全文获取类型
收费全文 | 83篇 |
免费 | 18篇 |
国内免费 | 10篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 7篇 |
地球物理 | 21篇 |
地质学 | 42篇 |
海洋学 | 25篇 |
天文学 | 1篇 |
综合类 | 1篇 |
自然地理 | 11篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 4篇 |
2012年 | 5篇 |
2011年 | 1篇 |
2010年 | 5篇 |
2009年 | 10篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 7篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1985年 | 2篇 |
1980年 | 1篇 |
排序方式: 共有111条查询结果,搜索用时 15 毫秒
71.
船载风控大容量气溶胶采集系统的开发和应用 总被引:2,自引:2,他引:0
在"我国近海环境综合调查与评价"的海洋气溶胶调查研究中,开发研制了新型船载风控大容量气溶胶采集系统。该系统由风向风速控制器、大容量采样器、自动控制器和抗风防雨防腐蚀箱体等组成。经过海上2 a 4个季度的海洋环境作业,表明该系统具有的大容量采集海洋空气体积,满足海洋气溶胶的微量组分的检出要求;具有的风速风向控制系统,能有效避免所采集的大气气溶胶样品受到船上发动机排出烟尘污染的影响。该系统还具防海水降雨、防腐蚀、结构牢固、流量稳定及抗风能力强等优点。系统采用单片机控制信号的采集、处理和显示,配有温度和压力补偿编程设定以及断电保护、自动修复等功能。海洋现场使用表明,该系统设计合理、数据可靠、灵敏度高,可满足海上大容量气溶胶采样要求。 相似文献
72.
Yuko Ogata Kaoruko Mizukawa Satoru Iwasa Yukie Mato Keiji Okuda Michio Murakami Ruchaya Booyatumanondo Le Quang Dung Carlos Miguez Charles Moore Steven Weerts Erick Burres Michael Van Velkenburg Richard C. Lang Brenda Danner Richard C. Thompson 《Marine pollution bulletin》2009,58(10):1437-1446
Samples of polyethylene pellets were collected at 30 beaches from 17 countries and analyzed for organochlorine compounds. PCB concentrations in the pellets were highest on US coasts, followed by western Europe and Japan, and were lower in tropical Asia, southern Africa and Australia. This spatial pattern reflected regional differences in the usage of PCBs and was positively correlated with data from Mussel Watch, another monitoring approach. DDTs showed high concentrations on the US west coast and in Vietnam. In Vietnam, DDT was predominant over its metabolites (DDE and DDD), suggesting the principal source may be current usage of the pesticide for malaria control. High concentrations of pesticide HCHs were detected in the pellets from southern Africa, suggesting current usage of the pesticides in southern Africa. This study demonstrates the utility and feasibility of the International Pellet Watch approach to monitor POPs at a global scale. 相似文献
73.
A system has been installed to automatically monitor rainfall, streamflow, bedload discharge and suspended sediment concentration in the arid to hyper‐arid setting of Nahal Rahaf, Southern Judean Desert in Israel. The Rahaf gauging station is located in a relatively steep, wide channel with an unsteady bed driven by flash floods. It is an attempt to deploy modern automatic equipment for continuous sediment transport monitoring in harsh, arid fluvial environments. Unit bedload discharges are the highest recorded hitherto, suggesting they may represent an upper end member in the worldwide climate–bedload discharge relationship. Suspended sediment concentration is much higher than is typical of perennial fluvial humid environments. There is high correlation between suspended sediment concentration and water discharge on an event scale, with diverse intra‐event relations. The sediment yield of individual events is large, but the small number of floods limits the mean annual sediment yield to low values in this arid environment. This also has environmental implications, as large‐scale quarrying requires a long period of self‐restoration in such an arid fluvial setting. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
74.
为解决国内现有天然气水合物采样器无法实现大深度保真取样的问题,提出一种配套气垫式保真筒的深海天然气水合物采样器,并以气垫式保真筒的保压特性作为研究重点。在考虑采样过程中样品自身体积膨胀因素的基础上,建立了不含气垫保真筒和气垫式保真筒的数学模型,并通过仿真计算,对不含气垫保真筒和气垫式保真筒的保压特性进行了分析。实验结果表明基于样品自身体积膨胀的不含气垫的保真筒和气垫式保真筒保压特性理论研究是正确的,同时,也表明气垫式保真筒具有良好的保压性能,极具开发价值。 相似文献
75.
Simulation of mineral grades with hard and soft conditioning data: application to a porphyry copper deposit 总被引:1,自引:0,他引:1
This work deals with the geostatistical simulation of mineral grades whose distribution exhibits spatial trends within the
ore deposit. It is suggested that these trends can be reproduced by using a stationary random field model and by conditioning
the realizations to data that incorporate the available information on the local grade distribution. These can be hard data
(e.g., assays on samples) or soft data (e.g., rock-type information) that account for expert geological knowledge and supply
the lack of hard data in scarcely sampled areas. Two algorithms are proposed, depending on the kind of soft data under consideration:
interval constraints or local moment constraints. An application to a porphyry copper deposit is presented, in which it is
shown that the incorporation of soft conditioning data associated with the prevailing rock type improves the modeling of the
uncertainty in the actual copper grades. 相似文献
76.
天然气水合物是一种潜力巨大的替代性能源,其可以稳定地存在于一定的低温高压条件之下。在天然气水合物钻探作业中,冷却保温技术是天然气水合物钻探的关键技术之一。低温可以抑制天然气水合物分解,这对获取水合物样品有着十分重要的作用。本文首先概述了海底天然气水合物取样器保温冷却技术研究现状,并对取样器冷却保温技术进行深入的调查研究和分析。然后对日本的PTCS取样器中的冷却保温技术和国内具有冷却保温功能的取样器进行了详细介绍,并对相关技术进行分析和总结,最后对海底天然气水合物取样器冷却保温技术的发展做了总结与展望。 相似文献
77.
积时式悬沙采样器进口管路的结构和几何参数是影响采样器管嘴进口流速的关键因素之一。为保证所采水样的真实和准确性,一般要求采样器进口流速接近河流的天然流速。本文通过建立采样器进口流速的数学模型,对采样器进口管路进行了参数优化。研究表明,通过优化结构参数,在水深0-40m。天然流速0-5m/s的范围内,采样器的进口流速系数K在[0.9,1.1]区间的概率可达98%。 相似文献
78.
A low-cost,large-volume general purpose water sampler 总被引:1,自引:0,他引:1
Here we describe the design, construction and subsequent routine use of a large-volume general purpose water sampler. The sampler is designed to be used in both remote sites and deep lakes with a minimum of logistical support, and can be made from commercially available parts at low cost. 相似文献
79.
P.C. Fleischack A.J. de Freitas R.B. Jackson 《Estuarine, Coastal and Shelf Science》1985,21(2):287-293
A suction corer which has been used in the turbulent surf zone is described as well as a scoop dredge which proved effective in shallow water and on dry beaches. The former is also effective under calm conditions in water ranging from a few centimetres to depths in excess of 20 m. These apparatuses both allow the rapid collection of consistent quantitative samples which is of prime importance in the surf zone. 相似文献
80.