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41.
海洋沉积地质过程模拟:性质与问题及前景 总被引:3,自引:0,他引:3
高抒 《海洋地质与第四纪地质》2011,(5):1-7
探讨了海洋沉积地质数值模拟的功能问题.地球科学研究以正演方法(以数值模拟为代表)和反演方法(以地层记录分析为代表)的结合为特征.数值模拟作为一种重要的研究工具,具有获得过程和机理分析结果、形成工作假说、指导现场观测和采样的作用.与此同时,在正反演交融中模型本身也得到了提高和完善.在海洋沉积地质领域,数值模拟在沉积物输运... 相似文献
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Growth and grazing rate dynamics of major phytoplankton groups in an oligotrophic coastal site 总被引:1,自引:0,他引:1
Andrés Gutiérrez-Rodríguez Mikel Latasa Renate Scharek Ramon Massana Gemma Vila Josep M. Gasol 《Estuarine, Coastal and Shelf Science》2011
There has been more attention to phytoplankton dynamics in nutrient-rich waters than in oligotrophic ones thus requiring the need to study the dynamics and responses in oligotrophic waters. Accordingly, phytoplankton community in Blanes Bay was overall dominated by Prymnesiophyceae, remarkably constant throughout the year (31 ± 13% Total chlorophyll a, Tchl a) and Bacillariophyta with a more episodic appearance (20 ± 23% Tchl a). Prasinophyceae and Synechococcus contribution became substantial in winter (Prasinophyceae = 30% Tchl a) and summer (Synechococcus = 35% Tchl a). Phytoplankton growth and grazing mortality rates for major groups were estimated by dilution experiments in combination with high pressure liquid chromatography and flow cytometry carried out monthly over two years. Growth rates of total phytoplankton (range = 0.30–1.91 d−1) were significantly higher in spring and summer (μ > 1.3 d−1) than in autumn and winter (μ ∼ 0.65 d−1) and showed a weak dependence on temperature but a significant positive correlation with day length. Microzooplankton grazing (range = 0.03–1.4 d−1) was closely coupled to phytoplankton growth. Grazing represented the main process for loss of phytoplankton, removing 60 ± 34% (±SD) of daily primary production and 70 ± 48% of Tchl a stock. Chla synthesis was highest during the Bacillarophyceae-dominated spring bloom (Chl asynt = 2.3 ± 1.6 μg Chl a L−1 d−1) and lowest during the following post-bloom conditions dominated by Prymnesiophyceae (Chl asynt = 0.23 ± 0.08 μg Chl a L−1 d−1). This variability was smoothed when expressed in carbon equivalents mainly due to the opposite dynamics of C:chl a (range = 11–135) and chl a concentration (range = 0.07–2.0 μg chl a L−1). Bacillariophyta and Synechococcus contribution to C fluxes was higher than to biomass because of their fast-growth rate. The opposite was true for Prymnesiophyceae. 相似文献
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2009年晚春黄海南部浮游植物群落 总被引:3,自引:0,他引:3
在2009年6月对黄海南部及中部海域30个站位进行综合调查,对获得的131个浮游植物样品用Utermohl方法进行初步分析,共鉴定浮游植物4门51属73种(不包括未定名种),其中硅藻32属47种(不包括未定名种),甲藻17属24种(不包括未定名种),定鞭藻1门1种,蓝藻1门1种,硅藻在物种丰富度上占有优势。浮游植物的生... 相似文献
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P.D. Tortell C. Guéguen M.C. Long C.D. PayneP. Lee G.R. DiTullio 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(3):241-259
We report results from two surveys of pCO2, biological O2 saturation (??O2/Ar) and dimethylsulfide (DMS) in surface waters of the Ross Sea polynya. Measurements were made during early spring (November 2006-December 2006) and mid-summer (December 2005-January 2006) using ship-board membrane inlet mass spectrometry (MIMS) for high spatial resolution (i.e. sub-km) analysis. During the early spring survey, the polynya was in the initial stages of development and exhibited a rapid increase in open water area and phytoplankton biomass over the course of our ∼3 week occupation. We observed a rapid transition from a net heterotrophic ice-covered system (supersaturated pCO2 and undersaturated O2) to a high productivity regime associated with a Phaeocystis-dominated phytoplankton bloom. The timing of the early spring phytoplankton bloom was closely tied to increasing sea surface temperature across the polynya, as well as reduced wind speeds and ice cover, leading to enhanced vertical stratification. There was a strong correlation between pCO2, ??O2/Ar, DMS and chlorophyll a (Chl a) during the spring phytoplankton bloom, indicating a strong biological imprint on gas distributions. Box model calculations suggest that pCO2 drawdown was largely attributable to net community production, while gas exchange and shoaling mixed layers also exerted a strong control on the re-equilibration of mixed layer ??2 with the overlying atmosphere. DMS concentrations were closely coupled to Phaeocystis biomass across the early spring polynya, with maximum concentrations exceeding 100 nM.During the summer cruise, we sampled a large net autotrophic polynya, shortly after the seasonal peak in phytoplankton productivity. Both diatoms and Phaeocystis were abundant in the phytoplankton assemblages during this time. Minimum pCO2 was less than 100 ppm, while ??O2/Ar exceeded 30% in some regions. Mean DMS concentrations were ∼2-fold lower than during the spring, although the range of concentrations was similar between the two surveys. There was a significant correlation between pCO2, ??O2/Ar and Chl a across the summer polynya, but the strength of these correlations and the slope of O2 vs. CO2 relationship were significantly lower than during the early spring. Summertime DMS concentrations were not significantly correlated to phytoplankton biomass (Chl a), pCO2 or ??O2/Ar. In contrast to the early spring time, there were no clear temporal trends in summertime gas concentrations. Rather, small-scale spatial variability, likely resulting from mixing and localized sea-ice melt, was clearly evident in surface gas distributions across the polynya. Analysis of length-scale dependent variability demonstrated that much of the spatial variance in surface water gases occurred at scales of <20 km, suggesting that high resolution analysis is needed to fully capture biogeochemical heterogeneity in this system. 相似文献
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山东半岛南部近岸海域渔业资源群落结构的季节变化 总被引:1,自引:0,他引:1
根据2006年夏、冬季和2007年春、秋季在山东半岛南部近岸海域进行的渔业资源底拖网调查资料,初步分析了该海域渔业资源群落结构特征。结果表明,该海域4个航次的调查共捕获渔业资源种类72种。2006年夏、冬,2007年春、秋4个航次的单位网次渔获量分别为18.1、6.9、1.3、10.3 kg/h。生物量的季节变化,依次呈夏季>冬季>秋季>春季。优势种类主要为赤鼻棱鳀(Thryssakammalensis)、长蛇鲻(Sauridaelongate)、方氏云鳚(Enedrias fangi)及口虾蛄(Oratosquillaorato-ria)、剑尖枪乌贼(Loligoedulis)、鹰爪虾(Rachypenaeus curvirostris)等。根据4个航次的调查数据,分别计算了渔业生物群落的种类丰度指数R、Shannon-Wiener多样性指数H′、Pielou均匀度指数J′。通过聚类分析、单因子相似性分析(ANOSI M)、相似性百分比分析(SI MPER),以及对该海域游泳动物资源结构现状与历史调查数据对比分析表明,该海域渔业资源群落结构存在衰退现象。本研究为山东半岛南部海域渔业生物多样性保护和资源管理提供了参考依据。 相似文献