全文获取类型
收费全文 | 419篇 |
免费 | 227篇 |
国内免费 | 111篇 |
专业分类
测绘学 | 50篇 |
大气科学 | 36篇 |
地球物理 | 160篇 |
地质学 | 351篇 |
海洋学 | 67篇 |
天文学 | 4篇 |
综合类 | 52篇 |
自然地理 | 37篇 |
出版年
2025年 | 1篇 |
2024年 | 16篇 |
2023年 | 11篇 |
2022年 | 21篇 |
2021年 | 18篇 |
2020年 | 19篇 |
2019年 | 20篇 |
2018年 | 28篇 |
2017年 | 32篇 |
2016年 | 22篇 |
2015年 | 28篇 |
2014年 | 38篇 |
2013年 | 35篇 |
2012年 | 30篇 |
2011年 | 26篇 |
2010年 | 30篇 |
2009年 | 27篇 |
2008年 | 43篇 |
2007年 | 31篇 |
2006年 | 43篇 |
2005年 | 41篇 |
2004年 | 23篇 |
2003年 | 19篇 |
2002年 | 23篇 |
2001年 | 27篇 |
2000年 | 15篇 |
1999年 | 13篇 |
1998年 | 18篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有757条查询结果,搜索用时 15 毫秒
81.
The rain-flow counting method is widely used to compile the fatigue load spectrum. The second stage counting of the rain-flow method is a troublesome process. In order to overcome this drawback, the rain-flow and reverse rain-flow counting method is proposed in this paper. In this counting method, the rule for counting of the rain-flow method is modified, so that the sequence of load-time need not be adjusted. This is a valid and useful method to count cycles and compile the load spectrum and it can be widely used in ocean engineering. 相似文献
82.
83.
GUI Maochang * WU Lingjuan . Institute of Oceanology Chinese Academy of Sciences Qingdao China. Laboratory of Numerical Modeling for Atmospheric Sciences Geophysical Fluid Dynamics Institute of Atmospheric Physics Chine-se Academy of Sciences Beijing China. Graduate School Chinese Academy of Sciences Beijing China 《海洋学报(英文版)》2005,(4)
1 IntroductionIt is well known that interaction between the trop-ical ocean and atmosphere produces the largest inter-annual climate signal, El Nino-Southern Oscillation(ENSO). In past decades many efforts have been madein understanding and predicting ENSO: such as the hy-pothesis of Bjerknes (1969) that ENSO arises as aself-sustained cycle in which SSTA in the Pacific O-cean causes the trade winds to strengthen or slackenand that this in turn drives the ocean circulation changesthat … 相似文献
84.
85.
以福州江滨地区2个有代表性的超高层建筑桩基础工程实例为依据,通过无卡式冲击 正循环,旋挖 气举反循环,回转 泵吸反循环3种成孔工艺之间的比对,提出了在福州市江滨地区超大粒径厚层卵石与花岗岩地层灌注桩施工成孔工艺方面的一些见解,认为回转 泵吸反循环是较为可靠的工艺。 相似文献
86.
川西龙门山中段彭州式铜矿形成于岛弧构造环境,其形成经历了晋宁期幔源火山沉积和褶皱变形、印支期-燕山期以来强烈的构造挤压和破坏。根据研究区地层形变的各种构造形迹,将区内构造体系划分为北北西向"多"字型和北东向华夏式两种构造体系。"多"字型构造体系是在晋宁期右行剪切作用下形成北东—北北东向的褶皱带,后经印支期-燕山期以来的左行旋转至北北西而保留至今,表现为黄水河群组成的复式背、向斜褶皱带;华夏式构造体系显示了印支期以来北东—南西方向强大的挤压,表现为前期的叠瓦状断裂和后期的"飞来峰"构造。两种构造体系共同控制着彭州式铜矿床的形成及改造。根据二者的平面展布形态、构造出露特征及其动力学标志,将其划分为包容和交接两种复合关系,即"多"字型构造体系包容于华夏式构造体系中,在研究区南部二者呈反接关系。 相似文献
87.
Time-clustering of natural hazards 总被引:1,自引:0,他引:1
Luciano Telesca 《Natural Hazards》2007,40(3):593-601
Natural hazards can be represented as point processes that are characterized by the occurrence times of the events and their
intensities. It is crucial to investigate the correlation properties of these processes in order to gain a deep knowledge
of the dynamical mechanisms which underlie hazardous phenomena. To this end, suitable methodologies must be developed to perform
these correlation analyses on processes, which are described as point-like processes. The concept of time-clustering implies
a time-structured organization of these processes, and is in direct opposition to the pure randomness typical of Poissonian
processes in which the events are uncorrelated. This article reports several examples of natural hazards within the framework
of time-clustering. 相似文献
88.
89.
90.
To study how the air and sea interact with each other during El Nino/La Nina onsets, extended associate pattern analysis (EAPA) is adopted with the simple ocean data assimilation (SODA) data. The results show that as El Nino/La Nina' s parents their behaviors are quite different, there does not exist a relatively independent tropical atmosphere but does exist a relatively independent tropical Pacific Ocean because the air is heated from the bottom surface instead of the top surface and of much stronger baroclinic instability than the sea and has a very large inter-tropical convergence zone covering the most tropical Pacific Ocean. The idea that it is the wester burst and wind convergence, coming from middle latitudes directly that produce the seawater eastward movement and meridional convergence in the upper levels and result in the typical El Nino sea surface temperature warm signal is confirmed again. 相似文献