全文获取类型
收费全文 | 7944篇 |
免费 | 799篇 |
国内免费 | 956篇 |
专业分类
测绘学 | 274篇 |
大气科学 | 1008篇 |
地球物理 | 1773篇 |
地质学 | 3994篇 |
海洋学 | 878篇 |
天文学 | 733篇 |
综合类 | 463篇 |
自然地理 | 576篇 |
出版年
2024年 | 32篇 |
2023年 | 108篇 |
2022年 | 296篇 |
2021年 | 323篇 |
2020年 | 307篇 |
2019年 | 354篇 |
2018年 | 458篇 |
2017年 | 467篇 |
2016年 | 519篇 |
2015年 | 333篇 |
2014年 | 509篇 |
2013年 | 566篇 |
2012年 | 571篇 |
2011年 | 540篇 |
2010年 | 556篇 |
2009年 | 471篇 |
2008年 | 448篇 |
2007年 | 447篇 |
2006年 | 366篇 |
2005年 | 216篇 |
2004年 | 139篇 |
2003年 | 138篇 |
2002年 | 138篇 |
2001年 | 144篇 |
2000年 | 156篇 |
1999年 | 138篇 |
1998年 | 125篇 |
1997年 | 132篇 |
1996年 | 111篇 |
1995年 | 104篇 |
1994年 | 93篇 |
1993年 | 67篇 |
1992年 | 72篇 |
1991年 | 43篇 |
1990年 | 34篇 |
1989年 | 33篇 |
1988年 | 20篇 |
1987年 | 15篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 18篇 |
1983年 | 9篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 3篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1968年 | 3篇 |
1958年 | 11篇 |
排序方式: 共有9699条查询结果,搜索用时 15 毫秒
1.
M. A. Vashkov’yak 《Astronomy Letters》2001,27(7):464-469
We consider the structural peculiarities of Uranus’s satellite system associated with its separation into two groups: inner equatorial satellites moving in nearly circular orbits and distant irregular satellites with retrograde motion in highly elliptical orbits. The intermediate region is free from satellites in a wide range of semimajor axes. By analyzing the evolution of satellite orbits under the combined effect of solar attraction and Uranus’s oblateness, we offer a celestial-mechanical explanation for the absence of equatorial satellites in this region. M.L. Lidov’s studies during 1961–1963 have served as a basis for our analysis. 相似文献
2.
随着河南区域化探扫面工作的结束,异常评价是摆在我们面前的当务之急。近年来,随着地质工作的不断深入,我们在异常评价程序及方法上作了一些探索,下面以桐柏县固庙—新集1:20万金银异常评价方法及效果为例,重点加以讨论。 相似文献
3.
4.
This review is devoted to problems in the photochemical modeling of atmospheric processes. The physicochemical and mathematical foundations underlying the construction of photochemical models are described, a classification of the atmospheric reactions is presented, and the features of photochemical modeling are considered under various irradiance conditions for various atmospheric layers and geographical regions. Atmospheric processes that are important to photochemical models are discussed. Applications involving photochemical models are outlined. Some results are presented to illustrate the capabilities of photochemical models. Special attention is given to relatively recent directions in photochemical modeling, such as data assimilation and inverse problems. The review can be used by experts in areas related to atmospheric chemistry as a basic source of knowledge on the subject and for the development of photochemical modules for atmospheric models. 相似文献
5.
韩宗珠 《中国海洋大学学报(自然科学版)》1994,(1)
以微量元素、稀土元素、Sr和Nd同位素变异特征为依据,确定鲁苏榴辉岩为多成因、多来源和多阶段,指出主要是在印支期扬子陆块与华北陆块碰撞造山作用过程中,挤入的上地幔碎片以及不同原岩类型的壳内高压变质岩碎块。燕山晚期的区域构造热事件使得某些榴辉岩的同位素体系再平衡。 相似文献
6.
V. N. Aref’ev F. V. Kashin V. K. Semenov R. M. Akimenko N. E. Kamenogradskii N. I. Sizov V. P. Sinyakov L. B. Upenek V. P. Ustinov 《Izvestiya Atmospheric and Oceanic Physics》2006,42(6):739-751
Refined data of systematic measurements of total water vapor in the atmosphere from May 1980 to April 2005 are presented. The data were obtained at the Issyk Kul atmospheric-monitoring station by the method of solar molecular-absorption spectroscopy. Over 25 years, the annual mean water-vapor content in the atmosphere increased by 4.5% at a mean rate of increase of 0.18% per year. However, the water-vapor content decreased in the last five years. The results of statistical processing of experimental data (general statistical characteristics, correlation coefficients, composite oscillations) are described. A refined model is proposed for forecasts of temporal variations in the monthly mean and annual mean water-vapor contents for the coming years. The model includes a linear trend and the sum of oscillations with periods close to the periods of a number of well-known geophysical phenomena. Regression equations are proposed to relate the water-vapor content in the atmospheric column to the surface temperature and absolute humidity. 相似文献
7.
8.
9.
10.