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91.
Possible connection between anomalous activity of Scandinavian Atmospheric Teleconnection Pattern and winter snowfall in the Yangtze-Huaihe River Basin of China
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利用中国地面气候资料日值数据集(V3.0)逐日气象资料研究了我国江淮冬季降雪的时空变化及其与斯堪的纳维亚遥相关型(SCAND)的可能联系。结果表明:江淮冬季降雪表现出空间一致的年际变化,SCAND与江淮地区冬季降雪异常关系密切。江淮冬季降雪偏多通常对于SCAND正位相,500hPa阻塞高压、东亚大槽加强,有利于冷空气活动增强,江淮地区垂直运动增强,水汽输送增强;降雪偏少则对应SCAND负位相。研究结果有助于深入理解江淮冬季降雪异常的相关机理。 相似文献
92.
Using NCEP/NCAR reanalysis geopotential height (GHT) and wind at 850 hPa, GHT at 500 hPa, precipitation rate, sea level pressure (SLP) and precipitation observations from more than 600 stations nationwide in June–August from 1951 to 2006, and focusing on the East Asia–West Pacific region (10o–80oN, 70o–180oE), interannual variation of East Asian summer monsoon (EASM) and its correlations with general circulation and precipitation patterns are studied by using statistical diagnostic methods such as 9-point high pass filtering, empirical orthogonal function (EOF) analysis, composite analysis and other statistical diagnosis, etc. It is concluded as follows: (1) EOF analysis of SLP in the East Asia–West Pacific region shows the existence of the zonal dipole oscillation mode (APD) between the Mongolia depression and the West Pacific high, and APD index can be used as an intensity index of EASM. (2) EOF analysis of GHT anomalies at 500 hPa in the East Asia–West Pacific region shows that the first EOF mode is characterized with an obvious meridional East Asian pattern (EAP), and EAP index can also be used as an EASM intensity index. (3) The composite analysis of high/low APD index years reveals the close correlation of APD index with EAP at 500 hPa (or 850 hPa). The study shows an obvious opposite correlation exists between APD index and EAP index with a correlation coefficient of –0.23, which passes the confidence test at 0.10 level. (4) Both APD and EAP indexes are closely correlated with precipitation during flood-prone season in China and precipitation rate over the East Asia–West Pacific region. The significant correlation area at 5% confidence level is mainly located from the southern area of the Yangtze River valley to the ocean around southern Japan, and the former is a positive correlation and the latter is a negative one. 相似文献
93.
Laura Valentini Bruno Capaccioni Piermaria Luigi Rossi Roberto Scandone Damiano Sarocchi 《Bulletin of Volcanology》2008,70(9):1087-1101
In order to provide new information about the source area and depositional mechanisms of the Upper Member of the Neapolitan
Yellow Tuff (NYT), a prominent pyroclastic deposit of the Campi Flegrei Volcanic District (southern Italy), statistics on
directional fabric, by means of computer-assisted image analysis on 32 rock samples, were compiled. Seventeen samples were
collected along vertical direction on two selected exposures and fifteen were taken from outcrops widely distributed all around
the Campi Flegrei Volcanic District. Fabric measurements within the investigated successions reveal a vertically homogeneous
direction of the mean particle iso-orientation, with considerable variability in the strength of particle iso-orientation
even at cm-scale. The existence of particle iso-orientation can be related to continuous sedimentation from a concentrated
bedload region beneath suspension currents, producing massive or inversely graded beds by traction carpet sedimentation. The
considerable vertical variability in the strength of iso-orientation is the result of very unstable flow regimes, up to the
extreme condition of discrete depositional events, with a variable combination of traction carpet and/or direct suspension
sedimentation. The vertical homogeneity in the mean orientation values, found in the investigated sections, may derive from
the sequential deposition of laminae to thin beds, whose relatively flat upper surfaces were unable to significantly deflect
the depositional system of the following currents. According to the observed homogeneous mean particle orientation values
along the investigated vertical profiles, samples collected through areal distribution are considered representative of the
local paleo-flow directions of the whole deposit. The mean directions of the samples collected areally show two different
coherent patterns which point to the existence of two different source areas. The first, which includes all samples from the
northern outcrops, appears to converge in a narrow area about 2 km NE of the town of Pozzuoli, largely in coincidence with
the inferred area on the basis of the pumice fall distribution. The second, which includes samples from Capo Miseno and Posillipo
areas, points to the central part of the Pozzuoli Bay, about 4 km offshore the town of Pozzuoli. 相似文献
94.
Identification of fuel samples from the Prestige wreckage by pattern recognition methods 总被引:1,自引:0,他引:1
Fernández-Varela R Andrade JM Muniategui S Prada D Ramírez-Villalobos F 《Marine pollution bulletin》2008,56(2):335-347
A set of 34 worldwide crude oils, 12 distilled products (kerosene, gas oils, and fuel oils) and 45 oil samples taken from several Galician beaches (NW Spain) after the wreckage of the Prestige tanker off the Galician coast was studied. Gas chromatography with flame ionization detection was combined with chemometric multivariate pattern recognition methods (principal components analysis, cluster analysis and Kohonen neural networks) to differentiate and characterize the Prestige fuel oil. All multivariate studies differentiated between several groups of crude oils, fuel oils, distilled products, and samples belonging to the Prestige's wreck and samples from other illegal discharges. In addition, a reduced set of 13 n-alkanes out of 36, were statistically selected by Procrustes Rotation to cope with the main patterns in the datasets. These variables retained the most important characteristics of the data set and lead to a fast and cheap analytical screening methodology. 相似文献
95.
96.
赤潮的爆发是生物、化学、物理等多因素综合作用的结果。温度、风力、风向、气压等气象条件,海况、潮汐、海流及海水的理化特征,如海水温度、盐度、营养盐、微量元素等都是赤潮爆发的重要因子或诱导因素。当前由于海洋生态领域的数值预报仍不成熟,国内的赤潮预测主要还是依靠经验和统计方法为主,如气象条件预报法、水文条件预报法、化学条件预报法、生物条件预报法、卫星遥感预报法或是综合预报法等。本文根据2001年~2005年《沿海海洋赤潮专报》中广东省阳江到汕尾沿海(112°~116°E)即珠江口地区发生赤潮的记录,使用NCEP再分析数据,从气象条件诱发赤潮的角度分析得出最易引发珠江口赤潮的5种天气形势,并用相关性分析方法得出其中两种天气形势的典型场,对预测珠江口沿海的赤潮发生具有一定的指导意义,可在实践中加以应用。 相似文献
97.
将SVM(Support Vector Machine)分类和回归方法首次应用于气象预报试验。利用1990~2000年4~9月ECMWF北半球的500 hPa高度、850 hPa温度、地面气压的00:00 UTC分析场资料,建立四川盆地分区面雨量有无大于15 mm的SVM分类推理模型、四川盆地内单站气温的SVM回归推理模型,进行相应的预报试验,试验结果显示对应的SVM推理模型具有良好的预报能力。 相似文献
98.
河南省区域暴雨的客观分型 总被引:3,自引:0,他引:3
从多层聚类分析入手,利用微机对1980~1995 年河南省213 场区域暴雨过程的500 hPa 高度场进行客观分型,得出了4 类天气形势及其与暴雨落区的对应关系。 相似文献
99.
以降水的成因和来源为基础出发点,对山西省的降水发生发展和分布特点进行全面研究,分析其在时间和空间上的变化趋势和特点,对水资源根本基础进行深入探讨,为整个地区的水资源分析评价和水资源发展战略规划及水生态和水环境保护提供科学参考依据. 相似文献