全文获取类型
收费全文 | 20735篇 |
免费 | 4191篇 |
国内免费 | 2604篇 |
专业分类
测绘学 | 775篇 |
大气科学 | 2140篇 |
地球物理 | 12741篇 |
地质学 | 5402篇 |
海洋学 | 2247篇 |
天文学 | 134篇 |
综合类 | 1536篇 |
自然地理 | 2555篇 |
出版年
2024年 | 66篇 |
2023年 | 245篇 |
2022年 | 570篇 |
2021年 | 804篇 |
2020年 | 759篇 |
2019年 | 919篇 |
2018年 | 774篇 |
2017年 | 837篇 |
2016年 | 709篇 |
2015年 | 914篇 |
2014年 | 1185篇 |
2013年 | 1248篇 |
2012年 | 1191篇 |
2011年 | 1241篇 |
2010年 | 1136篇 |
2009年 | 1403篇 |
2008年 | 1156篇 |
2007年 | 1301篇 |
2006年 | 1213篇 |
2005年 | 1153篇 |
2004年 | 1022篇 |
2003年 | 995篇 |
2002年 | 802篇 |
2001年 | 721篇 |
2000年 | 724篇 |
1999年 | 623篇 |
1998年 | 573篇 |
1997年 | 557篇 |
1996年 | 532篇 |
1995年 | 460篇 |
1994年 | 417篇 |
1993年 | 323篇 |
1992年 | 296篇 |
1991年 | 162篇 |
1990年 | 129篇 |
1989年 | 91篇 |
1988年 | 74篇 |
1987年 | 34篇 |
1986年 | 41篇 |
1985年 | 29篇 |
1984年 | 19篇 |
1983年 | 22篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 3篇 |
1979年 | 16篇 |
1978年 | 9篇 |
1977年 | 4篇 |
1972年 | 2篇 |
1954年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
21.
YANGYong-liang SHITong-guang JLANGLU-guang LIYue 《中国地理科学(英文版)》2003,13(2):130-133
In recent years, many coal-producing countries have paid great attention to the land subsidence causedby coal cutting. In China, because of the dense population in coalfield areas, the land subsidence hazard is more seri-ous. After a brief analysis on the mechanism of land subsidence, this paper gives a comprehensive and systematical ac-count on all kinds of hazards caused by the land subsidence in China. The study shows that land subsidence has endan-gered land, buildings, traffic and communication lines, dykes and dams. It also causes damage to ecological and socialenvironment. In order to lessen the hazard of land subsidence, preventive measures should be taken to reduce the col-lapse amount, such as extraction with stowing, banded mining system, succession and coordination mining system, orhigh-pressure mudflow between rock strata. Measures of reinforcing or moving certain buildings should also be taken toreduce the destructive degree. In order to harness the subsidence land and bring them under control for fanning, mea-sures should be taken such as filling with spoil or fine breeze, excavating the deeper and covering the shallower land. 相似文献
22.
形变大地测量学的进展、问题与地震预报 总被引:12,自引:7,他引:5
简要概括了形变大地测量学的革命性进展,研讨了它的科学特色、功能和定义以及对地球科学和防灾减灾的推动。形变大地测量学有助于从根本上击破多年来制约地震预报的“瓶颈”,但也存在不少急待解决的问题。着重研讨了在21世纪前10年,形变大地测量学如何依托多年的学科积累并充分受益于人造卫星和数字化等新技术,开展创新性研究和试验以推进地震预报。为此,对当前的研究工作提出了12条科学技术途径。最后对学科名称提出了建议。 相似文献
23.
模糊划分矩阵在岩土参数概率分布中的应用 总被引:1,自引:0,他引:1
讨论如何在小样本条件下用已有的过程经验与试验资料确定岩土参数概率分布,用模糊划分矩阵与BAYES方法相结合,给出由小样本试验数据确定岩土参数的概率分布。 相似文献
24.
In recent years,scholars at home and abroad have method,and that vanous disasters would be analyzed assynthetically studied natural dlsaste‘theoretically and an Integral.SHI Peilun(1991)putforwad a scientificmethodologlcally,as well as its cases analys。s(CND,term—regional disaster system,which Indicates that1987; MA et al,1990; MARBLE,1990; NE et al,the situation of a disaster(calamity loss)results from1999; PATAK et al,1982; SHI,1991;VAN et al,h… 相似文献
25.
Kenai, located on the west coast of the Kenai Peninsula, Alaska, subsided during the great earthquake of AD 1964. Regional land subsidence is recorded within the estuarine stratigraphy as peat overlain by tidal silt and clay. Reconstructions using quantitative diatom transfer functions estimate co‐seismic subsidence (relative sea‐level rise) between 0.28±0.28 m and 0.70±0.28 m followed by rapid post‐seismic recovery. Stratigraphy records an earlier co‐seismic event as a second peat‐silt couplet, dated to ~1500–1400 cal. yr BP with 1.14±0.28 m subsidence. Two decimetre‐scale relative sea‐level rises are more likely the result of glacio‐isostatic responses to late Holocene and Little Ice Age glacier expansions rather than to co‐seismic subsidence during great earthquakes. Comparison with other sites around Cook Inlet, at Girdwood and Ocean View, helps in constructing regional patterns of land‐level change associated with three great earthquakes, AD 1964, ~950–850 cal. yr BP and ~1500–1400 cal. yr BP. Each earthquake has a different spatial pattern of co‐seismic subsidence which indicates that assessment of seismic hazard in southern Alaska requires an understanding of multiple great earthquakes, not only the most recent. All three earthquakes show a pre‐seismic phase of gradual land subsidence that marked the end of relative land uplift caused by inter‐seismic strain accumulation. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
26.
Current plate motions 总被引:57,自引:0,他引:57
27.
This paper considers the problem of estimatingm, the number of components in a finite mixture of distributions from a parametric family. A step-up procedure using the bootstrap method is proposed. Some properties of the procedure are illustrated with simulation studies. An example of the method, applied to orientation of beach clasts, is given. 相似文献
28.
We report on a year's study of spatial and seasonal patterns of zooplankton abundance in Port Phillip and Westernport Bays, July 1982 to August 1983. These two bays, closely adjacent on the southern coast of Victoria, Australia, differ in several respects: Port Phillip is a nearly landlocked bay with a broad basin, while Westernport is an open tidal embayment with extensive mud and seagrass banks. Both bays have a resident zooplankton fauna distinct from that of Bass Strait. Although these resident communities have many species in common, patterns of abundance and dominance are quite different. We found that the holoplankton of Port Phillip was about half copepods, mostly Paracalanus indicus, with 23% Caldocera and 21% larvaceans. Westernport Bay zooplankton was dominated by Acartia tranteri, with no resident cladoceran fauna. Bass Strait species were more often found in Westernport than in Port Phillip Bay, but the resident community of Port Phillip Bay was more similar to that of Bass Strait than to that of Westernport.Although this study was undertaken in an exceptionally dry year, the available historical data show that the overall patterns found in 1982–1983 are typical for these bays. The differences in community composition probably relate to differences in depth profile, predator abundance, and suspended matter between the bays. 相似文献
29.
李新生 《地球科学与环境学报》1993,(Z2)
本文首先简述了斜坡演化过程与构造运动的关系,然后阐明了滑坡的空间分布、活动周期及活动规模与构造因素的联系。在此基础上指出:构造因素是滑坡产生的基础,对滑坡分布具宏观控制作用,并与滑坡的活动周期和活动规模密切相关,是滑坡研究及其灾害预测、预防研究工作中值得重视的重要因素。 相似文献
30.