全文获取类型
收费全文 | 119篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
大气科学 | 3篇 |
地球物理 | 23篇 |
地质学 | 21篇 |
海洋学 | 19篇 |
天文学 | 50篇 |
综合类 | 1篇 |
自然地理 | 7篇 |
出版年
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2011年 | 7篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 12篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有124条查询结果,搜索用时 468 毫秒
91.
A new magnetodynamic model for loop flares is proposed to explain the following observational facts obtained from space during the last solar activity maximum: (i) Blueshifted lines of Ca xix and Fe xxv appear in some cases a minute or so before the initiation of impulsive bursts and relax into the unshifted lines with large width by the time of the onset of impulsive bursts, (ii) the hot source is formed by that time at the top of a loop-like structure, and confined there for a considerable time, and (iii) -ray line enhancement occurs at about the same time as hard X-ray spikes.In our model, the supply of energy to the loop top comes from below the chromosphere immediately before the flare (30 s-1 min before the hard X-ray impulsive bursts) in the form of the relaxing fronts of magnetic twist of opposite sign. These packets are thought to be built up in the process of loop emergence, stored at the footpoints of the loop below the photosphere, and released when the part of the feet floats up further. These released packets of magnetic twist drive the mass in the high chromosphere and transition zone into helical flows with pinch heating, and when these collide at the top of the loop, a very hot region appears there with a violent unwinding of the twists, resulting in the rapid dynamical annihilation of the magnetic energy,
. Electrons and ions, raised to medium energies in the pinch at the incidence of the packets to the loop, are accelerated further by the Fermi-I mechanism between the approaching fronts of magnetic twist, and when B
is weakened by unwinding they are released towards the chromosphere, and cause simultaneous -ray and hard X-ray bursts. 相似文献
92.
93.
Akira Shibata 《Journal of Oceanography》2006,62(3):321-330
Ocean microwave emissions changed by the ocean wind at 6 GHz were investigated by combining data of the Advanced Microwave
Scanning Radiometer (AMSR) and SeaWinds, both aboard the Advanced Earth Observation Satellite-II (ADEOS-II). This study was
undertaken to improve the accuracy of the sea surface temperature (SST) retrieved from the AMSR 6 GHz data. Two quantities,
6V*(H*), were defined by the brightness temperature of the AMSR at 6 GHz with two polarizations (V-pol and H-pol), adjusted
for atmospheric effects and with a calm ocean surface emission removed. These quantities represent a microwave emission change
due to the ocean wind at 6 GHz. 6V* does not change in a region where 6H* is less than around 4 K (referred to as z0). Both
6V* and 6H* increase above z0. The 6V* to 6H* ratio, sp, varies with the relative wind directions. Furthermore, the sp values
vary with the SST, between the northern and southern hemisphere, and seasonally. By specifying appropriate values for z0 and
sp, the SST error between AMSR and buoy measurement became flat against 6H*, which is related to the ocean wind. Two extreme
cases were observed: the Arabian Sea in summer and the Northwestern Atlantic Ocean in winter. The air-sea temperature difference
in the former case was largely positive, while it was largely negative in the latter. The 6V* and 6H* relations differed from
global conditions in both cases, which resulted in incorrect SSTs in both areas when global coefficients were applied. 相似文献
94.
One-dimensional hydrodynamic simulations are performed in order to examine the influence of initial atmospheric structures on the dynamics of spicules. This is an extended version of our previous spicule theory: spicules are produced by the shock wave (MHD slow mode shock) which originates from a bright point appearance (sudden pressure increase) at the network in the photosphere or in the low chromosphere. Simulation results well reproduce the observational facts that spicules are absent over plages and long under coronal holes. The physical reason is that the growth of a shock wave during its propagation through the chromosphere is small in plage regions and large in coronal hole regions, since the growth of a shock is determined by the density ratio (
h
0/
c
) between the bright point and the corona. An empirical formula H
max (
h
0/
c
)0.46 is obtained, where H
max is the maximum height of spicules above the transition region. The cross-section of the vertical magnetic flux tube is assumed to be constant in the numerical simulations. 相似文献
95.
We study the structure of a stationary and axisymmetric charge-deficient region (or a potential gap) in the outer magnetosphere of a spinning neutron star. A large electric field along the magnetic field lines is created in this potential gap and accelerates migratory electrons (e− ) and/or positrons (e+ ) to ultrarelativistic energies. Assuming that the gap is immersed in a dense soft photon field, these relativistic e± radiate γ -ray photons via inverse Compton (IC) scattering. These γ -rays, in turn, produce yet more radiating particles by colliding with ambient soft photons, leading to a pair-production cascade in the gap. The replenished charges partially screen the longitudinal electric field, which is self-consistently solved together with the distribution of e± and γ -ray photons. It is demonstrated that the voltage drop in the gap is not more than 1010 V when the background X-ray radiation is as luminous as 1037 erg s−1 . However, this value increases with decreasing X-ray luminosity and attains 1012 V when the X-ray radiation is 1036 erg s−1 . In addition, we find useful expressions of the spatial distribution of the particle fluxes and longitudinal electric field, together with the relationship between the voltage drop and the current density. Amazingly, these expressions are valid not only when IC scattering dominates but also when curvature radiation dominates. 相似文献
96.
Kohtaro Hosoda Hiroshi Murakami Akira Shibata Futoki Sakaida Hiroshi Kawamura 《Journal of Oceanography》2006,62(3):291-291
ADEOS-II Ocean: Advanced Earth Observing Satellite-II Ocean
Preface 相似文献97.
Effect of NaCrSi2O6 component on Lindsley's pyroxene thermometer: An evaluation based on strongly metamorphosed LL chondrites
下载免费PDF全文
![点击此处可从《Meteoritics & planetary science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In Lindsley's thermometry, a revised sequence of calculation of components is proposed for clinopyroxene, in which kosmochlor component is added. Temperatures obtained for the components calculated by the revised method are about 50 °C lower than those obtained for the components calculated by the Lindsley's original method and agree well with temperatures obtained from orthopyroxenes. Ca‐partitioning between clino‐ and orthopyroxenes is then thought to be equilibrated in types 5 to 7 ordinary chondrites. The temperatures for Tuxtuac (LL5), Dhurmsala (LL6), NWA 2092 (LL6/7), and Dho 011 (LL7) are 767–793°, 818–835°, 872–892°, and 917–936°C, respectively, suggesting that chondrites of higher petrographic types show higher equilibrium temperatures of pyroxenes. The regression equations which relate temperature and Wo and Fs contents in the temperature‐contoured pyroxene quadrilateral of 1 atm of Lindsley (1983) are also determined by the least squares method. It is possible to reproduce temperatures with an error less than 20 °C (2SE) using the regression equations. 相似文献
98.
The solar neutron detector Space Environment Data Acquisition Equipment – Attached Payload (SEDA-FIB) onboard the International Space Station (ISS) detected several events from the solar direction associated with three large solar flares observed on 05 (X1.1), 07 (X5.4), and 09 (M6.3) March 2012. In this study, we focus on the interesting event of 05 March, present the temporal profiles of the neutrons, and discuss the physics that may be related to a possible acceleration scenario for ions above the solar surface. We compare our data with images of the flares obtained by the ultraviolet telescope Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). 相似文献
99.
100.
Takahiro Kudoh Ryoji Matsumoto Kazunari Shibata 《Astrophysics and Space Science》2003,287(1-4):99-102
We present the MHD simulation including accretion flows in disks, acceleration of outflows from disks, and collimation of the outflows self-consistently. Although it was considered that this kind of simulations only shows the transient phenomena of jets, we found that the outflow and accretion flow reached a quasi-steady state by performing a long-term calculation in a large calculation region. Though the final stage is not exactly the steady state, the acceleration and collimation mechanisms of the outflow were the same as those of the steady theory. The scale of the calculation is approaching to the scale that was observed by the VLBI technique, which provides the current highest resolution for YSO jets. 相似文献