全文获取类型
收费全文 | 49414篇 |
免费 | 674篇 |
国内免费 | 312篇 |
专业分类
测绘学 | 1335篇 |
大气科学 | 3833篇 |
地球物理 | 9290篇 |
地质学 | 16273篇 |
海洋学 | 4173篇 |
天文学 | 12176篇 |
综合类 | 116篇 |
自然地理 | 3204篇 |
出版年
2020年 | 339篇 |
2019年 | 338篇 |
2018年 | 828篇 |
2017年 | 810篇 |
2016年 | 1052篇 |
2015年 | 697篇 |
2014年 | 1171篇 |
2013年 | 2443篇 |
2012年 | 1111篇 |
2011年 | 1543篇 |
2010年 | 1437篇 |
2009年 | 1930篇 |
2008年 | 1775篇 |
2007年 | 1777篇 |
2006年 | 1680篇 |
2005年 | 1546篇 |
2004年 | 1510篇 |
2003年 | 1414篇 |
2002年 | 1358篇 |
2001年 | 1230篇 |
2000年 | 1158篇 |
1999年 | 1121篇 |
1998年 | 1058篇 |
1997年 | 1062篇 |
1996年 | 844篇 |
1995年 | 836篇 |
1994年 | 794篇 |
1993年 | 738篇 |
1992年 | 709篇 |
1991年 | 681篇 |
1990年 | 776篇 |
1989年 | 674篇 |
1988年 | 648篇 |
1987年 | 741篇 |
1986年 | 620篇 |
1985年 | 825篇 |
1984年 | 947篇 |
1983年 | 912篇 |
1982年 | 861篇 |
1981年 | 819篇 |
1980年 | 722篇 |
1979年 | 698篇 |
1978年 | 692篇 |
1977年 | 627篇 |
1976年 | 596篇 |
1975年 | 517篇 |
1974年 | 597篇 |
1973年 | 586篇 |
1972年 | 362篇 |
1971年 | 334篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
942.
943.
This paper is concerned with the analysis of the linear modely(n)=X(n)+S(n)+(n) for the data sequencey(n) (n=1, 2, ..., N) whereX={x
IJ} is a knownJ × M matrix of full rankM. Here, the(n) are unknown vectors, which we wish to estimate for eachn; S(n) (n=1, 2, ..., N) is a periodic component (which we wish to estimate or remove) superimposed on the linear structureX(n); and(n) is an error vector which is specified as having zero expectation (with possible further properties). Such models commonly occur in geophysical data analysis.Modified from Technical Report No. 33, Computer Centre, The Australian National University. 相似文献
944.
945.
The NASA Office of Space Science has established a series of archivalcenters where science data acquired through its space science missionsis deposited. The availability of high quality data to the generalpublic through these open archives enables the maximization of sciencereturn of the flight missions. The Astrophysics Data Centers CoordinatingCouncil, an informal collaboration of archival centers, coordinates datafrom five archival centers distiguished primarily by the wavelength rangeof the data deposited there. Data are available in FITS format. Anoverview of NASA's data centers and services is presented in this paper.A standard front-end modifyer called Astrowbrowse is described. Othercatalog browsers and tools include WISARD and AMASE supported by theNational Space Scince Data Center, as well as ISAIA, a follow on toAstrobrowse. 相似文献
946.
947.
Infrared (IR) imagery of microbreaking waves in the ocean and laboratory showed modulation of breaking by swell and paddle-generated waves, respectively. Skin temperature also was modulated by the long waves, with the maxima occurring on the rear face of the long waves in both the laboratory and the field. The IR imagery from the ocean and laboratory showed that long-wave-induced microbreaking occurred at or near the long wave crest, and the resulting warm wakes occurred on the rear face. Thus, microbreaking waves generated near the crest of low-amplitude long waves can produce modulation with the maxima on the rear face. This mechanism was shown to be responsible for modulation of the measured in the laboratory and also likely contributed to the modulation observed in the field. 相似文献
948.
A. R. Breen P. J. Moran C. A. Varley W. P. Wilkinson P. J. S. Williams W. A. Coles A. Lecinski J. Markkanen 《Annales Geophysicae》1998,16(10):1265-1282
Co-rotating interaction regions (CIRs) between fast and slow streams of plasma are a prominent feature of the solar wind. Measurements of interplanetary scintillation (IPS) using the three widely separated antennas of the EISCAT facility have been used to detect the compression regions at the leading edges of interaction regions and to determine the location and velocity of the structure. Observations show that interaction regions have developed as close to the Sun as 25–30 solar radii, a result supported by theoretical modelling which shows that the conditions needed for CIRs to develop exist inside 30 solar radii. 相似文献
949.
950.