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861.
位于内蒙古中西部地区的宝音图群,主要由云母片岩、斜长角闪岩、石英岩和大理岩等组成。其中云母片岩中发育典型的巴罗式递增变质带,目前对于该递增变质带的研究非常薄弱。本文对宝音图群的云母片岩开展了系统的岩相学、矿物化学、相平衡模拟以及锆石U-Pb年代学的研究。岩相学研究结果显示,三个云母片岩样品具有不同的峰期矿物组合,分别为石榴子石+白云母+黑云母+斜长石+石英,十字石+白云母+黑云母+斜长石+钛铁矿+石英,石榴子石+蓝晶石+白云母+黑云母+斜长石+钛铁矿+石英。此外,样品LS93和LS07存在晚期红柱石的叠加。相平衡模拟研究限定三个云母片岩的峰期温度压力分别为:577℃、0.73 GPa, 620℃、0.78 GPa和670℃、0.8 GPa,具有递增型特征,其峰期温度压力指示的地热梯度为18~20℃/km,为典型的中压相系;此外,三个样品的P-T轨迹均显示早期升温升压直至峰期阶段,随后降温降压的顺时针型,反映地壳加厚和后期抬升的演化过程。云母片岩中的锆石发育典型的变质边结构,变质边的Th/U=0.004~0.02,锆石U-Pb年代学结果显示该变质年龄为398±6 Ma,代表峰期或近峰期阶... 相似文献
862.
863.
864.
中国与基性—超基性岩有关的Cu-Ni(Pt)矿床成矿系列类型 总被引:2,自引:0,他引:2
中国与基性—超基性岩有关的Cu-Ni(Pt)矿床,主要形成于以前寒武系为基底的大陆裂谷,部分形成于增生褶皱带中显生宙地层为基底的裂陷槽环境。根据形成时代、当时所在的构造环境单元及成矿岩浆系列,划分为9个矿床成矿系列和8个矿床成矿亚系列。成矿时代以元古代、晚古生代为主。现今,矿床主要分布于地台边缘,造山带中也有产出,但不代表其当时形成的地质背景。成矿物质来源为上地幔,原始岩浆以上地幔部分熔融的高MgO拉斑玄武岩(拉斑橄榄玄武岩)岩浆系列为特征,也有钙碱性岩浆(喀拉通克)和科马提岩岩浆系列(桂北)。地壳物质混染比较普遍。矿床成因类型主要为岩浆熔离型,且以硅酸盐岩浆上侵前的深部熔离作用为主。还有热液成因类型(煎茶岭)。矿床成矿系列的时空分布与中国大陆的构造演化密切相关 相似文献
865.
LI Xianqing FENG Songbao XIAO Xianming TANG Yongchun XIAO Zhongyao MI Jingkui TIAN Hui LIU Dehan SHEN Jiagui 《中国地球化学学报》2013,32(2):157-169
The Kela-2 gas field, found in the Kuqa Depression of the Tarim Basin, northwestern China, is a large-sized dry gas field (C1 /C1-5 =0.992 0.999) and characterized by ultra-high pressure (pressure factor up to 2.0 2.2). The pyrolysis experiment was carried out under isothermal gold-tube closed system, with samples collected from the Jurassic coal, Jurassic mudstone and Triassic mudstone in the Kuqa Depression. The result of gas yield showed that the Middle and Lower Jurassic source rocks have higher gas generation potential than the Triassic source rocks. The kinetic modeling of gas generation and methane carbon isotope fractionation suggested that the Kela-2 gases belong to the products of high-over mature stages and were mainly derived from the Middle and Lower Jurassic coal-bearing strata. The Triassic source rocks made a minor contribution to the Kela-2 gases. The Kela-2 gases chiefly generated from coal-bearing source rocks with R o values from 1.3% to 2.5%, and thus primarily accumulated after 5 Ma. 相似文献
866.
长株潭城市群公路交通与区域协调发展研究 总被引:1,自引:0,他引:1
长株潭城市群是长江中游地区的重要组成部分,是开展新时期公路交通与区域协调发展研究的理想区域。从区域协调发展与主体功能区建设的视角,系统分析长株潭城市群公路交通发展的理论基础与现状特征,发现目前公路交通在路网结构、职能分工、产业统筹、公共交通、资源环境等方面存在诸多突出问题。在此基础上,构建以资源节约、环境友好、以人为本、区域一体为核心内涵的公路交通发展新模式,并从主体功能区划、空间拓展、产业布局、生态环境保护、体制与机制创新等维度提出公路交通与区域协调发展的对策。 相似文献
867.
Spatial patterns and environmental factors influencing leaf carbon content in the forests and shrublands of China 总被引:1,自引:0,他引:1
Hang Zhao Li Xu Qiufeng Wang Jing Tian Xuli Tang Zhiyao Tang Zongqiang Xie Nianpeng He Guirui Yu 《地理学报(英文版)》2018,28(6):791-801
Leaf carbon content (LCC) is widely used as an important parameter in estimating ecosystem carbon (C) storage, as well as for investigating the adaptation strategies of vegetation to their environment at a large scale. In this study, we used a dataset collected from forests (5119 plots) and shrublands (2564 plots) in China, 2011–2015. The plots were sampled following a consistent protocol, and we used the data to explore the spatial patterns of LCC at three scales: plot scale, eco-region scale (n = 24), and eco-region scale (n = 8). The average LCC of forests and shrublands combined was 45.3%, with the LCC of forests (45.5%) being slightly higher than that of shrublands (44.9%). Forest LCC ranged from 40.2% to 51.2% throughout the 24 eco-regions, while that of shrublands ranged from 35% to 50.1%. Forest LCC decreased with increasing latitude and longitude, whereas shrubland LCC decreased with increasing latitude, but increased with increasing longitude. The LCC increased, to some extent, with increasing temperature and precipitation. These results demonstrate the spatial patterns of LCC in the forests and shrublands at different scales based on field-measured data, providing a reference (or standard) for estimating carbon storage in vegetation at a regional scale. 相似文献
868.
869.
Temporal variation in soil detachment under different land uses in the Loess Plateau of China 总被引:9,自引:0,他引:9
Measurements of temporal variations in soil detachability under different land uses are badly needed to develop new algorithms or evaluate the existing ones for temporal adjustment of soil detachability in continuous soil erosion models. Few studies have been conducted in the Loess Plateau to quantify temporal variations in detachment rate of runoff under different land uses. The objectives of this study were to investigate the temporal variations of soil detachment rate under different land uses and to further identify the potential factors causing the change in detachment rate in the Loess Plateau. Undisturbed soil samples were collected in the fields of arable land (millet, soybean, corn, and potato), grassland, shrub land, wasteland, and woodland and tested in a laboratory flume under a constant hydraulic condition. The measurements started in mid‐April and ended in early October, 2006. The results showed that soil detachment rate of each land use fluctuated considerably over time. Distinctive temporal variation in detachment rate was found throughout the summer growing season of measurement in each land use. The maximum detachment rates of different land uses varied from 0·019 to 0·490 kg m–2 s–1 and the minimum detachment rates ranged from 0·004 to 0·092 kg m–2 s–1. Statistical analysis using a paired‐samples t‐test indicated that variations in soil detachment rate differed significantly at the 0·05 level between land uses in most cases. The major factors responsible for the temporal variation of soil detachment were tillage operations (such as planting, ploughing, weeding, harvesting), soil consolidation, and root growth. The influence of tillage operations on soil detachment depended on the degree of soil disturbance caused by the operations. The consolidation of the topsoil over time after tillage was reflected by increases in soil bulk density and soil cohesion. As soil bulk density and cohesion increased, detachment rate decreased. The impact of root density was inconclusive in this study. Further studies are needed to quantify the effects of root density on temporal variations of soil detachment. This work provides useful information for developing temporal adjustments to soil detachment rate in continuous soil erosion models in the Loess Plateau. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
870.
Oracle复制技术在地震前兆元数据交换中的应用 总被引:1,自引:1,他引:0
根据"十五"中国地震前兆信息网络建设的需要,在全国地震系统中实现地震前兆数据的自动化交换管理.我们分析提取出地震前兆元数据的管理模型并基于Oracle快照复制技术设计和实现了地震前兆元数据的交换管理.本文对Oraele快照复制技术做了较为详细的介绍,并分析指出了Oracle快照复制技术应用于地震前兆元数据交换的关键点,结合数据管理系统在地震前兆中的实际使用情况做了简要讨论.实践证明,基于Oracle快照复制技术实现的地震前兆台网数据管理系统软件完全满足了地震前兆网络建设的需要. 相似文献