全文获取类型
收费全文 | 303篇 |
免费 | 53篇 |
国内免费 | 56篇 |
专业分类
测绘学 | 17篇 |
大气科学 | 10篇 |
地球物理 | 45篇 |
地质学 | 235篇 |
海洋学 | 30篇 |
天文学 | 4篇 |
综合类 | 33篇 |
自然地理 | 38篇 |
出版年
2023年 | 1篇 |
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 12篇 |
2018年 | 7篇 |
2017年 | 12篇 |
2016年 | 18篇 |
2015年 | 12篇 |
2014年 | 22篇 |
2013年 | 19篇 |
2012年 | 18篇 |
2011年 | 13篇 |
2010年 | 11篇 |
2009年 | 22篇 |
2008年 | 22篇 |
2007年 | 19篇 |
2006年 | 15篇 |
2005年 | 13篇 |
2004年 | 19篇 |
2003年 | 12篇 |
2002年 | 15篇 |
2001年 | 22篇 |
2000年 | 12篇 |
1999年 | 16篇 |
1998年 | 10篇 |
1997年 | 2篇 |
1996年 | 12篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1991年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有412条查询结果,搜索用时 31 毫秒
361.
TTS系统中基于双音素的基元选择方法 总被引:1,自引:0,他引:1
为寻示能较好解决音节内和音节间的协同发音单元方案,提出了采用类似英文语转换系统中使用的双音素作为合成单元方案,并根据普通话音中只包含410个音节特点,进一步完善了双音素在汉语中的应用。试验结果表明,该方案包含了连续语流中的所有过渡音征,使合成语音转接流畅、自然。 相似文献
362.
Benzene polycarboxylic acids formed upon oxidative degradation of the macromolecular network of a set of French coals with ruthenium tetroxide are proposed as the basis of new coal rank indices. Their distribution probably reflects the degree of condensation of the polyaromatic subunits occurring in the network of the coals. This feature is illustrated in the case of the benzene tetracarboxylic acids. Application of these molecular indices to Gondwana coals, as well as to maceral concentrates indicates that they are also type related. They could prove particularly useful in the case of coals or kerogens having undergone secondary alteration processes. 相似文献
363.
364.
对1918年南澳地震的记录史料及有关文章进行了比较研究,并根据现场地震地质考察中发现的山体滑塌和地表破坏现象及其它宏观资料,重新圈定了这次地震的X度极震区,其形状为一北西向的长椭圆形,其内的北西向断裂带,应是该次地震的发震断裂。 相似文献
365.
Tectonostratigraphy deals with distinguishing megasequences and their interpretation in terms of tectonic settings. It is closely related to sequence stratigraphy and regional tectonics. Tectonosratigraphic units are distinctly displayed on seismic profiles. Examination of megasequences is a reliable tool for regional-scale research. We discuss, using several specific examples, the process of identifying tectonostratigraphic units in various types of sedimentary basins, as well as their relations to chronostratigraphic units. 相似文献
366.
A REVIEW OF THE PALEO-HYDROLOGICAL AND GEOMORPHOLOGICAL CHARACTER OF LAKE NAM CO,SOUTH-CENTRAL TIBET 下载免费PDF全文
The endorheic Lake Nam Co,south Eastern Tibetan Plateau,was selected to investigate the interrelation between drainage basin processes,especially post-glacial glacier decay,and lake level fluctuations.Landforms of the drainage basin are highly influenced by tectonics,superimposed by fluvial and periglacial processes,and locally by glacial and eolian processes.Thus,geomorphological features and hydrological characteristics were compiled for the lake-basin to provide an overview of the landscape character.Data show that during the Last Glacial Maximum melt water from the mountains accumulated fluvial deposits in the foreland.Concurrently,an increase of the lake level occurred which is presently shown by a cliff line all around Nam Co with its base approximately 29m above the present lake level.The Holocene decrease of the lake level is traced by beach ridges.As Nam Co is an endorheic lake post-glacial water loss has to be primarily explained by evaporation and moisture conditions.However,more detailed conclusions on quantitative and chronological patterns of both factors,melt-water input and evaporation output,still remain to be drawn. 相似文献
367.
滇西地区壳体大地构造单元的划分及其演化与运动特征 总被引:7,自引:3,他引:4
以壳体大地构造理论为基础,根据滇西三江地区的基本地质事实,对前人的观点进行重新认识和修正,首次提出了该区迄今最全面、最系统的壳体大地构造单元划分方案,将其细分为4个壳段,11个次级单元和3个挤压聚合带,从新的角度揭示了该区区域地质构造的时空演化规律,为区域成矿规律提供了重要的科学依据。 相似文献
368.
《China Geology》2019,2(4):439-457
With Songliao Basin in northeast China entering the middle-late stage of the exploration and development of oil and gas resources, it is urgent to open up new areas for oil and gas exploration on the periphery of the basin. Five sedimentary sags have been discovered in the western margin of the Da Hinggan Mountains through high-precision gravity, magnetic, and electrical prospecting engineering. According to the conditions of the 5 sags such as buried depth, area, and the scale of source rock, Hesigewula Sag was preferentially selected to deploy two-dimensional seismic prospecting and drilling. As a result, the stratigraphic distribution and structure of Hesigewula Sag were preliminarily ascertained, the main sedimentary facies developed in Aershan Formation-Tengger Formation of the Lower Cretaceous was summarized, and the assessment parameters of source rock of Hesigewula Sag were obtained. According to the research results, the Hesigewula Sag can be divided into 3 second-order tectonic units including the western bulge, the central sag, and the eastern bulge respectively, and the sag was formed mainly subject to the west fractures. Three sedimentary facies including fan delta facies, braided river delta facies, and lacustrine facies have been identified in the Aershan Formation-Tengger Formation of the sag. The source rock in the first member and second member of Tengger Formation in the sag features high abundance of organic matter, meeting the standards of good source rocks. The kerogen of the source rock is mainly of type II1 – II2. The organic matter in the source rock is characterized by low maturity and it entered the evolution stage of low maturity from the second member of Tengger Formation. Furthermore, Hesigewula Sag bears a strong similarity to other petroliferous sags in Erlian Basin in structure, sedimentation, source rock, and other characteristics. Therefore, it can be preliminarily determined that Hesigewula Sag boasts great potential for oil and gas resources. 相似文献
369.
李军辉 《吉林大学学报(地球科学版)》2012,42(4):961-969
分析在不同构造背景下发育的层序构成样式,可以更加精确地预测有利勘探区带和油气藏。利用地震、钻井、测井、岩心以及古生物等资料,依据层序界面特征,将呼和湖凹陷下白垩统划分为3个二级层序、5个三级层序。依据构造背景,将研究区划分出断控陡坡带、缓坡断阶带、洼槽带等3种构造单元,在此基础上分不同构造单元建立了相应的层序构成样式:断控陡坡型层序构成样式、缓坡断阶型层序构成样式、洼槽型层序构成样式。研究结果表明,不同的构造单元具有各自特征的层序构成样式和沉积体系域构成模式,不同类型层序构成样式也决定了不同的构造单元具有不同的油气成藏模式。在断控陡坡带主要发育断层-岩性和断鼻型油气藏,在缓坡断阶带发育断层-岩性和地层超覆型油气藏,在洼槽带主要发育自生自储型的透镜体油气藏;此外,洼槽边缘可发育断层-岩性型油气藏。 相似文献
370.
应用应力调制图像法,对上海地区1970~2007年以来的18次ML≥5.0地震进行了检验。结果显示,有15次地震的震前出现了Se值异常单元,虚报地震9次,漏报3次。 相似文献