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地图学是一门经过数千年的演进发展形成的科学,地图(地图集)是地图科学研究的主阵地,是任何时代和社会都不可或缺的,对人们的工作、学习和生活具有重要作用和意义。首先,简要论述了地图学作为一门科学的社会实践和科学实践的演进发展规律,以及地图集的特点;然后,从哲学角度分析与论述了地图是怎样重构复杂非线性地理世界的(实现由"地理世界"到"地图世界"的转变),人们是怎样利用地图进一步认识复杂非线性地理世界的(实现由"地图世界"到"地理世界"的转变),提出了基于传感器网络的由"感知的地理世界"到"重构的地理世界"再到"认知的地理世界"、指导行动并反馈信息的"双向"转变的认知模式;最后,论述了地图集作为重构复杂非线性地理世界的"百科全书"的作用,举例说明了中国改革开放以来地图集的快速发展和水平的大幅提升,并阐明人工智能时代中国地图集成果将比以往任何时候都更加兴旺发达,地图集作为人们进一步认知复杂非线性地理世界的"百科全书"的功能作用将比以往任何时候都更加强大。 相似文献
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《Climate Policy》2013,13(1):768-788
This article explores the critical role of labour market imperfections in climate stabilization cost formation, using a dynamic recursive energy—economy model that represents a second-best world with market imperfections and short-run adjustment constraints along a long-term growth path. The degree of rigidity of the labour markets is a central parameter, and a systematic sensitivity analysis of the model results confirms this. When labour markets are represented as highly flexible, the model results are in the usual range of the existing literature; that is, less than 2% GDP losses in 2030 for a stabilization target at 550 ppm CO2 equivalent. However, when labour market rigidities are accounted for, mitigation costs increase dramatically. Accompanying measures are identified, namely labour subsidies, which guarantee against the risk of large stabilization costs in the case of high rigidities of the labour markets. This complements the usual view that mitigation is a long-term matter that depends on technology, innovation, investment and behavioural change. The results support the view that mitigation is also a shorter-term issue and a matter of transition with regard to the labour market. 相似文献
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Isabel G. Teixeira Francisco G. Figueiras Bibiana G. CrespoSílvia Piedracoba 《Estuarine, Coastal and Shelf Science》2011
The dilution technique, combined with identification and enumeration of pico-, nano- and micro-plankton by microscopy, was used to estimate microzooplankton impact on the microbial community in surface waters of a coastal embayment on the NW Iberian upwelling system. Microzooplankton were important consumers of autotrophic and heterotrophic plankton in this system, feeding up to 93% of standing stock and more than 100% of production of several groups. Heterotrophic bacteria and heterotrophic picoflagellates experienced the highest and constant impact, with 75–84% of their standing stocks and 85–102% of their production being channelled through the microbial food web. Pico- and nano-phytoplankton were also consumed, although maximum grazing occurred on diatoms during upwelling events, coinciding with highest primary production. Predation on pico-nano-heterotrophs was especially relevant under downwelling conditions, when consumption of total carbon and particularly autotrophic carbon was considerably lower than during upwelling. The results suggest that the existence of a multivorous food web, extending from the microbial loop to the herbivorous food web, could be a major feature in this coastal upwelling system. The microbial loop, which occurs as a permanent background in the system, would contribute to sustain the microbial food web during downwelling, whereas the herbivorous food web could coexist with a microbial food web based on large diatoms during upwelling. The multivorous food web would partially divert diatoms from sinking and hence favour the retention of organic matter in the water column. This could enhance the energy transfer to higher pelagic trophic levels in coastal upwelling systems. 相似文献
406.
Dick van Oevelen Melanie Bergmann Karline Soetaert Eduard Bauerfeind Christiane Hasemann Michael Klages Ingo Schewe Thomas Soltwedel Nataliya E. Budaeva 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(11):1069-1083
The HAUSGARTEN observatory is located in the eastern Fram Strait (Arctic Ocean) and used as long-term monitoring site to follow changes in the Arctic benthic ecosystem. Linear inverse modelling was applied to decipher carbon flows among the compartments of the benthic food web at the central HAUSGARTEN station (2500 m) based on an empirical data set consisting of data on biomass, prokaryote production, total carbon deposition and community respiration. The model resolved 99 carbon flows among 4 abiotic and 10 biotic compartments, ranging from prokaryotes up to megafauna. Total carbon input was 3.78±0.31 mmol C m−2 d−1, which is a comparatively small fraction of total primary production in the area. The community respiration of 3.26±0.20 mmol C m−2 d−1 is dominated by prokaryotes (93%) and has lower contributions from surface-deposit feeding macro- (1.7%) and suspension feeding megafauna (1.9%), whereas contributions from nematode and other macro- and megabenthic compartments were limited to <1%. The high prokaryotic contribution to carbon processing suggests that functioning of the benthic food web at the central HAUSGARTEN station is comparable to abyssal plain sediments that are characterised by strong energy limitation. Faunal diet compositions suggest that labile detritus is important for deposit-feeding nematodes (24% of their diet) and surface-deposit feeding macrofauna (∼44%), but that semi-labile detritus is more important in the diets of deposit-feeding macro- and megafauna. Dependency indices on these food sources were also calculated as these integrate direct (i.e. direct grazing and predator–prey interactions) and indirect (i.e. longer loops in the food web) pathways in the food web. Projected sea-ice retreats for the Arctic Ocean typically anticipate a decrease in the labile detritus flux to the already food-limited benthic food web. The dependency indices indicate that faunal compartments depend similarly on labile and semi-labile detritus, which suggests that the benthic biota may be more sensitive to changes in labile detritus inputs than when assessed from diet composition alone. Species-specific responses to different types of labile detritus inputs, e.g. pelagic algae versus sympagic algae, however, are presently unknown and are needed to assess the vulnerability of individual components of the benthic food web. 相似文献
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为了进一步准确过滤对青少年危害较大的色情网页,在汉语词法分析系统添加去禁用词功能实现中文分词,通过改进的词频-逆文档频率及文档频率-互信息方法完成特征提取,从而实现基于支持向量机的过滤方案。并在给出的余弦夹角公式的基础上,提出了一种基于余弦夹角法的中文网页过滤方案。结合两种方案,实验证明在统一资源符总库存在条件下方案对色情等网页过滤效果进一步提高。 相似文献
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