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301.
本文基于多频组合观测值探测周跳的原理,利用模拟的GPS L5数据与L1、L2进行不同的线性组合,选取(0,1,-1)、(-1,8,-7)和(1,-6,5)3个波长较长、线性不相关且几何距离无关、观测噪声较小的组合,对实测数据人为加入了大小不同的周跳组合,周跳探测结果表明,三频甚至多频组合观测值能够实时探测各种情况下的周跳。 相似文献
302.
Reduced availability of plant nutrients such as nitrogen (N) and phosphorous (P) has detrimental effects on plant growth. Plant N:P ratio, calculated as the quotient of N and P concentrations, is an ecological indicator of relative N and P limitation. Remote sensing has already been widely used to detect plant traits in foliage, particularly canopy N and P concentrations and could be used to detect canopy N:P faster and at lower cost than traditional destructive methods. Despite the potential opportunity of applying remote sensing techniques to detect canopy N:P, studies investigating canopy N:P remote detection are scarce. In this study, we examined if vegetation indices developed for canopy N or P detection can also be used for canopy N:P detection. Using in situ spectrometry, we measured the reflectance of a common grass species, Yorkshire fog (Holcus lanatus L.), grown under different nutrient ratios and levels. We calculated 60 VIs found in literature and compared them to optimized VIs developed specifically for this study. The VIs were calculated using both the original narrow band spectra and the spectra resampled to the band properties of six satellite sensors (MSI – Sentinel 2, OLCI – Sentinel 3, MODIS – Terra/Aqua, OLI – Landsat 8, WorldView 4 and RapidEye) to investigate the influence of bandwidths and band positions. The results showed that canopy N:P was significantly related to both existing VIs (r2 = 0.16 - 0.48) and optimized VIs (r2 = 0.59 – 0.72) with correlations similar to what was observed for canopy N or canopy P. Existing VIs calculated with MSI and OLI sensors bands showed higher correlation with canopy N:P compared to the other sensors while the correlation with optimized VIs was not affected by the differences in sensors’ bands. This study might lead to future practical applications using in situ reflectance measurements to sense canopy N:P in grasslands. 相似文献
303.
The Householder transformation-norm structure function in L2 vector space of linear algebra is introduced, and the edge enhancement for remote sensing images is realized. The experiment result is compared with traditional Laplacian and Sobel edge enhancements and it shows that the effect of the new method is better than that of the traditional algorithms. 相似文献
304.
金新祥 《武汉大学学报(信息科学版)》1989,14(3):59-67
本文首先建立了先后对残差和未知数施加一次范数最小约束的观测值残差和未知数一次范数(以下简称L-X-1范数)最小平差模型然后提出了可以较好地解决L-1范数最小解不唯一性的L-X-1范数最小平差的平均极点解;接着讨论了一次范数最小解的精度评定问题;最后将L-X-1范数最小平差用于观测值中含粗差的变形分析,并给出了若干算例。 相似文献
305.
306.
基于2DPCA的图像融合算法是一种新近提出的图像融合技术,它是通过图像矩阵右乘投影矩阵来实现2DPCA分析的。因而,这种算法能够有效利用图像的二维结构信息,具有良好的性能,不仅能够提高融合图像的空间分辨率,而且使光谱信息得到较好保持。提出了一种通过图像矩阵左乘最优投影矩阵来实现2DPCA分析的图像融合算法,即L2DPCA图像融合算法,并将2DPCA算法和L2DPCA算法与经典的BROVEY、PCA和H IS三种图像融合算法进行了对比研究。结果表明:2DPCA算法和L2DPCA算法的性能明显优于这三种经典的算法。 相似文献
307.
首先对Baarda法的原理和不足进行了讨论,提出用L1-范数解的残差直接构成统计量进行粗差探测与定位,通过实例对两种方法进行了比较,得到一些有用的结论。 相似文献
308.
Shuxun SHAO Baoshan ZHENG Xiaoyan LI Mingshi WANG Xiaojing LIU Chong LUO Hongcan SU 《中国地球化学学报》2006,25(B08):134-134
The Enshi area, Hubei Province in China, is a typical seleniferous environment, where seleniferous carbonaceous shale and carbonaceous siliceous rocks of Permian widely occur. In the 1960's, the first selenosis case in the human population in the world had even brought out at Yutangba Village, Shuanghe community, which resulted in move-off all local residenters The Enshi area possesses the advantageous natural conditions to develop Se-hyperaccnmulator. The selenosis case of human population may be related to having eaten the wild vegetable hyperaccumulating selenium. Mao Dajun (1997) found that the most seleniferous plant was cabbage in the Enshi area which contains Se 224.30 mg/kg. In order to find out Se-hyperaccnmulator in China as soon as possible, the present research made a lot of work on many numbers of wild plants which grow in Enshi, Hubei Province, China. Finally, we found Thlaspi arvenst L., the first Se-hyperaccumulator of China at Yutangba Village. In this plant, Thlaspi arvenst L., the contents of selenium (DW) are 802-870 mg/kg (the average 843 mg/kg) for the whole plant, 1121 mg/kg for root, 511 mg/kg for stem and 1427 mg/kg for leaf, respectively. The newly found Thlaspi arvenst L. by us is the most seleniferous plant which has been found in China up to now, whose Se in its leaf is higher than the international criterion of 1000 mg/kg for Se-hyperaccnmulator. 相似文献
309.
天山中段及祁连山东段小冰期以来的冰川及环境 总被引:22,自引:0,他引:22
本文通过考察、航片判读、及AAR法测算了冰川变化,用地衣、文史资料、及树轮年表进行了小冰期的测年,使用实测资料分析、冰岩芯及树轮资料等估算了小冰期的气温与降水、并进而计算了地表径流的变化。在全部讨论中,还引用了一些试验性的方法和公式。 相似文献
310.