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 484 毫秒
71.
Li-Hong Yan Jian-Cheng Wang Yunnan Observatory /National Astronomical Observatories Key Laboratory for the Structure Evolution of Celestial Objects Chinese Academy of Sciences Kunming China Graduate School of Chinese Academy of Sciences Beijing China 《中国天文和天体物理学报》2011,(6)
We present a new explanation for the origin of the steep power-law(SPL) state of X-ray binaries.The power-law component of X-ray emission is the synchrotron radiation of relativistic electrons in highly magnetized compact spots orbiting near the inner stable circular orbit of a black hole.It has a hard spectrum that extends to above MeV energies,which is determined by the electron acceleration rate.These photons are then down-scattered by the surrounding plasma to form an observed steep spectrum.We discuss ... 相似文献
72.
Xiao-Yan Gao Jian-Cheng Wang Ming Zhou National Astronomical Observatories /Yunnan Observatories Chinese Academy of Sciences Kunming China Key Laboratory for the Structure Evolution of Celestial Objects China Graduate University of Chinese Academy of Sciences Beijing China 《中国天文和天体物理学报》2011,(8)
The external Compton(EC) model is used to study the high energy emission of some blazars,in which the external photon field is considered to dominate inverse Compton radiation. We explore the properties of the external photon field through analyzing the FERMI LAT bright AGN sample within three months of the start of operations in sky-survey mode. In the sample,assuming the high energy radiation of low synchrotron peaked blazars is from the EC process,we find that the external photon parameter Uext/νext may ... 相似文献
73.
Shi-Bi Pu Zhan-Wen Han National Astronomical Observatory /Yunnan Observatory Chinese Academy of Sciences Kunming China Graduate University of Chinese Academy of Sciences Beijing China Key Laboratory of the Structure Evolution of Celestial Objects China 《中国天文和天体物理学报》2011,(8)
We present high quality long slit spectra along the major and minor axes out to 1.5 effective radii of the massive galaxy NGC 4636 taken by the Hobby-Eberly Telescope. Using the Fourier Correlation Quotient method,we measured the stellar line-of-sight velocity distribution along the axes. Furthermore,six Lick/IDS indices(Hβ,Mgb,Fe5015,Fe5270,Fe5335,Fe5406) are derived from the clean spectrum. By comparing the measured absorption line strengths with the predictions of Simple Stellar Population(SSP) models,we... 相似文献
74.
东北亚各国自然地域相连,社会经济联系密切,形成了东北亚独特的经济地域系统。在全球变化背景下,深入探讨东北亚区域可持续发展面临的主要科学问题具有重要的理论与实践意义。东北亚区域生态经济巨系统的结构、功能和地域分异规律及其动态演变格局是该区域可持续发展的基本科学问题;驱动力因子是该区域可持续发展研究的重要问题;跨境区域社会经济可持续发展模式是该区域可持续发展的核心问题和归宿,而东北亚区域可持续发展支撑平台建设是重要的技术支撑和保障。东北亚、中亚地区作为一个资源、环境、经济和社会复杂巨系统,其可持续发展还有许多重要科学问题,需要该区域科学家联合攻关,共同探索。 相似文献
75.
M.D.Koppelman 《中国天文和天体物理学报》2005,5(2):137-143
Several new light minimum times for the eclipsing binary GSC 0445-1993 have been determined from the observations by Koppelman et al. and the orbital period of this system was revised. A photometric analysis was carried out using the 2003 version of the Wilson-Devinney code. The results reveal that GSC 0445-1993 is a W-type eclipsing binary with a mass ratio of q = 0.323(±0.002) and an over-contact degree of f = 22.8%(±4.2%). A small temperature difference between the components of △T = 135 K and an orbital inclination of i = 65.7°(±0.3°) were obtained. The asymmetry of its light curve (i.e., the O'Connell effect) for this binary star is explained by the presence of a dark spot on the more massive component. 相似文献
76.
近20年来,随着CCD和像增强器的发展,小巧灵活的流星视频观测系统在世界上逐渐多了起来.并且,最终将可能逐步取代流星的目视观测和普通照相观测.介绍云南天文台I号流星彗星视频照相系统的研制及其初步观测结果.这一系统由容易转换的5组件构成.用于流星观测的大视场相机的视场约36度,单帧图像可观测到约6等恒星.实测的恒星星等测量精度可达约0.2等.还讨论了视频照相机比传统的感光胶卷照相的长处,以及视频照相系统的改进与发展. 相似文献
77.
Xiao-Hong Zhao Yi-Ping Qin Yun-Ming Dong Zhao-Yang Peng Yunnan Observatory Chinese Academy of Sciences Kunming 《中国天文和天体物理学报》2004,4(4):349-356
The role of T50 in classifying gamma-ray bursts (GRBs) is investigated. We take T50=0.7s as the line of division and find that some bursts belonging to the class of long bursts defined by T90≥2s now become short bursts (sample 1), while some belonging to the class of short bursts defined by T90 < 2 s now become long bursts (sample 2). We study how these sources are affected by the two methods of classification and find the change of classes of sample 1 is due to some peculiar properties of the light curves. Based on their characters, most of the bursts of sample 1 should be taken as short bursts. 相似文献
78.
水资源是黄河流域生态保护和高质量发展的最大刚性约束,识别流域水资源利用变化驱动因素具有重要意义。首先从结构视角测度黄河流域水足迹变化,进而基于Tapio脱钩模型与Kaya-LMDI分解模型,解析水足迹与经济增长脱钩状态,并从技术效应、结构效应、规模效应、禀赋效应、城市化效应和人口效应识别水资源利用变化驱动因素。研究发现:(1)黄河流域水足迹总体呈现上升趋势,农业水足迹占比高达85%,用水结构与产业结构倒挂问题突出。(2)黄河流域上下游水资源量与水足迹空间分布不匹配,中下游面临更严重水资源约束。(3)水足迹与经济增长关系主要表现为弱脱钩,但2015—2019年各省区开始向强脱钩转变。(4)规模效应、城市化效应和人口效应对水足迹变化起拉动作用,技术效应、结构效应和禀赋效应对水足迹变化起抑制作用,但仍有提升潜力,各省区影响因素存在一定差异。为此,需要强化水资源利用技术研发与推广,推动农业集约式发展,提升农业用水效率,进一步优化产业结构和新型城镇化建设,缓解水资源约束困境,推动黄河流域经济高质量发展。 相似文献
79.
New Vetulicoliids from the Lower Cambrian Guanshan Fauna, Kunming 总被引:13,自引:3,他引:10
80.