全文获取类型
收费全文 | 1267篇 |
免费 | 227篇 |
国内免费 | 536篇 |
专业分类
测绘学 | 55篇 |
大气科学 | 75篇 |
地球物理 | 548篇 |
地质学 | 897篇 |
海洋学 | 275篇 |
天文学 | 6篇 |
综合类 | 78篇 |
自然地理 | 96篇 |
出版年
2024年 | 3篇 |
2023年 | 18篇 |
2022年 | 35篇 |
2021年 | 54篇 |
2020年 | 80篇 |
2019年 | 87篇 |
2018年 | 80篇 |
2017年 | 66篇 |
2016年 | 73篇 |
2015年 | 101篇 |
2014年 | 85篇 |
2013年 | 108篇 |
2012年 | 109篇 |
2011年 | 97篇 |
2010年 | 102篇 |
2009年 | 95篇 |
2008年 | 91篇 |
2007年 | 94篇 |
2006年 | 106篇 |
2005年 | 86篇 |
2004年 | 77篇 |
2003年 | 61篇 |
2002年 | 36篇 |
2001年 | 40篇 |
2000年 | 30篇 |
1999年 | 46篇 |
1998年 | 24篇 |
1997年 | 24篇 |
1996年 | 28篇 |
1995年 | 18篇 |
1994年 | 19篇 |
1993年 | 16篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有2030条查询结果,搜索用时 46 毫秒
101.
This study investigates the dynamic behavior of suspended sediment load transport at different temporal scales in the Mississippi River basin. Data corresponding to five successively doubled temporal scales (i.e. daily, two‐day, four‐day, eight‐day and 16‐day) from the St. Louis gaging station in Missouri are analyzed. The investigation is focused on identifying possible low‐dimensional deterministic behavior in the suspended sediment load transport dynamics, with an aim towards reduction in model complexity. The correlation dimension method is used to identify low‐dimensional determinism. The suspended sediment load dynamics are represented through phase‐space reconstruction, and the variability is estimated using the (proximity of) reconstructed vectors in the phase space. The results indicate the presence of low‐dimensional determinism in the suspended sediment load series at each of the five temporal scales, with the variables dominantly governing the dynamics in the order of three or four. These results not only suggest the appropriateness of relatively simpler models but also hint at possible scale invariance in the suspended sediment load transport dynamics. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
102.
魏家岗滑坡因保坎条石砌筑的施工质量差,保坎上又堆放弃土增加荷载,加之雨水渗透而形成工程滑坡,本文对滑坡形成的条件进行了论述,并提出了治理滑坡的措施。 相似文献
103.
104.
Sven HARTMANN Institute for Hydrosciences German Armed Forces University Munich Neubiberg Germany. 《国际泥沙研究》2001,16(2)
1 BASIC PROBLEMFlood protecton, sPreaing of settlements and occuPatin Of river valleys were maor reasons to damand lindt rivers throughout Europe in the ndd 19th century. Engineers of those days often knew very wellabout the effects of their plannings: shortening the river length would accelerat the now and thusencourage the erosion into the river's sedAnents. Two vital advanages could be obtalned from that kindof constrUction, landuse of the fOrmer flood plains on the one and increasin… 相似文献
105.
Thomas ELSNERand Sven HARTMANN Institute for Hydrosciences German Armed Forces University Munich Neubiberg Germany. Institute for Hydrosciences German Armed Forces University Munich Neubiberg Germany. 《国际泥沙研究》2001,16(2)
1 THE LOWhR unR INNThe Inn river has its source in the alPine region of the GraubUnden canton of Switzerand. ThecatChment area of about 260(X} kIn2 includes mountains of the central Alpes up to 40(X) m. The river runs5l7 km thrOugh the countries of SwitZerand, Austria and Germany on itS way into the Danube mver. Thedischarge of the river at its mouth in the city of Passau is mainly infiuenced by the snow melt in themountainous catchment area and vches between apProx. 200 m3ls durin… 相似文献
106.
107.
108.
介绍了检验复合地基承裁力及桩身完整性的主要方法静裁荷试验、低应变反射波法,并对检测应满足的前提条件进行了认识和探讨。 相似文献
109.
In this paper, the response of a visco-elastic half-space subjected to moving loads with static and dynamic components is investigated. Four types of vehicle loads are considered, including the moving point load, uniformly distributed wheel load, elastically distributed wheel load, and a train load simulated as a sequence of elastically distributed wheel loads. In each case, the influence of the moving loads traveling in the subsonic, transonic and supersonic ranges on the dynamic responses of the half-space is studied. The parametric study conducted herein enables us to grasp insight into the mechanism of wave propagation for a visco-elastic half-space under moving loads. 相似文献
110.
云南普洱地区6级以上地震前的Y值异常特征 总被引:1,自引:0,他引:1
本利用加卸载响应比方法研究了云南省普洱地区ML6.0级以上地震前的加卸载响应比随时间的变化,计算了这个地区近期的加卸载响应比,结果显示,普洱地区6级以上地震前Y值出现明显异常,近期的Y值显异常,表明该地区或在以其为中心方圆100-200公里的区域内在1995年或稍长时间内发生6.0级以上的地震的可能性很大。 相似文献