全文获取类型
收费全文 | 91421篇 |
免费 | 1419篇 |
国内免费 | 937篇 |
专业分类
测绘学 | 2171篇 |
大气科学 | 6242篇 |
地球物理 | 17925篇 |
地质学 | 33121篇 |
海洋学 | 8258篇 |
天文学 | 20777篇 |
综合类 | 259篇 |
自然地理 | 5024篇 |
出版年
2022年 | 569篇 |
2021年 | 990篇 |
2020年 | 1132篇 |
2019年 | 1184篇 |
2018年 | 2596篇 |
2017年 | 2423篇 |
2016年 | 2976篇 |
2015年 | 1686篇 |
2014年 | 2888篇 |
2013年 | 4937篇 |
2012年 | 3040篇 |
2011年 | 4040篇 |
2010年 | 3492篇 |
2009年 | 4521篇 |
2008年 | 4107篇 |
2007年 | 3975篇 |
2006年 | 3736篇 |
2005年 | 2824篇 |
2004年 | 2735篇 |
2003年 | 2567篇 |
2002年 | 2382篇 |
2001年 | 2219篇 |
2000年 | 2095篇 |
1999年 | 1681篇 |
1998年 | 1775篇 |
1997年 | 1696篇 |
1996年 | 1386篇 |
1995年 | 1387篇 |
1994年 | 1245篇 |
1993年 | 1093篇 |
1992年 | 1068篇 |
1991年 | 978篇 |
1990年 | 1101篇 |
1989年 | 891篇 |
1988年 | 825篇 |
1987年 | 1015篇 |
1986年 | 833篇 |
1985年 | 1103篇 |
1984年 | 1137篇 |
1983年 | 1068篇 |
1982年 | 1058篇 |
1981年 | 876篇 |
1980年 | 859篇 |
1979年 | 764篇 |
1978年 | 775篇 |
1977年 | 692篇 |
1976年 | 674篇 |
1975年 | 649篇 |
1974年 | 653篇 |
1973年 | 608篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
There are three major issues in modeling solar evanescent oscillations: the variation of the intensity [I]–velocity [V] phase difference of p-modes close to the base of photosphere; the existence of a plateau of negative I–V phase differences below and between the ridges of the low-frequency p-modes; the explanation of the I–V cross-spectra of the evanescent oscillations. We present new interpretations for the first two issues, based on modeling intensity fluctuations taking steep temperature gradients, opacity, and non-adiabatic cooling into account. We also discuss consequences of our model for the explanation of power spectra and cross-power spectra of p-modes. In particular, we present evidence that the acoustic sources that generate evanescent waves produce a coherent background that explains the plateau–interridge regime of negative I–V phase difference. 相似文献
943.
We obtain renormalized stress tensor of a mass-less, charge-less dynamical quantum scalar field, minimally coupled with a spherically symmetric static Lukewarm black hole. In two dimensional analog the minimal coupling reduces to the conformal coupling and the stress tensor is found to be determined by the nonlocal contribution of the anomalous trace and some additional parameters in close relation to the work presented by Christensen and Fulling. Lukewarm black holes are a special class of Reissner-Nordström-de Sitter space times where its electric charge is equal to its mass. Having the obtained renormalized stress tensor we attempt to obtain a time-independent solution of the well known metric back reaction equation. Mathematical derivations predict that the final state of an evaporating quantum Lukewarm black hole reduces to a remnant stable mini black hole with moved locations of the horizons. Namely the perturbed black hole (cosmological) horizon is compressed (extended) to scales which is smaller (larger) than the corresponding classical radius of the event horizons. Hence there is not obtained an deviation on the cosmic sensor-ship hypothesis. 相似文献
944.
The dependence of the position of the solar wind sonic point on the magnetic field in the solar corona during cycle 23 is studied. This dependence is shown to be rather strong in the rising phase and at the cycle maximum. As the coronal magnetic field grows, the distance to the sonic point decreases. Since the distance to the sonic point has been shown previously to anticorrelate with the solar wind speed, the result obtained suggests a strong positive correlation between the later and the coronal magnetic field. The situation changed dramatically two years after the calendar date of the cycle maximum. Beginning in 2004 the solar wind speed ceased to depend on the magnetic field up until the cycle minimum in December 2008. In 2009 a strong dependence of the wind speed on the coronal magnetic field was restored. It is hypothesized that this effect is associated with two different coronal heating mechanisms whose relative efficiency, in turn, depends on the contribution from magnetic fields of different scales. 相似文献
945.
Marine decapod Crustacea of southern Australia: a guide to identification. By Gary C. B. Poore. Published in 2004 by CSIRO Publishing, P.O. Box 1139, Collingwood, VIC 3066, Australia. 608 p., hardcover. ISBN: 0–643–06906–2. Price: AU$180.00 (orders: publishing.sales@csiro.au). Marine mammals: fisheries, tourism and management issues. Edited by Nicholas J. Gales, Mark A. Hindell and Roger Kirkwood. Published in 2003 by CSIRO Publishing, P.O. Box 1139, Collingwood, VIC 3066, Australia. 446 p., hardcover. ISBN: 0–643–06953–4. Price: AU$116 (orders: publishing.sales@csiro.au). Freshwater fishes of north‐eastern Australia. By Brad Pusey, Mark Kennard, and Angela Arthington. Published in 2004 by CSIRO Publishing, P.O. Box 1139, Collingwood, VIC 3066, Australia. 700 p., hardcover. ISBN: 0–643–06966–6. Price: au$89.00 (orders: publishing.sales@csiro.au). 相似文献
946.
I. N. Estcourt 《新西兰海洋与淡水研究杂志》2013,47(2):283-290
Grab samples were taken from a population of Pectinaria australis Ehlers in Tasman Bay, New Zealand, at intervals over a 2‐year period, March 1971 to March 1973. Settlement occurred in summer with the new recruits showing rapid growth and heavy mortality, giving an apparent life cycle time of 1 y. The population density varied greatly over short distances at one time, presumably due to random settlement of aggregations of larvae from the plankton. 相似文献
947.
Oceanology - New data on the geological structure and genesis of relict bottom relief forms, objects of underwater cultural heritage, and the structure of bottom sediments in the Baltic Sea were... 相似文献
948.
Oceanology - The article is devoted to studing of the features of sedimentation on the bottom of the northwestern shelf and western deep-water area of the Black Sea based on an analysis of our own... 相似文献
949.
Timofeyev Yu. M. Nerobelov G. M. Poberovskii A. V. Filippov N. N. 《Izvestiya Atmospheric and Oceanic Physics》2021,57(3):286-296
Izvestiya, Atmospheric and Oceanic Physics - Results obtained from ground-based high spectral resolution measurements of solar IR radiation absorption spectra are analyzed. These measurements have... 相似文献
950.
Abramova D. Yu. Philippov S. V. Abramova L. M. 《Izvestiya Atmospheric and Oceanic Physics》2021,57(9):1021-1028
Izvestiya, Atmospheric and Oceanic Physics - Geomagnetic data measured by the CHAMP satellite have been used to construct the spatial distribution of the lithospheric magnetic anomaly field in the... 相似文献