全文获取类型
收费全文 | 39923篇 |
免费 | 504篇 |
国内免费 | 287篇 |
专业分类
测绘学 | 978篇 |
大气科学 | 2893篇 |
地球物理 | 7745篇 |
地质学 | 14834篇 |
海洋学 | 3584篇 |
天文学 | 8421篇 |
综合类 | 109篇 |
自然地理 | 2150篇 |
出版年
2022年 | 274篇 |
2021年 | 444篇 |
2020年 | 461篇 |
2019年 | 504篇 |
2018年 | 1168篇 |
2017年 | 1075篇 |
2016年 | 1243篇 |
2015年 | 627篇 |
2014年 | 1152篇 |
2013年 | 2093篇 |
2012年 | 1315篇 |
2011年 | 1706篇 |
2010年 | 1521篇 |
2009年 | 1920篇 |
2008年 | 1674篇 |
2007年 | 1655篇 |
2006年 | 1583篇 |
2005年 | 1121篇 |
2004年 | 1119篇 |
2003年 | 1020篇 |
2002年 | 1011篇 |
2001年 | 939篇 |
2000年 | 921篇 |
1999年 | 685篇 |
1998年 | 683篇 |
1997年 | 757篇 |
1996年 | 575篇 |
1995年 | 595篇 |
1994年 | 574篇 |
1993年 | 471篇 |
1992年 | 444篇 |
1991年 | 448篇 |
1990年 | 458篇 |
1989年 | 405篇 |
1988年 | 418篇 |
1987年 | 457篇 |
1986年 | 399篇 |
1985年 | 526篇 |
1984年 | 499篇 |
1983年 | 544篇 |
1982年 | 490篇 |
1981年 | 437篇 |
1980年 | 485篇 |
1979年 | 407篇 |
1978年 | 383篇 |
1977年 | 365篇 |
1976年 | 322篇 |
1975年 | 323篇 |
1974年 | 332篇 |
1973年 | 316篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Meteorological excitation of the annual polar motion 总被引:2,自引:0,他引:2
J. B. Merriam 《Geophysical Journal International》1982,70(1):41-56
Summary. Numerous studies have indicated that the annual term in the polar motion cannot be explained in any detail by meteorological/hydrological excitation and no reasonable alternative excitations have been put forward. Part of the problem has been that the hydrostatic adjustment of the oceans to the atmospheric pressure changes has traditionally been computed using the inverse barometer approach. This approach does not properly model the gravitational interaction between the atmosphere and oceans, and the inverse barometer theory is modified in this paper to account for this properly. The information necessary to compute the ocean tide and polar excitation caused by any change in the atmospheric pressure pattern is presented. The results of the application of this theory to two global atmospheric pressure data sets are examined and compared to results of other workers.
It is concluded that the atmosphere is observed well enough to answer the question of the annual excitation of polar motion and it is argued that the ground water excitation is the component with the largest error and remains the chief obstacle to the successful solution of this problem. 相似文献
It is concluded that the atmosphere is observed well enough to answer the question of the annual excitation of polar motion and it is argued that the ground water excitation is the component with the largest error and remains the chief obstacle to the successful solution of this problem. 相似文献
92.
The galactic distribution and physical nature of X-ray transient sources is investigated. Two types of transients are considered. The observational data on 41 X-ray transient sources are given, and the average parameters of hard and soft X-ray transients are estimated. 相似文献
93.
94.
The specific features of the generation and intensification of internal gravity wave structures in different atmospheric-ionospheric regions, caused by zonal local nonuniform winds (shear flows), are studied. The model of the medium has been explained and an initial closed system of equations has been obtained in order to study the linear and nonlinear dynamics of internal gravity waves (IGWs) when they interact with the geomagnetic field in a dissipative ionosphere (for the D, E, and F regions). 相似文献
95.
96.
97.
The transition 111 ? 110 at 4.829 GHz of formaldehyde (H2CO) was the first one showing the anomalous absorption, i.e., the absorption against the cosmic microwave background. Anomalous absorption is an unusual phenomena. Structure of H2CC is very similar to that of H2CO and H2CS. Both H2CO and H2CS have already been identified in a number of cosmic objects. Though H2CC is not yet identified in the cosmic objects, we propose that H2CC may be identified in cool cosmic objects through its transition 111 ? 110 at 4.85 GHz in anomalous absorption. 相似文献
98.
A new protocol was devised to improve the efficiency of astrometric follow-up observations of Near Earth Asteroids for the
accurate determination of their orbits. It was implemented in the activities of the Spaceguard Central Node (SCN, a facility
of the Spaceguard Foundation, established with the support of the European Space Agency) in the form of a Priority List. Here
we describe this protocol and results obtained during five years of activity (2000–2004). 相似文献
99.
J. A. Vorpahl E. G. Gibson P. B. Landecker D. L. McKenzie J. H. Underwood 《Solar physics》1975,45(1):199-216
132 soft X-ray flare events have been observed with The Aerospace Corporation/Marshall Space Flight Center S-056 X-ray telescope that was part of the ATM complement of instruments aboard Skylab. Analyses of these data are reported in this paper. The observations are summarized and a detailed discussion of the X-ray flare structures is presented. The data indicated that soft X-rays emitted by a flare come primarily from an intense well-defined core surrounded by a region of fainter, more diffuse emission. Loop structures are found to constitute a fundamental characteristic of flare cores and arcades of loops are found to play a more important role in the flare phenomena than previously thought. Size distributions of these core features are presented and a classification scheme describing the brightest flare X-ray features is proposed. The data show no correlations between the size of core features and: (1) the peak X-ray intensity, as indicated by detectors on the SOLRAD satellite; (2) the rise time of the X-ray flare event, or (3) the presence of a nonthermal X-ray component. An analysis of flare evolution indicates evidence for preliminary heating and energy release prior to the main phase of the flare. Core features are found to be remarkably stable and retain their shape throughout a flare. Most changes in the overall configuration seem to be the result of the appearance, disappearance or change in brightness of individual features, rather than the restructuring or re-orientation of these features. Brief comparisons with several theories are presented. 相似文献
100.
I. B. Safarov 《Izvestiya Physics of the Solid Earth》2006,42(3):260-270
The elastic and density properties of rocks of the Shamakha-Ismailly seismogenic blocks are studied by the ultrasonic pulse method in quasi-hydrostatic high pressure apparatuses. An attempt is made to more accurately determine the upper crustal lithology of these blocks. The observed values of the elastic and density characteristics of the rocks at high pressures suggest that the upper layers in the Ismailly and Shamakha blocks can consist of sedimentary carbonate rocks such as marls, sandstones, mudstones, and limestones. The middle layers apparently consist of volcaniclastic rocks: lithoclastic tuffs, andesites, etc. The lower layer (basement) in both blocks is likely composed of basic rocks such as basalts, trachybasalts, etc. According to the values of elastic wave velocities and densities, gabbroid rocks may compose the fourth layer of the Buinuz intrusion, identified from seismic data. 相似文献