全文获取类型
收费全文 | 343篇 |
免费 | 3篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 21篇 |
大气科学 | 66篇 |
地球物理 | 45篇 |
地质学 | 158篇 |
海洋学 | 4篇 |
天文学 | 47篇 |
综合类 | 4篇 |
自然地理 | 6篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 6篇 |
2018年 | 14篇 |
2017年 | 23篇 |
2016年 | 32篇 |
2015年 | 18篇 |
2014年 | 18篇 |
2013年 | 25篇 |
2012年 | 26篇 |
2011年 | 19篇 |
2010年 | 18篇 |
2009年 | 23篇 |
2008年 | 13篇 |
2007年 | 13篇 |
2006年 | 13篇 |
2005年 | 4篇 |
2004年 | 8篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1991年 | 5篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有351条查询结果,搜索用时 46 毫秒
101.
On the role of resolution and topography in the simulation of East Asia precipitation 总被引:13,自引:0,他引:13
Xuejie Gao Ying Xu Zongci Zhao J. S. Pal F. Giorgi 《Theoretical and Applied Climatology》2006,86(1-4):173-185
Summary In this paper, we investigate the role that horizontal resolution plays in the simulation of East Asia precipitation. Two
sets of numerical experiments are performed using the Regional Climate Model (RegCM2) nested in one-way mode within the CSIRO
global coupled atmosphere-ocean model. In the first set we use the actual RegCM2 topography at the selected model resolutions,
which are 45, 60, 90, 120, 180, 240 and 360 km. In the second set of the experiments, the same coarse CSIRO model topography
is used in all simulations using the different resolutions of the first set. The results demonstrate that the simulation of
East Asian precipitation improves as the horizontal resolution is increased. Moreover, it is shown that the simulations using
a higher resolution along with the coarse CSIRO topography perform better than the simulations using a coarser model resolution
with corresponding model topography. This suggests that over East Asia adequate spatial resolution to resolve the physical
and dynamical processes is more important than topography. Lastly, the results indicate that model resolutions of 60 km or
higher are needed to accurately simulate the distribution of precipitation over China and East Asia. 相似文献
102.
103.
Summary Three sets of different formulae expressed as functions of dynamic elastic constants of rock and some design parameters involved in a buried explosion are derived explicitly for the prediction of peak particle velocity (PPV) and peak air pressure (PAP). Separate equations are derived to estimate PPV and PAP for inside, outside, and at the boundary of the crater zone. The equations incorporate the physical parameters including (i) longitudinal wave velocity, (ii) shear wave velocity, (iii) density of rock, (iv) characteristic impedance of air, (v) detonation pressure of explosive, (vi) depth of hole, (vii) radius of hole, (viii) distance of the measuring transducer. Suggested equations are tested for a few hard and medium-hard rocks. Characteristic features and important conclusions are described. 相似文献
104.
P. K. Pal B. M. Rao C. M. Kishtawal M. S. Narayanan G. Rajkumar 《Journal of Earth System Science》1989,98(4):353-364
INSAT visible and infrared imageries of three cyclones in the Bay of Bengal during the period 1984–1987 were analysed with
a view to improve the cyclone track prediction in this region. It was observed that the rotation in the major structural cloud
features (as seen from the cloud-top temperature maps) associated with these cyclones in the Bay of Bengal is followed with
a change in direction of their movement. This method is seen to be particularly effective when the cyclone is severe and when
the major cloud features persist for a reasonably longer time. In the present study, only the direction of movement is forecast
assuming a uniform speed of the cyclone. 相似文献
105.
C. Tuniz C.M. Smith R.K. Moniot T.H. Kruse W. Savin D.K. Pal G.F. Herzog R.C. Reedy 《Geochimica et cosmochimica acta》1984,48(9):1867-1872
Eleven samples taken from along the 35-cm core AIII of the LL-chondrite St. Severin have 10Be contents ranging from 20 to 28 dpm/kg and averaging 24.5 ± 0.9 dpm/kg. The 10Be contents increase with depth in the outermost 8 cm while at depths greater than 8 cm the 10Be contents change little. Calculations based on cross sections for proton-induced reactions that make 10Be disagree seriously with the measured values. Relatively large cross sections were constructed for neutron-induced reactions below 1 GeV. They give calculated 10Be production rates that agree with the measured values to within 10%. Cosmogenic 10Be in stony meteorites is better described as a medium-energy product than as a high-energy one. 相似文献
106.
Randhir Singh B. G. Vasudevan P. K. Pal P. C. Joshi 《Journal of Earth System Science》2004,113(1):89-101
Microwave sensor MSMR (Multifrequency Scanning Microwave Radiometer) data onboard Oceansat-1 was used for retrieval of monthly
averages of near surface specific humidity (Q
a) and air temperature (T
a) by means of Artificial Neural Network (ANN). The MSMR measures the microwave radiances in 8 channels at frequencies of 6.6,
10.7, 18 and 21 GHz for both vertical and horizontal polarizations.
The artificial neural networks (ANN) technique is employed to find the transfer function relating the input MSMR observed
brightness temperatures and output (Q
a andT
a) parameters. Input data consist of nearly 28 months (June 1999 – September 2001) of monthly averages of MSMR observed brightness
temperature and surface marine observations ofQ
a
andT
a
from Comprehensive Ocean-Atmosphere Data Set (COADS).
The performance of the algorithm is assessed with independent surface marine observations. The results indicate that the combination
of MSMR observed brightness temperatures as input parameters provides reasonable estimates of monthly averaged surface parameters.
The global root mean square (rms) differences are 1.0‡C and 1.1 g kg−1 for air temperature and surface specific humidity respectively. 相似文献
107.
I. Sadhu Khan D. Lohar D. K. Pal 《Journal of the Indian Society of Remote Sensing》2003,31(4):261-269
Changes in land surface characteristics have become a matter of great concern in the recent years. It is particularly important
when the mesoscale phenomena control the climatic variables of a region. Gangetic West Bengal with its neighbourhood is such
a region where during premonsoon season, mesoscale phenomena, i.e., sea breeze circulation and severe convective development,
control the local climate of the season. It is also reported that a drastic changes in land use pattern has taken place in
recent period over the region, which might affect the local climate, resulting in severe water crisis over the semi-arid part
of the region. A detailed study has been undertaken to investigate the changes in land use pattern through satellite data
over the area and its possible impact on the local climate through numerical modeling. Satellite (IRS-IC and Landsat 4 and
5) data shows a sharp change in dynamic vegetation during this period, which is due to, increased agricultural practices in
the recent years. Mesoscale model indicates that agricultural practices hinder the development of sea breezes over the coastal
and inland places, causing less incursion of moisture towards inland. This may be associated with less number of convective
developments over the coastal and neighbouring places. 相似文献
108.
Béla Paláncz Joseph L. Awange Piroska Zaletnyik Robert H. Lewis 《Journal of Geodesy》2010,84(1):79-95
A fundamental task in geodesy is solving systems of equations. Many geodetic problems are represented as systems of multivariate
polynomials. A common problem in solving such systems is improper initial starting values for iterative methods, leading to
convergence to solutions with no physical meaning, or to convergence that requires global methods. Though symbolic methods
such as Groebner bases or resultants have been shown to be very efficient, i.e., providing solutions for determined systems
such as 3-point problem of 3D affine transformation, the symbolic algebra can be very time consuming, even with special Computer
Algebra Systems (CAS). This study proposes the Linear Homotopy method that can be implemented easily in high-level computer languages like C++ and Fortran that are faster than CAS by at
least two orders of magnitude. Using Mathematica, the power of Homotopy is demonstrated in solving three nonlinear geodetic problems: resection, GPS positioning, and affine
transformation. The method enlarging the domain of convergence is found to be efficient, less sensitive to rounding of numbers,
and has lower complexity compared to other local methods like Newton–Raphson. 相似文献
109.
First Order Seismic Microzonation of Delhi,India Using Geographic Information System (GIS) 总被引:2,自引:4,他引:2
William K. Mohanty M. Yanger Walling Sankar Kumar Nath Indrajit Pal 《Natural Hazards》2007,40(2):245-260
A first order seismic microzonation map of Delhi is prepared using five thematic layers viz., Peak Ground Acceleration (PGA)
contour, different soil types at 6 m depth, geology, groundwater fluctuation and bedrock depth, integrated on GIS platform.
The integration is performed following a pair-wise comparison of Analytical Hierarchy Process (AHP), wherein each thematic
map is assigned weight in the 5-1 scale: depending on its contribution towards the seismic hazard. Following the AHP, the
weightage assigned to each theme are: PGA (0.333), soil (0.266), geology (0.20), groundwater (0.133) and bedrock depth (0.066).
The thematic vector layers are overlaid and integrated using GIS. On the microzonation theme, the Delhi region has been classified
into four broad zones of vulnerability to the seismic hazard. They are very high (> 52%), high (38–52%), moderate (23–38%)
and less ( < 23%) zones of seismic hazard. The “very high” seismic hazard zone is observed where the maximum PGA varies from
140 to 210 gal for a finite source model of Mw 8.5 in the central seismic gap. A site amplification study from local and regional earthquakes for Delhi region using Delhi
Telemetry Network data shows a steeper site response gradient in the eastern side of the Yamuna fluvial deposits at 1.5 Hz.
The ‘high’ seismic hazard zone occupies most of the study area where the PGA value ranges from 90 to 140 gal. The ‘moderate’
seismic hazard zone occurs on either side of the Delhi ridge with PGA value varying from 60 to 90 gal. The ‘less’ seismic
hazard zone occurs in small patches distributed along the study area with the PGA value less than 60 gal. Site response studies,
PGA distribution and destruction pattern of the Chamoli earthquake greatly corroborate the seismic hazard zones estimated
through microzonation on GIS platform and also establishes the methodology incorporated in this study. 相似文献
110.
Feed forward Artificial Neural Network model to predict the average summer-monsoon rainfall in India
Surajit Chattopadhyay 《Acta Geophysica》2007,55(3):369-382
In the present research, possibility of predicting average summer-monsoon rainfall over India has been analyzed through Artificial
Neural Network model. In formulating the ANN — based predictive model, three-layer network has been constructed with sigmoid
non-linearity. The monthly summer monsoon rainfall totals, tropical rainfall indices and sea surface temperature anomalies
have been considered as predictors while generating the input matrix for the ANN. The data pertaining to the years 1950–1995
have been explored to develop the predictive model. Finally, the prediction performance of neural net has been compared with
persistence forecast and Multiple Linear Regression forecast and the supremacy of the ANN has been established over the other
processes. 相似文献