全文获取类型
| 收费全文 | 89篇 |
| 免费 | 2篇 |
专业分类
| 测绘学 | 19篇 |
| 大气科学 | 1篇 |
| 地球物理 | 31篇 |
| 地质学 | 23篇 |
| 海洋学 | 13篇 |
| 天文学 | 3篇 |
| 自然地理 | 1篇 |
出版年
| 2022年 | 1篇 |
| 2018年 | 1篇 |
| 2017年 | 2篇 |
| 2016年 | 1篇 |
| 2012年 | 3篇 |
| 2011年 | 3篇 |
| 2009年 | 2篇 |
| 2008年 | 4篇 |
| 2007年 | 4篇 |
| 2006年 | 2篇 |
| 2005年 | 9篇 |
| 2004年 | 1篇 |
| 2003年 | 7篇 |
| 2002年 | 6篇 |
| 2000年 | 6篇 |
| 1999年 | 3篇 |
| 1998年 | 1篇 |
| 1997年 | 2篇 |
| 1996年 | 2篇 |
| 1995年 | 2篇 |
| 1994年 | 2篇 |
| 1993年 | 3篇 |
| 1992年 | 6篇 |
| 1991年 | 10篇 |
| 1990年 | 5篇 |
| 1989年 | 2篇 |
| 1978年 | 1篇 |
排序方式： 共有91条查询结果，搜索用时 15 毫秒
11.
12.
We report the direct observation of motion associated with a solar flare at a speed of 26,000 km s-1. The motion is seen from a radio source at 0.33 GHz, which suddenly starts moving during the flare. At its peak, the radio source covers a quiet region of dimension 500&arcsec;. Emission from any given location is sporadic. The disturbance itself does not seem to radiate, but it excites coronal features that continue to radiate after it passes. The inferred velocity is larger than any previously inferred velocity of a disturbance in the solar atmosphere apart from freely streaming beams of accelerated electrons. The observed motion of the source at a fixed frequency, low polarization, and moderate bandwidth are more consistent with the typical properties of moving type IV radio bursts than with classical coronal shock-associated type II bursts, but any disturbance at such a high velocity must be highly supersonic and should drive a shock. We speculate that the disturbance is associated with the realignment of magnetic fields connecting different portions of an active region. 相似文献
13.
Adams SM 《Marine pollution bulletin》2005,51(8-12):649-657
An operational framework is developed to serve as a guideline for investigating causal relationships between environmental stressors and effects on marine biota. Because of the complexity and variability of many marine systems, multiple lines of evidence are needed to understand relationships between stressors and effects on marine resources. Within this framework, a weight of evidence approach based on multiple lines of evidence are developed and applied in a sequential manner by (1) characterizing the study system which involves determining if target biota are impaired, assessment of food and habitat availability, and measuring contaminant levels in the environment, (2) assessing direct effects of contaminant exposure on target biota using biomarkers and assessing indirect effects of exposure using suites of bioindicators, and (3) applying standard causal criteria based on epidemiological principles and diagnostic health profiling techniques to assess potential causes. Use of multiple lines of evidence should also reduce the risk of false positives (Type I error or falsely concluding that there is a causal relationship when there is none) and false negatives (Type II error or falsely concluding there is not a causal relationship when there actually is). Understanding causal relationships and the mechanistic processes between environmental stressors and effects on biota is important in the effective management and restoration of impaired marine ecosystems. 相似文献
14.
15.
16.
18.
南印度克拉通(Godvari-Narmada裂系的南部和西南部)是由年龄为3400Ma～600Ma的岩石组成。这些岩石构成(1)太古代Karnataka和Jeypore-Bestar陆核(2600Ma);(2)早元古活动带(2300～2000Ma);(3)中元古活动带(2000～1500Ma);(4)元古代沉积盆地(1700～700Ma);和(5)Kerala和邻近地区的晚元古高级麻粒岩地体。两个陆核的太古代岩石,特别是Karnataka陆核,发育了1000Ma时期的岩石,并显示了较大的成分差异。这些陆核是由多期片岩带的片麻岩和花岗岩组成。现在发现几个 相似文献
19.
20.
无人机摄影测量在水体污染评估中的应用 总被引：1，自引：0，他引：1
无人机摄影测量是一种快捷、准确的测量技术,在测绘与空间信息行业得到越来越广泛的应用。本文针对水库库区的水体污染现状,探讨利用小型无人机进行摄影测量,并采用多视图几何理论与光束平差方法,以及空三解算模型进行影像处理,从而测量评估水体中的特定污染物分布情况,并以广东省梅州市青溪库区水浮莲污染调查为例进行污染分布的研究,为水库治理提供依据。 相似文献