全文获取类型
收费全文 | 206篇 |
免费 | 4篇 |
国内免费 | 6篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 13篇 |
地球物理 | 52篇 |
地质学 | 89篇 |
海洋学 | 14篇 |
天文学 | 26篇 |
综合类 | 2篇 |
自然地理 | 16篇 |
出版年
2023年 | 2篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 10篇 |
2016年 | 12篇 |
2015年 | 16篇 |
2014年 | 8篇 |
2013年 | 20篇 |
2012年 | 13篇 |
2011年 | 12篇 |
2010年 | 12篇 |
2009年 | 12篇 |
2008年 | 12篇 |
2007年 | 8篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1991年 | 2篇 |
排序方式: 共有216条查询结果,搜索用时 0 毫秒
51.
Sulfur dioxide measured at the Visitor’s Center of Hawai’i Volcanoes National Park, USA exhibits seasonal and diurnal patterns
and is sensitive to rainfall, but the relationship between wind direction and SO2 is too inconsistent to support deterministic predictions of hourly SO2 based on hourly wind direction. Although SO2 at the Visitor Center has usually been below regulatory levels, high SO2 levels and adverse health effects remain a concern. This investigation identified patterns in hourly SO2 based on wind direction, time of day, month, and rainfall occurrence using 4 years of hourly data. Empirical probabilities
were investigated using a Bayesian approach. Winds from the volcanic vents were rare, but when they did occur SO2 was elevated about half of the time. Conversely, half of the hours with elevated SO2 occurred when volcanic vents were not directly upwind. Episodes of elevated SO2 tended to occur during the months of November–March and between 8:00 a.m. and 5:00 p.m. Rainfall was associated with a marked
reduction in SO2 (29–81% depending on wind direction). Individuals that wish to avoid exposure to volcanic fumes can take these patterns into
account. 相似文献
52.
Timofey Samsonov Sergey Koshel Dmitry Walther Bernhard Jenny 《International journal of geographical information science》2019,33(10):2072-2093
Supplementary contour lines are placed between regular contour lines to visualize small but important forms that regular contour lines are unable to show. On topographic maps, typical forms are hillcrests, depressions, saddles, terraces, banks, and levees. No automated method for the selection of supplementary contour lines has been described so far. We document cartographic design principles for the selection of supplementary contour lines for topographic maps, and present an automated method for their placement. Results of the automated method are similar to manually placed supplementary contour lines. Our method helps map authors to create contour line maps that more effectively illustrate relevant small details in maps showing terrain elevation or other scalar fields. 相似文献
53.
Arto Miettinen Nalan Ko? Ian R. Hall Fred Godtliebsen Dmitry Divine 《Climate Dynamics》2011,36(3-4):533-543
August Sea Surface Temperatures (aSSTs) based on fossil diatom assemblages are generated with 2?year average resolution from a 230-year-long sediment core (Rapid 21-12B), from the Reykjanes Ridge in the subpolar North Atlantic. The results indicate a warming trend of ~0.5°C of the surface waters at the Reykjanes Ridge for the last 230?years. Superimposed on this warming trend there is a multidecadal to decadal aSST variability of up to 1°C. The interval from the 1770s to the 1830s represents the coldest period, whereas ~1860?C1880 represents the warmest period during the last 230?years. The last 25?years is characterized by a warming trend showing strong decadal aSST variability with several warm years, but also the coldest years since the 1820s. The time of these cold years in the mid-1970s, -1980s and -1990s correspond with the documented great salinity anomalies (GSA) in the North Atlantic suggesting increased fluxes of cold, low-salinity waters from the Arctic during the last decades. The aSST record and the August North Atlantic Oscillation (aNAO) index show similar multidecadal-scale variability indicating a close coupling between the oceanic and atmospheric patterns. The aSST record shows a negative correlation with the aNAO indicating cold aSST during the positive aNAO trend and vice versa. Results suggest that the wind driven variation in volume fluxes of the North Atlantic surface waters could be the major mechanism behind the observed relationship. 相似文献
54.
Bao Yang Dmitry M. Sonechkin Nina M. Datsenko Nadezda N. Ivashchenko Jingjing Liu Chun Qin 《Theoretical and Applied Climatology》2012,107(1-2):131-141
The technique of expanding meteorological fields on eigenvectors of the field covariation matrix is popular. In this paper, we propose for the first time to use a mathematically similar technique to solve the main problem of dendrochronology: classifying variations in tree-ring records as either age- and microenvironment-dependent or climate-induced. Applying this technique to a sample of very long-lived Qilian junipers (Sabina przewalskii Kom.) from the Dulan region in western China, we demonstrate that the ring-width variations projected on the first eigenvector are age-dependent, but those projected on several of the first subsequent vectors are mainly climate-induced. In particular, the second and third projections capture multi-centennial climatic variations, and the variations projected on the fourth through seventh eigenvectors show periodic variations that are probably induced by the 178-year solar cycle. The projections on the smallest eigenvectors seem to be negligible. 相似文献
55.
Models of the wave boundary layer 总被引:1,自引:1,他引:1
A general approach to model the structure of the wave boundary layer, based on the nonlinear Reynolds equations in a curvilinear system of coordinates, is described. Both spectral and numerical grid models are used. The energetic interactions between wind and wave in terms of Miles' parameter are studied. For waves outrunning or running against the wind, the range of the inverse flux of energy is found. For waves running slower than the wind, quadratic growth of is established. Vertical profiles of the wave momentum flux for different fetches are given. Following P. Janssen, a one-dimensional analytical model of the wave boundary layer is suggested. The effect of waves on the drag coefficient is analyzed. 相似文献
56.
We show that interaction of two monochromatic waves at the water surface enters a different dynamic regime if their wavenumbers become very close. The study is conducted by means of a fully nonlinear wave model. In the course of evolution of the two waves, downshifting of the initial wave energy and growth of the first mode occur depending on wave steepness and dk/k. Behaviour of these features changes if dk/k?<?0.0025: both downshifting and growth rate become independent of dk/k, accompanied by rapid transfer of wave energy to large scales. 相似文献
57.
The article considers the long-term(1941–2018) transformation of the Krasnodar valley reservoir, the largest in the North Caucasus. The main functions of the Krasnodar reservoir are irrigation of rice systems and flood protection of land in the Krasnodar reservoir region and the Republic of Adygea. According to topographic maps, Landsat satellite images(1974–2018) and field observations(2016–2018), four stages of transformation of the floodplain reservoir are identified. The selected stages are characterized by both natural causes(the transformation of the filling deltas into the extended deltas, etc.) and man-made causes(runoff diversions in the delta areas, etc.). The key factor of transformation is the formation of deltas of rivers flowing into the reservoir. Each of the selected stages, against the background of a gradual reduction in the area and volume of the reservoir, is characterized by the peculiarities of the formation of river deltas with the formation of genetically homogeneous sections of delta regions. During the period of operation of the reservoir, the delta of the main Kuban River moved up to 32.4 km and took away an area of 35.4 km~2 of the reservoir. During the formation of the deltas of the Kuban and Belaya rivers, a bridge was formed on the Krasnodar reservoir. The evolution of the delta regions led to the division of the reservoir into two autonomous reservoirs. The total area of the delta regions was 85.9 km~2 by 2018, i.e., 21% of the initial area of the reservoir. The transformation of the Krasnodar reservoir leads to a decrease in its regulated volume and gradual degradation. 相似文献
58.
Firsova Alena D. Chebykin Eugene P. Kopyrina Liubov I. Rodionova Elena V. Chensky Dmitry A. Gubin Nikita A. Panov Vsevolod S. Pogodaeva Tatyana V. Bukin Yurij S. Suturin Alexandr N. Likhoshway Yelena V. 《Journal of Paleolimnology》2021,66(4):407-437
Journal of Paleolimnology - In this study, radiocarbon-dated geochemical and diatom records from Lake Vorota located within the informal meteorological ‘pole of cold’ of the northern... 相似文献
59.
60.
Barbara Wohlfarth Pavel Tarasov Ole Bennike Terri Lacourse Dmitry Subetto Peter Torssander Fedor Romanenko 《Journal of Paleolimnology》2006,35(3):543-569
Three lake sediment sequences (lakes Nero, Chashnitsy, Zaozer’e) from the Rostov-Jaroslavl’ region north of Moscow were studied
to provide information on palaeoclimatic and palaeoenvironmental changes during the past 15,000 cal yr. The multi-proxy study
(i.e., pollen, macrofossils, mineral magnetic measurements, total carbon, nitrogen and sulphur) is chronologically constrained
by AMS 14C measurements. Lake Nero provided the longest sedimentary record back to ca. 15,000 cal yr BP, while sediment accumulation
began around ca. 11,000 cal yr BP in the two other lakes, possibly due to melting of permafrost. Limnic plant macrofossil
remains suggest increased lake productivity and higher mean summer temperatures after 14,500 cal yr BP. While the late glacial
vegetation was dominated by Betula and Salix shrubs and various herbs, it appears that Betula sect. Albae became established as early as 14,000 cal yr BP. Major hydrological changes in the region led to distinctly lower lake levels,
starting 13,000 cal yr BP in Lake Nero and ca. 9000 cal yr BP in lakes Chashnitsy and Zaozer’e, which are situated at higher
elevations. These changes resulted in sedimentary hiatuses in all three lakes that lasted 3500–4500 cal yr. Mixed broad-leaved
– coniferous forests were widespread in the area between 8200 and 6100 cal yr BP and developed into dense, species-rich forests
between 6100 and 2500 cal yr BP, during what was likely the warmest interval of the studied sequences. Agricultural activity
is documented since 500 cal yr BP, but probably began earlier, since Rostov was a major capital by 862 A.D. This apparent
gap may be caused by additional sedimentary hiatuses around 2500 and 500 cal yr BP. 相似文献