全文获取类型
收费全文 | 446篇 |
免费 | 19篇 |
国内免费 | 9篇 |
专业分类
测绘学 | 35篇 |
大气科学 | 43篇 |
地球物理 | 80篇 |
地质学 | 168篇 |
海洋学 | 43篇 |
天文学 | 69篇 |
综合类 | 1篇 |
自然地理 | 35篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 9篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 25篇 |
2015年 | 16篇 |
2014年 | 14篇 |
2013年 | 24篇 |
2012年 | 24篇 |
2011年 | 32篇 |
2010年 | 29篇 |
2009年 | 36篇 |
2008年 | 15篇 |
2007年 | 20篇 |
2006年 | 18篇 |
2005年 | 21篇 |
2004年 | 15篇 |
2003年 | 9篇 |
2002年 | 11篇 |
2001年 | 12篇 |
2000年 | 3篇 |
1999年 | 8篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有474条查询结果,搜索用时 15 毫秒
31.
32.
Pierre Bosser Olivier Bock Christian Thom Jacques Pelon Pascal Willis 《Journal of Geodesy》2010,84(4):251-265
This paper investigates the impact of rapid small-scale water vapor fluctuations on GPS height determination. Water vapor
measurements from a Raman lidar are used for documenting the water vapor heterogeneities and correcting GPS signal propagation
delays in clear sky conditions. We use data from four short observing sessions (6 h) during the VAPIC experiment (15 May–15
June 2004). The retrieval of wet delays from our Raman lidar is shown to agree well with radiosonde retrievals (bias and standard
deviation (SD) were smaller than 1 and 2.8 mm, respectively) and microwave radiometers (from two different instruments, bias
was 6.0/−6.6 mm and SD 1.3/3.8 mm). A standard GPS data analysis is shown to fail in accurately reproducing fast zenith wet
delay (ZWD) variations. The ZWD estimates could be improved when mean post-fit phase residuals were removed. Several methodologies
for integrating zenith lidar observations into the GPS data processing are also presented. The final method consists in using
lidar wet delays for correcting a priori the GPS phase observations and estimating a scale factor for the lidar wet delays
jointly with the GPS station position. The estimation of this scale factor allows correcting for a mis-calibration in the
lidar data and provides in the same way an estimate of the Raman lidar instrument constant. The agreement of this constant
with an independent determination using radiosonde data is at the level of 1–4%. The lidar wet delays were derived by ray-tracing
from zenith pointing measurements: further improvement in GPS positioning is expected from slant path lidar measurements that
would properly account for water vapor anisotropy. 相似文献
33.
Measuring the Reliability of Wheelchair User Route Planning based on Volunteered Geographic Information 总被引:1,自引:0,他引:1 下载免费PDF全文
Pascal Neis 《Transactions in GIS》2015,19(2):188-201
The development of a wheelchair user friendly route planning application inherits a number of special requirements and details that need to be considered during the generation of the routing graph and the corresponding algorithm, making this task much more complex than car or pedestrian related applications. Each wheelchair type and, more importantly, each individual user might have different needs with regards to the way condition or other criteria. This study proposes a new approach to route planning for wheelchair users tailored for individual and personal requirements provided by the user and the calculation of a reliability factor of the computed wheelchair path. The routing graph is based on the freely available Volunteered Geographic Information (VGI) retrieved from the OpenStreetMap (OSM) project. The newly created algorithm is evaluated and tested for a selected area in Bonn, Germany. A new reliability factor is introduced that gives direct feedback about the quality of the generated path. Similar factor estimations can also be utilized for multiple route planning applications where VGI or other commercial or administrative data is implemented and more detailed factors than a simple geometric representation of a street network are of importance. 相似文献
34.
High resolution simulation of the South Asian monsoon using a variable resolution global climate model 总被引:2,自引:1,他引:1
T. P Sabin R. Krishnan Josefine Ghattas Sebastien Denvil Jean-Louis Dufresne Frederic Hourdin Terray Pascal 《Climate Dynamics》2013,41(1):173-194
This study examines the feasibility of using a variable resolution global general circulation model (GCM), with telescopic zooming and enhanced resolution (~35 km) over South Asia, to better understand regional aspects of the South Asian monsoon rainfall distribution and the interactions between monsoon circulation and precipitation. For this purpose, two sets of ten member realizations are produced with and without zooming using the LMDZ (Laboratoire Meteorologie Dynamique and Z stands for zoom) GCM. The simulations without zoom correspond to a uniform 1° × 1° grid with the same total number of grid points as in the zoom version. So the grid of the zoomed simulations is finer inside the region of interest but coarser outside. The use of these finer and coarser resolution ensemble members allows us to examine the impact of resolution on the overall quality of the simulated regional monsoon fields. It is found that the monsoon simulation with high-resolution zooming greatly improves the representation of the southwesterly monsoon flow and the heavy precipitation along the narrow orography of the Western Ghats, the northeastern mountain slopes and northern Bay of Bengal (BOB). A realistic Monsoon Trough (MT) is also noticed in the zoomed simulation, together with remarkable improvements in representing the associated precipitation and circulation features, as well as the large-scale organization of meso-scale convective systems over the MT region. Additionally, a more reasonable simulation of the monsoon synoptic disturbances (lows and disturbances) along the MT is noted in the high-resolution zoomed simulation. On the other hand, the no-zoom version has limitations in capturing the depressions and their movement, so that the MT zone is relatively dry in this case. Overall, the results from this work demonstrate the usefulness of the high-resolution variable resolution LMDZ model in realistically capturing the interactions among the monsoon large-scale dynamics, the synoptic systems and the meso-scale convective systems, which are essential elements of the South Asian monsoon system. 相似文献
35.
Fletcher Lyndsay López Fuentes Marcelo C. Mandrini Cristina H. Schmieder Brigitte Démoulin Pascal Mason Helen E. Young Peter R. Nitta Nariaki 《Solar physics》2001,203(2):255-287
We present multi-instrument observations of active region (AR) 8048, made between 3 June and 5 June 1997, as part of the SOHO
Joint Observing Program 33. This AR has a sigmoid-like global shape and undergoes transient brightenings in both soft X-rays
and transition region (TR) lines. We compute a magneto-hydrostatic model of the AR magnetic field, using as boundary condition
the photospheric observations of SOHO/MDI. The computed large-scale magnetic field lines show that the large-scale sigmoid
is formed by two sets of coronal loops. Shorter loops, associated with the core of the SXT emission, coincide with the loops
observed in the hotter CDS lines. These loops reveal a gradient of temperature, from 2 MK at the top to 1 MK at the ends.
The field lines most closely matching these hot loops extend along the quasi-separatrix layers (QSLs) of the computed coronal
field. The TR brightenings observed with SOHO/CDS can also be associated with the magnetic field topology, both QSL intersections
with the photosphere, and places where separatrices issuing from bald patches (sites where field lines coming from the corona
are tangent to the photosphere) intersect the photosphere. There are, furthermore, suggestions that the element abundances
measured in the TR may depend on the type of topological structure present. Typically, the TR brightenings associated with
QSLs have coronal abundances, while those associated with BP separatrices have abundances closer to photospheric values. We
suggest that this difference is due to the location and manner in which magnetic reconnection occurs in two different topological
structures.
Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1013302317042 相似文献
36.
Evidence for threshold gradients is reviewed. The consolidation problem, with threshold gradient, is properly formulated and solved numerically. An approximate analytical solution is also developed. The influence of a threshold gradient on the time rate of settlement is examined, and it is shown that by modifying the definition of the degree of consolidation a good approximation to the threshold gradient problem can be obtained directly from the Terzaghi solution. It is also shown that threshold gradients will have no influence on odometer testing and their effect is, therefore, to reduce the primary compression below that predicted from standard tests. 相似文献
37.
38.
Paulina Lopez Pascal Sirguey Yves Arnaud Bernard Pouyaud Pierre Chevallier 《Global and Planetary Change》2008,61(3-4):103-116
The snow cover of the Northern Patagonia Icefield (NPI) was monitored after applying the Normalized Difference Snow Index (NDSI) and the Red/NIR band ratio to 134 Moderate Resolution Imaging Spectroradiometer (MODIS) images captured between 2000 and 2006. The final results show that the snow cover extent of the NPI fluctuates a lot in winter, in addition to its seasonal behaviour. The minimum snow cover extent of the period (3600 km2) was observed in March 2000 and the maximum (11,623 km2) in August 2001. We found that temperature accounts for approximately 76% of the variation of the snow cover extent over the entire icefield. We also show two different regimes of winter snow cover fluctuations corresponding to the eastern and the western sides of the icefield. The seasonality of the snow cover on the western side was determined by temperature rather than precipitation, while on the east side the seasonality of the snow cover was influenced by the seasonal behaviour of both temperature and precipitation. This difference can be explained by the two distinct climates: coastal and continental. The fluctuations in the winter snow cover extent were more pronounced and less controlled by temperature on the western side than on the eastern side of the icefield. Snow cover extent was correlated with temperature R2 = 0.75 and R2 = 0.74 for the western and eastern sides, respectively. Since limited meteorological data are available in this region, our investigation confirmed that the change in snow cover is an interesting climatic indicator over the NPI providing important insights in mass balance comprehension. Since snow and ice were distinguished snow cover fluctuations can be associated to fluctuations in the snow accumulation area of the NPI. In addition, days with minimum snow covers of summer season can be associated to the period in which Equilibrium Line Altitude (ELA) is the highest. 相似文献
39.
Madeleine Pascal 《Celestial Mechanics and Dynamical Astronomy》1985,36(4):319-347
We consider the motion of a dual spin satellite placed in the gravitational field of n material points, assuming that the satellite has no influence on the motion of these points. The main bodies are located at the libration points of the classical n bodies problem. We investigate the set of relative equilibria of the satellite. As in the elementary case of a gyrostat attracted by a single point, we show that this problem is equivalent to find the extremum of a quadratic function. We obtain all possible equilibria of the satellite by solving two algebraic equations. Sufficient conditions of stability of these relative equilibria are given. 相似文献
40.
Patrick Berrebi Pascal Rodriguez Jean-Antoine Tomasini Ghislaine Cattaneo-Berrebi Alain J. Crivelli 《Estuarine, Coastal and Shelf Science》2005,65(4):708-716
The presence and the distribution of two cryptic sedentary gobies, Pomatoschistus microps and Pomatoschistus marmoratus, were investigated in several lagoons stretching along the Golfe du Lion, southern France Mediterranean coast, and Corsica. Pomatoschistus microps is the only sedentary Pomatoschistus species in two shallow lagoons with large variations of salinity and temperature. In contrast, P. marmoratus, another sedentary species, can be found preferentially in a deep salty lagoon with small salinity variations. Both species occur sympatrically in the Rhone Delta and hybridise, producing fertile offspring. Using allozymes, competition, linked to fitness, is invoked to explain the distribution pattern of these sibling species. 相似文献