全文获取类型
收费全文 | 1662篇 |
免费 | 364篇 |
国内免费 | 199篇 |
专业分类
测绘学 | 15篇 |
大气科学 | 102篇 |
地球物理 | 386篇 |
地质学 | 462篇 |
海洋学 | 1124篇 |
天文学 | 1篇 |
综合类 | 48篇 |
自然地理 | 87篇 |
出版年
2024年 | 8篇 |
2023年 | 31篇 |
2022年 | 56篇 |
2021年 | 55篇 |
2020年 | 59篇 |
2019年 | 68篇 |
2018年 | 67篇 |
2017年 | 177篇 |
2016年 | 84篇 |
2015年 | 92篇 |
2014年 | 159篇 |
2013年 | 93篇 |
2012年 | 71篇 |
2011年 | 119篇 |
2010年 | 110篇 |
2009年 | 112篇 |
2008年 | 116篇 |
2007年 | 101篇 |
2006年 | 71篇 |
2005年 | 49篇 |
2004年 | 42篇 |
2003年 | 52篇 |
2002年 | 96篇 |
2001年 | 33篇 |
2000年 | 35篇 |
1999年 | 44篇 |
1998年 | 46篇 |
1997年 | 20篇 |
1996年 | 26篇 |
1995年 | 19篇 |
1994年 | 10篇 |
1993年 | 28篇 |
1992年 | 8篇 |
1991年 | 19篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 2篇 |
1978年 | 1篇 |
排序方式: 共有2225条查询结果,搜索用时 0 毫秒
31.
正20141900Lan Xianhong(Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology,Ministry of Land and Resources,Qingdao 266071,China);Zhang Zhixun Geochemical Characteristics of Trace Elements of Sediments from Drillhole SFK-1 相似文献
32.
正20142093Chen Daohua(Guangzhou Marine Geological Survey,Guangzhou 510075,China);Diao Shaobo The Latest Progress of Geological Marine Testing Technology in China(Rock and Mineral Analysis,ISSN0254-5357,CN11-2131/TD,32(6),2013,p.850-859,105refs.)Key words:chemical analysis,China 相似文献
33.
Analysis on Marine Science and Technology Strategy and Key Layout of Japan and the Inspirations to China 总被引:1,自引:0,他引:1
The Basic Ocean Law (BOL) and Basic Ocean Plan (BLP) are important guarantee for the maritime strategy of Japan, which has established a complete policy system for the development of marine science and technology. On the other hand, the Japanese Government has started some major marine strategies and plans to promote the BLP. In this paper, the marine science and technology plans launched by the Japanese Government and its participation in the international cooperative research projects were introduced. The research of Japan Marine Science and Technology Center and the University of Tokyo Institute of Oceanography in the long-term planning and focus on the layout features, deep sea research technology layout, contents and advanced equipment were analyzed. At last, some recommendations for China’s development on marine science and technology were proposed, such as strengthening the legislation work and process, carrying out research and development of marine infrastructure with independent intellectual property rights, actively participating in international large-scale ocean plan, improving the discourse right and enhancing national maritime awareness and suggestions and so on. 相似文献
34.
《Marine Policy》2016
This paper uses spatial, temporal, and use-intensity data for 27 major marine uses in Washington waters to feature a method for assessing potential use conflicts in a variety of scenarios. The study represents a first step towards quantifying potential conflicts within Washington’s Marine Spatial Planning (MSP) study area by using a cumulative analysis to highlight high- and low-use intensity areas and the novel Marine Potential Conflict Index (MPCI), which incorporates space, time, and intensity of use, to quantify pairwise potential conflicts between uses. About 10% of pairs of uses do not overlap spatially and are likely compatible with one another. Temporally, the number of uses peaks in July and August and falls during January and February. Additionally, the MPCI identified three important use types with a substantial degree of potential conflict: commercial fishing, tribal fishing, and shipping. External data were used in three cases to ground-truth the analysis, as a limited test of its utility in managing any potential conflict. This article assesses the extent of Washington’s existing marine uses along spatial, temporal, and intensity axes, and more broadly provides a straightforward way to examine potential conflicts between marine uses. 相似文献
35.
以渤海湾沿海低地的QX02孔为研究对象,进行了沉积岩石学分析和底栖有孔虫统计,结合加速器质谱~(14)C测年和光释光(optically stimulated luminescence,OSL)测年,探讨了该孔记录的第Ⅱ海相层埋深和形成时代。第Ⅱ海相层厚度11.4m,记录相对海面高度-26.83~-15.43m。AMS~(14)C年龄表明,Ⅱ海形成于MIS 3早期、甚至更早。OSL年代学研究显示,Ⅱ海样品等效剂量离散度较高,并且主要集中在2个区间,计算得到新、老2个年龄阶段。基于OSL测年原理的常规判断,认为较老的83.5~62.6ka阶段系受曝光不充分组分的影响,通常采用较年轻的51.9~39.9ka阶段为QX02孔的Ⅱ海沉积年龄。但是,较老的一组年龄从新的视角,暗示了可能的原始沉积过程及相应的海侵发生时间,因而具有重要的年代学和沉积学意义。 相似文献
36.
《China Geology》2021,4(4):541-552
The intersection of the Kyushu-Palau Ridge (KPR) and the Central Basin Rift (CBR) of the West Philippine Basin (WPB) is a relic of a trench-trench-rift (TTR) type triple-junction, which preserves some pivotal information on the cessation of the seafloor spreading of the WPB, the emplacement and disintegration of the proto-Izu-Bonin-Mariana (IBM) Arc, and the transition from initial rifting to steady-state spreading of the Parece Vela Basin (PVB). However, the structural characteristics of this triple-junction have not been thoroughly understood. In this paper, using the newly acquired multi-beam bathymetric, gravity, and magnetic data obtained by the Qingdao Institute of Marine Geology, China Geological Survey, the authors depict the topographic, gravity, and magnetic characteristics of the triple-junction and adjacent region. Calculations including the upward continuations and total horizontal derivatives of gravity anomaly are also performed to highlight the major structural features and discontinuities. Based on these works, the morphological and structural features and their formation mechanisms are analyzed. The results show that the last episode amagmatic extension along the CBR led to the formation of a deep rift valley, which extends eastward and incised the KPR. The morphological and structural fabrics of the KPR near and to the south of the triple-junction are consistent with those of the western PVB, manifesting as a series of NNE-SSW- and N-S-trending ridges and troughs, which were produced by the extensional faults associated with the initial rifting of the PVB. The superposition of the above two reasons induced the prominent discontinuity of the KPR in deep and shallow crustal structures between 15°N–15°30′N and 13°30′N–14°N. Combined with previous authors’ results, we propose that the stress produced by the early spreading of the PVB transmitted westward and promoted the final stage amagmatic extension of the CBR. The eastward propagation of the CBR destroyed the KPR, of which the magmatism had decayed or ceased at that time. The destruction mechanism of the KPR associated with the rifting of the PVB varies along strike the KPR. Adjacent to the triple-junction, the KPR was destroyed mainly due to the oblique intersection of the PVB rifting center. Whereas south of the triple-junction, the KPR was destroyed by the E-W-directional extensional faulting on its whole width.©2021 China Geology Editorial Office. 相似文献
37.
38.
39.
AbstractTenure security is commonly recognized as an important factor in stimulating long-term investments in land. Recent studies suggest that a distinction between legal, actual and perceived tenure security needs to be made in analyzing tenure security. This study discusses the relationships between legal, actual and perceived land tenure security in rural China, and empirically examines the impact of actual on perceived land tenure security by applying Probit models to household and village survey data collected in four provinces. Using household expectations about the absence of land reallocations within the next five years as the dependent variable, we find that tenure security is positively affected by the possession of land certificates in villages that periodically reallocated land but not in villages that did not do so. The estimated impact is larger for land certificates issued in the new round of land certification than for land certificates that were issued earlier. 相似文献
40.
为完善我国海洋功能区划制度,提高海洋功能区划的编制和实施水平,促进其在我国海洋空间规划乃至国土空间规划中发挥应有作用,文章对我国现行海洋功能区划的实施情况进行回顾性评价,并对新一轮海洋功能区划的编制提出建议。研究结果表明:我国海洋功能区划法律地位高、管控范围广,现行海洋功能区划实施以来,通过建立定量目标管控体系、协调保障行业用海和保护海洋生态环境,对我国海洋经济和海洋生态环境的可持续发展做出巨大贡献;针对实施过程中存在的问题,新一轮海洋功能区划的编制应扩大海洋保护区的规模和种类、提高前瞻性和动态适应性、加强公众实质性参与以及完善技术体系。 相似文献