全文获取类型
收费全文 | 11126篇 |
免费 | 1955篇 |
国内免费 | 2718篇 |
专业分类
测绘学 | 565篇 |
大气科学 | 2253篇 |
地球物理 | 2225篇 |
地质学 | 5200篇 |
海洋学 | 2339篇 |
天文学 | 175篇 |
综合类 | 735篇 |
自然地理 | 2307篇 |
出版年
2024年 | 63篇 |
2023年 | 201篇 |
2022年 | 414篇 |
2021年 | 482篇 |
2020年 | 512篇 |
2019年 | 601篇 |
2018年 | 467篇 |
2017年 | 522篇 |
2016年 | 568篇 |
2015年 | 568篇 |
2014年 | 749篇 |
2013年 | 833篇 |
2012年 | 776篇 |
2011年 | 778篇 |
2010年 | 689篇 |
2009年 | 719篇 |
2008年 | 681篇 |
2007年 | 753篇 |
2006年 | 707篇 |
2005年 | 548篇 |
2004年 | 514篇 |
2003年 | 458篇 |
2002年 | 382篇 |
2001年 | 332篇 |
2000年 | 350篇 |
1999年 | 302篇 |
1998年 | 265篇 |
1997年 | 269篇 |
1996年 | 238篇 |
1995年 | 182篇 |
1994年 | 170篇 |
1993年 | 136篇 |
1992年 | 155篇 |
1991年 | 89篇 |
1990年 | 72篇 |
1989年 | 53篇 |
1988年 | 42篇 |
1987年 | 22篇 |
1986年 | 28篇 |
1985年 | 25篇 |
1984年 | 16篇 |
1983年 | 20篇 |
1982年 | 14篇 |
1981年 | 10篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 10篇 |
1977年 | 3篇 |
1972年 | 2篇 |
1954年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Susan Marriott 《地球表面变化过程与地形》1992,17(7):687-697
Samples of sediment collected from the Severn floodplain between Worcester and Gloucester following the severe flooding in January and February 1990, were analysed for their grain size distribution. The results show that most sand was deposited within 20 m of the channel bank, but that fine sand may contribute to flood sediment across the width of the floodplain. James' (1985) numerical model of overbank sedimentation attempts to predict the transfer of sediment to the floodplain during flooding. Geometrical and hydraulic data relating to the Severn flood are used as input for a computer program of James' (1985) model. The pattern of sediment concentrations predicted by the model was compared with that obtained from statistical analysis of the flood sediment. The patterns were found to be similar, so James' (1985) model was considered to predict in a relative sense the distribution of flood sediment. 相似文献
972.
运用多项式回归分析和双随机样本检验,模拟日照时数和总辐射及其影响因子(可照时间、总云量和天文辐射、日照百分率)年值和1月值、7月值的三度空间分布场,取得了满意结果。这可应用在无测站地区,仅凭经纬度和海拔估算出上述气候要素值,估算的平均相对误差大多在5%以下(最好的达0.3‰)。 相似文献
973.
974.
Considerations on the global seismic sequences: the second and the third largest aftershocks 总被引:1,自引:0,他引:1
Theodoros M. Tsapanos 《Geophysical Journal International》1992,111(3):630-636
976.
Chih-Hsiang Ho 《Mathematical Geology》1992,24(4):347-364
In this article, we model the volcanism near the proposed nuclear waste repository at Yucca Mountain, Nevada, U.S.A. by estimating the instantaneous recurrence rate using a nonhomogeneous Poisson process with Weibull intensity and by using a homogeneous Poisson process to predict future eruptions. We then quantify the probability that any single eruption is disruptive in terms of a (prior) probability distribution, since not every eruption would result in disruption of the repository. Bayesian analysis is performed to evaluate the volcanic risk. Based on the Quaternary data, a 90% confidence interval for the instantaneous recurrence rate near the Yucca Mountain site is (1.85×10–6/yr, 1.26×10–5/yr). Also, using-these confidence bounds, the corresponding 90% confidence interval for the risk (probability of at least one disruptive eruption) for an isolation time of 104 years is (1.0×10–3, 6.7×10–3), if it is assumed that the intensity remains constant during the projected time frame. 相似文献
977.
Analysis of the distribution of ore-bodies in space can be useful generally in the estimation of mineral resources or the management of exploration. This study is directed to analysis of the undiscovered potential of well known areas of mining district size, referred to as metallogenic units (MUs). The analysis employs an effort-adjusted and truncated probability model for number of occurrences within a subdivision (quadrat) of a MU and Monte Carlo sampling to generate an approximation to the probability distribution for number of occurrences and number of mines within an MU when it is totally explored. Exploration potential for Monitor, Bodie, Aurora, and Camp Douglas MUs (Walker Lake quadrangle of Nevada and California) are estimated to be 9, 4, 7, and 4 mines, respectively. 相似文献
978.
查册桥矿区位于江南过渡带,包括牛头高家金矿床、程檀金矿床、路源金矿点和东边金矿化点、杨梅尖金矿点.其中牛头高家金矿是安徽省首次发现的具一定规模的红土型金矿.研究区主体位于东至断裂与高坦断裂带交汇处及其两侧,三岗尖-杨美桥背斜核部及北翼.区内存在多个重要的赋矿层位,主要包括南华系休宁组、南沱组,震旦系蓝田组,寒武系黄柏岭组、杨柳岗组,奥陶系仑山组、东至组.高坦断裂带、兰程畈断裂带、奥陶系/志留系间的推覆-滑覆断层界面均是重要的控岩控矿构造,区内岩浆岩主要受其控制,物化探异常也主要沿其分布.通过对矿床地质特征总结,并结合前人研究成果,对找矿潜力进行分析,认为区内具有寻找低温热液型-叠改型、层控夕卡岩型、岩浆热液脉型金、铜、钨、钼、银、铅锌等矿化的潜力. 相似文献
979.
980.