全文获取类型
收费全文 | 123篇 |
免费 | 26篇 |
国内免费 | 16篇 |
专业分类
测绘学 | 9篇 |
大气科学 | 24篇 |
地球物理 | 52篇 |
地质学 | 46篇 |
海洋学 | 14篇 |
天文学 | 1篇 |
综合类 | 6篇 |
自然地理 | 13篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 2篇 |
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 8篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 11篇 |
2012年 | 5篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 10篇 |
2008年 | 6篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 4篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有165条查询结果,搜索用时 375 毫秒
151.
为了解决数据挖掘算法的高效性、工具智能性与所获取知识无效性之间的矛盾,同时使所获取知识能有效地解决地层评价领域中的各种疑难问题,提出任务驱动数据挖掘方法。结合数据挖掘的概念和技术,阐述了任务驱动数据挖掘的概念和基本原理,分为建立数据仓库、数据预处理、选择特征子集、形成模型、模型评估、模型修正和模型发布等7个部分,是一个循环迭代的过程,直到构建能有效解决目标任务的预测模型为止。并以低阻油层的识别为例,详述整个分析处理过程,结合决策树形成的白盒模型和支持向量机构建的黑盒模型综合识别目标区的低阻油层,获得了准确率大于90%的识别效果。 相似文献
152.
通过讨论已有的60年来大气中CO2浓度数据的分布状态,采用趋势分析方法,给出了具体趋势方程形式.与冰芯分析或观测数据对比结果表明,趋势方程曲线与已有数据基本符合,随后初步给出了2010年至2016年间大气中CO2浓度预测值. 相似文献
153.
154.
Power Maximization of A Point Absorber Wave Energy Converter Using Improved Model Predictive Control 总被引:1,自引:0,他引:1
This paper considers controlling and maximizing the absorbed power of wave energy converters for irregular waves. With respect to physical constraints of the system, a model predictive control is applied. Irregular waves’ behavior is predicted by Kalman filter method. Owing to the great influence of controller parameters on the absorbed power, these parameters are optimized by imperialist competitive algorithm. The results illustrate the method’s efficiency in maximizing the extracted power in the presence of unknown excitation force which should be predicted by Kalman filter. 相似文献
155.
在分析1951-2001年潼关、花园口、兰州水文站年最大流量的变化规律基础上,提出了一个建立多步预测模型的新方案,该预测模型具有可以直接作多步预测和对异常极值有较好预测技巧等特点。将该预测模型用于1995-2001年多步独立样本的预测试验,取得了较好的预测效果,利用这一预测模型对未来直至2005年的年最大流量变化趋势进行了预测。 相似文献
156.
Abstract. Facilitating more predictive ore discovery is becoming an increasingly challenging task for the resources geology research and exploration industry. The numerical geodynamic modeling, which uses numerical code to reproduce feedback coupling of geodynamic processes in the computer, is one of endeavors for forming sound predictive exploration strategy by thoroughly understanding the mineralization system and its controlling factors. The FLAC (Fast Lagrangian Analysis of Continua) is a two-dimensional finite-difference code for studying the mechano-thermo-hydrological behavior of a continuous porous medium after it reached equilibrium or steady plastic flow. We used the FLAC to simulate the syn-deformation cooling and fluid flowing after the intrusion was emplaced and solidified in the Fenghuangshan ore field, Tongling Cu district for guiding analysis of ore-controlling factors and selection of the exploration target area. The results of numerical computation demonstrate that the dilatant deformation zones along the contact of the intrusion control the fluid focus and the location and scale of ore bodies. Further more, the simulation results suggest a most prospective exploration area in the south high dilation zone, where the subsequent exploration supported the prediction and the test bore hole disclosed the high quality copper ore bodies in the target. This example has demonstrated the positive role of the numerical geodynamic modeling in facilitating predictive ore discovery. 相似文献
157.
This study presents a river invertebrate and classification system (RIVPACS) type bioassessment methodology for the Manawatu‐Wanganui region of New Zealand. Aquatic macroinvertebrates and related physico‐chemical data were collected at 127 sites, with minimal human impacts (reference sites) in 2000. The reference sites were classified into five groups based on their macroinvertebrate data using TWINSPAN. These biotic groupings were then applied to their corresponding physico‐chemical data and discriminant functions were obtained to assign sites into the biotic groups using the physico‐chemical data. The discriminant functions correctly allocated 72% of the sites to the correct classification group using a jack‐knife validation. The probabilities from the discriminant functions were used to predict macroinvertebrate assemblages and these were compared with observed macroinvertebrate assemblages. The model was then used to assess the health of 29 test sites with known impacts. All test sites were assessed as impacted based on the 10th percentile of the reference data. To evaluate the temporal reliability of the model, data available for 11 sites sampled in 1997 and 2000 were run through the model. The results of this comparison showed little variation in O/E ratios over time and the two sites classed as impacted in 1997 were also classed as impacted in 2000. 相似文献
158.
159.
以卫星遥感技术为主要手段,结合适量野外调查验证,综合分析了腾冲芒棒盆地聚煤作用及聚煤期后构造对煤层的改造作用,最终在盆地内圈定了两个遥感含煤远景区即橄榄寨——大崩嘎含煤远景区和弄岗——团田含煤远景区,为该区今后进一步煤炭资源勘探工作提供了靶区和基础资料。 相似文献
160.
在隐伏矿体三维预测中,预测模型的准确性在很大程度上取决于找矿指标对矿化富集部位的指示性。然而,找矿指标容易受到找矿概念模型可靠性和成矿信息提取有效性限制,从而影响预测的准确性。论文以山东大尹格庄金矿隐伏矿体三维预测为例,基于深度学习方法,构建矿床深部隐伏矿体三维预测模型,旨在利用深度网络模型,学习获得对矿化具有显著指示性的找矿指标,提升三维预测的准确性。该方法将三维地质模型及其形态特征转换为适合卷积网络二维图像,采用卷积神经网络实现找矿指标的自动提取,并构建三维地质模型到矿化富集地段的定量关联。利用该方法建立了大尹格庄金矿的三维预测模型,经与几种人工建立找矿指标预测模型的对比分析,表明基于深度学习的预测模型较大地提升了预测准确性。 相似文献