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   728篇
  免费   37篇
  国内免费   7篇
测绘学   16篇
大气科学   52篇
地球物理   226篇
地质学   270篇
海洋学   77篇
天文学   89篇
综合类   2篇
自然地理   40篇
  2023年   3篇
  2022年   10篇
  2021年   21篇
  2020年   30篇
  2019年   20篇
  2018年   31篇
  2017年   26篇
  2016年   42篇
  2015年   27篇
  2014年   46篇
  2013年   60篇
  2012年   28篇
  2011年   42篇
  2010年   43篇
  2009年   51篇
  2008年   45篇
  2007年   28篇
  2006年   31篇
  2005年   19篇
  2004年   19篇
  2003年   14篇
  2002年   17篇
  2001年   9篇
  2000年   7篇
  1999年   9篇
  1998年   8篇
  1997年   2篇
  1996年   9篇
  1995年   3篇
  1994年   7篇
  1993年   3篇
  1992年   6篇
  1991年   3篇
  1990年   5篇
  1989年   5篇
  1988年   3篇
  1987年   4篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1981年   2篇
  1980年   1篇
  1979年   4篇
  1978年   4篇
  1977年   3篇
  1976年   2篇
  1975年   5篇
  1974年   7篇
  1973年   3篇
  1970年   1篇
排序方式: 共有772条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
This study investigates the recent near-surface temperature trends over the Antarctic Peninsula.We make use of available surface observations,ECMWF’s ERA5 and its predecessor ERA-Interim,as well as numerical simulations,allowing us to contrast different data sources.We use hindcast simulations performed with Polar-WRF over the Antarctic Peninsula on a nested domain configuration at 45 km(PWRF-45)and 15 km(PWRF-15)spatial resolutions for the period 1991?2015.In addition,we include hindcast simulations of KNMI-RACMO21P obtained from the CORDEX-Antarctica domain(~50 km)for further comparisons.Results show that there is a marked windward warming trend except during summer.This windward warming trend is particularly notable in the autumn season and likely to be associated with the recent deepening of the Amundsen/Bellingshausen Sea low and warm advection towards the Antarctic Peninsula.On the other hand,an overall summer cooling is characterized by the strengthening of the Weddell Sea low as well as an anticyclonic trend over the Amundsen Sea accompanied by northward winds.The persistent cooling trend observed at the Larsen Ice Shelf station is not captured by ERA-Interim,whereas hindcast simulations indicate that there is a clear pattern of windward warming and leeward cooling.Furthermore,larger temporal correlations and lower differences exhibited by PWRF-15 illustrate the existence of the added value in the higher spatial resolution simulation.  相似文献   
75.
In a flat Friedmann–Lemaitre–Robertson–Walker background, a scheme of dark matter–dark energy interaction is studied considering a holographic Ricci-like model for the dark energy. Without giving a priori some specific model for the interaction function, we show that this function can experience a change of sign during the cosmic evolution. The parameters involved in the holographic model are adjusted with Supernova data and we obtained results compatible with the observable universe.  相似文献   
76.
77.
We have been studying direct current glow discharges aiming at the production of different paint of coatings on steel substrates. In a set of preliminary experiments, long lasting (hours) discharges performed in a Nitrogen atmosphere between a stell anode (holding the substrates) and a titanium cathode separated by a small gap (few mm) produced very thin coatings of the substrates whose colour depend on the parameter of (interelectrodes gap, gas pressure, discharge current and time duration). In some conditions, the coatings showed a golden colour, typical of the Nti compound. A discussion of the results is given.  相似文献   
78.
79.
A spatially-homogenous and anisotropic cosmological model in self-creation theory of gravitation proposed by Barber is obtained when the source of gravitational field is a perfect fluid and the metric is of Marder's cyclindrically-symmetric form. Some properties of the model are discussed.  相似文献   
80.
A first estimate of the energy that reaches the Earth's surface and is produced by the inverse Compton effect between the electrons in the Van Allen belt and the solar flux was made. Since in the belt there are electrons with energies between 0.5 and 7 MeV, it was possible to use the Klein-Nishina formula in an approximate form and estimate the energy that is Compton scattered by all the electrons in the Van Allen belt by using Vette, Lucero and Bright's model. The result was compared (a) with the measurements of the continuum in the regions of soft X-rays, and (b) with the energy that is produced by the trapped electrons through the synchrotron mechanism.This paper was presented at the COSPAR meeting held in leningrad on May 20–29, 1970.  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