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951.
A modified counter propagation network model and an extended self-organizing map model have the same three-layer network architecture
while employing slightly different learning rules. Their network architecture comprises an input layer, a Kohonen layer and
an output layer. The neurons between two neighboring layers are fully connected and the neighboring neurons within the Kohonen
layer also have neighborhood connections. The modified counter propagation network model employs the Kohonen algorithm to
train the Kohonen layer while using the Widrow–Hoff rule to train the output layer. However, the extended self-organizing
map model applies a modified Kohonen’s learning rule to train both the Kohonen layer and the output layer. This paper compares
the performances of these two models in supervised classification of remotely sensed data. The training results show that
compared to the extended self-organizing map model, the modified counter propagation model has faster learning speed but larger
output errors. The classification results indicate that the extended self-organizing map model has a faster classification
speed and a much higher classification precision than the modified counter propagation model. 相似文献
952.
Trace变换是一种新的图象重建工具,在图象重建方面已取得很好的效果。推导了Trace变换公式中的一个公式:∫(ε(t))rdtq的反变换公式,并结合τ-p变换中坐标系的转换关系,讨论了它在地震勘探中应用的可能性。对80道单一理论水平合成记录作了正、反变换的分析。从原记录和反变换记录中分别取道分析,分析结果表明对80道理论水平记录能很好的恢复。 相似文献
953.
中国城市固体废弃物甲烷排放研究 总被引:2,自引:0,他引:2
The greenhouse effect of methane (CH4) is only inferior to that of carbon dioxide (CO2). As an important anthropogenic emission source, the calculation of the emission amount of CH4 from waste treatment in landfills plays an important role in compiling greenhouse gases inventory and in estimating the climate change effects caused by increasing of greenhouse gases. Based on the previous work, and according to the sampling and analysis on municipal solid waste (MSW) in typical cities, the degradable organic carbon (DOC) percentile was identified in typical cities in recent years. According to the IPCC greenhouse gases inventory guideline and default method of CH4 emission from MSW landfills, and in light of MSW managing situation in different regions, the amount of CH4 emission was calculated. The results show that the amount of CH4 emission decreases geographically from east to west and it increases temporally from 1994 to 2004 in China. 相似文献
954.
955.
CHEN Luyao YUE Jianwei JIANG Weiguo LI Jing CHEN Yunhao 《地球空间信息科学学报》2007,10(4):299-302
The unceasing change problem of land information systems can be resolved through the refactoring and design pattern. To promote the implementation of design pattern and refactoring methods in developin... 相似文献
956.
针对三维激光测高拟合问题,本文采用BP神经网络进行拟合,该方法可以有效地消除或减弱数据中的系统误差影响,提高计算精度。实际算例证明,在数据无粗差情况下,BP神经网络的内符合与外符合精度优于传统的二次曲面拟合的精度。 相似文献
957.
古代测量是中国古代文明的重要组成部分,它是适应农耕与征战的需要最早发展起来的实用技术之一。中国大地测量源于距今近5000年的原始社会末期的三皇五帝时代。几千年来,中国大地测量经历了从步量、丈量到立杆测影、仪器观测的发展过程。距今2000年的西汉时期,发明了浑天仪,开始了使用仪器测量地面点地理坐标的新阶段。公元724年,僧人一行与南宫说在黄河中游的平坦地区进行了世界上最早的子午线测量。16世纪后期,意大利人利玛窦带来了西方的测量技术,从此开始了中国传统大地测量与西方测量方法并行、融合的进程。明末清初,利用天文测地的方法在全国范围内测定了几十个经纬度点,为地图绘制提供了控制基础。天圆地方是中国古代最典型宇宙观,是中国古代测量与制图中未能考虑地球曲率的认识根源。简言之,中国古代大地测量成就辉煌,特色明显,与西方古代测量并驾齐驱。 相似文献
958.
959.
本文就利用导航卫星的电文通信功能,进行大数据量数字地图数据传输的通信协议进行了论述。提出了等待式ARQ和选择重发式ARQ相结合的ARQ协议,介绍了该协议的基本思想,详细分析了协议性能并给出了实现协议的算法流程。 相似文献
960.
Observed pollutants are of both primary and secondary origins, influenced by local topography and meteorology. Identifying
sources and relative contribution often require vast detailed data collection and complicated models. This study applied a
statistical time series analysis to two selected pollution events, spring and fall, at two sites in northern Taiwan. Vector
moving average representations were used to quantitatively examine relationships among chemical pollutants and estimate their
lifetimes. Results from impulse responses show that wind direction change alters the characteristic of pollution observed
in opposite sites of Taipei City, from chemical dominant system to transport dominant one and vice versa. Chemicals are clearly
separated into photochemical pollutants and primary pollutants. Results pointed out that Taipei City is the major source of
photochemical smog, but not these primary pollutants. Derived chemical lifetimes at same location vary from 20% to four times
under different meteorological condition. Estimated concentrations of hydroxyl radical range between 2 to 8 × 107 cm−3. Photochemical pollutants are responsible for parts of PM10 collected in both station observed. Oxidation of SO2 is only important in PM10 observed at one station. This study provides a simpler tool to derive information usually from
complex models, therefore, is suitable as complement in decision-making process. 相似文献