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本文针对阵列式天线探地雷达系统的目标成像问题,理论模拟分析了最小二乘(LS)估计、Capon估计、幅度相位估计(APES)三种波束形成算法在目标回波到达角(direction of arrival,DOA)估计上的效果和精度,提出了基于DOA估计的阵列式探地雷达逆向投影目标成像方法。该方法综合利用多输入多输出(MIMO)阵列信号估计得到的目标回波信号DOA和阵列空间观测信息对目标体进行成像,通过成像点空间扫描对各测点估计DOA幅度值在成像点的加权积分进行目标定位及反射强度估计。该方法实现简单高效,可以广泛应用于地下简单目标体的快速成像。 相似文献
344.
The characteristics of net radiation (Rn)(0.3--10 μm) in Lhasa and
Haibei in the Tibetan Plateau were analyzed based on long-term in-situ
measurements of surface radiation data. The monthly average of daily
Rn reached a minimum during the winter period followed by an increase
until May and then a decline until January. This variation is consistent
with solar activity. The annual mean daily total Rn values were 0.92 MJ
m-2 d-1 and 0.66 MJ m-2d-1 in Lhasa and Haibei,
respectively.
A relationship between Rn and broadband solar radiation (Rs) was
demonstrated by a good linear correlation at the two sites. Rn can be an
accurate estimate from Rs. The estimated Rn values were similar to the
observed values, and the relative deviations between the estimates and
measurements of Rn were 2.8% and 3.8% in Lhasa and Haibei,
respectively. The application of the Rn estimating model to other
locations showed that it could provide acceptable estimated Rn values from the Rs data. Furthermore, we analyzed the influence of clouds on
Rn by different clear index (Ks), defined as the ratio of Rs to the
extraterrestrial solar irradiance on a horizontal surface. The results
indicate that more accurate results are associated with increased cloudy
conditions. The influence of the albedo was also considered, but its
inclusion in the model resulted in only a slight improvement. Because
surface albedo is not usually measured, an expression based solely on global
solar radiation could be of more extensive use. 相似文献
345.
三维探地雷达数值模拟中UPML边界研究 总被引:1,自引:0,他引:1
应用时域有限差分进行探地雷达正演计算时,边界条件的吸收效果是提高雷达波响应模拟精度的关键因素之一。这里推导出了三维各向异性完全匹配空间UPML吸收边界的计算公式,并编程实现。模拟结果表明:UPML吸收边界在吸收效果,反射误差及计算效率等方面,都明显优于常用的Mur、PML吸收边界,具有较好的模拟效果。采用三维UPML边界的时域有限差法,可以提高探地雷达正演模拟的可靠性、准确度。 相似文献
346.
347.
Tomisław Gołębiowski 《Acta Geophysica》2006,54(4):413-429
The paper presents the results of georadar investigations carried out in the area of the monastery at Tyniec near Cracow for
archaeological purposes. The georadar profiles were designed on the abbey courtyard in a regular grid, which covered the area
of the buildings that currently do not exist. The aim of the measurements was to produce a 3D visualization of former buildings’
foundation. The results of the geophysical measurements were correlated with the information obtained from archaeological
investigations. The georadar surveys confirmed the location of foundations documented by archeologists and new underground
structures were discovered. To aid the interpretation, numerical modelling of the electromagnetic wave field was performed.
Computer modelling allowed to determine the kind and condition of underground structures. 相似文献
348.
The joint application of electromagnetic techniques for near-surface exploration is a useful tool for soil pollution monitoring
and can also contribute towards describing the spatial distribution of pollutants. The results of a geophysical field survey
that was carried out for characterizing the heavy metal and waste disposal soil pollution phenomena in the industrial area
of Val Basento (Basilicata region, Southern Italy) are presented here. First, topsoil magnetic susceptibility measurements
have been carried out for defining the spatial distribution of superficial pollution phenomena in the investigated area. Second,
detailed and integrated measurements based on a high-resolution magnetic mapping and ground probing radar (GPR) profiling
have been applied to investigate the subsurface in two industrial areas located in more polluted sites that were identified
during the first phase. Our monitoring strategy discloses the way to rapidly define the zone characterized by high pollution
levels deriving from chemical industries and traffic emissions and to obtain the way information about the presence of local
buried sources of contamination. 相似文献
349.
钢筋混凝土GPR检测图像的目标体快速识别技术 总被引:2,自引:0,他引:2
HUANG Ling ZENG Zhao-fa YAO Jian ZHANG Dai-guo College of GeoExploration Science Technology Jilin University Changchun China 《吉林大学学报(地球科学版)》2006,(Z2)
在一般的城建工程结构体的探地雷达检测中,为减小检测工作周期,需要进行现场探测、处理及解释;或是检测工区数据量大,逐个剖面进行人工处理解释需要很大的工作量和工作时间。为解决这些问题,引入了基于F—K偏移及小波变换法图像分割的目标体快速识别技术,对钢筋混凝土探地雷达检测图像进行处理,达到了对钢筋混凝土结构探地雷达检测图像快速处理与解释的效果,也为能够把数据处理程序直接嵌入探地雷达系统中提供理论基础。 相似文献
350.