全文获取类型
收费全文 | 48573篇 |
免费 | 8192篇 |
国内免费 | 11400篇 |
专业分类
测绘学 | 4322篇 |
大气科学 | 5606篇 |
地球物理 | 9836篇 |
地质学 | 30051篇 |
海洋学 | 5435篇 |
天文学 | 2171篇 |
综合类 | 3388篇 |
自然地理 | 7356篇 |
出版年
2024年 | 255篇 |
2023年 | 698篇 |
2022年 | 1373篇 |
2021年 | 1549篇 |
2020年 | 1632篇 |
2019年 | 1875篇 |
2018年 | 1501篇 |
2017年 | 1793篇 |
2016年 | 1958篇 |
2015年 | 2091篇 |
2014年 | 2584篇 |
2013年 | 2488篇 |
2012年 | 2853篇 |
2011年 | 3039篇 |
2010年 | 2618篇 |
2009年 | 3112篇 |
2008年 | 3082篇 |
2007年 | 3438篇 |
2006年 | 3318篇 |
2005年 | 2925篇 |
2004年 | 2720篇 |
2003年 | 2639篇 |
2002年 | 2368篇 |
2001年 | 2073篇 |
2000年 | 1921篇 |
1999年 | 1776篇 |
1998年 | 1531篇 |
1997年 | 1425篇 |
1996年 | 1293篇 |
1995年 | 1075篇 |
1994年 | 1132篇 |
1993年 | 958篇 |
1992年 | 748篇 |
1991年 | 538篇 |
1990年 | 475篇 |
1989年 | 378篇 |
1988年 | 283篇 |
1987年 | 188篇 |
1986年 | 120篇 |
1985年 | 81篇 |
1984年 | 33篇 |
1983年 | 32篇 |
1982年 | 31篇 |
1981年 | 21篇 |
1980年 | 23篇 |
1979年 | 28篇 |
1978年 | 35篇 |
1977年 | 24篇 |
1975年 | 4篇 |
1954年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
831.
832.
近年来,在国土资源部的高度重视下,我区相继建立了一系列地学数据库。这些地学数据库的建立不仅为地矿行业提供了基础性数据,也加速了"数字国土工程"和国土资源信息化建设的步伐。随着信息技术的高速发展,利用地理信息系统(GIS)将各类地学数据有机地结合起来,形成地学数据应用与管理系统,最终通过网络服务于社会,必将是各类地学数据发展的必然趋势。 相似文献
833.
华容县注滋口大桥12#墩钻孔灌注桩工程条件极差,经多种方法试验,最后采用了经济合理的冲击与回旋相结合的处理措施,成功地解决了上部大厚度、大体积的块石层及下部砂砾层整体失稳等技术难题。 相似文献
834.
835.
Analysis of monthly momentum transport of zonal waves at 850 hPa for the period 1979 to 1993, between ‡S and ‡N for January
to April, using zonal (u) and meridional (v) components of wind taken from the ECMWF reanalysis field, shows a positive correlation (.1% level of significance) between
the Indian summer monsoon rainfall (June through September) and the momentum transport of wave zero TM(0) over latitudinal
belt between 25‡S and 5‡N (LB) during March. Northward (Southward) TM(0) observed in March over LB subsequently leads to a
good (drought) monsoon season over India which is found to be true even when the year is marked with the El-Nino event. Similarly
a strong westerly zone in the Indian Ocean during March, indicates a good monsoon season for the country, even if the year
is marked with El-Nino. The study thus suggests two predictors, TM(0) over LB and the strength of westerly zone in the Indian
Ocean during March. 相似文献
836.
837.
华北陆块北缘西段狼山—白云鄂博裂谷系中元古代形成的大型多金属矿床 ,是我国重要的铁、稀土、铜、铅、锌矿产地。矿床为产于沉积岩中热水沉积型多金属矿床。其形成受地层、构造控制 ,与裂谷作用有着密切的关系。裂谷系内外分支的地质环境及矿床矿种不同 ,导致矿床特征及成因具有一定差异。白云鄂博铁、稀土矿床为钾、钠、磷等含量较高的热水沉积型 ,霍各乞铜、铅、锌多金属矿床为与中基性火山岩有关的过渡热水沉积型 ,东升庙和甲生盘等铅、锌多金属矿床为热水沉积型。文中将对上述矿床分别进行论述。 相似文献
838.
Preparation of a New Geological Survey of Japan Geochemical Reference Material: Coral JCp-1 总被引:2,自引:0,他引:2
Takashi Okai Atsushi Suzuki Hodaka Kawahata Shigeru Terashima Noboru Imai 《Geostandards and Geoanalytical Research》2002,26(1):95-99
A new geochemical reference material, coral Porites sp. JCp-1 has been prepared by the Geological Survey of Japan (GSJ). Provisional values for twenty one major, minor and trace elements are presented. The homogeneity tests showed that all elements studied are considered to be homogeneously distributed. 相似文献
839.
Abstract. The Hishikari epithermal gold deposit consists of the Honko-Sanjin zone and Yamada zone. On the basis of observed crosscutting relationships of veins, vein system in the Hishikari deposit was classified into the early and late veins. They differ from orientation, width, control by unconformity, the amount of displacement and structural features, but have similarity in gold grade and Au/Ag ratios. K-Ar ages are presented for the classified veins to clarify timing of fracturing and duration of mineralization.
Age determination revealed that the early veins in the Honko-Sanjin zone range from 0.86 to 1.11 Ma and that the late veins range from 0.73 to 0. 84 Ma. The economically most important mineralization in the Hishikari deposit occurred around 0.90 Ma in a very short period (about 0.05 million years).
The distribution of mineralization age in the whole Hishikari deposit, occurrences of slickensides and ground water temperatures imply that mineralization lasted longer in the southern part of the deposit. As compared the early veins with late veins, structural changes including width, strike, dip and vein characteristics occurred at around 0.85 Ma. 相似文献
Age determination revealed that the early veins in the Honko-Sanjin zone range from 0.86 to 1.11 Ma and that the late veins range from 0.73 to 0. 84 Ma. The economically most important mineralization in the Hishikari deposit occurred around 0.90 Ma in a very short period (about 0.05 million years).
The distribution of mineralization age in the whole Hishikari deposit, occurrences of slickensides and ground water temperatures imply that mineralization lasted longer in the southern part of the deposit. As compared the early veins with late veins, structural changes including width, strike, dip and vein characteristics occurred at around 0.85 Ma. 相似文献
840.