全文获取类型
收费全文 | 508篇 |
免费 | 90篇 |
国内免费 | 99篇 |
专业分类
测绘学 | 120篇 |
大气科学 | 146篇 |
地球物理 | 156篇 |
地质学 | 141篇 |
海洋学 | 57篇 |
天文学 | 25篇 |
综合类 | 23篇 |
自然地理 | 29篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 11篇 |
2020年 | 14篇 |
2019年 | 14篇 |
2018年 | 10篇 |
2017年 | 23篇 |
2016年 | 16篇 |
2015年 | 25篇 |
2014年 | 29篇 |
2013年 | 36篇 |
2012年 | 40篇 |
2011年 | 32篇 |
2010年 | 26篇 |
2009年 | 32篇 |
2008年 | 43篇 |
2007年 | 39篇 |
2006年 | 40篇 |
2005年 | 24篇 |
2004年 | 20篇 |
2003年 | 18篇 |
2002年 | 25篇 |
2001年 | 20篇 |
2000年 | 12篇 |
1999年 | 22篇 |
1998年 | 12篇 |
1997年 | 26篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 19篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
排序方式: 共有697条查询结果,搜索用时 312 毫秒
151.
152.
东太湖风生流套网格模式模拟 总被引:3,自引:0,他引:3
根据1984年8月水位、1993年9月湖流资料,通过建立太湖风生流模式,并在此基础上采用数值嵌套技术,设计太湖风生流套风格模式,对不同风情下的东太湖风生流进行模拟研究,结果表明:湖区风场了东太湖风生流的流型及流向,对峙方位风场形成的风生流流向几乎相反,稳定风生流流态表现为湖中若干环流区和沿岸流的有机结合风场作用初期,风生流流各与湖区风向近乎一致。偏NW风向作用,西太湖湖水流水流入东太湖,并在东太湖 相似文献
153.
154.
Collision and grounding are the most common accidents in ship operation. Some accidents are due to human failure, but several research projects have shown that a high percentage of these accidents could have been avoided if the ship have had better manoeuvrability characteristics. This paper describes how, when the shipyard select some important ship parameters and dimensions at the design stage, these set of parameters influence manoeuvrability characteristics. To obtain these effects, some IMO manoeuvres have been numerically simulated for a sample ship and a non-linear numerical model proposed by the authors to study ship manoeuvrability is described in this work. The day to day practice of a shipyard where fast modelisation and calculations are required, and modifications to the original design are quite common at the preliminary design stage, requires fast but accurate numerical models. 相似文献
155.
An analytically derived distribution function of reflected and accelerated electrons at a nearly perpendicular shock is presented. Then this distribution in a simplified form is introduced into a 1.5-D relativistic electromagnetic particle-in-cell (PIC) model and a generation of waves is studied. Numerical modeling shows not only a generation of Langmuir and high-frequency electromagnetic waves as expected, but also an efficient generation of whistler waves. Their role in emission processes of type II solar radio bursts is discussed. 相似文献
156.
̨�庣Ͽ�����ؿ�����˶����� 总被引:3,自引:1,他引:2
????1995~2003????GPS????????????????????????? ?????????GPS????????????????????????????仯????????????????????????????????????????????????????,??1995~1997???2001~2003???????????????????????????????????????????????????С??????н??仯??????仯????????1999????弯??7.6????????????????????????? 相似文献
157.
元素富集机制的研究是重现成矿过程和查明成矿机制的基础,有助于深化对矿床的认识,为找矿提供理论依据。本文总结了近年来关于铅锌元素的迁移与沉淀机制的研究及其应用,包括3种铅锌迁移沉淀模式,4种含铅锌流体驱动模式,铅锌的迁移形式及其沉淀机制;同时简述了我国高温高压实验的发展历程以及4种高温高压模拟实验方法。重点介绍了4种高温高压实验模拟方法及其研究现状:(1)高压釜实验;(2)热液金刚石压腔—激光拉曼实验;(3)熔融毛细硅管—激光拉曼实验;(4)计算机模拟实验。从封闭—平衡—静止到(半)开放—非平衡—流动、淬火分析到原位观察,应是今后高温高压实验的发展方向。以地质特征为基础,采用高温高压成岩成矿模拟实验结合计算机模拟,精细刻画成矿过程并揭示元素富集机制不仅是解决实际地质问题的有效手段,更是很长一段时间内要为之努力的方向。 相似文献
158.
In this study, the impact of different land initial conditions on the simulation of thunderstorms and monsoon depressions is investigated using the Weather Research and Forecasting (WRF) model. A control run (CNTL) and a simulation with an improved land state (soil moisture and temperature) using the High Resolution Land Data Assimilation System (HRLDAS, experiment name: EHRLDAS) are compared for three different rainfall cases in order to examine the robustness of the assimilation system. The study comprises two thunderstorm cases (one in the pre-monsoon and one during the monsoon) and one monsoon depression case that occurred during the Interaction of Convective Organisation, Atmosphere, Surface and Sea (INCOMPASS) field campaign of the 2016 Indian monsoon. EHRLDAS is shown to yield improvements in the representation of location-specific rainfall, particularly over land. Further, it is found that surface fluxes as well as convective indices are better captured for the pre-monsoon thunderstorm case in EHRLDAS. By analysing components of the vorticity tendency equation, it is found that the vertical advection term is the major contributor towards the positive vorticity tendency in EHRLDAS compared to CNTL, hence improving localised convection and consequently facilitating rainfall. Significant improvements in the simulation of the pre-monsoon thunderstorm are noted, as seen using Automatic Weather Station (AWS) validation, whereas improvements in the monsoon depression are minimal. Further, it is found that vertical advection (moisture flux convergence) is the major driver modulating the convective circulation in localised thunderstorm (monsoon depression) cases and these dynamics are better represented by EHRLDAS compared to CNTL. These findings underline the importance of accurate and high resolution land-state conditions in model initial conditions for forecasting severe weather systems, particularly the simulation of localised thunderstorms over India. 相似文献
159.
160.