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   76401篇
  免费   864篇
  国内免费   1470篇
测绘学   2741篇
大气科学   5663篇
地球物理   14219篇
地质学   29857篇
海洋学   5888篇
天文学   14342篇
综合类   2314篇
自然地理   3711篇
  2022年   365篇
  2021年   629篇
  2020年   659篇
  2019年   708篇
  2018年   6069篇
  2017年   5270篇
  2016年   4323篇
  2015年   1201篇
  2014年   1815篇
  2013年   2881篇
  2012年   2758篇
  2011年   4901篇
  2010年   3953篇
  2009年   4820篇
  2008年   4068篇
  2007年   4567篇
  2006年   2245篇
  2005年   1810篇
  2004年   2023篇
  2003年   1926篇
  2002年   1708篇
  2001年   1341篇
  2000年   1267篇
  1999年   1006篇
  1998年   1060篇
  1997年   947篇
  1996年   816篇
  1995年   782篇
  1994年   686篇
  1993年   605篇
  1992年   592篇
  1991年   593篇
  1990年   622篇
  1989年   493篇
  1988年   504篇
  1987年   528篇
  1986年   487篇
  1985年   610篇
  1984年   673篇
  1983年   590篇
  1982年   561篇
  1981年   518篇
  1980年   486篇
  1979年   477篇
  1978年   458篇
  1977年   368篇
  1976年   351篇
  1975年   357篇
  1974年   308篇
  1973年   342篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
Solar System Research - Abstract—Results of the implementation of a single concept for the development of the double launch system (SDZ) are presented, in particular the SDZ-La5 for the...  相似文献   
962.
Astronomy Letters - We consider the effect of a change in the rate of flux decline in the $$U$$ band for type II-P supernovae (SNe IIP) as a function of metallicity $$Z$$ . Based on this effect, we...  相似文献   
963.
Astronomy Letters - An example of simultaneous spectroscopic redshift measurements for a large number of galaxies in a cluster by multiobject spectroscopy with the medium- and low-resolution TFOSC...  相似文献   
964.
965.
Izvestiya, Atmospheric and Oceanic Physics - The possibility for approximate basic statistical characteristics of atmospheric models using periodic trajectories (closed solutions of equations of...  相似文献   
966.
Libina  N. V.  Nikiforov  S. L. 《Oceanology》2020,60(6):854-860
Oceanology - A new area of oceanography, operational oceanography, involves a comprehensive assessment and forecast of the variability of the state of the marine environment. This requires...  相似文献   
967.
Solar System Research - The paper is dedicated to the study of dust vortices on the Earth and Mars. The hydrodynamic similarity of convective vortices is considered, and the similarity criteria are...  相似文献   
968.
Solar System Research - The article describes the trajectory scenario for the Venera-D mission. The main aspects of optimal launch dates are considered. A scenario, which enables insertion of an...  相似文献   
969.
Virtual citizen science platforms allow nonscientists to take part in scientific research across a range of disciplines, including planetary science. What is required of the volunteer can vary considerably in terms of task type, variety, judgment required, and autonomy—even when the overall goal is unchanged. Through analysis of our live Zooniverse Planet Four: Craters citizen science platform, the effects of task workflow design factors including volunteer autonomy, task variety, task type, and judgment required on volunteer engagement and crater marking performance were investigated. Website analytics showed volunteers using the Full interface (most autonomy and variety) were more likely to return to the platform, although the amount of time spent per visit was unaffected by the interface used. However, analysis of performance suggested that how this time was used did differ. The interface involving the least complex task resulted in the greatest amount of data and rate of collection, although this also coincided with a greater number of false positives when compared with the expert. Performance in terms of agreement, both between participants and with the expert judgment, was significantly improved when using the Stepped interface for crater position and the Ramped (Mark) when measuring diameter—interfaces that both directly measured the metric with a specific, delineated task. The implications for planetary scientists considering the citizen science route is that there is a balancing act to perform, weighing the importance of volunteer engagement with scientists' data needs and the resources that can be committed to data validation.  相似文献   
970.
Natural Resources Research - Oil shale impurities prevent its direct usage as a source of energy. Removing or reducing of these impurities before retorting can reduce the cost of oil shale...  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