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   1605篇
  免费   51篇
  国内免费   4篇
测绘学   30篇
大气科学   80篇
地球物理   881篇
地质学   346篇
海洋学   14篇
天文学   276篇
综合类   3篇
自然地理   30篇
  2021年   21篇
  2020年   23篇
  2018年   38篇
  2017年   52篇
  2016年   62篇
  2015年   56篇
  2014年   66篇
  2013年   69篇
  2012年   25篇
  2011年   30篇
  2010年   51篇
  2009年   42篇
  2008年   40篇
  2007年   35篇
  2006年   31篇
  2004年   24篇
  2003年   24篇
  2002年   30篇
  2001年   23篇
  2000年   22篇
  1999年   18篇
  1998年   27篇
  1996年   31篇
  1995年   19篇
  1994年   27篇
  1993年   25篇
  1992年   27篇
  1991年   20篇
  1990年   23篇
  1989年   19篇
  1988年   28篇
  1987年   25篇
  1986年   29篇
  1985年   15篇
  1984年   28篇
  1983年   29篇
  1982年   34篇
  1981年   23篇
  1980年   21篇
  1979年   36篇
  1978年   26篇
  1977年   23篇
  1976年   16篇
  1975年   20篇
  1974年   23篇
  1973年   23篇
  1972年   24篇
  1971年   24篇
  1970年   15篇
  1967年   16篇
排序方式: 共有1660条查询结果,搜索用时 15 毫秒
891.
Summary A method is proposed for determining the precise shape of the isolines, corresponding to any continuous and non-constant function of two variables. The co-ordinates of the points of the isolines are determined by solving numerically two ordinary differential equations of the first order which describe the isoline. A model example is given, in which the isolines of a function, determined by bicubic spline interpolation from values, given in a regular network, are found.  相似文献   
892.
Summary Virtual geomagnetic poles, corresponding to the directions of primary remanent magnetization of the neovolcanic occurrences studied in the Lower Jeseník, form a close group which is positionally considerably removed from the present geographic pole. By comparison with some published data on the extent of the secular variation of the geomagnetic field, a conclusion was drawn that the assumption of a practically simultaneous generation of the considered volcanites (over a period of about one third of the longest secular variation cycle) is at least twice as probable as the assumption of an expressive difference in their age.  相似文献   
893.
894.
Probability distribution of output from a linear reservoir is derived for a random and a first-order Markovian input. In the first case it is expressed in terms of the input distribution, in the second in terms of the distribution of its random component.  相似文献   
895.
Summary Using the data in[1], the scale factor for lengths is derived of the geopotential model R 0 =GM/W 0 (W 0 is the potential on a generalized geoid). The resulting value, R 0 ==6 363 672.9 m, which is2 m less than the original value[5], is practically the same as that in[6].  相似文献   
896.
897.
Summary Three important characteristics of the stochastic relation between the position of one point of a geodetic network and the positions of the remaining points are investigated: a) Change of the ellipse of confidence of the position of a point of the network to the ellipse of confidence of the position of a point of the network, relative to any other point of the network. (This characteristic is called the change of the global ellipse of confidence to the relative ellipse). b) The regression between the positional vector of the investigated point and the positional vectors of some group of other points of the network and c) the so-called total correlation between any two points of the network. The latter characteristic is a question of determining a characteristic direction for each pair of investigated points, which would have the property that the correlation coefficient between the random displacement of the first point in its characteristic direction and the random displacement of the second point in its characteristic direction is maximum.  相似文献   
898.
Summary Using the method of two-component spectral analysis of planar oscillation events by means of computer processing of A-t records, a series of about 100 samples of geomagnetic beating-type pulsations pc3 was treated. The quantitative data obtained on the internal structure of the pulsations (frequency spectra and polarization characteristics) were treated statistically. The pattern of the daily variations of the frequencies and amplitudes of the fundamental amplitude-dominating frequency components of the pulsations and the daily variations of the polarization characteristics of these components, the ellipticity of the polarization ellipses, the directions of the main axes of these ellipses and the sense of rotation of the disturbance vector along the ellipses were obtained.A part of the results was reported at the XVth General Assembly of the IUGG, Moscow, August 1971.  相似文献   
899.
Summary A new method is presented of computer processing of amplitude-time records. The method is based on a two-component spectral analysis, suitable for investigating a planar stationary oscillatory event. The method is applied to the study of the fine structure of short-period geomagnetic pulsations. Apart from a semi-quantitative representation of the directional distribution of the pulsation event in the plane of oscillation, the proposed method enables one to obtain quantitative information on the frequency components, representing the pulsation — the distribution of the overall energy in the spectrum of the pulsation, the ellipticity of the polarization ellipses, the orientation of the major axes of the ellipses, and the sense of rotation of the disturbance vector.  相似文献   
900.
Summary The potential energy of the Earth—Moon system is derived and, thus, also the disturbing potential function, responsible for the lunar precession of the Earth's axis, with preserving the terms from the non-spherical disturbing body. The gravitational fields of the Earth and Moon are considered in the form of a development in terms of spherical harmonics upto n=4.  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