全文获取类型
收费全文 | 4737篇 |
免费 | 698篇 |
国内免费 | 719篇 |
专业分类
测绘学 | 433篇 |
大气科学 | 643篇 |
地球物理 | 1013篇 |
地质学 | 2111篇 |
海洋学 | 753篇 |
天文学 | 8篇 |
综合类 | 278篇 |
自然地理 | 915篇 |
出版年
2024年 | 38篇 |
2023年 | 112篇 |
2022年 | 174篇 |
2021年 | 230篇 |
2020年 | 203篇 |
2019年 | 228篇 |
2018年 | 167篇 |
2017年 | 240篇 |
2016年 | 242篇 |
2015年 | 213篇 |
2014年 | 359篇 |
2013年 | 345篇 |
2012年 | 316篇 |
2011年 | 323篇 |
2010年 | 304篇 |
2009年 | 287篇 |
2008年 | 301篇 |
2007年 | 301篇 |
2006年 | 304篇 |
2005年 | 233篇 |
2004年 | 179篇 |
2003年 | 160篇 |
2002年 | 179篇 |
2001年 | 110篇 |
2000年 | 104篇 |
1999年 | 84篇 |
1998年 | 83篇 |
1997年 | 54篇 |
1996年 | 52篇 |
1995年 | 42篇 |
1994年 | 42篇 |
1993年 | 45篇 |
1992年 | 37篇 |
1991年 | 12篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有6154条查询结果,搜索用时 8 毫秒
21.
22.
通过野外调查,在收集统计大量基础地质、经济地质、环境地质、旅游地质、农(林)业地质等数据信息的基础上,在GIS技术指导下,采用定量定性相结合的半定量分析评价方法,对森林浅覆盖区生态地质现状及各类资源的开发利用潜力进行了综合评价。在研究和探讨森林浅覆盖区生态地质综合评价方法的基础上,提出了森林浅覆盖区生态地质评价模型,确定了综合参数,划分了生态地质类型。 相似文献
23.
24.
区域土壤环境地球化学研究——异常成因判别·环境质量·污染程度评价的思路与方法 总被引:8,自引:2,他引:8
从概念内涵和应用目标出发,认为土壤环境地球化学质量评价应该分为质量现状和污染程度两个方面.在此基础上探讨了区域地球化学资料在土壤环境现状质量评价、异常成因识别、污染元素累积速率和土壤污染程度评价研究的基本思路和方法. 相似文献
25.
Ken Durham 《Natural Hazards》2003,30(2):251-261
Cairns is exposed to the well-known natural hazards oftropical cyclone, flood, stormsurge and thunderstorm, but is also exposed to thelesser-known hazards of landslip, earthquake and dam break flooding. Recommendations fortreating the risks associated with these hazards have been made that will involve amulti-disciplinary approach to treatment strategies, require the cooperation of allthree levels of government, involve public utility authorities and private enterprise andinvolve the community as a whole.This paper summarises the suggested mitigation treatmentoptions, presented to the Cairns City Council and identified in the LocalGovernment Disaster Mitigation Project conducted in Cairns in 1999/2000 by theQueensland Department of Emergency Services. 相似文献
26.
Quantifying Storm Tide Risk in Cairns 总被引:6,自引:5,他引:6
Ken Granger 《Natural Hazards》2003,30(2):165-185
The United Nations International Decade for Natural Disaster Reduction (IDNDR)gave rise to an increasing level of attention to the risks posed by a range of naturalhazards and the development of strategies by which to reduce those risks. It waswidely recognised that in order to evaluate risk treatment strategies it was necessaryto `measure' the level of risk that already existed and the level of risk that would beencountered with the treatment strategy(s) in place.This paper outlines the methodology developed under the AGSO (now GeoscienceAustralia) Cities Project to quantify the risk associated with storm tide inundation. It includes the methodology for `measuring' the level of community exposure to storm tide hazards and the methodology for `measuring' community vulnerability. The Far North Queensland city of Cairns is used as the case study to demonstrate the application of these methods. 相似文献
27.
28.
The Multi frequency Scanning Microwave Radiometer (MSMR) onboard Oceasat-1 was used to develop a retrieval method fornear-surface specific humidity by means of multivariate regressiontechnique. The MSMR measures the microwaveradiances in 8 channels at the frequencies of 6.6, 10.7, 18 and 21 GHzfor both vertical and horizontal polarizations. Regression coefficients were derived using the ship reports of the Comprehensive Ocean-Atmosphere Data Set (COADS) for the months of July, October and December, in 1999. Daily near-surface specific humidity data from COADS in 2° × 2° latitude/longitude bins and collocated brightness temperature data from MSMR were used to derive the coefficients. The derived coefficients werevalidated with humidity given in COADS.A linear relationship is established to determine the near-surface specifichumidity from MSMR brightness temperature (Tb) with an rms error of 1.2 g kg-1 for individual situations and an rms errorof 0.84 g kg-1 for monthly time scales over global oceans.The retrieval algorithm is validonly for the open sea regions. 相似文献
29.
Application of discovery process models in estimating petroleum resources at the play level in China
Discovery process modeling has gained wide acceptance in the Chinese exploration community. In recent years, a variety of
discovery process models have been applied to the prediction of undiscovered petroleum resources at the play level in sedimentary
basins in China. However, challenging problems have been encountered, particularly when one method alone has been applied
to small plays in nonmarine sedimentary basins or in plays with an unusual order of discovery wells. This paper presents results
gotten by using the lognormal discovery process model of the Geological Survey of Canada and the geoanchored method for three
petroleum plays in basins with different geologic settings. Although the predicted shapes of the parentsize distributions
which use these two models, were not always similar, the expected values of the total resources and the number of fields (pools)
to be discovered are comparable. The combined use of two discovery process models in the same play compensates for the weaknesses
in one method compared with the other and vice versa. Thus, more reliable estimates are the result. 相似文献
30.
介绍了安阳电厂冷却塔碎石桩复合地基静载、动力触探、瑞利波法系列原位试验。根据试验结果,对冷却塔地基加固与改良效果及施工质量进行了评价。 相似文献