全文获取类型
收费全文 | 266篇 |
免费 | 10篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 8篇 |
大气科学 | 38篇 |
地球物理 | 43篇 |
地质学 | 83篇 |
海洋学 | 44篇 |
天文学 | 49篇 |
综合类 | 4篇 |
自然地理 | 11篇 |
出版年
2023年 | 1篇 |
2022年 | 9篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 21篇 |
2015年 | 9篇 |
2014年 | 26篇 |
2013年 | 21篇 |
2012年 | 18篇 |
2011年 | 14篇 |
2010年 | 12篇 |
2009年 | 11篇 |
2008年 | 14篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 13篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1984年 | 2篇 |
1980年 | 1篇 |
排序方式: 共有280条查询结果,搜索用时 15 毫秒
41.
Resilience assessment on coastline changes and urban settlements: A case study in Seribu Islands, Indonesia 总被引:1,自引:0,他引:1
The sustainable development in the ocean and costal areas has been an issue for the archipelago nation. Since two decades ago, some archipelago nations have attempted to implement the concept of both scientifically and politically sounding sustainability. The vulnerability assessment is one of the methods that are being used to measure the ocean and coastal sustainability in order to have better evaluation and redesign of the land development as well as policy making. Most of the vulnerability assessment has been conducted based on pressures, damages and changes that involve in the region. A common understanding of the vulnerability assessment is that there are three aspects to be considered: hazards, resilience and damages. These three aspects must be well defined at first in order to have better indicators or sub-indices for the vulnerability index. There are several issues and factors that should be considered before performing the vulnerability assessment. Firstly, each country has different coastal characteristics due to a different geologic process. Secondly, the three aspects of the vulnerability (i.e. hazards, resilience and damages) are impacting on each country at a different scale. Thirdly, the vulnerability of a small island region is different from that of a large island region. Finally, policies and regulations vary in each country.From the data analysis results, it is found that the urban settlement in Seribu Islands is one of the resilient factors in addition to the geological and geomorphological conditions. The resilience factors in Seribu Islands are classified into four categories: 1) settlements area, 2) population density, 3) hard infrastructure such as airfields, ports and roads, 4) geological process such as abrasion and erosion. Based on the island characteristics of Seribu Islands, a unique vulnerability index that fits to this locality is developed. It is shown that the vulnerability index developed in this study can measure the resilience of Seribu Islands. In addition to the aforementioned resilience factors, the unique geographical condition and the geological stability in Seribu Islands made the outer islands become a barrier from oceanographic conditions and made the inner islands protected. However, the population growth made significant changes in terms of ecology, water, sanitation and pollution within the region. 相似文献
42.
43.
44.
This paper examines the performance of the Jacobi preconditioner when used with two Krylov subspace iterative methods. The number of iterations needed for convergence was shown to be different for drained, undrained and consolidation problems, even for similar condition number. The differences were due to differences in the eigenvalue distribution, which cannot be completely described by the condition number alone. For drained problems involving large stiffness ratios between different material zones, ill‐conditioning is caused by these large stiffness ratios. Since Jacobi preconditioning operates on degrees‐of‐freedom, it effectively homogenizes the different spatial sub‐domains. The undrained problem, modelled as a nearly incompressible problem, is much more resistant to Jacobi preconditioning, because its ill‐conditioning arises from the large stiffness ratios between volumetric and distortional deformational modes, many of which involve the similar spatial domains or sub‐domains. The consolidation problem has two sets of degrees‐of‐freedom, namely displacement and pore pressure. Some of the eigenvalues are displacement dominated whereas others are excess pore pressure dominated. Jacobi preconditioning compresses the displacement‐dominated eigenvalues in a similar manner as the drained problem, but pore‐pressure‐dominated eigenvalues are often over‐scaled. Convergence can be accelerated if this over‐scaling is recognized and corrected for. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
45.
S.P.S. Eyres A. Evans A. Salama P. Barr J. Clavel N. Jenkins K. Leech M. Kessler T. Lim L. Metcalfe B. Schulz 《Astrophysics and Space Science》1997,255(1-2):361-366
A number of symbiotic stars have been observed with ISO. In addition to a number of emission lines, SWS observations of the
symbiotic novae RR Tel and V1016 Cyg reveal prominent, broad 10 & 18 μm silicate dust features. The 10 μm features are similar
to the crystalline silicate profiles seen in classical novae. There is some evidence that the silicate brightness in V1016
Cyg varies with Mira-component phase. However, the silicate feature in RR Tel also showed some variation even though observations
were made at very similar Mira-component phases. PHT observations of S-type symbiotic stars show the IR emission to be dominated
by the red-giant component. However, an excess in the PHT-P filters from 10 to 15 μm is evident in all the stars, and there
may be a broad 3.2 μm absorption feature or a broad 3.8 μm emission feature. At this time we have no adequate physical explanations
for any of these features.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
46.
47.
We compare the millimeter, microwave, and soft X-ray emission from a number of solar flares in order to determine the properties of the high-frequency radio emission of flares. The millimeter observations use a sensitive interferometer at 86 GHz which offers much better sensitivity and spatial resolution than most previous high-frequency observations. We find a number of important results for these flares: (i) the 86 GHz emission onset appears often to be delayed with respect to the microwave onset; (ii) even in large flares the millimeter-wavelength emission can arise in sources of only a few arc sec dimension; (iii) the millimeter emission in the impulsive phase does not correlate with the soft X-ray emission, and thus is unlikely to contain any significant thermal bremsstrahlung component; and (iv) the electron energy distributions implied by the millimeter observations are much flatter (spectral indices of 2.5 to 3.6) than is usual for microwave or hard X-ray observations. 相似文献
48.
Future climate change scenarios over Korea using a multi-nested downscaling system: A pilot study 总被引:1,自引:0,他引:1
Song-You Hong Nan-Kyoung Moon Kyo-Sun Sunny Lim Jong-Won Kim 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(4):425-435
This study examines a scenario of future summer climate change for the Korean peninsula using a multi-nested regional climate system. The global-scale scenario from the ECHAM5, which has a 200 km grid, was downscaled to a 50 km grid over Asia using the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM). This allowed us to obtain large-scale forcing information for a one-way, double-nested Weather and Research Forecasting (WRF) model that consists of a 12 km grid over Korea and a 3 km grid near Seoul. As a pilot study prior to the multi-year simulation work the years 1995 and 2055 were selected for the present and future summers. This RSM-WRF multi-nested downscaling system was evaluated by examining a downscaled climatology in 1995 with the largescale forcing from the NCEP/Department of Energy (DOE) reanalysis. The changes in monsoonal flows over East Asia and the associated precipitation change scenario over Korea are highlighted. It is found that the RSM-WRF system is capable of reproducing large-scale features associated with the East-Asian summer monsoon (EASM) and its associated hydro-climate when it is nested by the NCEP/DOE reanalysis. The ECHAM5-based downscaled climate for the present (1995) summer is found to suffer from a weakening of the low-level jet and sub-tropical high when compared the reanalysis-based climate. Predicted changes in summer monsoon circulations between 1995 and 2055 include a strengthened subtropical high and an intensified mid-level trough. The resulting projected summer precipitation is doubled over much of South Korea, accompanied by a pronounced surface warming with a maximum of about 2 K. It is suggested that downscaling strategy of this study, with its cloud-resolving scale, makes it suitable for providing high-resolution meteorological data with which to derive hydrology or air pollution models. 相似文献
49.
Thomas G. Müller Emmanuel Lellouch Hermann Böhnhardt John Stansberry Antonella Barucci Jacques Crovisier Audrey Delsanti Alain Doressoundiram Elisabetta Dotto René Duffard Sonia Fornasier Olivier Groussin Pedro J. Gutiérrez Olivier Hainaut Alan W. Harris Paul Hartogh Daniel Hestroffer Jonathan Horner Dave Jewitt Mark Kidger Csaba Kiss Pedro Lacerda Luisa Lara Tanya Lim Michael Mueller Raphael Moreno Jose-Luis Ortiz Miriam Rengel Pablo Santos-Sanz Bruce Swinyard Nicolas Thomas Audrey Thirouin David Trilling 《Earth, Moon, and Planets》2009,105(2-4):209-219
Over one thousand objects have so far been discovered orbiting beyond Neptune. These trans-Neptunian objects (TNOs) represent the primitive remnants of the planetesimal disk from which the planets formed and are perhaps analogous to the unseen dust parent-bodies in debris disks observed around other main-sequence stars. The dynamical and physical properties of these bodies provide unique and important constraints on formation and evolution models of the Solar System. While the dynamical architecture in this region (also known as the Kuiper Belt) is becoming relatively clear, the physical properties of the objects are still largely unexplored. In particular, fundamental parameters such as size, albedo, density and thermal properties are difficult to measure. Measurements of thermal emission, which peaks at far-IR wavelengths, offer the best means available to determine the physical properties. While Spitzer has provided some results, notably revealing a large albedo diversity in this population, the increased sensitivity of Herschel and its superior wavelength coverage should permit profound advances in the field. Within our accepted project we propose to perform radiometric measurements of 139 objects, including 25 known multiple systems. When combined with measurements of the dust population beyond Neptune (e.g. from the New Horizons mission to Pluto), our results will provide a benchmark for understanding the Solar debris disk, and extra-solar ones as well. 相似文献
50.
Jeong Yul Kim Martin G. Lockley Haang Mook Kim Jong-Deock Lim Kyung Soo Kim 《Cretaceous Research》2009,30(6):1387-1397
Twelve trackways of ornithopods from Lower Cretaceous lacustrine margin deposits of the Jindong Formation represent new dinosaur trackways described from Korea. The site, discovered during highway construction, was rescued by removing the most important trackways to the Korean Natural Heritage Center in Daejeon, where they are on permanent display. The new ichnotaxon Ornithopodichnus masanensis ichnogen. et ichnosp. nov. is recognized as a distinctive robust tridactyl track, slightly wider than long (l/w ratio = 0.91), with positive (inward) rotation. The toe prints are very thick, broad and U-shaped, resulting in a trefoil outline with a smoothly rounded hind margin. Digit III is short and projects anteriorly much less than digit II and IV (= weak mesaxony). Divarication of digits II-IV is about 70° with interdigital angle II-III larger than III-IV. Trackway width is narrow and the stride length/track length ratio is about 4.2–4.6. The Ornithopodichnus trackways evidently represent gregarious blunt-toed Iguanodon-like bipedal ornithopods, although poorly preserved manus traces are discerned in a few trackways. Ornithopodichnus is distinct from other well known iguanodontid tracks that display much stronger mesaxony and indicates a polarity in ornithopod foot morphology that can be verified by reference to known foot skeletons. 相似文献