首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   248篇
  免费   6篇
  国内免费   1篇
测绘学   2篇
大气科学   12篇
地球物理   71篇
地质学   83篇
海洋学   43篇
天文学   29篇
自然地理   15篇
  2023年   2篇
  2022年   5篇
  2021年   3篇
  2020年   6篇
  2019年   4篇
  2018年   5篇
  2017年   11篇
  2016年   6篇
  2015年   5篇
  2014年   9篇
  2013年   13篇
  2012年   7篇
  2011年   17篇
  2010年   27篇
  2009年   16篇
  2008年   13篇
  2007年   18篇
  2006年   15篇
  2005年   3篇
  2004年   7篇
  2003年   4篇
  2002年   4篇
  2001年   4篇
  2000年   2篇
  1999年   4篇
  1998年   5篇
  1997年   2篇
  1996年   1篇
  1995年   4篇
  1994年   1篇
  1993年   3篇
  1992年   1篇
  1991年   2篇
  1990年   2篇
  1989年   1篇
  1988年   1篇
  1986年   2篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1981年   3篇
  1980年   2篇
  1978年   1篇
  1977年   4篇
  1976年   1篇
  1974年   1篇
  1968年   1篇
  1966年   2篇
排序方式: 共有255条查询结果,搜索用时 562 毫秒
61.
A landslide occurred in colluvial deposits at one of the lagoons of Wadi Es-Sir Sewage Treatment Plant Project (under construction) in Jordan. This paper summarizes the geotechnical investigations conducted at three lagoon sites in the project area including the failed lagoon. Results of stability analyses are presented along with recommendations to stabilize the slided lagoon and surrounding areas.  相似文献   
62.
A model was developed for pollutant dispersion from a point source simulating the Hadera (Israel) power plant stack. The model is based on the NCAR mesoscale meteorological MM4 model that provides the wind fields and coefficients of turbulent diffusion. The model was implemented using an implicit numerical scheme with changing directions. A comparison between the model calculations and an analytical solution for the advection-diffusion equation shows good agreement. Relatively low numerical diffusion of the adopted advection scheme was noted. Results for the hilly region of central Israel are presented for a summer case.  相似文献   
63.
The paper discusses the results of geodetic investigations performed in the region of the large 1975–1976 Tolbachik fissure eruption in Kamchatka. Using data from repeated triangulation and trigonometric levelings, horizontal and vertical displacements have been detected in an area of 3,500 km2. Two zones have been recognized: the tension and uplift zone that is probably due to magma intrusion from depths to the surface along the line of new cones and the extensive compensative subsidence zone located at a distance of 20–50 km from the nearest newly-formed cones. Measurements made with small distance measuring device showed the dynamics of feeding basalt dykes intrusion and made it possible to determine their width (a little greater than 1 m) and magma and gas overpressure (50–250 bar). Data have been obtained on dimensions and growth of cones and on vertical ground deformation in the area of new cones during and after the eruption.  相似文献   
64.
65.
Ambient mixing ratios of NO, NO2, and O3 were determined together with the photolysis frequency of NO2, JNO2, at a rural, agricultural site in Germany. The data were collected during the POPCORN-campaign from August 1 to August 24, 1994, in a maize field 6 m above ground. The medians of the NO, NO2, and O3 mixing ratios between 10:00 and 14:00 UT were 0.25, 1.09, and 45 ppbv, respectively. The corresponding median of JNO2 was 6.0 · 10–3 s–1. NOx = NO + NO2 showed a strong diurnal variation with maximum mixing ratios at night, suggestive of a strong local surface source of NO, probably by microbial activity in the soil. The estimated average emission rate was 40 ng(N) m–2 s–1 of NOx, the major part of it probably in the form of NO. The available measurements allowed the estimation of the local NOx budget. At night the budget is almost closed and the measured NOx mixing ratios can be explained by the local source, local dry deposition of NO2, formation of NO3 and N2O5, and vertical exchange of air across the nocturnal inversion. During day-time, the local surface source of NO is not sufficient to explain the measured mixing ratios, and horizontal advection of NOx to the site must be included. The NO2/NO ratio during the morning und late afternoon is lower than predicted from the photostationary state owing to the local NO surface source, but is regulary higher during the hours around noon. For noon, August 10, 1994, the NO2/NO ratio was used to derive the momentary lower limit for the concentration of the peroxy-radicals of 2.2 · 109 cm–3 (86 pptv).  相似文献   
66.
67.
68.
Ezer  Tal 《Ocean Dynamics》2020,70(2):241-255
Ocean Dynamics - Sea level rise (SLR) is causing acceleration in the frequency and duration of minor tidal flooding (often called “sunny-day” or “nuisance” flooding) along...  相似文献   
69.
For more than a decade, the global network of GPS stations whose measurements are part of the International GPS Service (IGS) have been recording cyclic variations in the radius vector of the geodetic ellipsoid with a period of one year and amplitude of ~10 mm. The analysis of the figure of the Earth carried out by us shows that the observed variations in the vertical component of the Earth’s surface displacements can induce small changes in the flattening of the Earth’s figure which are, in turn, caused by the instability of the Earth’s rotation. The variations in the angular velocity and flattening of the Earth change the kinetic energy of the Earth’s rotation. The additional energy is ~1021 J. The emerging variations in the flattening of the Earth’s ellipsoid lead to changes in the surface area of the Earth’s figure, cause the development of deformations in rocks, accumulation of damage, activation of seismotectonic processes, and preparation of earthquakes. It is shown that earthquakes can be caused by the instability of the Earth’s rotation which induces pulsations in the shape of the Earth and leads to the development of alternating-sign deformations in the Earth’s solid shell.  相似文献   
70.
Recent studies show that in addition to wind and air pressure effects, a significant portion of the variability of coastal sea level (CSL) along the US East Coast can be attributed to non-local factors such as variations in the Gulf Stream and the North Atlantic circulation; these variations can cause unpredictable coastal flooding. The Florida Current transport (FCT) measurement across the Florida Straits monitors those variations, and thus, the study evaluated the potential of using the FCT as an indicator for anomalously high water level along the coast. Hourly water level data from 12 tide gauge stations over 12 years are used to construct records of maximum daily water levels (MDWL) that are compared with the daily FCT data. An empirical mode decomposition (EMD) approach is used to divide the data into high-frequency modes (periods T < ~30 days), middle-frequency modes (~30 days < T < ~90 days), and low-frequency modes (~90 days < T < ~1 year). Two predictive measures are tested: FCT and FCT change (FCC). FCT is anti-correlated with MDWL in high-frequency modes but positively correlated with MDWL in low-frequency modes. FCC on the other hand is always anti-correlated with MDWL for all frequency bands, and the high water signal lags behind FCC for almost all stations, thus providing a potential predictive skill (i.e., whenever a weakening trend is detected in the FCT, anomalously high water is expected along the coast over the next few days). The MDWL-FCT correlation in the high-frequency modes is maximum in the lower Mid-Atlantic Bight, suggesting influence from the meandering Gulf Stream after it separates from the coast. However, the correlation in low-frequency modes is maximum in the South Atlantic Bight, suggesting impact from variations in the wind pattern over subtropical regions. The middle-frequency and low-frequency modes of the FCT seem to provide the best predictor for medium to large flooding events; it is estimated that ~10–25% of the sea level variability in those modes can be attributed to variations in the FCT. An example from Hurricane Joaquin (September–October, 2015) demonstrates how an offshore storm that never made landfall can cause a weakening of the FCT and unexpected high water level and flooding along the US East Coast. A regression-prediction model based on the MDWL-FCT correlation shows some skill in estimating high water levels during past storms; the water level prediction is more accurate for slow-moving and offshore storms than it is for fast-moving storms. The study can help to improve water level prediction since current storm surge models rely on local wind but may ignore remote forcing.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号