全文获取类型
收费全文 | 5281篇 |
免费 | 950篇 |
国内免费 | 2134篇 |
专业分类
测绘学 | 46篇 |
大气科学 | 1209篇 |
地球物理 | 827篇 |
地质学 | 2874篇 |
海洋学 | 2603篇 |
天文学 | 30篇 |
综合类 | 219篇 |
自然地理 | 557篇 |
出版年
2024年 | 33篇 |
2023年 | 81篇 |
2022年 | 243篇 |
2021年 | 210篇 |
2020年 | 232篇 |
2019年 | 296篇 |
2018年 | 261篇 |
2017年 | 271篇 |
2016年 | 277篇 |
2015年 | 264篇 |
2014年 | 410篇 |
2013年 | 454篇 |
2012年 | 307篇 |
2011年 | 363篇 |
2010年 | 256篇 |
2009年 | 386篇 |
2008年 | 424篇 |
2007年 | 410篇 |
2006年 | 404篇 |
2005年 | 351篇 |
2004年 | 330篇 |
2003年 | 283篇 |
2002年 | 266篇 |
2001年 | 218篇 |
2000年 | 212篇 |
1999年 | 184篇 |
1998年 | 148篇 |
1997年 | 166篇 |
1996年 | 112篇 |
1995年 | 81篇 |
1994年 | 117篇 |
1993年 | 80篇 |
1992年 | 49篇 |
1991年 | 41篇 |
1990年 | 24篇 |
1989年 | 25篇 |
1988年 | 23篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1954年 | 2篇 |
排序方式: 共有8365条查询结果,搜索用时 859 毫秒
101.
102.
Baraza J. Ercilla G. Farrán M. Casamor J. L. Sorribas J. Flores J. A. Sierro F. Wersteeg W. 《Marine Geophysical Researches》1997,19(2):115-135
Multibeam bathymetric and ultra high-resolution seismic data reveal that the distal course of the Equatorial Atlantic Mid-Ocean Channel (EAMOC) extends further east and south than was previously known, and is controlled by the presence of morphologic highs related to the Fernando de Noronha Fracture Zone. Distal course of the EAMOC is buried by sediments, and does not have bathymetric expression on the seafloor. The channel fill consists of three seismic sequences, suggesting that the recent geological evolution of the channel is composed of successive phases of decreasing sedimentary activity that finally resulted in its complete burial. Tectonic and volcanic activity related to the Fernando de Noronha Fracture Zone and Ridge, together with the effect of strong pulses of the Antarctic bottom water current during the upper Pliocene are suggested to have contributed to the progressive burial and the final abandonment of the EAMOC. 相似文献
103.
南海中部和冲绳海槽沉积物中的氨基酸物质 总被引:2,自引:0,他引:2
本文通过对南海中部和冲绳海槽三个深海沉积物柱状样腐植物质水解氨基酸的研究,试图阐述南海和冲绳海槽沉积物的演化与沉积环境。 相似文献
104.
南海中北部表层沉积物的矿物沉积 总被引:10,自引:0,他引:10
本文研究了南海中北部500多个样品的矿物学。认为,本区表层沉积物中矿物种类繁多,分布较为普遍,碎屑矿物(含火山物质)、粘土矿物、自生矿物常有出现。以前者为最显著(共60多种,其中重矿物50多种,轻矿物近10种),主要分布于陆架区及深海盆;粘土矿物次之,多分布于陆坡~深海盆;自生矿物较少,陆架~深海盆均有分布。文中根据矿物沉积特征和环境差异,把它划分为6个矿物区。 相似文献
105.
Crustal Structures of the Northernmost South China Sea: Seismic Reflection and Gravity Modeling 总被引:2,自引:0,他引:2
The South China Sea (SCS) is a marginal sea off shore Southeast Asia. Based on magnetic study, oceanic crust has been suggested in the northernmost SCS. However, the crustal structure of the northernmost SCS was poorly known. To elaborate the crustal structures in the northernmost SCS and off southwest Taiwan, we have analyzed 20 multi-channel seismic profiles of the region. We have also performed gravity modeling to understand the Moho depth variation. The volcanic basement deepens southeastwards while the Moho depth shoals southeastwards. Except for the continental margin, the northernmost SCS can be divided into three tectonic regions: the disturbed and undisturbed oceanic crust (8–12 km thick) in the southwest, a trapped oceanic crust (8 km thick) between the Luzon-Ryukyu Transform Plate Boundary (LRTPB) and Formosa Canyon, and the area to the north of the Formosa Canyon which has the thickest sediments. Instead of faulting, the sediments across the LRTPB have only displayed differential subsidence offset of about 0.5–1 s in the northeast side, indicating that the LRTPB is no longer active. The gravity modeling has shown a relatively thin crust beneath the LRTPB, demonstrating the sheared zone character along the LRTPB. However, probably because of post-spreading volcanism, only the transtension-shearing phenomenon of volcanic basement in the northwest and southeast ends of the LRTPB can be observed. These two basement-fractured sites coincide with low gravity anomalies. Intensive erosion has prevailed over the whole channel of the Formosa Canyon. 相似文献
106.
Comparison among four kinds of data of sea surface wind stress in the South China Sea 总被引:1,自引:0,他引:1
By using remote sensing (ERS) data, FSU data, COADS data and Hellerman & Rosen-stein objective analysis data to analyze the sea surface wind stress in the South China Sea, it is found that the remote sensing data have higher resolution and more reasonable values. Therefore we suggest that remote sensing data be chosen in the study of climatological features of sea surface wind stress and its seasonal variability in the South China Sea, especially in the study of small and middle scale eddies. 相似文献
107.
108.
本文记述了南海晚第四纪沉积物中发现的两个新种[线形辐环藻(Actinocyclus lineatus Liu,Cheng et Lan sp.nov.)、星圆筛藻(Coscinodiscus aster-aeus Cheng,Liu et Lan sp.nov.)]以及在我国首次记录的圆筛藻的7个种。 相似文献
109.
本文根据分析结果阐述了两种不同样品处理方法所获得的硅藻丰度和微型硅藻的人主要种类和相对百分含量。研究表明洗涤富集法所获得的硅藻丰度存在较大误差;微型硅藻的含量普遍介于10%-20%之间,最高可达42.31%,最低为5.66%,并指出了在微型硅藻相对含量大于20%的样品中 ,其主要种类为具槽直链藻和条纹小环藻等沿岸底格格不入中,并成群体产出。 相似文献
110.
W. R. Roest J. J. Dañobeitia J. Verhoef B. J. Collette 《Marine Geophysical Researches》1992,14(1):1-24
The data from a recent magnetic compilation by Verhoefet al. (1991) off west Africa were used in combination with data in the western Atlantic to review the Mesozoic plate kinematic evolution of the central North Atlantic. The magnetic profile data were analyzed to identify the M-series sea floor spreading anomalies on the African plate. Oceanic fracture zones were identified from magnetic anomalies and seismic and gravity measurements. The identified sea floor spreading anomalies on the African plate were combined with those on the North American plate to calculate reconstruction poles for this part of the central Atlantic. The total separation poles derived in this paper describe a smooth curve, suggesting that the motion of the pole through time was continuous. Although the new sea floor spreading history differs only slightly from the one presented by Klitgord and Schouten (1986), it predicts smoother flowlines. On the other hand, the sea floor spreading history as depicted by the flowlines for the eastern central Atlantic deviates substantially from that of Sundvik and Larson (1988). A revised spreading history is also presented for the Cretaceous Magnetic Quiet Zone, where large changes in spreading direction occurred, that can not be resolved when fitting magnetic isochrons only, but which are evident from fracture zone traces and directions of sea floor spreading topography.Deceased 11 November 1991 相似文献