全文获取类型
收费全文 | 481篇 |
免费 | 12篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 17篇 |
大气科学 | 49篇 |
地球物理 | 94篇 |
地质学 | 219篇 |
海洋学 | 14篇 |
天文学 | 47篇 |
综合类 | 5篇 |
自然地理 | 53篇 |
出版年
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 15篇 |
2017年 | 14篇 |
2016年 | 14篇 |
2015年 | 16篇 |
2014年 | 19篇 |
2013年 | 25篇 |
2012年 | 23篇 |
2011年 | 25篇 |
2010年 | 19篇 |
2009年 | 18篇 |
2008年 | 20篇 |
2007年 | 24篇 |
2006年 | 21篇 |
2005年 | 13篇 |
2004年 | 19篇 |
2003年 | 16篇 |
2002年 | 10篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 11篇 |
1998年 | 9篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 15篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1970年 | 2篇 |
1967年 | 2篇 |
1966年 | 4篇 |
排序方式: 共有498条查询结果,搜索用时 15 毫秒
1.
Nie Yufeng Shen Yunzhong Pail Roland Chen Qiujie Xiao Yun 《Surveys in Geophysics》2022,43(4):1169-1199
Surveys in Geophysics - The gravity field recovery from GRACE (Gravity Recovery and Climate Experiment) mission data is contaminated by both observation noise and dynamic force errors, especially... 相似文献
2.
Savage Cory A. M. Remmer Casey R. Telford James V. Kay Mitchell L. Mehler Eva Wolfe Brent B. Hall Roland I. 《Journal of Paleolimnology》2021,66(3):297-312
Journal of Paleolimnology - The oxygen isotope composition (δ18O) of aquatic cellulose extracted from lake sediment cores has long been used to reconstruct past hydrological responses to... 相似文献
3.
Hgbomite, a rare exotic mineral, is found to be associated with the vanadiferous–titaniferous(V-Ti) bearing magnetite bands at Bhakatarhalli, Nuggihalli greenstone belt, western Dharwar Craton, India. We report on a second occurrence of hgbomite from the Dharwar craton in Karnataka, which is the sixth documented occurrence of this mineral from India. We evaluate the chemical characteristics of hgbomite and associated Fe-Ti-minerals in an attempt to identify its formation as a primary hydrothermal mineral in a metamorphosed magnetite layer.We report here the presence of hgbomite as a complex oxide of Fe, Mg, Al and Ti with accessory of Zn, V and Sn. Petrographic studies suggest the(V–Ti) bearing magnetite(Mt) contain spinel, hgbomite, chlorite, martite, ilmenite(Il) and minor amounts of diaspore. The hgbomite displays euhedral to subhedral textures, and is up to 250 μm along the grain boundaries of magnetite and ilmenite. In the samples studied, hgbomite is prismatic, irregular and elongated in shape. The genesis of hgbomite in veins between magnetite and ilmenite implies its precipitation from fluids without involving complicated reactions. Several models were proposed for the formation of hgbomite; however, the subject is still debatable. 相似文献
4.
Susanne?M.?McDowellEmail author Calvin?F.?Miller Roland?Mundil Charles?A.?Ferguson Joseph?L.?Wooden 《Contributions to Mineralogy and Petrology》2014,168(1):1031
The Silver Creek caldera (southern Black Mountains, western Arizona) is the source of the 18.8 Ma, >700 km3 Peach Spring Tuff (PST) supereruption, the largest eruption generated in the Colorado River Extensional Corridor (CREC) of the southwestern United States. Within and immediately surrounding the caldera is a sequence of volcanics and intrusions ranging in age from ~19 to 17 Ma. These units offer a record of magmatic processes prior to, during, and immediately following the PST eruption. To investigate the thermal evolution of the magmatic center that produced the PST, we applied a combination of Ti-in-zircon thermometry, zircon saturation thermometry, and high-precision U–Pb CA–TIMS zircon dating to representative pre- and post-supereruption volcanic and intrusive units from the caldera and its environs. Similar to intracaldera PST zircons, zircons from a pre-PST trachytic lava (19 Ma) and a post-PST caldera intrusion (18.8 Ma) yield exceptionally high-Ti concentrations (most >20 ppm, some up to nearly 60 ppm), corresponding to calculated temperatures that exceed 900 °C. In these units, Ti-in-zircon temperatures typically surpass zircon saturation temperatures (ZSTs), suggesting the entrainment of zircon that had grown in hotter environments within the magmatic system. Titanium concentrations in younger volcanic and intrusive units (~18.7–17.5 Ma) decline through time, corresponding to an average cooling rate of 10?3.5 °C/year. The ~200 k.y. thermal peak evident at Silver Creek caldera is spatially limited: elsewhere in the Miocene record of the northern CREC, Ti-in-zircon concentrations and ZSTs are much lower, suggesting that felsic magmas were generally substantially cooler. 相似文献
5.
6.
7.
Marcel Bliedtner Roland Zech Jana Zech Imke Schäfer Hans von Suchodoletz 《第四纪科学杂志》2020,35(5):625-633
The Holocene paleoclimate of the Caucasus region is rather complex and not yet well understood: while existing studies are mainly based on pollen records from high-altitude and humid lowland regions, no records are available from the semi-humid to semi-arid south-eastern Caucasian lowlands. Therefore, this study investigated compound-specific δ2H and δ13C isotopes of leaf wax biomarkers from Holocene floodplain soils in eastern Georgia. Our results show that the leaf wax δ2H signal from the paleosols mostly reflects changes in the moisture source and its isotopic composition. Depleted δ2H values before ~8 cal ka bp change towards enriched values after ~5 cal ka bp and become again depleted after ~1.6 cal ka bp. This trend could be caused by Holocene changes of the isotopic compositions of the Black and eastern Mediterranean Sea, and/or by varying contribution of both moisture sources linked with the North Atlantic Oscillation. The leaf wax δ13C signal from the paleosols directly indicates varying local water availability and drought stress. Depleted δ13C values before ~8 and after ~5 cal ka bp indicate wetter local conditions with higher water availability, whereas more enriched values during the middle Holocene (~8 until at least 5 cal ka bp ) indicate drier conditions with increased drought stress. 相似文献
8.
Gravimetric monitoring of the first field‐wide steam injection in a fractured carbonate field in Oman – a feasibility study 下载免费PDF全文
Marcin Glegola Pavel Ditmar Femke Vossepoel Rob Arts Fahad Al‐Kindy Roland Klees 《Geophysical Prospecting》2015,63(5):1256-1271
Gas‐Oil Gravity Drainage is to be enhanced by steam injection in a highly fractured, low permeability carbonate field in Oman. Following a successful pilot, field‐wide steam injection is being implemented, first of this type in the world. A dedicated monitoring program has been designed to track changes in the reservoir. Various observations are to be acquired, including, surface deformation, temperature measurements, microseismic, well logs, pressure and saturation measurements to monitor the reservoir. Because significant changes in the reservoir density are expected, time‐lapse gravimetry is also being considered. In this paper we investigate the feasibility of gravimetric monitoring of the thermally enhanced gravity drainage process at the carbonate field in Oman. For this purpose, forward gravity modelling is performed. Based on field groundwater measurements, the estimates of the hydrological signal are considered and it is investigated under what conditions the groundwater influences can be minimized. Using regularized inversion of synthetic gravity data, we analyse the achievable accuracy of heat‐front position estimates. In case of large groundwater variations at the field, the gravity observations can be significantly affected and, consequently, the accuracy of heat‐front monitoring can be deteriorated. We show that, by applying gravity corrections based on local observations of groundwater, the hydrological influences can to a large extent be reduced and the accuracy of estimates can be improved. We conclude that gravimetric monitoring of the heat‐front evolution has a great potential. 相似文献
9.
Barthel Roland Haaf Ezra Giese Markus Nygren Michelle Heudorfer Benedikt Stahl Kerstin 《Hydrogeology Journal》2021,29(5):1693-1709
Hydrogeology Journal - A new concept is proposed for describing, analysing and predicting the dynamic behaviour of groundwater resources based on classification and similarity. The concept makes... 相似文献
10.
Evidence for Century-Timescale Acceleration in Mean Sea Levels and for Recent Changes in Extreme Sea Levels 总被引:2,自引:0,他引:2
Two of the most important topics in Sea Level Science are addressed in this paper. One is concerned with the evidence for the apparent acceleration in the rate of global sea level change between the nineteenth and twentieth centuries and, thereby, with the question of whether the twentieth century sea level rise was a consequence of an accelerated climate change of anthropogenic origin. An acceleration is indeed observed in both tide gauge and saltmarsh data at different locations around the world, yielding quadratic coefficients ??c?? of order 0.005 mm/year2, and with the most rapid changes of rate of sea level rise occurring around the end of the nineteenth century. The second topic refers to whether there is evidence that extreme sea levels have increased in recent decades at rates significantly different from those in mean levels. Recent results, which suggest that at most locations rates of change of extreme and mean sea levels are comparable, are presented. In addition, a short review is given of recent work on extreme sea levels by other authors. This body of work, which is focused primarily on Europe and the Mediterranean, also tends to support mean and extreme sea levels changing at similar rates at most locations. 相似文献