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41.
Hu Zeyong CHENG Guodong QIAN Zeyu WANG Jiemin Wei Guoan HOU Xuhong GU Lianglei YAN Yuping 《中国科学D辑(英文版)》2004,47(Z1)
The data obtained through the roadbed surface thermal regime experiment (ROBSTREX), which was carried out at Beiluhe test section of Qinghai-Tibetan Railway from October to December in 2002, were used to estimate the cooling effect of ballast revetment on the roadbed. The results show that both riprap rock ballast revetment and crushed stone ballast revetment can reduce the temperature of the roadbed. But the cooling effect of riprap rock ballast revetment is better than that of crushed stone ballast revetment when the temperature of roadbed is higher. The cooling effect of crushed stone ballast revetment is better than that of riprap rock ballast revetment when the temperature of the roadbed is lower, especially at deeper roadbed layers. In the frozen season, the heat release from the roadbed also shows that the cooling effect of ballast revetment on the roadbed is obvious, and the cooling effect of crushed stone-ballast revetment on the roadbed is much evident than that of riprap rock ballast revetment. 相似文献
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WU Huixian SHEN Chen WANG Qiong Richard B. ARONSON CHEN Chen XUE Junzeng 《海洋湖沼学报(英文)》2019,(2):580-588
Phytoplankton diversity and abundance were determined in ballast water from 26 vessels in the Shanghai Yangshan Deep-Water Port from April 2015 to January 2016. In total, 84 species of phytoplankton were identified, belonging to 43 genera and 5 phyla. Bacillariophyta (75.0%, including 30 genera and 63 species) were the dominant algae in the ballast water. Their density ranged from (5.55±9.62) SD to (1.878±0.872)×10 3 cells/L, with a mean of 410.1 cells/L. Nine potentially harmful phytoplankton taxa were detected: Ceratium furca , Ce . marcroceros , Leptocylindrus danicus , Coscinodiscus radiatus , Co . granii , Prorocentrum micans , Melosira sulcata , Meuniera membranacea and Skeletonema costatum . Our survey and identification results showed that Microcystis aeruginosa , Ankistrodesmus falcatus and Scenedesmus survived in the high-salinity ballast water, even though they are freshwater species. We identified the common features of surviving phytoplankton and impacts on the phytoplankton assemblage of ballast water age and source. Our goal was to understand the adaptative mechanisms of phytoplankton in ballast water, providing statistical and theoretical support for future ballast water research and suggesting a scientific basis of ballast water management and inspection of vessels entering the port. 相似文献
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福建外来船舶压舱水中浮游植物种类组成与丰度及其影响因素的初步研究 总被引:5,自引:0,他引:5
2006~2008年间对进入福建沿海4个主要港口的12艘国际航船所携带的压舱水进行浮游植物种类组成和丰度分布的调查.此调查共检测出浮游植物7个门86属239种(含变种和变型),77μm孔径网滤样和20μm孔径网滤样的平均藻类丰度分别为1.2×10^2cells/dm^3(变动在0~9.1×10^2cells/dm^3间)和3.4×10^3cells/dm^3(变动在0~3.0×10^4cells/dm^3间).同时对其中6艘船舶的压舱水样品用f/2培养基培养,共有13种硅藻和1种甲藻被成功培养.文中还分析了压舱水中浮游植物丰度与盐度、水龄的关系,并结合历史资料讨论了压舱水里各类浮游植物的分布. 相似文献
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青藏高原封闭道碴层对下部多年冻土保护作用的现场实验研究 总被引:1,自引:1,他引:0
为了研究封闭道碴层对其下部多年冻土是否具有积极的保护作用,在青藏铁路北麓河试验段附近建立了封闭碎石道碴坑和卵石地表对比试验场,并对下部地温进行监测.结果发现:经过两个冻融循环后,道碴坑底部(1.3 m深度处)年平均地温为-1.11℃,比卵石地表相同深度低0.73℃;道碴坑中部(0.7m深度处)年平均地温为-1.60℃,比卵石地表相同深度地温低1.4℃.封闭碎石道碴层可以提升冻土上限,降低多年冻土温度,对下部多年冻土起到很好的保护作用.封闭道碴层的这种降温效果是由于道碴层具有可变导热系数的特点,暖季道碴层上部温度高,下部温度低,不产生对流,等效导热系数小,传入道碴层以下土体的热量较少;相反寒季道碴层上部温度低,下部温度高,产生自然对流,等效导热系数增大,有利于道碴层以下土体释放热量. 相似文献
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Study on Treating Halobios Pollution by Hydroxyl Radical 总被引:1,自引:0,他引:1
Human beings are facing a serious environmental crisis which is even threatening their existence. Therefore, many scholars propose the concept of advanced oxidation method (technology or process, abbr. AOP or AOT). The advanced oxidation method includes the process of producing hydroxyl radicals (OH·) and a series of chain reactions excited by OH·. The radicals can attack various kinds of pollutants and microorganisms in water and finally decompose them into CO2, H2O and inorganic salt… 相似文献
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积沙对铁路道碴层反射率的影响研究 总被引:1,自引:1,他引:0
青藏铁路建成后,随着全球气温的升高及人类活动的影响,青藏高原地表沙化正在呈现加速发展的趋势,地表积沙入侵路基,填堵和覆盖青藏铁路道碴层,影响了青藏铁路道碴层的反射率。为此开展了积沙对于铁路道碴层反射率影响的研究。为此本文将测量碎石层等粗糙表面的反射率的方法进行了改进,使其适用于测量混有流动性材料(如积沙等)的粗糙表面(如铁路道碴层等)的反射率。结果表明:随着铁路道碴层模型积沙覆盖率的增大,铁路道碴层的反射率先减小后增大,当积沙完全覆盖道碴层时,其反射率达到最大。并将该测试方法与ASTM-E1918A标准测试方法进行对比分析发现,在天气晴朗、无云、无雾霾且太阳辐射入射量瞬时强度变化<20W·m-2时,两种测试方法计算非常接近,其测量差值0~0.002,综合分析认为在测量带有流动材料的反射率时,采用本测试方法方便可靠。但积沙对道碴层的热流平衡影响有待进一步研究。 相似文献
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In order to reduce the maintenance costs of ballasted railway track and improve passenger comfort, the railway ballast particle breakage and its effect on track settlement need to be better understood. The failure process of individual railway ballast loaded between flat platens is simulated using the discrete element method, considering its irregular shape with the incorporation of parallel bonds. The tensile strength, the stress of a survival probability of 37% of samples, is obtained and compared with laboratory results from published literature for the verification of DEM simulations. The evolution to failure of the particle is understood from the stress-strain curve and progressive failure modes. The internal breakage mechanisms are analysed by tracking the accumulation of bond breakage number and the contact force distributions. 相似文献