全文获取类型
收费全文 | 128篇 |
免费 | 36篇 |
国内免费 | 25篇 |
专业分类
测绘学 | 15篇 |
大气科学 | 37篇 |
地球物理 | 29篇 |
地质学 | 45篇 |
海洋学 | 9篇 |
天文学 | 3篇 |
综合类 | 21篇 |
自然地理 | 30篇 |
出版年
2021年 | 10篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 9篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 8篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 15篇 |
2006年 | 6篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 4篇 |
1984年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有189条查询结果,搜索用时 31 毫秒
81.
利用1951—2012年冬季全国160个站月平均气温以及NCEP/NACR再分析资料和海温、北极海冰等资料,分析了我国冬季气温及其关键影响因子的年代际变化特征,重点研究了关键影响因子对我国冬季气温影响关系的年代际变化。研究表明:我国冬季气温在1985年之前处于冷期,之后为暖期; 我国冬季气温异常与影响因子的关系发生了显著的年代际变化,而且影响因子之间的关系也发生了显著的年代际变化。针对这种年代际变化的基本事实,提出针对冷期和暖期中不同影响因子与冬季气温的关系分时段建立冬季气温的多因子回归预测模型,可以反映冬季气温及其影响因子关系的年代际变化特征。正确的预测策略是利用相同年代际背景下预测对象与预测因子的时间序列资料建立预测模型,以确保预测模型中反映的预测对象与预测因子关系的稳定性,进而保持较高的拟合及预测水平。 相似文献
82.
利用在南海西南海盆南缘首次发现的花岗闪长岩样品,通过等离子质谱仪、岩相显微镜和电子探针等设备对其地球化学组成进行了分析;并对其组分中黑云母矿物进行了40Ar/39Ar年代学研究。40Ar/39Ar等时线年龄显示岩石的结晶年龄为(109.5±1.5)Ma,是早白垩世岩浆入侵的产物。地球化学测试表明:样品以富SiO2、K2O,高Al2O3、贫TiO2为特征。地球化学-构造判别图解显示,样品属于火山弧花岗岩,为造山类花岗岩。样品可能是海盆早期张裂阶段裂谷系组成的重要岩石类型,而裂谷拉张的过程可能与现代红海的演化相似,经历了裂谷沉陷过程,当裂谷宽度、深度达到一定规模时,洋壳随之而产生。该样品的发现,揭示其产出位置可能是南海西南海盆的南部边界,而且是洋盆扩张初期断裂系统的组成部分,为探讨南海的张裂、形成与演化历史提供了新的线索。 相似文献
83.
84.
85.
A prediction of sea level rising amplitude in 2030 and defensive countermeasures in the Zhujiang delta 总被引:1,自引:0,他引:1
HUANG Zhenguo ZHANG Weiqiang WU Houshui CHEN Tegu FAN Jinchun JIANG Peilin Li Zihao Huang Bensheng 《中国科学D辑(英文版)》2001,44(5):446-454
By analysing comprehensively the factors such as theoretical sea level, abnormal fluctuation of sea level, rising amplitude
of floodtide water level and land deformation, a rising amplitude of 22-33 cm of relative sea level by the year of 2030 is
forecasted in the Zhujiang Delta. From the forecasted amplitude of 30 cm, using hydraulic and hydrometric models the scope
influenced by sea level rise is delimited and the reappearing periods of floodtide water level, protecting ability of embankments,
design parameters of water conservancy project, drain waterlogging, saline intrusion, resource of mud beach and comprehensive
prevention measures are discussed. 相似文献
86.
According to archaeological data from about sixty samples the relative stability of physical and human geographical environment
in the tropical zone of China is discussed in this paper. Because of the superior natural environment, sufficient food resources
and a sparse population resulting in the absence of social requirement to transform the productive forces, the advancement
of economy and society was stagnated during prehistorical period in China’s tropics. Compared with northern China, the appearance
of ground stone tool stagnated about 3,000 years, the beginning of Bronze Age, about 1,000 years, and the agriculture, 2,500–3,000
years. The no ceramics age continued till the early Neolithic Age and the appearance of colour or white ceramics was 2,000
years later than that in northern China. The life form of migration to gather and to hunt continued till the middle Neolithic
Age, and the fixed settlement based on agriculture 1,000–2,000 years stagnated. The clan commune just appeared at the end
of the Neolithic Age which was 2, 000–3,000 years later than that in northern China. 相似文献
87.
88.
本文论述陕西部分黄土台塬区深层地下水六价铬超标的水文地球化学异常,并提出了还原—微絮凝分离的除铬方案,设计了高效低成本的处理工艺。除铬效率达到98%以上,出水水质稳定,各项指标达到饮用水卫生标准。 相似文献
89.
This paper examines the increased potential risk of tidalinundations in the Pearl River delta, China, due to futurerises in sea level. The research is based on tidal recordsof 54 tide gauges distributed across the delta plain, andemploys mathematical calculations to predict potentialrises of water level in different parts of the delta undera number of flood scenarios. After assessing a 72-yeartidal record of Hong Kong and factors such as estuarinebackwater effects and long-term geological subsidence,it suggests that a 30 cm rise in relative sea level at themouth of the estuary is possible by 2030. Based on theprediction and five freshwater discharge scenarios, thepotential impacts on water levels across the delta plain arecalculated. Three zones are identified as least affected,heavily affected and severely affected. The impacts arealso translated into return periods of water level. It issuggested that in a large part of the delta plain, returnperiods will be shortened and hence will be increasinglyvulnerable to tidal inundation. Finally, managementimplications are discussed along with assessment ofthe adequacy of the existing tidal flood defences, as well asevaluation of the cost implications if they are to be improved. 相似文献
90.
The eastern and western fronts of plate movement in Taiwan Island and Tibetan Plateau respectively are the two major sources
of tectonic force for the morphogensis during Quaternary in China’s tropics. Seven examples of geomorphological effects of
plate movement are enumerated to discuss the differentiation of tectonic landforms in space and time during Quaternary. The
tectonic movement tends to be more active since middle Pleistocene. Some phenomena such as the arc-shape mountain systems,
volcanism and crustal deformation imply that the juncture zone of eastern and western tectonic forces is located at about
110°E. 相似文献