全文获取类型
收费全文 | 8464篇 |
免费 | 904篇 |
国内免费 | 1257篇 |
专业分类
测绘学 | 331篇 |
大气科学 | 1243篇 |
地球物理 | 1996篇 |
地质学 | 4308篇 |
海洋学 | 935篇 |
天文学 | 822篇 |
综合类 | 434篇 |
自然地理 | 556篇 |
出版年
2024年 | 31篇 |
2023年 | 112篇 |
2022年 | 238篇 |
2021年 | 298篇 |
2020年 | 278篇 |
2019年 | 288篇 |
2018年 | 449篇 |
2017年 | 453篇 |
2016年 | 495篇 |
2015年 | 360篇 |
2014年 | 496篇 |
2013年 | 575篇 |
2012年 | 549篇 |
2011年 | 591篇 |
2010年 | 579篇 |
2009年 | 513篇 |
2008年 | 458篇 |
2007年 | 461篇 |
2006年 | 393篇 |
2005年 | 257篇 |
2004年 | 196篇 |
2003年 | 250篇 |
2002年 | 313篇 |
2001年 | 297篇 |
2000年 | 221篇 |
1999年 | 207篇 |
1998年 | 139篇 |
1997年 | 170篇 |
1996年 | 142篇 |
1995年 | 123篇 |
1994年 | 115篇 |
1993年 | 83篇 |
1992年 | 72篇 |
1991年 | 51篇 |
1990年 | 41篇 |
1989年 | 38篇 |
1988年 | 47篇 |
1987年 | 39篇 |
1986年 | 24篇 |
1985年 | 14篇 |
1984年 | 22篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1975年 | 8篇 |
1958年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
A constitutive relation is derived for describing the mechanical response of chalk. The approach is based on a phenomenological framework which employs chemo‐plasticity. The properties of the material are assumed to be affected by the physico‐chemical processes that occur through the interaction between the skeleton and the pore fluid. The underlying mechanism is discussed by invoking a micromechanical analysis. The performance of the framework is illustrated by examining the evolution of mechanical characteristics in the presence of different pore fluids. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
2.
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
3.
4.
On September 14–18, 2000, a medium-small solar active region was observed at Ganyu Station of Purple Mountain Observatory. Its spots were not large, but it had a peculiar active filament. On Sep.16, a flare of importance IIIb with rather intense geophysical effects was produced. Our computation of the magnetic structure of the active region reveals that the rope-shaped filament was concerned with a low magnetic arc close to magnetic neutral line. An intense shear of magnetic field occurred near magnetic rope. The QSL analysis shows that a 3-D magnetic reconnection might appear in the vicinity of filament, and this can be used to interpret the formation of a large flare. 相似文献
5.
6.
This paper explores the links between a strategic policy, urban consolidation, and house prices by examining the changes in
the mix of housing and in house price for the period 1991–2004. We contend that urban consolidation could be seen as a source
of additional supply, (which might be expected to be felt in lower prices and so contribute to a local policy objective) but
also as a stimulus to demand (by developers who could bid up the price of lots where it was understood more housing could
be built). Analyses were carried out at the metropolitan and sub-regional scales using correlation tests. The research finds
very weak statistical connections, and concludes that this policy has not been associated with price changes. 相似文献
7.
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
8.
9.
SubunitcompositionandchromophorecontentofR-phycocyaninandallophycocyaninfromPorphyrahaitanensis¥GaoHongfeng;CaoWendaandJiMing... 相似文献
10.
PathogensandpathogenicitytoPenaeusorientalisKishinouyeINTRODUCTIONBacteria,especiallyvibriosareoneofthemajorpathogenstocultur... 相似文献