全文获取类型
收费全文 | 14376篇 |
免费 | 2914篇 |
国内免费 | 4324篇 |
专业分类
测绘学 | 1393篇 |
大气科学 | 3080篇 |
地球物理 | 3147篇 |
地质学 | 7729篇 |
海洋学 | 2357篇 |
天文学 | 541篇 |
综合类 | 1355篇 |
自然地理 | 2012篇 |
出版年
2024年 | 141篇 |
2023年 | 355篇 |
2022年 | 798篇 |
2021年 | 903篇 |
2020年 | 778篇 |
2019年 | 857篇 |
2018年 | 876篇 |
2017年 | 790篇 |
2016年 | 936篇 |
2015年 | 855篇 |
2014年 | 1016篇 |
2013年 | 1029篇 |
2012年 | 1056篇 |
2011年 | 1076篇 |
2010年 | 1067篇 |
2009年 | 1006篇 |
2008年 | 977篇 |
2007年 | 872篇 |
2006年 | 733篇 |
2005年 | 636篇 |
2004年 | 499篇 |
2003年 | 451篇 |
2002年 | 492篇 |
2001年 | 467篇 |
2000年 | 389篇 |
1999年 | 443篇 |
1998年 | 330篇 |
1997年 | 305篇 |
1996年 | 264篇 |
1995年 | 238篇 |
1994年 | 178篇 |
1993年 | 179篇 |
1992年 | 132篇 |
1991年 | 91篇 |
1990年 | 69篇 |
1989年 | 81篇 |
1988年 | 49篇 |
1987年 | 37篇 |
1986年 | 34篇 |
1985年 | 22篇 |
1984年 | 16篇 |
1983年 | 22篇 |
1982年 | 14篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1958年 | 6篇 |
1957年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
STUDY ON SPATIAL AUTOCORRELATION OF URBAN LAND PRICE DISTRIBUTION IN CHANGZHOU CITY OF JIANGSU PROVINCE 总被引:2,自引:0,他引:2
LIU Zhong-gang LI Man-chun SUN Yan MA Wen-bo 《中国地理科学(英文版)》2006,16(2):160-164
1INTRODUCTION The level and periodic changes of land price are interest- ing subjects for the governors, investors, researchers and grass-roots. Currently, the higher land price in China has become the focus among the people, from central go- vernment tocommon citizens,especially in theChang- jiang (Yangtze) River Delta area around Shanghai City. So that studyingthisproblem have both an academic and practicalmeaning. One characteristic ofland is fixed location (the others are high cost… 相似文献
992.
潮汐形变资料中地震前兆信息的识别与提取 总被引:30,自引:17,他引:13
将小波变换的多分辨率分析引入潮汐形变资料处理中,对近年来云南地区的3次强震前的潮汐形变观测资料进行了处理与分析,发现在地震前2~5个月,震中附近的形变台站都接收到一个频段相同的异常信号,且它们之间是相关的,相关系数达80%以上,由此可以确定信号是由同一个源发出来的。出现在多个台站的相同频段的异常信号很可能就是我们想要得到的地震前兆信息。 相似文献
993.
The spatial division of industries of the pearl river delta in the 1990s: Characteristics and trends
The article analyzed the spatial division of industries of the Pearl River Delta (PRD) in the 1990s, a period that witnessed
the deepening of the reform and opening policies and continued rapid development of the region. By adopting the index of specialization,
the extent of specialization, its change and its spatial distribution in the region are measured and demonstrated. The research
revealed that, despite the trend of more balanced development of the secondary sector between the PRD and the rest of the
province, in the PRD, it is the unbalanced development that dominated and the spatial division of the secondary sector has
been shaped. The tertiary industry has also been experiencing unbalance development and the spatial division of the tertiary
sector has been emerging, its extent of concentration appearing even more evident than that of the secondary sector. The author
also discussed the linkage between the spatial division of the two sectors. In the end of the paper, the trends of the spatial
division of the industries in the PRD are forecasted.
Foundation item: Under the auspices of the National Natural Science Foundation of China (No. 49831030).
Biography: XU Yong-jian (1972 – ), female, a native of Changsha City, Ph. D.. Her research interest includes urban geography. 相似文献
994.
Song Guo-xuan Yan Hao-jian Xu Tong-qi Zhu Shi-chang 《Chinese Astronomy and Astrophysics》1981,5(3):332-336
We have found an interior solution of the Einstein equation containing a vector graviton field under a special mass distribution. 相似文献
995.
996.
Yan Li 《Chinese Astronomy and Astrophysics》1989,13(4):424-431
A decoupling method is developed in this paper to deal with linear non-adiabatic non-radial pulsations of stars. The sixth order differential equation of linear pulsation is decomposed into a fourth order and a second order differential equations. The decoupling overcomes such difficulties encountered in the numerical solution as small domain and slowness of convergence and provides a natural guess solution needed in Henyey's method. 相似文献
997.
998.
This paper concerns the reconstruction of a dynamic system based on phase space continuation of monthly mean temperature 1D
time series and the assumption that the equation for the time-varying evolution of phase-space state variables contains linear
and nonlinear quadratic terms, followed by the fitting of the dataset subjected to continuation so as to get, by the least
square method, the coefficients of the terms, of which those of greater variance contribution are retained for use. Results
show that the obtained low-order system may be used to describe nonlinear properties of the short range climate variation
shown by monthly mean temperature series. 相似文献
999.
On the evolution and histology of some Cambrian protoconodonts,paraconodonts and primitive euconodonts 总被引:4,自引:0,他引:4
DONG Xiping Department of Geology Peking University Beijing China Laboratory of Palaeobiology & Stratigraphy Nanjing Institute of Ge-ology Palaeontology Chinese Academy of Sciences Nanjing China 《中国科学D辑(英文版)》2004,47(7):577-584
Although the history of Cambrian conodont study goes back to a century ago, it was not until 1959 that the systematic study of Cambrian conodonts was initi-ated[1]. During the last 44 years Cambrian conodonts have been well documented from all continents but Africa. However, the morphological evolution of para- conodonts and protoconodonts have been subjected to less study than the primitive euconodonts in the inter-val across the Cambrian-Ordovician boundary. Miller (1984) proposed a Weste… 相似文献
1000.
DONGSheng GANBuhong HAOXiaoli 《中国海洋大学学报(英文版)》2004,3(1):111-114
1 Introduction InChina ,coastalcitiesaremostlyregionaleconomicdevelopmentcenters.Becauseoftheirspecialgeogra phiclocations ,typhoonsandassociatedstormsurgescauseheavylossesoflivesandproperties.In 1 992 Qing daowasfloodedduetothecoincidenceoftheastrono m… 相似文献