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   3916篇
  免费   35篇
  国内免费   41篇
测绘学   42篇
大气科学   320篇
地球物理   655篇
地质学   1978篇
海洋学   334篇
天文学   474篇
综合类   64篇
自然地理   125篇
  2023年   4篇
  2022年   49篇
  2021年   66篇
  2020年   84篇
  2019年   99篇
  2018年   222篇
  2017年   217篇
  2016年   252篇
  2015年   110篇
  2014年   244篇
  2013年   318篇
  2012年   319篇
  2011年   313篇
  2010年   334篇
  2009年   269篇
  2008年   253篇
  2007年   280篇
  2006年   218篇
  2005年   102篇
  2004年   39篇
  2003年   28篇
  2002年   30篇
  2001年   28篇
  2000年   27篇
  1999年   9篇
  1998年   9篇
  1997年   18篇
  1996年   8篇
  1995年   3篇
  1994年   2篇
  1993年   1篇
  1992年   3篇
  1991年   4篇
  1990年   1篇
  1989年   1篇
  1988年   2篇
  1987年   3篇
  1986年   3篇
  1985年   3篇
  1984年   5篇
  1982年   2篇
  1980年   2篇
  1979年   1篇
  1976年   1篇
  1975年   1篇
  1972年   1篇
  1968年   1篇
  1958年   2篇
  1955年   1篇
排序方式: 共有3992条查询结果,搜索用时 250 毫秒
831.
A detailed analysis of climatic trends in the longitudinally averaged temperature, zonal wind velocity, and activity of a stationary planetary wave with the zonal wave number 1 (SPW1) is made for January. The results of analysis indicate that marked climatic temperature variations having opposite signs in the low and high latitudes are observed. These variations cause the relevant variations in the intensity and arrangement of maxima of tropospheric jet flows and, thereby, are responsible for changes in SPW1 propagation conditions. SPW1 propagation from the troposphere into the upper atmosphere is calculated with a linearized model by using the distributions of zonal mean flow that are characteristic of the 1960s and the early 21st century. These calculations indicate that, over the past 40 years, the propagation conditions have improved “on average” and the calculated SPW1 amplitude in the stratosphere and mesosphere of the winter hemisphere has increased substantially. Analysis of the amplitudes of the zonal wind velocity for SPW1 that were obtained from the NCEP/NCAR data is consistent with the results of simulation and shows that some enhancement of SPW1 activity in the lower stratosphere has been actually observed in recent years. These variations in the amplitudes are also accompanied by the enhancement of SPW1 interannual variability.  相似文献   
832.
Presented are the data of observations carried out in the fall of 2000 in the Gavan?? Gaidamak Inlet (Vostok Bay, Peter the Great Bay, Sea of Japan). It is revealed that the main transport of water takes place in the surface horizons from 0 to 1?C2 m predominantly in the meridional direction (north-south). It is demonstrated that in spite of not being under wind influence, the inlet area has a high degree of water flow turbulization. It was also registered that the wind-induced phenomena promote the development of turbulent processes and serve as the main self-cleaning mechanism of the inlet.  相似文献   
833.
The spatiotemporal distribution of harp seal pups around breeding grounds in the White Sea is considered. It is shown that spatial localization of groups of females with different terms of mass pup birth takes place. This somewhat confirms the data on the gregarious structure of White Sea harp seal population. It is possible to explain the structure of this adaptation of the seal population to different living conditions in different feeding areas.  相似文献   
834.
Over the past two decades, skeptics of the reality and significance of anthropogenic climate change have frequently accused climate scientists of “alarmism”: of over-interpreting or overreacting to evidence of human impacts on the climate system. However, the available evidence suggests that scientists have in fact been conservative in their projections of the impacts of climate change. In particular, we discuss recent studies showing that at least some of the key attributes of global warming from increased atmospheric greenhouse gases have been under-predicted, particularly in IPCC assessments of the physical science, by Working Group I. We also note the less frequent manifestation of over-prediction of key characteristics of climate in such assessments. We suggest, therefore, that scientists are biased not toward alarmism but rather the reverse: toward cautious estimates, where we define caution as erring on the side of less rather than more alarming predictions. We call this tendency “erring on the side of least drama (ESLD).” We explore some cases of ESLD at work, including predictions of Arctic ozone depletion and the possible disintegration of the West Antarctic ice sheet, and suggest some possible causes of this directional bias, including adherence to the scientific norms of restraint, objectivity, skepticism, rationality, dispassion, and moderation. We conclude with suggestions for further work to identify and explore ESLD.  相似文献   
835.
Doklady Earth Sciences - The research results were received from studying the Pechenga ore-bearing Paleoproterozoic structure, which is located on the northwestern part of the Kola region. The...  相似文献   
836.
We have performed deep searches for radio pulsations from four southern anomalous X-ray pulsars (AXPs) to investigate their physical nature in comparison with the rotation powered pulsars. The data were acquired using the Parkes radio telescope with the 1.4 GHz multibeam receiver. No pulsed emission with periodicity matching the X-ray ephemeris have been found in the observed targets down to a limit of ∼0.1 mJy. A blind search has also been performed on all the 13 beams of the multibeam receiver (the central beam being pointed on the target AXP), leading to the serendipitous discovery of two new radio pulsars and to the further detection of 18 pulsars. Also a search for single dispersed pulses has been performed in the aim to detect signals similar to those of the recently discovered rotating radio transients.   相似文献   
837.
838.
839.
This paper is based on data from engineering-geological research on the landslide slopes of the Moscow River valley from the site of a proposed bridge crossing reconstruction. A method for delineating the slippage surface is suggested, which allows a more reliable evaluation of landslide stability and pressure for planning and decision-making purposes during the reconstruction of the bridge crossing, and an appropriate mitigation strategy.  相似文献   
840.
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