全文获取类型
收费全文 | 457篇 |
免费 | 54篇 |
国内免费 | 130篇 |
专业分类
测绘学 | 8篇 |
大气科学 | 43篇 |
地球物理 | 120篇 |
地质学 | 258篇 |
海洋学 | 32篇 |
天文学 | 84篇 |
综合类 | 28篇 |
自然地理 | 68篇 |
出版年
2023年 | 2篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2012年 | 3篇 |
2011年 | 31篇 |
2010年 | 33篇 |
2009年 | 36篇 |
2008年 | 35篇 |
2007年 | 28篇 |
2006年 | 62篇 |
2005年 | 53篇 |
2004年 | 60篇 |
2003年 | 25篇 |
2002年 | 28篇 |
2001年 | 20篇 |
2000年 | 19篇 |
1999年 | 27篇 |
1998年 | 11篇 |
1997年 | 13篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 10篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1985年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 11篇 |
1976年 | 10篇 |
1970年 | 1篇 |
1962年 | 1篇 |
1956年 | 1篇 |
1942年 | 1篇 |
1937年 | 1篇 |
1933年 | 9篇 |
1931年 | 1篇 |
1923年 | 2篇 |
1922年 | 2篇 |
排序方式: 共有641条查询结果,搜索用时 15 毫秒
81.
中国天文学会天文学名词审定委员会 《天文学进展》2008,26(1):95-99
中国天文学会名词审定委员会从1985年开始在<天文学进展>发表天文学名词的推荐译名,到2007年已公布了14批2280个名词.现再推荐第十五批151个名词,其中大多数是近年来出现的天文学新词.希望读者在试用过程中对译名提出改进意见. 相似文献
82.
A Simple Monte Carlo Method for Locating the Three-dimensional Critical Slip Surface of a Slope 总被引:2,自引:0,他引:2
XIE Mowen Institute of Environmental Systems Kyushu University Hakozaki -- Higashi Ku Fukuok Japan College of Resource Engineering the University of Science Technology Beijing Xueyuan Ro Haidian District Beijing China 《《地质学报》英文版》2004,78(6):1258-1266
Based on the assumption of the plain-strain problem, various optimization or random search methods have been developed for locating the critical slip surfaces in slope-stability analysis, but none of such methods is applicable to the 3D case. In this paper, a simple Monte Carlo random simulation method is proposed to identify the 3D critical slip surface. Assuming the initial slip to be the lower part of a slip ellipsoid, the 3D critical slip surface is located by means of a minimized 3D safety factor. A column-based 3D slope stability analysis model is used to calculate this factor. In this study, some practical cases of known minimum safety factors and critical slip surfaces in 2D analysis are extended to 3D slope problems to locate the critical slip surfaces. Compared with the 2D result, the resulting 3D critical slip surface has no apparent difference in terms of only cross section, but the associated 3D safety factor is definitely higher. 相似文献
83.
LI Chao HU Xiumian HOU Mingcai WANG Chengshan YANG Jianghai DDE Sedimentary Data Group 《《地质学报》英文版》2019,93(Z1):34-36
正On the platform of the Deep-time Digital Earth Program(DDE),sedimentary data are essential for achieving its scientific objectives.These data will take stratigraphic units as their core data carrier,for quantitative or qualitative data analysis.The DDE Sedimentary Data Group is responsible for the management of the sedimentary data on the DDE platform and has now developed into a group of nearly 40 disciplinary experts.This groups main tasks are constructing sedimentary knowledge 相似文献
84.
Mr.T.F.Hou,geologist of the National Geological Survey of Chinabrought back in 1931 from Liaoning province,a specimen of subbituminous coalin which are included patches or aggregates of small oolites.This interestingspecimen was given to the writer for microscopical investigation.Both polished 相似文献
86.
《江西省气象局业务技术体制改革实施方案》编写组 《气象与减灾研究》2005,28(4):47-50
对江西气象科技创新体系改革与建设的内容和方向进行了论述,认为江西气象科技创新体系改革与建设,应坚持“自主创新,重点跨越,支撑发展,引领未来”的科技发展方针,明确科技型、基础性社会公益事业定位,深入实施科技兴气象战略,深化气象科技体制改革,加强原始创新、集成创新和引进消化吸收再创新;促进业务与科研的结合,形成科技创新引领事业发展的研究型业务,提升气象科技创新能力,提高气象科技水平和气象业务的科技含量,提高气象队伍素质,培养造就具有创新能力、既懂科研又懂业务的学科、技术带头人和复合型人才。 相似文献
87.
A.V.Ovcharenko 《中国地震研究》1999,(1)
Traditionally, when creating 4-D models of elastic offsets in the Earth's crust, the data from geodesic and GPS monitoring of offsets on the ground surface, earthquake catalogs, monitoring of the water level and radon content in wells, sea level fluctuations, as well as gravitational and magnetic fields, etc., can be taken as bases for information. In essence, the reason for creating a 4-D model of slow elastic deformations is to approximate the process by a set of plane deformation solitons (solitary waves). The parameters of a set of deformation solitons are obtained by a two-stage inversion. First, the parameters of the model are determined in a kinematic way by the use of a modified simplification of the method. Then, a calibration of the amplitude characteristics of the model is carried out in terms of elastic dynamic offsets. Taking Ural, Northern Tianshan, Greece, and China as examples, models for these regions are created on the basis of seismological, geodesic, deformation, hydrogeological, and 相似文献
88.
Nelson pointed out that the wave breaking criterion(H/d)_b for gentle slopes(i<1/100),inwhich H is the wave height and d is the water depth at the breaking point,is smaller than that for beachslopes of i>1/100),i.e.,the value of(H/d)_b for gentle slopes may be smaller than 0.6.Goda indicatedthat the wave breaking criterion given by himself is a result based on theoretical study,so it should be alsocorrect and can be used for gentle beaches,i.e.,the value of(H/d)_b for gentle slopes may be still largerthan 0.7.By use of high order nonlinear wave theory,this problem is analyzed in this study and the reasonwhy there is a large difference between different studies is explained.Moreover,the bottom energy loss dur-ing wave propagation is considered and the critical slope for the absence of wave breaking is also analyzed. 相似文献
89.
LI Yucheng
Professor the State Key Laboratory of Coastal Offshore Engineering Dalian University of Technology Dalian P. R. China. 《中国海洋工程》1999,(2)
-The hydrodynamic coefficients C_d and C_m are not only dependent on the size of slender cylin-der,its location in water,KC number and Re number,but also vary with environmental conditions,i.e.,in regular waves or in irregular waves,in pure waves or in wave-current coexisting field.In this paper,thenormalization of hydrodynamic coefficients for various environmental conditions is discussed.When aproper definition of KC number and proper characteristic values of irregular waves are used,a unified re-lationship between C_d,C_m and KC number for regular waves,irregular waves,pure waves and wave-cur-rent coexisting field can be obtained. 相似文献
90.
ZHANG Jing CHEN Yanjing QI Jinping GE Jun State Key Laboratory of Geological Process Mineral Resources China University of Geosciences Beijing China Key Laboratory of Metallogenic Dynamics Guangzhou Institute of Geochemistry the Chinese Academy of Sciences Guangzhou China 《《地质学报》英文版》2009,83(2)
The Tongbai-East Qinling Mountains,an important part of the Central orogenic belt,is one of the most important metallogenic belts in China and contains lots of orogenic-type and VMS-type (Volcanogenic Massive Sulfide type)metallogenic systems.The Dahe and Shuidongling VMS-type Cu-Zn deposits,located in the Erlangping Group in Tongbai and East Qinling Mountains,respectively, show similar geological and geochemical features.The Huoshenmiao Formation in the East Qinling region and the Liushanyan Formation i... 相似文献