全文获取类型
收费全文 | 5538篇 |
免费 | 1127篇 |
国内免费 | 1748篇 |
专业分类
测绘学 | 707篇 |
大气科学 | 1167篇 |
地球物理 | 1309篇 |
地质学 | 2967篇 |
海洋学 | 865篇 |
天文学 | 197篇 |
综合类 | 540篇 |
自然地理 | 661篇 |
出版年
2024年 | 34篇 |
2023年 | 116篇 |
2022年 | 330篇 |
2021年 | 413篇 |
2020年 | 322篇 |
2019年 | 409篇 |
2018年 | 333篇 |
2017年 | 363篇 |
2016年 | 395篇 |
2015年 | 391篇 |
2014年 | 479篇 |
2013年 | 428篇 |
2012年 | 447篇 |
2011年 | 460篇 |
2010年 | 413篇 |
2009年 | 357篇 |
2008年 | 309篇 |
2007年 | 286篇 |
2006年 | 271篇 |
2005年 | 237篇 |
2004年 | 152篇 |
2003年 | 138篇 |
2002年 | 141篇 |
2001年 | 138篇 |
2000年 | 131篇 |
1999年 | 134篇 |
1998年 | 99篇 |
1997年 | 101篇 |
1996年 | 101篇 |
1995年 | 90篇 |
1994年 | 68篇 |
1993年 | 62篇 |
1992年 | 60篇 |
1991年 | 32篇 |
1990年 | 26篇 |
1989年 | 50篇 |
1988年 | 26篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 13篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1958年 | 8篇 |
1957年 | 1篇 |
1954年 | 2篇 |
1942年 | 1篇 |
排序方式: 共有8413条查询结果,搜索用时 15 毫秒
41.
42.
XU Shaokang XIA Xuehui YUAN Congjian WANG Bingquan YAN Fei YAN Shengxian ZHENG Xingquan 《《地质学报》英文版》2008,82(4)
The new type hot water sedimentary rock - magnetite-fluorite rock occurs as quasi-layers inflat parts of contact zones between rock body and strata in Bamiaushan of Changshan County,Zhejiang Province, China. The main mineral assemblage is fluorite magnetite cassiterite. The rockshows typical laminated structure and obvious mosaic texture. Its formation temperature is between123℃-160℃, averaging at 142℃. The major chemical composition of the rock includes CaF2, SiO2,Al2O3, FeO, and Fe2O3; the high-content microelement association includes W, Sn, Be, Rb, Sr, S, andCl; and the total content of REE is low (∑REE between 35.34x10-6-38.35x10-6), showing LREEenrichment type of distribution pattern. Diagenesis: driven by the tectonic stress, the formation waterheated in the deep strata had moved along the fissures or fractures in strata and had extractedcomponents from the strata on the way, and finally stagnated in the flat parts of contact zones betweenrock body and strata. With drop in temperature, magnetite and fluorite were separated from the hotwater and precipitated alternately, forming this hot water sedimentary rock with new typemineralogical composition, typical laminated structure, obvious mosaic texture and sub-horizontaloccurrence. The characteristics of the new type mineralogical composition, sedimentary tectonicenvironment and chemical composition are different from that of the well-known traditionalhydrothermai sedimentary rocks. 相似文献
43.
Xin Li Dongliang Wang Baoquan Liu Chunling Ren Jianying Guo Xuefeng Su Jian Wang 《中国地球化学学报》2008,27(4):412-419
The northern margin of the Qaidam Basin is one of the main oil-gas exploration areas in western China, where source rocks are composed mostly of Middle and Lower Jurassic dark mud shale, carbargillite and coal. A large number of subsurface and outcrop samples differing in lithology with different types of organic matter were selected for resource evaluation, research and calculation. And among them, 13 samples were used for simulation experiment on hydrocarbon generating potential of various source rocks. At first, two kinds of heating modes were compared through simulation experiment, including single temperature-step heating and continual heating. Perhaps, the process of hydrocarbon generation and expulsion occurred naturally between a close system and an open system. In addition, the first heating mode was convenient, and all its reaction products were involved in the whole thermal evolution, and the final simulation experimental results were basically in consistency with the natural evolution trend Therefore, the first heating mode was adopted and the hydrocarbon yield of every sample was worked out. According to the type and lithology of organic matter and the hydrocarbon yield of samples for simulation experiment, hydrocarbon generation and expulsion mode with three kinds of lithology and five types of source rock has been established to provide the basis for hydrocarbon generation evaluation, research and resource calculation. 相似文献
44.
45.
46.
47.
三峡水库区兴山后坝滑坡成因分析 总被引:2,自引:0,他引:2
文章通过对三峡水库区兴山后坝滑坡的地质、结构及变形特征研究以及稳定性分析,阐明了该滑坡成因和影响因素。研究发现,滑坡活动主要受地形地貌、地层岩性、人类工程活动以及降雨等因素的影响。运用剩余推力法对比分析天然及暴雨条件下不同层位的滑坡稳定性系数,得出在暴雨作用下滑坡表层滑带稳定性系数最小,不同滑带的稳定性受降雨的影响也各不相同,呈表层〉浅层〉深层的规律;这主要受滑带土的粘土矿物组分的影响。 相似文献
48.
通过对呼伦贝尔市煤矿地质环境敏感性的综合评价,结合当地实际情况,提出了以修筑拦挡建筑物、支撑与坡面防护、锚固、排水、选择更合理的开采工艺等技术手段,对该地区地质灾害进行防治的方案。方案对海拉尔河河道治理、生物措施、井下回填工程、加固边坡、抽排水、发展煤矸石砖厂、移民避让、招商引资8个部分提出了防治方法,促进地质环境治理工作的进行。 相似文献
49.
50.