全文获取类型
收费全文 | 1098篇 |
免费 | 16篇 |
国内免费 | 13篇 |
专业分类
系统科学 | 7篇 |
丛书文集 | 15篇 |
教育与普及 | 4篇 |
现状及发展 | 3篇 |
综合类 | 1098篇 |
出版年
2024年 | 3篇 |
2023年 | 4篇 |
2022年 | 6篇 |
2021年 | 9篇 |
2020年 | 12篇 |
2019年 | 15篇 |
2018年 | 9篇 |
2017年 | 22篇 |
2016年 | 16篇 |
2015年 | 28篇 |
2014年 | 61篇 |
2013年 | 39篇 |
2012年 | 75篇 |
2011年 | 68篇 |
2010年 | 44篇 |
2009年 | 28篇 |
2008年 | 35篇 |
2007年 | 35篇 |
2006年 | 34篇 |
2005年 | 34篇 |
2004年 | 33篇 |
2003年 | 40篇 |
2002年 | 51篇 |
2001年 | 27篇 |
2000年 | 26篇 |
1999年 | 75篇 |
1998年 | 33篇 |
1997年 | 37篇 |
1996年 | 39篇 |
1995年 | 23篇 |
1994年 | 21篇 |
1993年 | 17篇 |
1992年 | 16篇 |
1991年 | 33篇 |
1990年 | 24篇 |
1989年 | 24篇 |
1988年 | 18篇 |
1987年 | 8篇 |
1986年 | 3篇 |
1985年 | 2篇 |
排序方式: 共有1127条查询结果,搜索用时 359 毫秒
991.
The 40Ar-39Ar age method is employed in this work to analyze the aurif erous altered rocks from the middle-deep section of the Q875 gold-quartz vein in the Xiaoqinling area, and the results show that the main gold deposition of the Q875 occurred in ca. 128-126 Ma. As a typical gold-bearing quartz vein in this gold-rich area, the age data obtained from the Q875 also constrain on the metal logenic time of the lode gold deposits developed in the same geological settings . This geochronological study supplies new evidence for further understanding the timing of gold mineralization, the genesis of gold deposits and the geodynamic settings in Xiaoqinling area. 相似文献
992.
Fluid mineralization of the Dajing Sn-polymetal deposit: Evidence from LA-ICP-MS analysis of individual fluid inclusions 总被引:2,自引:0,他引:2
WANG Lijuan 《科学通报(英文版)》2006,51(22):2781-2788
LA-ICP-MS analyses on single fluid inclusions trapped in fluorite and quartz from the Sn-Cu orebody of the Dajing deposit and from the Sn ore-body of the Huanggangliang deposit were conducted to trace the source and evolution of Cu-rich and Sn-rich fluids in the Dajing deposit using the Rb/Sr and Sn/Cu ratios of the fluids. The results show that the Cu-rich fluids in the Dajing deposit, relatively rich in Na and probably derived from deep-seated basic magma, contain Cu several to several tens of times more than Sn, and Sr several to several tens of times more than Rb, while the Sn-rich fluids, relatively rich in K and probably derived from high level granitic magma, contain Sn several to several tens of times more than Cu, and Rb several to several tens of times more than Sr. It is suggested that the Sn-rich and the Cu-rich fluids were mixed at the stage of moderate to low temperature and low salinity, resulting in the formation of Cu-Sn orebodies at the central part of the Dajing deposit. 相似文献
993.
中国网纹红土研究进展 总被引:1,自引:0,他引:1
综述了近年来网纹红土研究的事实成果。结果表明:网纹红土的强酸、富铝化特征明显;其形成是百万年以来的事,发育盛期在中更新世;其形成过程是先红土化,再网纹化,成因有风成和水成的说法;关于对网纹化机制、红土化是否仍在进行、网纹红土对古气候事件的指示意义等问题仍存在争议。 相似文献
994.
马郧 《科技情报开发与经济》2004,14(5):68-69
随着金融形势的变化,隐性存款保险制度已不能适应当前国情,迫切需要建立规范的存款保险制度,以保障中小储户利益,维护金融安全与稳定。浅析了隐性存款保险制度存在的弊端,提出了建立我国存款保险制度的设想。 相似文献
995.
996.
化学镀Ni-P合金的工艺条件研究 总被引:1,自引:0,他引:1
采用单因素试验法和正交试验法研究了还原荆以及化学镀时间、温度、pH值对化学镀沉积速度的影响,得到了一种稳定性好、镀速快的化学镀Ni—P合金的工艺.其最佳工艺条件为:NiSO4·6H2O30g/L,NaH2PO2·H2O40g/L,柠檬酸钠10g/L,醋酸9mL/L,乳酸9mL/L,pH值6.0,施镀温度90℃,施镀时间1.5h.该工艺条件下,镀速可达11.14mg/(cm2·h),化学镀1.5h后镀层厚度可达23.6-24.0μm.镀层具有较强的耐蚀性,孔隙率分布较窄.镀层表面平整、光亮、分布均匀,有可视性很好的淡黄色的光泽,无麻点、裂纹、起泡、分层或结瘤等缺馅. 相似文献
997.
在Black-Scholes框架下,采用均值回复的Vasicek利率模型和偏微分方程的方法,用百慕大期权来近似,给出了定期存款的定价公式. 相似文献
998.
矿床的体视化仿真技术与实现 总被引:3,自引:2,他引:3
为解决矿床仿真构模中对矿床几何信息描述和属性信息描述中存在的模型分离问题,采用体视化技术,建立了体矿床模型.通过分析矿床体视化仿真中的数据流程,建立了表现矿体空间分布、矿体中重点区域、矿体剖切分层的三类体模型,并实现了直接基于体模型的矿石储量、金属量的计算工作.经实例分析表明,利用体矿床建模技术,不仅能够进行矿床属性的定性分析,而且便于进行定量计算,为完善矿床建模技术提供了一条途径. 相似文献
999.
SUN Xiaoming CHEN Wen WANG Min XUE Ting SUN Kai & CHEN Binghui . Department of Earth Sciences Sun Yat-sen University Guangzhou China . State Key Laboratory of Mineral Deposit Research Nanjing China . Institute of Geology Geophysics Chinese Academy of Sciences Beijing China . Institute of Geology Chinese Academy of Geological Sciences Bei-jing China 《科学通报(英文版)》2003,(17)
Ore-forming age is one of the most important data in studying the genesis of mineral deposits. Dating of sedi-ment-hosted disseminated-type gold deposits, which areone of the most important types of gold deposits in theworld, is always a difficult task for ore geologists. Themajor reason is that most of the ores in this type deposit are of various siliceous and are composed of extremely fine-grained minerals, thus it will be very difficult to de-termine their ages by using conventional isotopi… 相似文献
1000.
Mineralizing age of the Rushan lode gold deposit in the Jiaodong Peninsula:SHRIMP U-Pb dating on hydrothermal zircon 总被引:29,自引:0,他引:29
HU Fangfang FAN Hongrui YANG Jinhui WAN Yusheng LIU Dunyi ZHAI Mingguo & JIN Chengwei .Key Laboratory of Mineral Resources Institute of Geology Geo- physics Chinese Academy of Sciences Beijing China .Beijing SHRIMP Centre Institute of Geology Chinese Academy of Geological Sciences Beijing China Correspondence should be addressed to Fan Hongrui 《科学通报(英文版)》2004,49(15):1629-1636
Knowledge of the mineralizing timing is fundamen-tal to understand the genesis of mineral deposits, and ex-act time spectrum of mineralization is essential to com-prehending the relationship among the genesis of en-dogenic hydrothermal deposits, regional tectonic-magma-tism event and the geodynamics of mineral deposits. The Jiaodong or eastern Shandong gold province islocated in the southeastern margin of the North Chinacraton, and belongs to the Mesozoic circum-Pacific oro-genic gold system… 相似文献