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991.
分析了多种金字塔数据结构的生成方法,比较了不同方法在影像匹配中的优劣,并提出了一种影像金字塔生成的快速算法。 相似文献
992.
数据质量控制是良好的数字地形图质量的重要保证。文中从野外采集数据和地图数字化两个方面分析了影响大比例尺数字地形图数据质量的因素,讨论了数据质量控制的方法。 相似文献
993.
994.
QIAO Yanxiao LI Miwen Remote Sensing Center of Hebei Province Huaizhong Rd. Shijiazhuang Hebei 《《地质学报》英文版》2000,74(2):334-338
The Taihang Mountains area is an area in North China where serious mudflow hazards take place frequently. The hazards often obstrust traffic and make it difficult to carry out conventional ground investigations of the mudflow hazards. This paper introduces the feasibility study of mudflow hazards by using Landsat-5TM data. The study has achieved a great success through adopting both the faint spectral enhancement technique for mudflow fans (or other depositional areas) and comprehensive study of the environmental background of pregnant mudflows. Thus, remote sensing as a fast, convenient, low-cost and effective technical method can be used to recognise the situation of mudflow hazards so that effective rescue can be provided. 相似文献
995.
电视测井中的图象处理问题 总被引:5,自引:3,他引:2
电视测井采集到的原始视频图象经过几何空间变换,图像象素重采样,最终生成可供地质分析解释的井壁表面图象文件。此外,必须动态识别指北针的图像以确定井下探头的方位,并以识别的北方位为起点守成图象的几何空间变换。基于井场施工效率和井下探头的安全原因,探头井中以4cm/s左右的速度下落,图像处理过程必须与探的落保持同步,因而还具有一定程度的实时性要求。 相似文献
996.
辽东湾绥中海岸演变及悬沙分布特征的遥感分析 总被引:6,自引:0,他引:6
本文利用辽东湾绥中地区22个年度(1975~1997年)的多时相卫星资料,分析绥中海岸自芷锚湾至狗河口约30km岸线的动态特征、近岸泥沙运动特点和悬浮泥沙的分布状况。所得结果表明,该段海岸近期处于相对稳定状态,近岸悬浮泥沙浓度较小,一般在10~50mg/L范围,是建设大中型海港码头的可选优良岸段。此外,通过遥感图象处理并结合现场调查,分析了近期近岸输沙特征和已建码头突堤堤根岸线淤涨特征,指出绥中沿岸输沙的主要方向是自西向东。 相似文献
997.
998.
C. Baccigalupi L. Bedini C. Burigana G. De Zotti A. Farusi D. Maino M. Maris F. Perrotta E. Salerno L. Toffolatti A. Tonazzini 《Monthly notices of the Royal Astronomical Society》2000,318(3):769-780
We implement an independent component analysis (ICA) algorithm to separate signals of different origin in sky maps at several frequencies. Owing to its self-organizing capability, it works without prior assumptions on either the frequency dependence or the angular power spectrum of the various signals; rather, it learns directly from the input data how to identify the statistically independent components, on the assumption that all but, at most, one of the components have non-Gaussian distributions.
We have applied the ICA algorithm to simulated patches of the sky at the four frequencies (30, 44, 70 and 100 GHz) used by the Low Frequency Instrument of the European Space Agency's Planck satellite. Simulations include the cosmic microwave background (CMB), the synchrotron and thermal dust emissions, and extragalactic radio sources. The effects of the angular response functions of the detectors and of instrumental noise have been ignored in this first exploratory study. The ICA algorithm reconstructs the spatial distribution of each component with rms errors of about 1 per cent for the CMB, and 10 per cent for the much weaker Galactic components. Radio sources are almost completely recovered down to a flux limit corresponding to ≃0.7 σCMB , where σ CMB is the rms level of the CMB fluctuations. The signal recovered has equal quality on all scales larger than the pixel size. In addition, we show that for the strongest components (CMB and radio sources) the frequency scaling is recovered with per cent precision. Thus, algorithms of the type presented here appear to be very promising tools for component separation. On the other hand, we have been dealing here with a highly idealized situation. Work to include instrumental noise, the effect of different resolving powers at different frequencies and a more complete and realistic characterization of astrophysical foregrounds is in progress. 相似文献
We have applied the ICA algorithm to simulated patches of the sky at the four frequencies (30, 44, 70 and 100 GHz) used by the Low Frequency Instrument of the European Space Agency's Planck satellite. Simulations include the cosmic microwave background (CMB), the synchrotron and thermal dust emissions, and extragalactic radio sources. The effects of the angular response functions of the detectors and of instrumental noise have been ignored in this first exploratory study. The ICA algorithm reconstructs the spatial distribution of each component with rms errors of about 1 per cent for the CMB, and 10 per cent for the much weaker Galactic components. Radio sources are almost completely recovered down to a flux limit corresponding to ≃0.7 σ
999.
A. Müller 《Geophysical Journal International》2000,142(1):257-269
Error estimates from statistical regression analysis are often obviously too small, leading to doubts about the given equations, the statistical method itself and finally, with resignation, to the conclusion that mathematical equations and reality never agree. However, for magnetotelluric data we have found an almost perfect fit between observed scattering and predicted confidence limits of regression coefficients after accounting for a systematic error—the bias.
Different methods to compensate for bias in magnetotelluric impedance estimation have been described using additional data from a reference station. However, sufficiently accurate reference data are often not available. A new method has been developed that enables bias compensation without additional data. For the new method we derive a linear relationship between the effect of bias and an expression depending on the data fit. From this we extrapolate the solution for the unbiased impedance. The new method assumes a special model of uncorrelated noise as well as an approximation for the structure of the impedance tensor. From each pair of components of the unrotated impedance tensor corresponding to the same output channel, one of the pair can be compensated if its magnitude is large compared to that of the other.
The method has been successfully applied in many cases. We claim that the solution is closer to the true impedance than any solution based on the selection of events. It gives a measure of the partitioning of noise between the electric and magnetic channels.
We applied the method to measurements from the North Anatolian Fault Zone (Turkey) and from the Merapi volcano (Central Java) in the period range 10–2500 s. Different instrumentation was used for the two sets of measurements, but in both cases we used fluxgate magnetometers to measure the magnetic variations. 相似文献
Different methods to compensate for bias in magnetotelluric impedance estimation have been described using additional data from a reference station. However, sufficiently accurate reference data are often not available. A new method has been developed that enables bias compensation without additional data. For the new method we derive a linear relationship between the effect of bias and an expression depending on the data fit. From this we extrapolate the solution for the unbiased impedance. The new method assumes a special model of uncorrelated noise as well as an approximation for the structure of the impedance tensor. From each pair of components of the unrotated impedance tensor corresponding to the same output channel, one of the pair can be compensated if its magnitude is large compared to that of the other.
The method has been successfully applied in many cases. We claim that the solution is closer to the true impedance than any solution based on the selection of events. It gives a measure of the partitioning of noise between the electric and magnetic channels.
We applied the method to measurements from the North Anatolian Fault Zone (Turkey) and from the Merapi volcano (Central Java) in the period range 10–2500 s. Different instrumentation was used for the two sets of measurements, but in both cases we used fluxgate magnetometers to measure the magnetic variations. 相似文献
1000.