全文获取类型
收费全文 | 128篇 |
免费 | 23篇 |
国内免费 | 24篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 3篇 |
地球物理 | 56篇 |
地质学 | 59篇 |
天文学 | 41篇 |
综合类 | 6篇 |
自然地理 | 9篇 |
出版年
2023年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2015年 | 6篇 |
2013年 | 2篇 |
2012年 | 1篇 |
2011年 | 12篇 |
2010年 | 10篇 |
2009年 | 6篇 |
2008年 | 2篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 10篇 |
2004年 | 22篇 |
2003年 | 21篇 |
2002年 | 13篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1937年 | 1篇 |
排序方式: 共有175条查询结果,搜索用时 312 毫秒
101.
在山东莱芜-新泰地区盘车沟剖面固山组底界上下首次发现了副蝴蝶虫(Parablackwelderia).研究表明Parablackwelderia是独立的属,而非Blackwelderia的晚出异名.长期以来,作为我国华北寒武纪崮山组和崮山阶(期)的标准地区,山东的崮山组被认为与崮山阶完全相当,这个认识在莱芜-新泰地区需... 相似文献
102.
Lei-Lei Sun Sheng-Hong Gu Xiao-Bin Wang Andrew Collier Cameron Dong-Tao Cao Yi-Bo Wang Yue Xiang Ho-Keung Hui Chi-Tai Kwok Bill Yeung Kam-Cheung Leung 《天文和天体物理学研究(英文版)》2015,(1):117-126
We report new photometric observations of the transiting exoplanetary system WASP-32 made by using CCD cameras at Yunnan Observatories and Ho Koon Nature Education cum Astronomical Centre, China from 2010 to 2012. Following our usual procedure, the observed data are corrected for systematic errors according to the coarse decorrelation and SYSREM algorithms so as to enhance the signal of the transit events. Combined with radial velocity data presented in the literature, our newly observed data and earlier photometric data in the literature are simultaneously analyzed to derive the physical parameters describing the system by employing the Markov chain Monte Carlo technique. The derived parameters are consistent with the result published in the original paper about WASP-32b, but the uncertainties of the new parameters are smaller than those in the original paper. Moreover, our modeling result supports a circular orbit for WASP-32b. Through the analysis of all available mid-transit times, we have refined the orbital period of WASP-32b; no evident transit timing variation is found in these transit events. 相似文献
103.
We present the results of a study on the north-south asymmetry of solar filaments at low(50°) and high(60°) latitudes using daily filament numbers from January 1998 to November 2008(solar cycle 23). It is found that the northern hemisphere is dominant at low latitudes for cycle 23. However, a similar asymmetry does not occur for solar filaments at high latitudes. The present study indicates that the hemispheric asymmetry of solar filaments at high latitudes in a cycle appears to have little connection with that at low latitudes. Our results support that the observed magnetic fields at high latitudes include two components: one comes from the emergence of the magnetic fields from the solar interior and the other comes from the drift of the magnetic activity at low latitudes. 相似文献
104.
In many astrophysical black hole systems, episodic jets of plasma blobs have been observed, which are much faster and more powerful than continuous jets. A magnetohydrodynamical model was proposed by Yuan et al. to study the formation of episodic jets in Sgr A*. By taking Sgr A* and a stellar mass black hole as examples, we modify the model of Yuan et al. by including the effects of relativity, and further study the relativistic motion and expansion of episodic jets of plasma blobs. Then we study the collision between two consecutive ejections in the modified model, and calculate the magnetic energy released in the collision. Our results show two consecutive blobs can collide with each other, and the released magnetic energy is more than 1050 erg,which supports the idea that a gamma-ray burst is powered by the collision of episodic jets, as suggested by Yuan & Zhang. 相似文献
105.
106.
Yun-Fei Yang Hui-Xue Qu Kai-Fan Ji Song Feng Hui Deng Jia-Ben Lin Feng Wang 《天文和天体物理学研究(英文版)》2015,(4):569-582
We study the motion of G-band bright points(GBPs)in the quiet Sun to obtain the characteristics of different motion types.A high resolution image sequence taken with the Hinode/Solar Optical Telescope(SOT)is used,and GBPs are automatically tracked by segmenting 3D evolutional structures in a space-time cube.After putting the GBPs that do not move during their lifetimes aside,the non-stationary GBPs are categorized into three types based on an index of their motion type.Most GBPs that move in straight or nearly straight lines are categorized as a straight motion type,a few moving in rotary paths into rotary motion,and the others fall into a motion type we called erratic.The mean horizontal velocities are 2.18±0.08 km s-1,1.63±0.09 km s-1and 1.33±0.07 km s-1for straight,erratic and rotary motion types,respectively.We find that a GBP drifts at a higher and constant velocity during its whole life if it moves in a straight line.However,it has a lower and variational velocity if it moves on a rotary path.The diffusive process is ballistic-,super-and sub-diffusion for straight,erratic and rotary motion types,respectively.The corresponding diffusion index(γ)and coefficients(K)are 2.13±0.09 and 850±37 km2s-1,1.82±0.07 and331±24 km2s-1,and 0.73±0.19 and 13±9 km2s-1.In terms of direction of motion,it is homogeneous and isotropic,and usually persists between neighboring frames,no matter what motion type a GBP is classified as. 相似文献
107.
Christopher A.Tout 《中国天文和天体物理学报》2007,(2)
Based on previous works of OPAL, we construct a series of opacity tables for various metallicities Z=0, 0.000 01, 0.000 03, 0.000 1, 0.000 3, 0.001, 0.004, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08 and 0.1. These tables can be easily used in Eggleton's stellar evolution code in place of the old tables without changing the code. The OPAL tables are used for log10(T/K) > 3.95 and Alexander's for log10(T/K) < 3.95. At log10(T/K) = 3.95, the two groups' data fit well for all hydrogen mass fractions. Conductive opacities are included by reciprocal addition according to the formulae of Yakovlev and Urpin. A comparison of 1 and 5 M models constructed with the older OPAL tables of Iglesias and Rogers shows that the new opacities have most effect in the late stages of evolution, the extension of the blue loop during helium burning for intermediate-mass and massive stars. 相似文献
108.
断层模型在火山区形变和重力反演中的应用 总被引:8,自引:2,他引:6
利用腾冲火山区1998~2002年的垂直形变和重力测量资料,应用多元Mogi模型对测区的等效岩浆房位置及大小进行了反演计算,得出了最佳拟合值。但当对形变和重力资料联合分析时却发现:实测重力数据比用球形Mogi模型计算所得的值要大得多。为了对此进行合理的解释,提出了断层模型。当岩浆沿断层上升时,充填了断层中原先存在的大量空隙.因而可以只对重力产生影响.而不对形变产生影响。为此沿断层积分得出上升岩浆所产生的重力异常,其结果与实测重力资料拟合得较好。同时断层模型也对负的岩浆源(即岩浆的流失)作出了较为合理的解释。 相似文献
109.
SHIRO Chikamatsu Jose Ireneu Furtad SHEN Lixin YAN Mei 《山地科学学报》2007,4(1):57-70
Traditional farming practices conform to sustainable rural livelihoods, while agricultural modernisation tends to undermine these practices through various perturbations. A case study in Tengchong County (western Yunnan, China) shows that transformation of traditional alder (Alnus nepalensis) and dry rice (upland rice) rotational farming to introduced Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations leads to localised water scarcity and soil fertility decline. While farmers are aware of ecological sustainability of traditional farming, they prefer Chinese fir forestry because it is less labour-intensive, has a high market value, and releases time for profitable off-farm work. Farmers adapt to economic liberalization by planting high value crops and trees. However, alternatives to make local agricultural production more profitable through competitive business strategies, cooperative approaches, innovations in integrating high value crops and 'downstream' processingfor sustainable rural livelihoods have been overlooked largely due to poor information availability and lack of organisational framework. 相似文献
110.
Guang-Zhong Xie Ben-Zhong Dai En-Wei Liang Zhao-Hua Xie Yunnan Astronomical Observatory Chinese Academy of Science Kunming National Astronomical Observatories Chinese Academy of Sciences Beijing Yunnan Astrophysics Center Yu 《中国天文和天体物理学报》2001,1(6):494-500
1 INTaoDUCTIONMany blazar-boe active galedes have recelltly been detected in MeVGeV 7-ray energyrange by detectors on board the Compton Ganuna-Ray Obsewtory (Von Mootigny et al. 1995;Hartman et al. 1999). More recently, TeV ends8ion is obsemd in some object8, such as Mrk421 (z = 0.031, Punch et al. l992), Mrk 501 (z = 0.034, Qbo et al. 1996), 1ES 2344 514(z == 0.044, Catanese et al. 1998), PKS 2155304 (z = 0.117, Chadwick et al. 1999), and1ES 1959 650 (z = 0.048, NisWa 1999). Th… 相似文献