全文获取类型
收费全文 | 4607篇 |
免费 | 909篇 |
国内免费 | 1288篇 |
专业分类
测绘学 | 309篇 |
大气科学 | 807篇 |
地球物理 | 1177篇 |
地质学 | 2245篇 |
海洋学 | 939篇 |
天文学 | 243篇 |
综合类 | 601篇 |
自然地理 | 483篇 |
出版年
2024年 | 50篇 |
2023年 | 111篇 |
2022年 | 226篇 |
2021年 | 264篇 |
2020年 | 241篇 |
2019年 | 257篇 |
2018年 | 318篇 |
2017年 | 282篇 |
2016年 | 299篇 |
2015年 | 222篇 |
2014年 | 277篇 |
2013年 | 262篇 |
2012年 | 356篇 |
2011年 | 312篇 |
2010年 | 300篇 |
2009年 | 280篇 |
2008年 | 226篇 |
2007年 | 253篇 |
2006年 | 206篇 |
2005年 | 191篇 |
2004年 | 131篇 |
2003年 | 127篇 |
2002年 | 96篇 |
2001年 | 111篇 |
2000年 | 158篇 |
1999年 | 213篇 |
1998年 | 146篇 |
1997年 | 169篇 |
1996年 | 119篇 |
1995年 | 109篇 |
1994年 | 102篇 |
1993年 | 98篇 |
1992年 | 68篇 |
1991年 | 53篇 |
1990年 | 45篇 |
1989年 | 30篇 |
1988年 | 20篇 |
1987年 | 19篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 12篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1958年 | 2篇 |
1957年 | 1篇 |
1954年 | 2篇 |
排序方式: 共有6804条查询结果,搜索用时 15 毫秒
71.
Sea surface height variations in the Mindanao Dome region in response to the northern tropical Pacific winds 总被引:1,自引:0,他引:1
Sea surface height (SSH) variability in the Mindanao Dome (MD) region is found to be one of the strong variations in the northern Pacific. It is only weaker than that in the Kuroshio Extension area, and is comparable to that in the North Pacific Subtropical Countercurrent region. Based on a 1.5-layer reduced gravity model, we analyzed SSH variations in this region and their responses to northern tropical Pacific winds. The average SSH anomaly in the region varies mainly on a seasonal scale, with significant periods of 0.5 and 1 year, ENSO time scale2-7years, and time scale in excess of 8 years. Annual and long-term variabilities are comparably stronger. These variations are essentially a response to the northern tropical Pacific winds. On seasonal and ENSO time scales, they are mainly caused by wind anomalies east of the region, which generate westward-propagating, long Rossby waves. On time scales longer than 8 years, they are mostly induced by local Ekman pumping. Long-term SSH variations in the MD region and their responses to local winds are examined and discussed for the first time . 相似文献
72.
73.
通过钻井、测井与地震数据,依据不整合面分析、断层活动速率分析与地层的"负向结构"分析,在义和庄凸起东部燕山期内识别出一期发生于中晚侏罗世之交的构造负反转,并据此将义和庄凸起燕山期划分为早期与晚期两个阶段.通过单井与连井层序地层分析,分别建立了燕山早期与晚期的层序地层样式,两者在层序结构及内部沉积充填等方面表现出巨大差异.早期层序地层不具有显著的沉积厚度分异,且格架内部充填河流相沉积;晚期因构造负反转而形成小型拉张断陷盆地,沉积厚度分异明显,内部以扇三角洲沉积充填为主,呈现出对构造负反转的显著响应.燕山期构造-层序地层学的研究可为中国东部其他具有相似构造背景盆地前新生代的油气勘探提供借鉴. 相似文献
74.
Yonghong Yao Weidong Guo Yaoming Song 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(4):475-481
Using data archived in the Coordinated Enhanced Observing Period (CEOP) project, comparisons between field observations undertaken at Tongyu CEOP reference site in China and model output from year 2003 to 2004 have been implemented, and in particular, the time series and diurnal cycles of precipitation, near-surface temperature, air temperature, and latent and sensible heat fluxes are presented. The results show that the ability of the model simulations on the temperatures, such as air temperature and the surface temperature, is satisfactory compared with the simulations on the land surface heat fluxes and the precipitation at Tongyu site. In addition, the multi-model ensemble exhibits better results over all items in comparison with the observations. The differences of the precipitation at the interannual and the seasonal time scales between the model results and observations indicate that some of the models are able to reproduce the larger amount of precipitation in 2003 than that in 2004, which is consistent with the trend of the observations at Tongyu site even though the mean square errors of models output calculated from daily precipitation during year 2003 and 2004 are even greater than the daily amount of the precipitation. The poor skill in the quantitative simulation of the precipitation indicates that the deficiency of the models in simulating the surface heat fluxes may be closely related to the biases of the precipitation simulations. In terms of the seasonal time series of the precipitation, there is an increase during summer, accompanied by the same increased trend of the latent heat flux and the decreased trend of the sensible heat flux from the insitu observations. 相似文献
75.
76.
The research on diagenesis of clastic-rock reservoir is developing rapidly in recent ten years. Thus, it is of great significance in academic and scientific exploration to summarize the domestic and international research progress and the key issues of frontier research on diagenesis. The research progress, main achievement and recognition in diagenesis of clastic-rock reservoirs in recent years is discussed, and the hot issues or developing trend of diagenesis in the future is probed in this paper, on the basis of summarizing the previous research results and understanding, combined with the typical research examples at home and abroad. It is believed that great progress was obtained in provenance and parent rock constraints on sandstone types and their diagenetic evolution pathways, impact of fluid-rock interaction and its product on diagenesis, influence of thermodynamics and overpressure background on diagenesis and pore development, the timing sequence between hydrocarbon accumulation and filling process and the sandstone reservoir becoming low permeability-densification. At present, diagenetic research is developing in direction of the spatial and temporal dynamics and quantitative evolution mechanistic and diagenetic system controlled by the basin fluid dynamics, thermal dynamic processes, combining the micro-scale diagenesis research with the basin macroscopic background such as sedimentation from the source to the basin, burial history, hydrocarbon maturity and charge into reservoirs, tectonic evolution and fluid activity, and fluid and rock interaction.The aim of this paper is to induce the academic peers and experts in diagenesis and the related research fields to come forward with their valuable contributions, to cooperate and work together and joint efforts on the research exquisite, profundity and breadth of diagenesis, and application of the most advanced analytical measurement techniques and methods, as well as integration and infiltration of multidisciplinary, in order to promote the course of the clastic-rock reservoir diagenetic research in China. 相似文献
77.
The transfer processes of organic pollutants during sewage-seawater mixing were simulated in three different mixing systems.
The release rate of organic matter from sewage particles to seawater was found to be about 0.02–0.04 d−1. The release processes can be simulated by an exchange-equilibrium kinetic model. Degradation of COD was observed in all
three mixing systems and can be described by a first order kinetic equation. The degradation rate constantk ranged between 0.04 and 0.07 d−1. These results have provided important parameters for estimation of environmental capacity. 相似文献
78.
2000国家GPS大地控制网数据处理方法与结果 总被引:7,自引:2,他引:7
介绍了我国GPS大地控制网的基本情况,阐述了结合地壳运动观测网络工程建立全国统一的“2000国家GPS大地控制网”的意义,并介绍了整网平差中采用的技术方法和最后平差结果及精度。 相似文献
79.
80.