全文获取类型
收费全文 | 5902篇 |
免费 | 916篇 |
国内免费 | 1081篇 |
专业分类
测绘学 | 1442篇 |
大气科学 | 656篇 |
地球物理 | 788篇 |
地质学 | 2827篇 |
海洋学 | 552篇 |
天文学 | 26篇 |
综合类 | 623篇 |
自然地理 | 985篇 |
出版年
2024年 | 36篇 |
2023年 | 77篇 |
2022年 | 223篇 |
2021年 | 299篇 |
2020年 | 261篇 |
2019年 | 315篇 |
2018年 | 209篇 |
2017年 | 318篇 |
2016年 | 309篇 |
2015年 | 316篇 |
2014年 | 435篇 |
2013年 | 360篇 |
2012年 | 471篇 |
2011年 | 462篇 |
2010年 | 361篇 |
2009年 | 392篇 |
2008年 | 388篇 |
2007年 | 417篇 |
2006年 | 343篇 |
2005年 | 293篇 |
2004年 | 254篇 |
2003年 | 207篇 |
2002年 | 171篇 |
2001年 | 180篇 |
2000年 | 141篇 |
1999年 | 118篇 |
1998年 | 113篇 |
1997年 | 104篇 |
1996年 | 70篇 |
1995年 | 64篇 |
1994年 | 53篇 |
1993年 | 42篇 |
1992年 | 38篇 |
1991年 | 10篇 |
1990年 | 10篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1977年 | 2篇 |
排序方式: 共有7899条查询结果,搜索用时 15 毫秒
11.
12.
海底管道开沟机械的技术经济性能评定与选型 总被引:1,自引:0,他引:1
本文在对水下管道开沟机械的需求市场、实际应用和研制开发动向作深入调研的基础上,选择水下管道开沟机械特有的技术先进性、适用性、安全可靠性以及经济性评价指标,构造评价模型,对水下管道施工作业中广为应用的水力冲射开沟机械、海底管道犁、机械开沟机和土壤液化法埋管设备及其机型的技术经济性能作了较为详尽地分析对比及综合评价。在此基础上,笔者提出了水下管道开沟机械的一般选型原则和对我国海底管道开沟机械研究开发工 相似文献
13.
14.
15.
16.
A. Mascle R. Vially E. Deville B. Biju-Duval J.P. Roy 《Marine and Petroleum Geology》1996,13(8):941-961
The Southeast Basin of France is the thickest onshore French sedimentary basin which contains locally as much as 10 km of Mesozoic-Cenozoic sediment. Basin development occurred in several stages between late Carboniferous and late Cretaceous times. Partial tectonic inversion took place during two compressive events, the so-called ‘Pyrenean’ and ‘Alpine’ phases of late Cretaceous-early Tertiary and late Tertiary ages respectively. They are separated by an intervening stretching event of Oligocene age, which further south resulted in the opening of the western Mediterranean oceanic basin. As a result of this complex tectonic history, structural traps were difficult to image on the seismic data shot during the first phase of exploration prior to 1980. Oil and gas natural seeps, and shows in several wells, indicate that some petroleum systems are, or have been active, at least in some places.The present erosional western margin of the basin is more or less superimposed on the initial Triassic-Jurassic margin. Margin subsidence and Tertiary inversion are discussed using regional sections on which the polyphase history of the entire basin is well shown. These sections are located on three major segments where the Mesozoic margin is either partly preserved (Ardèche), or has been partly inverted in late Tertiary times (Vercors-Chartreuse), or has been completely inverted in early Tertiary times (Corbières-eastern Pyrenees). 1-D ‘Genex’ basin modelling on the Ardèche segment, and 2-D ‘Thrustpack’ structural-maturity modelling in the Vercors-Chartreuse segment are used to further assess the remaining petroleum plays. 相似文献
17.
18.
This paper investigates the use of data assimilation in coastal area morphodynamic modelling using Morecambe Bay as a study site. A simple model of the bay has been enhanced with a data assimilation scheme to better predict large-scale changes in bathymetry observed in the bay over a 3-year period. The 2DH decoupled morphodynamic model developed for the work is described, as is the optimal interpolation scheme used to assimilate waterline observations into the model run. Each waterline was acquired from a SAR satellite image and is essentially a contour of the bathymetry at some level within the inter-tidal zone of the bay. For model parameters calibrated against validation observations, model performance is good, even without data assimilation. However the use of data assimilation successfully compensates for a particular failing of the model, and helps to keep the model bathymetry on track. It also improves the ability of the model to predict future bathymetry. Although the benefits of data assimilation are demonstrated using waterline observations, any observations of morphology could potentially be used. These results suggest that data assimilation should be considered for use in future coastal area morphodynamic models. 相似文献
19.
20.
Risk-based decision-making for drilling waste discharges using a fuzzy synthetic evaluation technique 总被引:5,自引:0,他引:5
Offshore petroleum drilling wastes contain toxic substances that are potentially harmful to the marine ecosystem. Despite environmentally benign characteristics, wastes associated with synthetic-based fluids still contain a certain amount of pollutants due to contamination with formation oil and the presence of trace heavy metals in barite, which may pose risk when discharged into the marine environment. A framework is presented here for a decision support system for the selection of the best drilling waste discharge option. Uncertainties in the quantification of risk, cost and technical feasibility are expressed by fuzzy numbers. An analytical hierarchy process with a technique called fuzzy synthetic evaluation is employed to determine the best management alternative (discharge scenario). 相似文献