全文获取类型
收费全文 | 1375篇 |
免费 | 219篇 |
国内免费 | 220篇 |
专业分类
测绘学 | 141篇 |
大气科学 | 31篇 |
地球物理 | 238篇 |
地质学 | 855篇 |
海洋学 | 115篇 |
天文学 | 114篇 |
综合类 | 132篇 |
自然地理 | 188篇 |
出版年
2024年 | 9篇 |
2023年 | 10篇 |
2022年 | 38篇 |
2021年 | 44篇 |
2020年 | 51篇 |
2019年 | 43篇 |
2018年 | 40篇 |
2017年 | 60篇 |
2016年 | 61篇 |
2015年 | 56篇 |
2014年 | 67篇 |
2013年 | 97篇 |
2012年 | 66篇 |
2011年 | 76篇 |
2010年 | 65篇 |
2009年 | 75篇 |
2008年 | 77篇 |
2007年 | 90篇 |
2006年 | 76篇 |
2005年 | 74篇 |
2004年 | 63篇 |
2003年 | 65篇 |
2002年 | 67篇 |
2001年 | 56篇 |
2000年 | 66篇 |
1999年 | 57篇 |
1998年 | 57篇 |
1997年 | 35篇 |
1996年 | 27篇 |
1995年 | 26篇 |
1994年 | 27篇 |
1993年 | 26篇 |
1992年 | 18篇 |
1991年 | 12篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1978年 | 2篇 |
排序方式: 共有1814条查询结果,搜索用时 234 毫秒
1.
韩崇德 《地球科学与环境学报》1992,(4)
洛坝铅锌矿床位于黄诸关韧脆性变形带所波及的范围内,断裂、褶皱、劈理、节理等形态构造类型均很发育,经对小型构造的统计及应力场分析证明,矿区变形主要是在海西—印支期长期存在的南北向古应力场持续作用下形成的。 相似文献
2.
3.
Yulia A. Chernetenko 《Celestial Mechanics and Dynamical Astronomy》2001,80(3-4):185-194
International programs of observations of selected minor planets have lasted about 50 years and the last one comes to the end in 2000. The main aim of these observational programs consists in obtaining the orientation of the stellar reference frame with respect to the dynamical one using observations of the bright minor planets. The observations are also useful for the orbital improvements of the asteroids themselves. They are available from the author via e-mail at the address .During the above mentioned period more than 23 000 observations of minor planets, referred to different reference star catalogues, have been obtained. The reduction procedure of observations to the PPM star catalogue is described. The orientation parameters are given and discussed. 相似文献
4.
北天山东段康古尔塔格带是晚古生代塔里木板块和准噶尔板块碰撞的结果。它是一条复杂的、强烈的高应变带.并具有独特的变形机制、应变序列以及构造变形。本文运用构造-地层研究方法对该碰撞带的构造特征加以分析和研究。 相似文献
5.
Zoran Knežević 《Celestial Mechanics and Dynamical Astronomy》1993,55(4):387-404
Leverrier's development of the indirect part of the disturbing function has been extended to include terms up to degree 4 in eccentricity and inclination; the resulting series has been expressed with respect to a fixed plane, and in a computer readable form (a list of integers). Tests have been performed for the relative significance of the terms of degrees 2, 3 and 4, and estimates have been obtained for the accuracy of the short periodic perturbations of a minor planet, and of the corresponding mean orbital elements. It was found that: (i) even in extreme cases, the indirect part of the disturbing function gives rise to very small short periodic perturbations; (ii) bodies of very high eccentricity/inclination and those close to mean motion resonances are most significantly affected; (iii) indirect perturbations for minor planets can be computed up to the degree 2 terms only, without any significant loss of accuracy; and (iv) higher degree indirect perturbations appear to be important only for their contribution to the long periodic effects of higher order (with respect to the perturbing mass). 相似文献
6.
APPLICATION OF GEOGRAPHICAL PARAMETER DATABASE TO ESTABLISHMENT OF UNIT POPULATION DATABASE 总被引:1,自引:1,他引:0
Now GIS is turning into a good tool in handling geographical, economical, and population data, so we can obtain more and more information from these data. On the other hand, in some cases, for a calamity, such as hurricane, earthquake, flood, drought etc., or a decision-making, such as setting up a broadcasting transmitter, building a chemical plant etc., we have to evaluate the total population in the region influenced by a calamity or a project. In this paper, a method is put forward to evaluate the population in such special region. Through exploring the correlation of geographical parameters and the distribution of people in the same region by means of quantitative analysis and qualitative analysis, unit population database (1km× 1km) is established. In this way, estimating the number of people in a special region is capable by adding up the population in every grid involved in this region boundary. The geographical parameters are obtained from topographic database and DEM database on the scale of 相似文献
7.
文章阐述了地勘单位物业管理社会化的必然性和内函 ,提出发展地勘单位物业管理的基本内容和需要解决的问题 ,最终实现以业养业 ,自我发展。 相似文献
8.
本文用理想结构单元法对空间刚架结构进行了极限强度分析,理想结构单元法在于将结构分成最大可能的单元。以简单的形式归并几何非线性与材料非线性。按增量形式加载,直到达到极限强度。本文根据Rashed理论导出了对称的切向方程组,节省了存贮单元、改善了破坏准则的描述。算例结果与非线性有限单元法结果十分吻合。 相似文献
9.
10.