全文获取类型
| 收费全文 | 150篇 |
| 免费 | 31篇 |
| 国内免费 | 27篇 |
专业分类
| 测绘学 | 12篇 |
| 大气科学 | 56篇 |
| 地球物理 | 53篇 |
| 地质学 | 64篇 |
| 海洋学 | 13篇 |
| 天文学 | 1篇 |
| 综合类 | 2篇 |
| 自然地理 | 7篇 |
出版年
| 2024年 | 1篇 |
| 2021年 | 4篇 |
| 2020年 | 4篇 |
| 2019年 | 6篇 |
| 2018年 | 6篇 |
| 2017年 | 3篇 |
| 2016年 | 3篇 |
| 2015年 | 2篇 |
| 2014年 | 10篇 |
| 2013年 | 4篇 |
| 2012年 | 11篇 |
| 2011年 | 19篇 |
| 2010年 | 8篇 |
| 2009年 | 14篇 |
| 2008年 | 4篇 |
| 2007年 | 14篇 |
| 2006年 | 9篇 |
| 2005年 | 11篇 |
| 2004年 | 7篇 |
| 2003年 | 9篇 |
| 2002年 | 5篇 |
| 2001年 | 10篇 |
| 2000年 | 3篇 |
| 1999年 | 3篇 |
| 1998年 | 5篇 |
| 1997年 | 8篇 |
| 1996年 | 4篇 |
| 1995年 | 6篇 |
| 1994年 | 7篇 |
| 1993年 | 3篇 |
| 1992年 | 2篇 |
| 1991年 | 1篇 |
| 1983年 | 1篇 |
| 1980年 | 1篇 |
排序方式： 共有208条查询结果，搜索用时 171 毫秒
21.
磁暴是源自太阳磁场剧烈变化的地球空间效应,随着电网规模的增大和电压等级的增高,磁暴灾害已经成为诱发电网故障风险的威胁之一.研究电力系统磁暴灾害风险的影响因素可为预防与控制其引发的电网事故提供重要参考.在分析历史典型磁暴事件的基础上,剖析了磁暴诱发电力系统故障的机理,阐述了故障传播与电力系统响应的过程,总结了近年来关于影响电力系统的地磁感应电流水平及其产生的变压器无功损耗方面的研究成果,从磁暴本身的特点和电力系统的参数与结构两方面将影响因素分类.以GIC标准模型,通过改变磁暴扰动环境和电力系统参数,说明了各因素对电网磁暴灾害风险的影响程度,并比较了不同因素影响后果的差异,最后指出了尚未解决的问题和可能的研究方向. 相似文献
22.
Based on the large scale land and resources survey project--groundwater contamination survey in southeast China, a certain polluted river and its typical sites along its bank were selected as research objectives. Such river is a comprehensive sewage channel for certain provincial capital city, with complicated types of pollutants. Based on the analysis on water level of horizonal and vertical hydrogeologic profile and water quality monitoring data, the impact and range of the polluted river on local groundwater were evaluated. Data show that the polluted river supplies water to underground aquifers throughout the year, which has great impact on groundwater horizontally, but different ions have different responses. Major influential indexes such as inorganic component 3-nitrogen, sulphate, chloride etc. present an obvious relevance, while iron, manganese, fluoride, arsenic and heavy metal and so on are less impacted. The first four indexes in groundwater are less impacted by the surface sewage because of their protogenesis, and heavy metal components become less due to sediment filtration. Data also show that deep groundwater is less influenced, on the contrary, ammonia nitrogen ion is obviously impacted. On the basis of influence degree as well as range of evaluation, some factors that caused the existing influence were discussed and proposes feasible study direction. 相似文献
23.
The fundamental researches about thermal physical properties of rocks have much concern in oil and gas field. They go through four stages and are applied in thermal structure of lithosphere, thermal evolution of sedimentary basins, geotechnical engineering and geothermal area. This article summarized the current research progress on the basis of thermal physical properties of rocks and proposed the development of tendency for the future. Moreover, some cylindrical heat pipe, disc heat pipe, spherical heat pipe based on in-situ measurement method and prediction model based on mathematical statistics have been developed. The scholars discuss the internal relation between thermal conductivity parameter of rocks and other physical properties by a large number of experiments. The researches show that the thermal conductivity of rocks is affected by many factors, and the petrologic characteristic is the most important factor. The porosity of rocks, filled fluid properties, acoustic characteristics are also related to thermal conductivity, which is affected by temperature, pressure and anisotropy. In consideration of the study of thermal physical properties of rocks, we proposed the following tendency for the future. First of all, shale gas is regarded as a hot spot in oil-gas exploration and the formation mechanism and the formation of shale gas reservoir are under the control of thermal physical properties of shale gas, but the relationship among thermal conductivity and organic porous, organic carbon content, gas content, fractured characteristics remains unknown. Therefore, exploring the thermal physical properties of gas-bearing shale is an important research direction in oil and gas field. Secondly, the study of big data represents the general trend. Though the database of rocks thermal parameter is continually expanding, measuring in-situ thermal conductivity continuously in well is the best method to get the accurate in-situ thermal conductivity of rocks. Hence, the development of logging method principle and logging instruments based on thermal physical properties of rocks is a necessary trend for the future. 相似文献
24.
在大型工程的岩土工程勘察中,如何确定岩石地基的承载力,直接影响到建筑的质量、造价和进度。载荷试验作为模拟建筑物基础受力条件的试验,科学、直观地提供了地基的承载力和变形模量,给设计部门提供了不可或缺的设计依据。然而,岩基载荷试验结果受基岩埋深及孔径的影响尚不清楚。利用ABAQUS有限元分析软件,对深层岩基载荷试验影响因素进行数值模拟分析,得出的结论可为今后岩土工程勘察提供借鉴。 相似文献
25.
多维决策就是在具有相互冲突、相互影响的多个因素下对评价目标进行的决策,把它应用到圈闭评价时,就是把影响圈闭评价的各个因素看成一个整体,这些影响因素共同反映圈闭的优劣,将多个因素系统合成为一个能从总体上度量圈闭优劣的单因子来进行评价优选。在使用多维决策对研究区进行实际的圈闭评价时,通过多维目标函数,求解各圈闭与所假设的最优和最劣圈闭之间的距离,最后得到综合评价因子序列,此时选出距最优圈闭较近而距最劣圈闭较远的圈闭可作为优先勘探的对象。对四川盆地某区进行了圈闭评价实践,并与地质风险概率法作了对比,证明多维决策圈闭评价方法是有效的。此方法具有简单、实用、易操作、分辨率高等优点,人为因素的干预比较少,预测结果更为客观。 相似文献
26.
结合深圳地铁2号线盾构过富水砂层施工实际,考虑流-固藕合水土本构关系,用FLAC3D软件建立了盾构施工数值分析模型。计算结果与工程实测数据对比验证了数值模型的合理性。进一步研究了盾构过富水砂层对地表不同位置建筑的影响:建筑物基础在隧道正上方时产生沉降最大且较均匀,水平位移最小;盾构机开挖下穿时建筑物差异沉降最大,建筑物倾向盾构开挖方向;建筑物基础横向上离隧道中心一倍隧道埋深时,建筑物水平移动最大,易受剪切破坏,倾向垂直盾构开挖方向,周边地表沉降差最大;建筑物离隧道中心横向距离超过两倍隧道埋深时,盾构开挖对建筑物基础沉降的影响较小,建筑物沉降与其周边地表沉降较均匀。 相似文献
27.
28.
多方面原因影响煤样视相对密度项目检测。对多个样品检测数据的汇总和对比,深入讨论样品制备阶段对视相对密度检测结果的影响因素。 相似文献
29.
本文介绍了区内主要岩溶含水层分布规律、富水性等情况,并分别从岩性、地貌、构造、埋深、地下水活动及古水文网发育状况等方面,分析了其对岩溶发育的影响。 相似文献
30.