全文获取类型
收费全文 | 53篇 |
免费 | 23篇 |
国内免费 | 47篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 50篇 |
地球物理 | 15篇 |
地质学 | 31篇 |
海洋学 | 20篇 |
天文学 | 1篇 |
综合类 | 1篇 |
自然地理 | 2篇 |
出版年
2024年 | 2篇 |
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 7篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 6篇 |
2009年 | 1篇 |
2008年 | 7篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1986年 | 1篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1942年 | 1篇 |
1938年 | 1篇 |
排序方式: 共有123条查询结果,搜索用时 29 毫秒
21.
安徽省濉溪县邹楼铁矿为接触交代型铁矿床,矿床地质特征与华北地块“邯邢式”铁矿类似,矿体位于燕山期闪长质侵入岩与下奥陶统萧县组碳酸盐岩接触带附近,矿床规模较小,矿体个数多。邹楼铁矿物探异常特征较为明显,处于重力高、磁力高、电阻率等值线低阻扭曲部位。通过对该矿床的地质、物探异常特征进行总结,以期为该区乃至华北地块其他地区寻找类似矿床提供借鉴。 相似文献
22.
This paper presents flume and field observations of a bank-confined braided river. Morphological features, including plan form configuration, channel width, and main channel migration, were examined by a series of experiments. Repeated measurements of channel morphology, provided a basis to estimate the relationship between noncumulative frequency of bars and bar area. Additional results from the Dajia River, located in Central Western Taiwan, were presented to provide a reference data set for comparing the laboratory and field data. The results indicate that the relationship between bar length and width can be predicted by a simple best-fit power function relating to self-similarity characteristics. The Hurst index by Walsh and Hicks (2002) provides acceptable predictions of the bar length and width observed in the experiments and confirmed by the field investigations. Eexperimental and field results both show that large river width yields a uniform distribution of bar areas with the similar discharge, leading to a large value of exponent (β) in the model. The river width is confirmed to be a critical parameter in the main channel shift. A small increase in channel width likely increased rapidly the shift cycle. 相似文献
23.
正 In studying the Carboniferous stratigraphy, one is always struck by the fact that those Namurian and Westphalian plants, abundant in other Arcto- 相似文献
24.
25.
A non-parametric method is used in this study to analyze and predict short-term rainfall due to tropical cyclones(TCs) in a coastal meteorological station. All 427 TCs during 1953-2011 which made landfall along the Southeast China coast with a distance less than 700 km to a certain meteorological station- Shenzhen are analyzed and grouped according to their landfalling direction, distance and intensity. The corresponding daily rainfall records at Shenzhen Meteorological Station(SMS) during TCs landfalling period(a couple of days before and after TC landfall) are collected. The maximum daily rainfall(R-24) and maximum 3-day accumulative rainfall(R-72) records at SMS for each TC category are analyzed by a non-parametric statistical method, percentile estimation. The results are plotted by statistical boxplots, expressing in probability of precipitation. The performance of the statistical boxplots is evaluated to forecast the short-term rainfall at SMS during the TC seasons in 2012 and 2013. Results show that the boxplot scheme can be used as a valuable reference to predict the short-term rainfall at SMS due to TCs landfalling along the Southeast China coast. 相似文献
26.
27.
An understanding of fluvial-aeolian deposition derived from modern case-examples in a previous study is applied to the Permian Cutler Formation and Cedar Mesa Sandstone on the Colorado Plateau. These formations supply an excellent three-dimensional exposure of intertonguing fluvial and aeolian strata. Four distinct facies associations form the bulk of the Cutler Formation and Cedar Mesa Sandstone: (1) aeolian dune deposits; (2) wet interdune deposits; (3) fluvial channel deposits; and (4) overbank-interdune deposits. In addition, two distinctive types of erosion surfaces are found within the Cutler Formation and Cedar Mesa Sandstone: pebble- to granule-rich erosion surfaces (aeolian deflation surfaces) and flood surfaces. Fluvial and aeolian intertonguing result in extensive tabular sheets of aeolian sandstone separated by flood surfaces and overbank-interdune deposits. Fluvial channels are associated with the deposits overlying flood surfaces and are incised into the underlying aeolian sandstones. Overbank-interdune deposits and wet interdune deposits cover flood surfaces and intertongue with overlying aeolian sandstones. The primary characteristics of ancient fluvial-aeolian deposition are overbank-interdune deposits and pronounced extensive erosion surfaces (flood surfaces), which are parallel to underlying fluvial sandstones and thus trend parallel to the palaeoslope and palaeohydrological gradient. 相似文献
28.
An improved sensitive automated method for the determination of mercury in geological materials by cold vapor atomic absorption has been developed. Sample is digested with nitric and hydrochloric acids at low heat. Mercuric ions in the digested sample solution are reduced to elemental mercury by stannous chloride. The gaseous mercury separated from the solution is swept by a stream of argon into the absorption cell of an LDC/Milton Roy Mercury Monitor where the atomic absorption at 253.7 nm is measured. The precision of the method is 2.7% r.s.d., and the detection limit is 1 ppb. The results on 53 international geochemical reference samples are presented. 相似文献
29.
利用单因素实验对海洋解木糖赖氨酸芽孢杆菌(Lysinibacillus xylanilyticus sp.JZ008)培养条件进行了优化.优化后的培养条件:温度为35℃、pH值为7.5、接种量为3%(V/V)、装液量为50cm3/250 cm3时,菌量达到2.01×108CFU/cm3,比优化之前提高了40.6%.添加海藻寡糖可以促进菌株生长,添加量为5.0 g/dm3时发酵液中活菌数是对照组的2.51倍.研究了菌株JZ008对Cd~(2+)、Cr~(3+)、Cu~(2+)3种重金属离子的吸附特性,结果表明菌株JZ008对3种重金属离子污染的水溶液吸附率效果明显,20 d吸附率分别达到95.6%、96.4%、87.0%.土壤重金属吸附实验结果表明,海藻寡糖复配菌株JZ008组对Cd~(2+)、Cr~(3+)、Cu~(2+)吸附效果明显,60 d吸附率分别达到82.5%、82.0%、86.9%.菌株JZ008对重金属的优良吸附作用为进一步开发解木糖赖氨酸芽孢杆菌在重金属修复方面的应用奠定了基础. 相似文献
30.
为研究剧毒卡尔藻(Karlodinium veneficum)与东海原甲藻(Prorocentrum donghaiense)之间的化感作用,在f/2营养盐条件下,分别采用了混合培养及滤液培养的方法。结果表明:剧毒卡尔藻指数生长后期的无藻细胞滤液明显抑制了东海原甲藻的生长,而东海原甲藻滤液对剧毒卡尔藻的生长几乎无影响,化感作用作为重要的影响因素使剧毒卡尔藻获得竞争优势。将剧毒卡尔藻指数生长末期的无藻细胞滤液置于固相萃取(SPE) C18小柱,经吸附、不同比例的甲醇溶液洗脱,考察不同洗脱部分对东海原甲藻生长的影响,发现80%的甲醇洗脱部分明显抑制了东海原甲藻的生长。本研究为了解剧毒卡尔藻的竞争机制提供了重要的科学依据,今后将重点分析剧毒卡尔藻释放的有效抑制东海原甲藻生长的化感物质。 相似文献