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   3153篇
  免费   88篇
  国内免费   74篇
测绘学   77篇
大气科学   431篇
地球物理   681篇
地质学   802篇
海洋学   743篇
天文学   359篇
综合类   42篇
自然地理   180篇
  2022年   24篇
  2021年   42篇
  2020年   53篇
  2019年   64篇
  2018年   135篇
  2017年   123篇
  2016年   172篇
  2015年   89篇
  2014年   173篇
  2013年   249篇
  2012年   132篇
  2011年   167篇
  2010年   176篇
  2009年   180篇
  2008年   168篇
  2007年   168篇
  2006年   136篇
  2005年   120篇
  2004年   116篇
  2003年   84篇
  2002年   76篇
  2001年   62篇
  2000年   59篇
  1999年   53篇
  1998年   35篇
  1997年   32篇
  1996年   21篇
  1995年   25篇
  1994年   16篇
  1993年   22篇
  1992年   19篇
  1991年   17篇
  1990年   16篇
  1989年   15篇
  1988年   13篇
  1987年   15篇
  1986年   11篇
  1985年   22篇
  1984年   15篇
  1983年   15篇
  1982年   15篇
  1981年   10篇
  1980年   18篇
  1979年   14篇
  1978年   10篇
  1977年   13篇
  1976年   11篇
  1975年   10篇
  1974年   9篇
  1973年   10篇
排序方式: 共有3315条查询结果,搜索用时 15 毫秒
131.
132.
133.
134.
In this study,cloud base height(CBH) and cloud top height(CTH) observed by the Ka-band(33.44 GHz) cloud radar at the Boseong National Center for Intensive Observation of Severe Weather during fall 2013(September-November) were verified and corrected.For comparative verification,CBH and CTH were obtained using a ceilometer(CL51) and the Communication,Ocean and Meteorological Satellite(COMS).During rainfall,the CBH and CTH observed by the cloud radar were lower than observed by the ceilometer and COMS because of signal attenuation due to raindrops,and this difference increased with rainfall intensity.During dry periods,however,the CBH and CTH observed by the cloud radar,ceilometer,and COMS were similar.Thin and low-density clouds were observed more effectively by the cloud radar compared with the ceilometer and COMS.In cases of rainfall or missing cloud radar data,the ceilometer and COMS data were proven effective in correcting or compensating the cloud radar data.These corrected cloud data were used to classify cloud types,which revealed that low clouds occurred most frequently.  相似文献   
135.
136.
137.
138.
139.
Preliminary analysis with a solar radiation model is generally performed for photovoltaic power generation projects. Therefore, model accuracy is extremely important. The temporal and spatial resolutions used in previous studies of the Korean Peninsula were 1 km × 1 km and 1-h, respectively. However, calculating surface solar radiation at 1-h intervals does not ensure the accuracy of the geographical effects, and this parameter changes owing to atmospheric elements (clouds, aerosol, ozone, etc.). Thus, a change in temporal resolution is required. In this study, one-year (2013) analysis was conducted using Chollian geostationary meteorological satellite data from observations recorded at 15-min intervals. Observation data from the intensive solar site at Gangneung-Wonju National University (GWNU) showed that the coefficient of determination (R²), which was estimated for each month and season, increased, whereas the standard error (SE) decreased when estimated in 15-min intervals over those obtained in 1-h intervals in 2013. When compared with observational data from 22 solar sites of the Korean Meteorological Administration (KMA), R2 was 0.9 or higher on average, and over- or under-simulated sites did not exceed 3 sites. The model and 22 solar sites showed similar values of annual accumulated solar irradiation, and their annual mean was similar at 4,998 MJ m?2 (3.87 kWh m?2). These results show a difference of approximately ± 70 MJ m?2 (± 0.05 kWh m?2) from the distribution of the Korean Peninsula estimated in 1-h intervals and a higher correlation at higher temporal resolution.  相似文献   
140.
As the 2018 Winter Olympics are to be held in Pyeongchang, both general weather information on Pyeongchang and specific weather information on this region, which can affect game operation and athletic performance, are required. An ensemble prediction system has been applied to provide more accurate weather information, but it has bias and dispersion due to the limitations and uncertainty of its model. In this study, homogeneous and nonhomogeneous regression models as well as Bayesian model averaging (BMA) were used to reduce the bias and dispersion existing in ensemble prediction and to provide probabilistic forecast. Prior to applying the prediction methods, reliability of the ensemble forecasts was tested by using a rank histogram and a residualquantile-quantile plot to identify the ensemble forecasts and the corresponding verifications. The ensemble forecasts had a consistent positive bias, indicating over-forecasting, and were under-dispersed. To correct such biases, statistical post-processing methods were applied using fixed and sliding windows. The prediction skills of methods were compared by using the mean absolute error, root mean square error, continuous ranked probability score, and continuous ranked probability skill score. Under the fixed window, BMA exhibited better prediction skill than the other methods in most observation station. Under the sliding window, on the other hand, homogeneous and non-homogeneous regression models with positive regression coefficients exhibited better prediction skill than BMA. In particular, the homogeneous regression model with positive regression coefficients exhibited the best prediction skill.  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