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911.
研究了12次7级地震和44次6级地震震前震源区及其附近发生的显著地震地方平太阴时τ的分布规律.根据月亮在地球内任一点形成的起潮力是一个主要周期为12h25min左右的周期性函数及月亮在地方平太阴时相隔180°的两个位置上对地球内任一点起潮力基本相同这一现象,计算了大地震前两个显著地震地方平太阴时τ的夹角△τA以及两个显著地震地方平太阴时与主震地方平太阴时夹角的平均值△τB。计算结果表明,对大部分地震,△τA≤45°和△τB≤45°,说明显著地震和主震发生时,月亮差不多都在震源区的同一方位或与这一方位相隔180°的位置附近.用裂隙串通地震孕育模式对这一现象作了解释,认为显著地震和主震的地方平太阴时的分布都与主震断层走向有关.指出△τA≤45°这一现象可作为一种地震前兆用于地震预报。 相似文献
912.
本文展示了1989年9月22日小金北Ms6.6级强烈地震前,距震中140km、150km和160km的三处不同台基条件、不同型号的倾斜仪、一处水氡观测点所观测到的中、短期和临震异常。中期异常表现为:长期的规律被打破。短临异常表现为中期异常基础上的急剧加速、回跳。 相似文献
913.
Tide gauge records of Hong Kong covering the past 45 years (1954.0–1999.0) are adopted to analyze the basic features of sea
level changes in the region. Data sets of atmospheric pressure, southern oscillation index and sea surface temperature during
the same time span are also used to determine the possible link between the sea level changes in Hong Kong and local and global
geophysical processes. Results indicate that the sea level of Hong Kong has a rising trend of 1.9 ± 0.4 mm per year, and that
there is an upward offset of about 15 cm in the pre-1957.0 tide gauge records. The effect of local atmospheric pressure variations
on the amplitude of the annual sea level change is about 30% of the amplitude that is calculated after the effect is corrected.
It is also found that the interannual variations in the sea level of Hong Kong are related to El Ni?o and La Ni?a events that
happen frequently in the tropical Pacific.
Received: 27 October 1999 / Accepted: 15 August 2000 相似文献
914.
915.
在总结辽宁非网上位、流量固体潮畸变震例的基础上,探讨了水位、流量固体潮畸变异常与地震时、空、强三要素关系,并在利用地下水微动态预报地震方面做了有益地探索。 相似文献
916.
乌鲁木齐和阿拉木图地区部分地震前固体潮小震调制比的异常 总被引:2,自引:0,他引:2
利用固体潮小震调制比方法,从外因调制的角度出发,定量研究新疆乌鲁木齐和苏联阿拉木图地区小震活动。结果发现,若干次较大地震前出现调制比的异常变化是固体潮引潮力对地震的调制触发作用而引起的。依据耗散结构理论解释固体潮小震调制比方法的物理机制。 相似文献
917.
It is proved that the Testing Geopotential Model (TGM) results in identical model distortions when TGM is performed in the mean, zero, and tide- free systems. The Molodensky quasigeoid height is invariant in relation to different tide systems, however, the Molodensky normal height, the ellipsoidal height, as well as, the actual geopotential, expressed in the above different tide systems, differ. 相似文献
918.
919.
920.
Longwave Measurements for the Coast of British Columbia and Improvements to the Tsunami Warning Capability 总被引:1,自引:0,他引:1
A few years ago the Canadian Hydrographic Service initiated a major upgrade toall tide gauges and tsunami stations on the coast of British Columbia (B.C.). Thisprogram was undertaken to address shortcomings of the earlier digital systems andwas driven by concerns about emergency response continuity in the year 2000. By1999, thirteen tide gauge stations had been installed and were operational. Three ofthese stations (Tofino, Winter Harbour, and Langara) were selected for use as tsunamiwarning stations. Several years of continuous, high quality data have now been collectedat these stations and used for analysis of long waves in the tsunami frequency band.Careful examination of these data revealed two weak tsunamis recorded by severalB.C. stations: a distant tsunami of June 23, 2001 generated by the Peru Earthquake(Mw = 8.4), and a local tsunami of October 12, 2001 induced by the Queen Charlotte Earthquake (Mw = 6.3$). Spectral characteristics of these two tsunamis are compared with the spectral characteristics of long waves generated by a strong storm (October, 2000) and of ordinary background oscillations. The topographic admittance functions (frequency responses) constructed for all stations showed that most of them (in particular, Winter Harbour, Tofino, Bamfield, Port Hardy, and Victoria) have strong resonance at periods from 2.5 to 20 min, indicating that these locations are vulnerable to relatively high-frequency tsunamis. The Winter Harbour station also has two strong resonant peaks with periods of 30 and 47 min and with amplification factors of about 7. The estimated source functions show very clear differences between long waves associated with the seismic source (typical periods 10–30 min) and those generated by a storm, which typically have shorter periods and strong energy pumping from high-frequencies due to non-linear interaction of wind waves. 相似文献