全文获取类型
| 收费全文 | 73篇 |
| 免费 | 2篇 |
| 国内免费 | 1篇 |
专业分类
| 测绘学 | 2篇 |
| 大气科学 | 3篇 |
| 地球物理 | 10篇 |
| 地质学 | 19篇 |
| 海洋学 | 30篇 |
| 自然地理 | 12篇 |
出版年
| 2017年 | 1篇 |
| 2016年 | 1篇 |
| 2015年 | 3篇 |
| 2014年 | 4篇 |
| 2013年 | 1篇 |
| 2011年 | 2篇 |
| 2010年 | 1篇 |
| 2009年 | 3篇 |
| 2008年 | 5篇 |
| 2007年 | 6篇 |
| 2006年 | 6篇 |
| 2005年 | 2篇 |
| 2004年 | 3篇 |
| 2003年 | 2篇 |
| 2002年 | 6篇 |
| 2001年 | 2篇 |
| 2000年 | 2篇 |
| 1999年 | 1篇 |
| 1996年 | 1篇 |
| 1995年 | 1篇 |
| 1994年 | 3篇 |
| 1991年 | 1篇 |
| 1990年 | 1篇 |
| 1989年 | 1篇 |
| 1986年 | 3篇 |
| 1985年 | 2篇 |
| 1984年 | 3篇 |
| 1983年 | 2篇 |
| 1982年 | 3篇 |
| 1981年 | 1篇 |
| 1980年 | 1篇 |
| 1978年 | 1篇 |
| 1972年 | 1篇 |
排序方式： 共有76条查询结果，搜索用时 15 毫秒
31.
Studying the winter survival of forage grasses under a changing climate requires models that can simulate the dynamics of soil conditions at low temperatures. We developed a simple model that simulates depth of snow cover, the lower frost boundary of the soil and the freezing of surface puddles. We calibrated the model against independent data from four locations in Norway, capturing climatic variation from south to north (Arctic) and from coastal to inland areas. We parameterized the model by means of Bayesian calibration, and identified the least important model parameters using the sensitivity analysis method of Morris. Verification of the model suggests that the results are reasonable. Because of the simple model structure, some overestimation occurs in snow and frost depth. Both the calibration and the sensitivity analysis suggested that the snow cover module could be simplified with respect to snowmelt and liquid water content. The soil frost module should be kept unchanged, whereas the surface ice module should be changed when more detailed topographical data become available, such as better estimates of the fraction of the land area where puddles may form. 相似文献
32.
The application of directional waves in design processes has clearly received much interest during recent years. Thus, in model testing with moored ships and offshore structures, significant deviations have been revealed between results obtained in traditional uni-directional wave trains and those obtained in directional wave fields. Whether the same tendency is valid in connection with the design of rubble mound breakwaters is studied in the present project. A breakwater with a front slope of 1:2 is tested at the scale 1:40. The weight and diameter of the stones in the core, filter and armour layers were carefully selected, and the sources of scatter in repeated tests were minimized. Furthermore, the incident wave energy was accurately adjusted to keep the same level in both uni-directional and directional waves. For the actual rubble-mound breakwater unambiguous results were obtained. When uni-directional waves were applied, the damage increased by 30–50% relative to the directional wave situation. 相似文献
33.
34.
Mjelde Rolf Aurvåg Roar Kodaira Shuichi Shimamura Hideki Gunnarsson Karl Nakanishi Ayako Shiobara Hajime 《Marine Geophysical Researches》2002,23(2):123-145
The horizontal components from twenty Ocean Bottom Seismometers deployed along three profiles near the Kolbeinsey Ridge, North Atlantic, have been modelled with regard to S-waves, based on P-wave models obtained earlier. Two profiles were acquired parallel to the ridge, and the third profile extended eastwards across the continental Jan Mayen Basin. The modelling requires a thin (few 100 m) layer with very high V
p/V
s-ratio (3.5–9.5) at the sea-floor in the area lacking sedimentary cover. The obtained V
p/V
s-ratios for the remaining part of layer 2A, 2B, 3 and upper mantle, correspond to the following lithologies: pillow lavas, sheeted dykes, gabbro and peridotite, respectively. All crustal layers exhibit a decreasing trend in V
p/V
s-ratio away-from-the-axis, interpreted as decreasing porosity and/or crack density in that direction. A significant S-wave azimuthal anisotropy is observed within the thin uppermost layer of basalt near the ridge. The anisotropy is interpreted as being caused by fluid-filled microcracks aligned along the direction of present-day maximum compressive stress, and indicates crustal extension at the ridge itself and perpendicular-to-the-ridge compression 12 km off axis. Spreading along the Kolbeinsey Ridge has most likely been continuous since its initiation ca. 25 Ma: The data do not suggest the presence of an extinct spreading axis between the Kolbeinsey Ridge and the Aegir Ridge as has been proposed earlier. The V
p/V
s-ratios found in the Jan Mayen Basin are compatible with continental crust, overlain by a sedimentary section dominated by shale. 相似文献
35.
The basic features of higher harmonic waves were originally presented by Stokes in 1847 who showed that a 2nd-order regular wave would attain a higher, sharper crest and a flatter trough than the basic linear one. In this paper, these characteristics are investigated for an irregular wave train. This was done to make it possible to reproduce in a laboratory flume a wave train which has the correct profile and rms according to 2nd-order theory. The 2nd-order wave heights and the overall horizontal asymmetries of the wave train were calculated for a 1st-order PM and a Jonswap spectrum. The theoretical predictions show that the traditional wave generation in a laboratory flume which is based on linear theory produces free 2nd-order waves in addition to the bound 2nd-order waves described by Stokes. These free, parasitic waves incorrectly distort the shape of the waves and produce a varying rms as a function of distance from the wave paddle. In the 2nd-order theory presented in this paper, these free (parasitic) waves are calculated for the entire spectrum. Knowing these, they can be eliminated by compensating for them by using a 2nd-order control signal on the wave paddle. This is verified by a series of model tests which show that realistic wave profiles can be generated only by means of 2nd-order control signals. The theory and corresponding paddle control are presented for any type of translating, rotating or combined wave generator. 相似文献
36.
Stig E. Sand 《Ocean Engineering》1982,9(6):567-580
37.
38.
39.
Thomas H. Pearson Hans-Petter Mannvik Rosalie Evans Stig Falk-Petersen 《Journal of Sea Research》1996,35(4):301-314
The fauna of the Snorre oil field is diverse and varies along a 40 m depth gradient across the area. Abundance and species richness increase with increasing depth but diversity is highest in the centre of the gradient. The communities present differ widely from those of the adjacent but shallower Statfjord, Gullfaks and Tordis Fields and from the major communities found throughout much of the northern North Sea, a fact attributable to the greater depth, finer sediments, higher sediment organic levels and position on the western slope of the Norwegian Trench. They have greater affinities with the communities in the Troll Field, 85 km SE on silt/clay sediments in the floor of the trench and the Heidrun Field, situated approximately 390 km N at similar depths and in an area of similar sedimentary composition. However the Snorre communities have a much higher number of suspension feeding and surface deposit feeding organisms than either of these other areas. This might be caused by higher current speeds in the Snorre area which could create favourable conditions for suspensivores. Such water movements might bring occasional incursions of intermediate Norwegian Sea water into the area. Indeed the Snorre fauna appears to bear some relationships to the intermediate depth faunas of the Norwegian Sea, and is clearly different from most of the better described northern North Sea faunas. 相似文献
40.
奥陶系研究百余年:从英国标准到国际标准 总被引：4，自引：0，他引：4
英国学者Sedgwick、Murchison和Lapworth等早在19世纪便对奥陶系作出了先驱性的研究,包括创建了奥陶系。但百年来各国主要都集中于地区性的奥陶系研究,并建立了地区性的序列和标准,这在事实上一直都把英国的奥陶系划分作为国际间的对比标准。近三十年来,随着国际奥陶系分会不断推进各国奥陶系的研究工作,并在2007年完成了奥陶系三统七阶的全部全球层型剖面和点位(GSSP)的研究,建立了全球标准。为了便于运用,建议将奥陶系的三统七阶分为20个间隔段,以利于洲际对比,并把地区性的统与阶准确地对比到国际标准上去。同时附上与年代地层划分相一致的奥陶系全球碳同位素的变化曲线。 相似文献