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991.
Urban roadside soils are the “recipients” of large amounts of heavy metals from a variety of sources including vehicle emissions,
coal burning waste and other activities. The behavior of heavy metals in urban roadside soils depends on the occurrence as
well as the total amount. Accordingly, knowledge of the interactions between heavy metals and other constituents in the soil
is required to judge their environmental impact. In this study, correlations of heavy metal concentrations (Pb, Zn, Cu, Ag,
Se, Ni, Cr and Ba) to iron extracted using dithionite–citrate–bicarbonate (DCB) buffer (FeDCB), fulvic acids and particle size fractions were examined from the Xuzhou urban roadside soils. Heavy metals except for Cr
and fulvic acids had a positive significant correlation with FeDCB, indicating these metals and fulvic acids are principally associated with the surfaces of iron oxides of the soils. Significant
positive correlations were also found between the contents of fulvic acids and heavy metals, showing these heavy metals (especially
for Cu, Ni and Cr) form stable complexes with fulvic acids. Such finding is of importance with regard to the increased mobilization
of heavy metals, e.g., into freshwater ecosystems. Ag, Se and Cr are independent of particle size fractions because of their
low concentrations of Ag and Se in the studied soils. Pb, Zn, Cu, Ba and Ag are mainly enriched in the finer soil particles
(especially <16 μm). 相似文献
992.
将偏最小二乘回归(PLS)与神经网络(NN)耦合,建立了储层参数预报模型。利用偏最小二乘对影响储层参数的诸多因素进行分析,提取对因变量影响强的成分,从而克服了变量间的多重相关性问题,降低了神经网络的输入维数;同时,利用神经网络建模可以较好地解决非线性的储层参数预测问题。计算实例表明,本耦合模型的拟合和预报精度优于独立使用神经网络模型的精度。 相似文献
993.
基于人工免疫算法的数据压缩技术在滑坡异常提取中的应用研究 总被引:1,自引:0,他引:1
滑坡异常信息提取对滑坡预测预报至关重要。以四川丹巴滑坡为例,应用人工免疫算法对滑坡镜2、镜6和镜9的位移监测数据进行压缩,分别获得最优压缩率为0.821,0.819,0.829,保真度为0.95。并在置信水平为0.95的条件下,对压缩后数据进行异常提取,分别获得了3个监测点的4个异常信息。这些异常信息所反映的滑坡变形发展演化规律与滑坡声发射等其他监测信息所反映的规律基本保持一致,说明应用人工免疫算法对滑坡位移监测数据进行压缩处理可以在保持原有数据的特性与规律的同时,有效除去监测数据中的冗余与不相关信息,增加有效数据密度,有利于准确提取滑坡异常信息。 相似文献
994.
995.
1:10000地形图植被要素的采集和更新较为复杂,考虑国土部门现有的现势性较强的土地利用现状数据可以用来补充1:10000地形图中的植被信息,积极开展试验。本文作者利用广东省现有的土地利用现状数据,结合航空(卫星)正射影像图、1:10000矢量数据进行了充分试验,走出了一条植被更新的新路子,为省级基础地理信息数据库的完善和更新提供了一种新方法。 相似文献
996.
This article treats the possibility of using artificial neural networks for road detection from high-resolution satellite images on a part of RGB Ikonos and Quick-Bird images from Kish Island and Bushehr Harbor, respectively. Attempts are also made to verify the impacts of different input parameters on network's ability to find out optimum input vector for the problem. A variety of network structures with different iteration times are used to determine the best network structure and termination condition in training stage.It was found that when the input parameters are made up of spectral information and distances of pixels to road mean vector in a 3 × 3 window, the network's ability in both road and background detection can be improved in comparison with simple networks that simply use spectral information of a single pixel in their input vector. 相似文献
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Sequential chemical extraction procedure has been widely used to partition particulate trace metals into vari-ous fractions and to describe the distribution and the statue of trace metals in geo-environment.One sequential chemical extraction procedure was employed here to partition various fractions of Mn in soils.The experiment was designed with quality controlling concept in order to show sampling and analytical error.Experimental results obtained on duplicate analy-sis of all soil samples demonstrated that the precision was less than 10%(at 95% confidence level).The accuracy was estimated by comparing the accepted total concentration of Mn in standard reference materials (SRMs) with the measured sum of the individual fractions.The recovery of Mn from SRM1 and SRM2 was 94.1% and 98.4%,respectively.The detection limit,accuracy and precision of the sequential chemical extraction procedure were discussed in detailed.All the results suggest that the trueness of the analytical method is satisfactory. 相似文献