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31.
32.
基于前人有关膨润土在碱性环境下的室内试验和数值模拟的研究结果 ,重点阐述了碱金属离子及碱溶液对膨润土矿物成分、微观结构、膨胀性和渗透性等方面的影响,讨论了温度、pH值与溶液浓度等对上述过程的影响。碱金属离子及碱性溶液不仅可交换膨润土中蒙脱石层间阳离子,而且可溶解膨润土中的蒙脱石,生成非膨胀性矿物,并随着温度和pH值升高,蒙脱石被溶解程度增加,从而导致了膨润土膨胀力减小,且随着温度、溶液浓度及pH值的增加,膨胀力削弱程度加强;同时,膨润土与碱金属离子及碱溶液接触时孔隙增多,进而渗透性增强,随着温度和溶液浓度增加,渗透性也明显增强。数值模拟可实现膨润土与碱性溶液长期接触时发生的矿物成分及渗透性变化的预测。高温、不同pH值的低碱性溶液及其耦合作用对膨润土的矿物化学成分、微观结构、膨胀力和渗透性的影响及机理研究应该是今后研究的重点。 相似文献
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Wei-min Ye Zi-yuan Qi Bao Chen Ji Xie Yu Huang Yao-ru Lu Yu-Jun Cui 《Environmental Earth Sciences》2011,64(1):269-276
Karst rocky desertification is a process of land degradation involving serious soil erosion, extensive exposure of basement
rocks. It leads to drastic decrease in soil productivity and formation of a desert-like landscape. In this regard, changes
in climatic conditions are the main origin of the soils degradation. Indeed, soils subjected to successive dry/wet cycling
processes caused by climate change develop swelling and shrinkage deformations which can modify their water retention properties,
thus inducing the degradation of soil–water capacity. The ecological characteristics of cultivation soils in karst areas,
Southwest of China, are extremely easy to be affected by external environmental factors due to its shallow bedding and low
vegetation coverage. Based on the analysis of the climate (precipitation) of this region during the past decades, an experimental
study has been conducted on a cultivated soil obtained from the typical karst area in southwestern China. Firstly, the soil–water
properties have been investigated. The measured soil–water retention curve shows that the air-entry value of the soil is between
50 and 60 kPa, while the residual saturation is about 12%. Based on the experimental results, three identifiable stages of
de-saturation have been defined. Secondly, a special apparatus was developed to investigate the volume change behavior of
the soil with controlled suction cycles. The vapor equilibrium technique was used for the suction control. The obtained results
show that under the effect of dry/wet cycles, (1) the void ratio of the cultivated soil is continuously decreasing, leading
to a gradual soil compaction. (2) The permeability decreases, giving rise to a deterioration of water transfer ability as
well as a deterioration of soil–water retention capacity. It is then obvious that the long-term dry/wet cycling process caused
by the climate change induce a continuously compaction and degradation of the cultivated soil in karst rocky desertification
areas. 相似文献
36.
Contamination and distribution of heavy metals in urban and suburban soils in Zhangzhou City,Fujian, China 总被引:2,自引:0,他引:2
Zhen-ang Cui Sheng-ying Qiao Zheng-yu Bao Neng-you Wu 《Environmental Earth Sciences》2011,64(6):1607-1615
The urban environment is of growing concern as its continued population increase in China. Due to the urbanization and industrialization,
heavy metals have been continuously discharged into the soil recently, and creating the anthropogenic contamination. This
study investigated heavy metals contamination in urban and suburban soils in Zhangzhou City, Fujian, China. Multivariate analysis
and geographical information system technology were employed in source identification and contamination assessment of heavy
metals in the city soils. The survey results indicated that the urban soils were contaminated by heavy metals, especially
by Hg, Cd and Pb. The multivariate analysis demonstrated that the distribution of Cu, Zn, Cr and Ni was controlled by pedogenesis,
Cd and Pb had been disturbed by industrialization in some urban locations, and Hg was mainly influenced by the hot-spring
in some urban park sites. The distribution of heavy metals and soil pollution index suggested the soils of Zhangzhou City
have been affected by human activities. 相似文献
37.
A spectral mixture model analysis of the Kuroshio variability and the water exchange between the Kuroshio and the East China Sea 总被引:1,自引:0,他引:1
For understanding more about the water exchange between the Kuroshio and the East China Sea,We studied the variability of the Kuroshio in the East China Sea(ECS) in the period of 1991 to 2008 using a three-dimensional circulation model,and calculated Kuroshio onshore volume transport in the ECS at the minimum of 0.48 Sv(1 Sv ;106 m3/s) in summer and the maximum of 1.69 Sv in winter.Based on the data of WOA05 and NCEP,The modeled result indicates that the Kuroshio transport east of Taiwan Island decreased since 2000.Lateral movements tended to be stronger at two ends of the Kuroshio in the ECS than that of the middle segment.In addition,we applied a spectral mixture model(SMM) to determine the exchange zone between the Kuroshio and the shelf water of the ECS.The result reveals a significantly negative correlation(coefficient of-0.78) between the area of exchange zone and the Kuroshio onshore transport at 200 m isobath in the ECS.This conclusion brings a new view for the water exchange between the Kuroshio and the East China Sea.Additional to annual and semi-annual signals,intra-seasonal signal of probably the Pacific origin may trigger the events of Kuroshio intrusion and exchange in the ECS. 相似文献
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对安徽巢湖地区平顶山和马家山剖面下二叠统栖霞组和下三叠统南陵湖组进行了地层沉积特征及暗色石灰岩生烃潜力的综合分析,并对这两个层位的样品进行了饱和烃生物标志物特征研究。结果表明,两个层位的石灰岩都属于有效烃源岩,均具有一定的生烃潜力。南陵湖组石灰岩饱和烃以高丰度的长链三环萜烷、重排藿烷、重排甾烷为特征,表明其形成于偏弱氧化的沉积环境。栖霞组沉积期水体能量相对较低,受陆源物质影响明显,栖霞组石灰岩萜烷系列为常规的分布模式,但其甾烷成熟度参数明显低于平衡值,认为高的热演化程度是造成栖霞组石灰岩20S/(20S+20R)-ααα-C29甾烷值和ββ/(ββ+αα)-C29甾烷值"倒转"的主要原因。 相似文献
40.
钻探取心是天然气水合物资源调查研究的一种重要技术手段,也是识别天然气水合物最有效的方法之一。青海木里煤田三露天调查区地质构造复杂,水合物钻探施工时极易出现孔壁坍塌、水合物分解、气侵泥浆及孔内涌气、涌水、漏失等问题,取芯困难、钻进效率低。针对这些技术难题,开展了泥浆制冷技术、大口径绳索快速取心钻进技术、聚合物低温泥浆工艺及泥浆防塌体系、钻孔结构及钻进参数优化、钻头选型、气体防喷等技术工艺研究,并在现场实践中取得了较好的效果,为今后青藏高原冻土地带进行天然气水合物钻探施工提供借鉴。 相似文献