全文获取类型
收费全文 | 545篇 |
免费 | 56篇 |
国内免费 | 72篇 |
专业分类
测绘学 | 26篇 |
大气科学 | 122篇 |
地球物理 | 139篇 |
地质学 | 218篇 |
海洋学 | 43篇 |
天文学 | 28篇 |
综合类 | 35篇 |
自然地理 | 62篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 20篇 |
2021年 | 27篇 |
2020年 | 30篇 |
2019年 | 21篇 |
2018年 | 36篇 |
2017年 | 40篇 |
2016年 | 39篇 |
2015年 | 31篇 |
2014年 | 46篇 |
2013年 | 34篇 |
2012年 | 26篇 |
2011年 | 28篇 |
2010年 | 32篇 |
2009年 | 35篇 |
2008年 | 22篇 |
2007年 | 17篇 |
2006年 | 16篇 |
2005年 | 13篇 |
2004年 | 14篇 |
2003年 | 10篇 |
2002年 | 5篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 14篇 |
1998年 | 15篇 |
1997年 | 10篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1964年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有673条查询结果,搜索用时 171 毫秒
231.
五台山早前寒武纪变质岩中的白云母属二八面体的2M型多型变体,其中五台群中的白云母为富含绿鳞石分子的普通白云母,滹沱群为多硅白云母。通过对这些白云母化学成分和b_0值测定,确定五台群变质条件属中低压相系,滹沱群属中高压相系。五台群绿片岩相的变质压力为0.3—0.5 GPa,滹沱群为0.5—0.6 GPa。基于白云母成分和b_0值的研究,对划分变质级别、变质类型;确定变质作用期次;进行地层对比和构造分析等方面是可行的。 相似文献
232.
Xu Hui Zhang Weiping Lang Xuxing Guo Xi Ge Wenzhong Dang Renqing TakaoTakeda 《大气科学进展》2000,17(3):403-412
During the Meiyu period in June and July of 1998, intensified field observations have been carried out for the project “Huaihe River Basin Energy and Water Cycle Experiment (HUBEX)”. For studying Meiyu front and its precipitation in Huaihe River basin, the present paper has performed analysis on the middle and lower level wind fields in the troposphere by using the radar data obtained from the two Doppler radars located at Fengtai district and Shouxian County. From June 29 to July 3 in 1998, the continuous heavy precipitation occurred in Huaihe River basin around Meiyu front. The precipitation process on July 2 occurred within the observation range of the two Doppler radar in Fengtai district and Shouxian County. The maximum rainfall of the Meiyu front was over 100 mm in 24 h, so it can be regarded as a typical mesoscale heavy precipitation process related to Meiyu front. Based on the wind field retrieved from the dual Doppler radar, we find that there are meso-γ scale vertical circulations in the vertical cross-section perpendicular to Meiyu front, the strong upward motion of which corresponds to the position of the heavy rainfall area. Furthermore, other results obtained by this study are identical with the results by analyzing the conventional synoptic data years ago. For example: in the vicinity of 3 km level height ahead of Meiyu front there exists a southwest low-level jet; the rainstorm caused by Meiyu front mainly occurs at the left side of the southwest low-level jet; and the Meiyu front causes the intensification of the low-level convergence in front of it. 相似文献
233.
In-Hyuk Kwon Hyo-Jong Song Ji-Hyun Ha Hyoung-Wook Chun Jeon-Ho Kang Sihye Lee Sujeong Lim Youngsoon Jo Hyun-Jun Han Hanbyeol Jeong Hui-Nae Kwon Seoleun Shin Tae-Hun Kim 《Asia-Pacific Journal of Atmospheric Sciences》2018,54(1):319-335
This study introduces the operational data assimilation (DA) system at the Korea Institute of Atmospheric Prediction Systems (KIAPS) to the numerical weather prediction community. Its development history and performance are addressed with experimental illustrations and the authors’ previously published studies. Milestones in skill improvements include the initial operational implementation of three-dimensional variational data assimilation (3DVar), the ingestion of additional satellite observations, and changing the DA scheme to a hybrid four-dimensional ensemble-variational DA using forecasts from an ensemble based on the local ensemble transform Kalman filter (LETKF). In the hybrid system, determining the relative contribution of the ensemble-based covariance to the resultant analysis is crucial, particularly for moisture variables including a variety of horizontal scale spectra. Modifications to the humidity control variable, partial rather than full recentering of the ensemble for humidity further improves moisture analysis, and the inclusion of more radiance observations with higher-level peaking channels have significant impacts on stratosphere temperature and wind performance. Recent update of the operational hybrid DA system relative to the previous 3DVar system is described for detailed improvements with interpretation. 相似文献
234.
Antibiotics in the Hong Kong metropolitan area: Ubiquitous distribution and fate in Victoria Harbour 总被引:7,自引:0,他引:7
Tu Binh Minh I. Ha Loi Man Ka So David Choi Gene Zheng Joseph H.W. Lee Bruce J. Richardson 《Marine pollution bulletin》2009,58(7):1052-5312
We investigated the presence and fate of 16 antibiotics belonging to seven groups (β-lactams, fluoroquinolones, macrolides, sulfonamides, tetracyclines, trimethoprim and amphenicols) in effluents of sewage plants and receiving waters in Hong Kong. Cefalexin, amoxicillin, ofloxacin and erythromycin-H2O were ubiquitous in sea water throughout Victoria Harbour, indicating continuous discharge to the environment. This is one of the few studies reporting the frequent occurrence of cefalexin and amoxicillin in sewage effluents and sea water (170-5070 and 64-1670 ng/L in sewage; 6.1-493 and 0.64-76 ng/L in sea water, respectively). Mass flows from seven sewage plants discharged an estimated total of 14.4 kg/day to the Harbour. Typhoon shelters also appeared to play an important role as sources of antibiotics, as evidenced by elevated concentrations within their boundaries. Mass balance estimations suggested significant quantities of antibiotics are discharged to the Harbour without passage through treatment plants. 相似文献
235.
基于增量动力分析(IDA)的倒塌易损性分析方法是评估建筑结构抗地震倒塌能力的精细方法,但分析过程比较繁杂且非常费时。为了较快地评估建筑结构的抗地震倒塌能力,首先利用静力非线性(pushover)分析,获得结构倒塌能力的初步估计值aS*,然后将每个地面运动记录调整到aS*,对结构进行动力时程分析,记录结构的动力时程反应,利用IDA的思想得到结构的中值数倒塌谱强度?CTS。该方法与传统的增量动力分析方法相比较,可提高计算效率,计算精度也满足要求。 相似文献
236.
An interdisciplinary approach is necessary for flood risk assessment. Questions are often raised about which factors should
be considered important in assessing the flood risk in an area and how to quantify these factors. This article defines and
quantitatively evaluates the flood risk factors that would affect the Day River Flood Diversion Area in the context of integrated
flood management in the Red River Delta, Vietnam. Expert analysis, in conjunction with field survey and Analytical Hierarchy
Process (AHP), is applied to define and quantify parameters (indicators, subcomponents, and components) that contribute to
flood risk. Flood duration is found to be the most prominent indicator in determining flood hazard. Residential buildings,
population, and pollution are other fairly significant indicators contributing to flood vulnerability from the economic, social,
and environmental perspectives, respectively. The study results will be useful in developing comprehensive flood risk maps
for policy-makers and responsible authorities. Besides, local residents will also be able to implement suitable measures for
reducing flood risk in the study area. 相似文献
237.
238.
239.
煤矸石-水相互作用的溶解动力学及其环境地球化学效应研究 总被引:17,自引:1,他引:17
党志 《矿物岩石地球化学通报》1997,(4)
煤矸石—水相互作用的溶解动力学及其环境地球化学效应研究党志(中国科学院地球化学研究所,贵阳550002)关键词水—岩作用煤矸石地球化学动力学采煤矿区复垦环境效应收稿日期:1997-3-10作者简介:党志男1962年生博士生环境地球化学煤矸石以其量多、... 相似文献
240.
Ding Ziwei Nguyen Hoang Bui Xuan-Nam Zhou Jian Moayedi Hossein 《Natural Resources Research》2020,29(2):751-769
Natural Resources Research - In this paper, we developed a novel hybrid model ICA–XGBoost for estimating blast-produced ground vibration in a mine based on extreme gradient boosting (XGBoost)... 相似文献