SiO4–Si > 3.5 μM). Despite the system being highly eutrophic, response in the biological activity was low. In the upwelling zone, although the nutrient concentrations were lower compared to the cyclonic eddy, the surface phytoplankton biomass and production were high (Chl a – 0.25 mg m−3, PP – 9.23 mg C m−3 day−1), and mesozooplankton biovolume (1.12 ml m−3) was rich. Normally in oligotrophic, open ocean ecosystems, primary production is based on ‘regenerated’ nutrients, but during episodic events like eddies the ‘production’ switches over to ‘new production’. The switching over from ‘regenerated production’ to ‘new production’ in the open ocean (cyclonic eddy) and establishment of a new phytoplankton community will take longer than in the coastal system (upwelling). Despite the functioning of a cyclonic eddy and upwelling being divergent (transporting of nutrients from deeper waters to surface), the utilization of nutrients leading to enhanced biological production and its transfer to upper trophic levels in the upwelling region imply that the energy transfer from primary production to secondary production (mesozooplankton) is more efficient than in the cyclonic eddy of the open ocean. The results suggest that basin-scale and mesoscale processes influence the abundance and spatial heterogeneity of plankton populations across a wide spatial scale in the BoB. The multifaceted effects of these physical processes on primary productivity thus play a prominent role in structuring of zooplankton communities and could consecutively affect the recruitment of pelagic fisheries.  相似文献   
925.
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   
926.
We propose and validate a linear regression model which enables us to predict the summer (June–August) mean of the monthly 90th percentile of significant wave heights (H90) in the western North Pacific (WNP). The most prevailing interannual variability of H90 is identified by applying an Empirical Orthogonal Function analysis to H90 obtained from the ERA-40 wave reanalysis as well as from the optimally interpolated TOPEX/Poseidon (OITP) wave data. It is found that the increase of H90 is correlated with cyclonic circulation in the WNP which links with warm SST anomalies in the Niño-3.4 region. We adopt zonal wind anomaly averaged over the region 5°N–15°N, 130°E–160°E (U10N) as a predictor of the first principal component (PC1) of H90, since U10N is closely correlated with the PC1 of H90. It is revealed that regression models obtained from two different wave datasets are nearly identical. The predictability of the regression model is assessed in terms of the reduction of the root-mean-square (rms) errors between H90 and the reconstructed data. The predictor is found to be successful in reducing the rms errors by up to 40% for the ERA-40 wave reanalysis and by up to 70% for the OITP wave data within the latitudinal band 10°N–25°N, though rms errors exceeding 0.3 m still remain, particularly in the East China Sea.  相似文献   
927.
对中国真马尾藻亚属SubgenusSargassum刺托组SectionAcanthocarpicae宾德系SeriesBinderiana斯氏种群SpeciesgroupSwartzia的研究中,发现该种群新种4个,它们是原始马尾藻SargassumprimitivumTsengetLusp.nov,模式标本于1992年4月10日采自海南省文昌县,模式标本号AST92-0296;海南马尾藻SargassumhainanenseTsenget,Lusp.nov,模式标本于1955年3月25日采自海南省文昌县清澜港,模式标本号AST55-0714;文昌马尾藻SargassumwenchangenseTsengetLusp.nov,模式标本于1958年6月22日采自海南省文昌县,模式标本号A5T58-6059;微小马尾藻SARGASSUMPUSILLUMTsengetLusp.nov,模式标本于1955年4月28日采自广西涠洲岛,模式标本号AST55-1973。  相似文献   
928.
Abstract. The sponge fauna of three neighbouring submarine caves of the Island of Majorca (Balcaric Islands) is studied along a light gradient; 45 species have been recorded and systematic data are given for those showing morphological, pigmentary, or spicule differences. Adaptation to darkness and precarious trophic conditions is also discussed.  相似文献   
929.
对虾白斑综合症病毒核衣壳蛋白VP664的鉴定研究   总被引:1,自引:0,他引:1  
熊生良  杨丰 《台湾海峡》2007,26(1):46-52
对虾白斑综合症病毒核衣壳蛋白VP664是至今知道的分子量最大的结构蛋白,全长18234bp,预计编码6077个氨基酸.从编码vp664基因的两端各选600bp,分别命名为vp664n、vp664c进行原核表达,成功表达纯化了目的蛋白并制备抗体.蛋白印记杂交(Western blot)实验中蛋白特异抗体只与完整的病毒和核衣壳裂解蛋白中的VP664蛋白反应,而不和膜蛋白反应,证明VP664基因所编码的蛋白在完整病毒颗粒上定位于核衣壳.  相似文献   
930.
Complementary to previous work mainly based on seismic interpretation, our compilation of geophysical data (multibeam bathymetry, gravity, magnetic and seismic) acquired within the framework of the ZoNéCo (ongoing since 1993) and FAUST (1998–2001) programs enables us to improve the knowledge of the New Caledonia Basin, Fairway Basin and Fairway Ridge, located within the Southwest Pacific region. The structural synthesis map obtained from geophysical data interpretation allows definition of the deep structure, nature and formation of the Fairway and New Caledonia Basins. Development of the Fairway Basin took place during the Late Cretaceous (95–65 Ma) by continental stretching. This perched basin forms the western margin of the New Caledonia Basin. A newly identified major SW–NE boundary fault zone separates northern NW–SE trending segments of the two basins from southern N–S trending segments. This crustal-scale fault lineament, that we interpret to be related to Cretaceous-early Cainozoic Tasman Sea spreading, separates the NW–SE thinned-continental and N–S oceanic segments of the New Caledonia Basin. We can thus propose the following pattern for the formation of the study area. The end of continental stretching within the Fairway and West Caledonia Basins ( 65–62 Ma) is interpreted as contemporaneous with the onset of emplacement of oceanic crust within the New Caledonia Basin’s central segment. Spreading occurred during the Paleocene (62–56 Ma), and isolated the Gondwanaland block to the west from the Norfolk block to the east. Finally, our geophysical synthesis enables us to extend the structural Fairway Basin down to the structural Taranaki Basin, with the structural New Caledonia Basin lying east of the Fairway Basin and ending further north than previously thought, within the Reinga Basin northwest of New Zealand.  相似文献   
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