全文获取类型
收费全文 | 105427篇 |
免费 | 1424篇 |
国内免费 | 992篇 |
专业分类
测绘学 | 2632篇 |
大气科学 | 7268篇 |
地球物理 | 20168篇 |
地质学 | 39778篇 |
海洋学 | 9085篇 |
天文学 | 23068篇 |
综合类 | 376篇 |
自然地理 | 5468篇 |
出版年
2022年 | 569篇 |
2021年 | 990篇 |
2020年 | 1128篇 |
2019年 | 1185篇 |
2018年 | 4371篇 |
2017年 | 4061篇 |
2016年 | 3935篇 |
2015年 | 1761篇 |
2014年 | 2906篇 |
2013年 | 4929篇 |
2012年 | 3708篇 |
2011年 | 5836篇 |
2010年 | 5043篇 |
2009年 | 6164篇 |
2008年 | 5338篇 |
2007年 | 5646篇 |
2006年 | 3762篇 |
2005年 | 3111篇 |
2004年 | 2969篇 |
2003年 | 2841篇 |
2002年 | 2561篇 |
2001年 | 2242篇 |
2000年 | 2124篇 |
1999年 | 1681篇 |
1998年 | 1774篇 |
1997年 | 1694篇 |
1996年 | 1386篇 |
1995年 | 1386篇 |
1994年 | 1242篇 |
1993年 | 1092篇 |
1992年 | 1068篇 |
1991年 | 976篇 |
1990年 | 1099篇 |
1989年 | 891篇 |
1988年 | 825篇 |
1987年 | 1015篇 |
1986年 | 832篇 |
1985年 | 1102篇 |
1984年 | 1136篇 |
1983年 | 1064篇 |
1982年 | 1058篇 |
1981年 | 887篇 |
1980年 | 873篇 |
1979年 | 764篇 |
1978年 | 772篇 |
1977年 | 689篇 |
1976年 | 678篇 |
1975年 | 648篇 |
1974年 | 650篇 |
1973年 | 608篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Khamitov I. M. Bikmaev I. F. Burenin R. A. Glushkov M. V. Melnikov S. S. Lyapin A. R. 《Astronomy Letters》2020,46(1):1-11
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
992.
Astronomy Letters - The reduction of all the available photometry for the Cepheid ET Vul has allowed its $$O-C$$ diagram spanning a time interval of 130 years to be constructed. This has made it... 相似文献
993.
Ali Moamen Abdelhady A. Abdelmaksoud Ahmed Darwish M. Essa M. A. 《Natural Resources Research》2020,29(2):1259-1281
Natural Resources Research - The Albian/Cenomanian reservoir is one of the two main reservoirs composing the petroleum system in the Komombo Basin. However, these reservoirs have not previously... 相似文献
994.
Natural Resources Research - Single-borehole tracer dilution tests are used to estimate the Darcy velocity (vd) which is important for investigating contaminant transport and distribution within... 相似文献
995.
Natural Resources Research - Identification of geochemical anomalies is of particular importance for tracing the footprints of anomalies. This can be implemented by advanced techniques of... 相似文献
996.
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
997.
Ivanova J. N. Vyhristenko R. I. Vikentyev I. V. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(12):1537-1545
Izvestiya, Atmospheric and Oceanic Physics - The central part of the Malouralsky volcanic–plutonic belt, which includes the Manyukuyu–Vorchatinsky ore cluster, is analyzed using... 相似文献
998.
Photometric properties of deep Tautenburg Schmidt plates in the UBV system over the whole field and over a wide range of stellar magnitudes are discussed. Different reduction models based on the calibration curve alone and with additional terms containing colour and plate coordinates are considered. With the filter-emulsion combinations used the Johnson UBV system can be reproduced quite well by the Tautenburg telescope. The accuracy of photometric data can be improved if geometrical terms are taken into account. For deep plates with a significant effect of background nebulosity a supplementary term is to be included in the reduction model. The polynomial coefficients vary in dependence on spectral bands and individual properties of each plate. 相似文献
999.
N. Snchez 《Astronomische Nachrichten》1990,311(4):231-238
A general method to quantize strings in curved space-times is exposed. It treats the space-time metric exactly and the string excitations small as compared with the energy scale of the geometry. The method is applied to cosmological (de Sitter) and black-hole (Schwarzschild) geometries. The critical dimension decreases in one for de Sitter and stays unaltered for black-holes as compared with flat space-time values. Bogoliubov transformations in the context of string theory are derived and the Bogoliubov coefficients describing elastic and inelastic scattering and excitation of modes are computed explicitely. The string-black-hole cross section is derived and a pair mode creation phenomena is found. The quantization and scattering of strings in shockwave geometries (ultrarelativistic boosted black-holes or Aichelburg-Sexl space time) is found to be exactly solvable. 相似文献
1000.
M. Frster 《Astronomische Nachrichten》1990,311(3):208-208