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991.
地震是大量的岩石破裂事件.很多大地震之前都存在瞬态信号:电磁信号、磁场变化、电离层扰动、土壤导电率的变化以及其他震前信号.令监测人员奇怪的是,在震前短时间内一些震前信号会衰弱甚至消失不见.岩石中应力活化电流的发现提供了一个可能的解释,应力能够激活岩石中的移动电荷载体,即电子空位缺陷(electron vacancy d... 相似文献
992.
Global upper ocean heat content and climate variability 总被引:3,自引:2,他引:1
Peter C. Chu 《Ocean Dynamics》2011,61(8):1189-1204
Observational data from the Global Temperature and Salinity Profile Program were used to calculate the upper ocean heat content
(OHC) anomaly. The thickness of the upper layer is taken as 300 m for the Pacific/Atlantic Ocean and 150 m for the Indian
Ocean since the Indian Ocean has shallower thermoclines. First, the optimal spectral decomposition scheme was used to build
up monthly synoptic temperature and salinity dataset for January 1990 to December 2009 on 1° × 1° grids and the same 33 vertical
levels as the World Ocean Atlas. Then, the monthly varying upper layer OHC field (H) was obtained. Second, a composite analysis was conducted to obtain the total-time mean OHC field ([`([`(H)])] \bar{\bar{H}} ) and the monthly mean OHC variability (
[(\textH)\tilde] \widetilde{\text{H}} ), which is found an order of magnitude smaller than
[^(\textH)] \widehat{\text{H}} . Third, an empirical orthogonal function (EOF) method is conducted on the residue data (
[^(\textH)] \widehat{\text{H}} ), deviating from
[(\textH)\tilde] \widetilde{\text{H}} +
[(\textH)\tilde] \widetilde{\text{H}} , in order to obtain interannual variations of the OHC fields for the three oceans. In the Pacific Ocean, the first two EOF
modes account for 51.46% and 13.71% of the variance, representing canonical El Nino/La Nina (EOF-1) and pseudo-El Nino/La
Nina (i.e., El Nino Modoki; EOF-2) events. In the Indian Ocean, the first two EOF modes account for 24.27% and 20.94% of the
variance, representing basin-scale cooling/warming (EOF-1) and Indian Ocean Dipole (EOF-2) events. In the Atlantic Ocean,
the first EOF mode accounts for 49.26% of the variance, representing a basin-scale cooling/warming (EOF-1) event. The second
EOF mode accounts for 8.83% of the variance. Different from the Pacific and Indian Oceans, there is no zonal dipole mode in
the tropical Atlantic Ocean. Fourth, evident lag correlation coefficients are found between the first principal component
of the Pacific Ocean and the Southern Oscillation Index with a maximum correlation coefficient (0.68) at 1-month lead of the
EOF-1 and between the second principal component of the Indian Ocean and the Dipole Mode Index with maximum values (around
0.53) at 1–2-month advance of the EOF-2. It implies that OHC anomaly contains climate variability signals. 相似文献
993.
994.
草莓状黄铁矿是指由等粒度的亚微米级黄铁矿晶体或微晶体紧密堆积而成,形似草莓的黄铁矿球形集合体.它们在氧化和缺氧海洋环境中形成的机理不同,沉积岩中草莓状黄铁矿的粒径分布特征是恢复古海洋的氧化还原状态行之有效的方法之一.然而,草莓状黄铁矿粒径统计仅能区分出氧化和缺氧硫化的环境,不能进一步区分缺氧程度及状态(如次氧化、缺氧含... 相似文献
995.
An improved particle swarm optimization algorithm with harmony strategy for the location of critical slip surface of slopes 总被引:1,自引:0,他引:1
The determination of optimal values for three parameters required in the original particle swarm optimization algorithm is very difficult.It is proposed that two new parameters simulating the harmony search strategy can be adopted instead of the three parameters which are required in the original particle swarm optimization algorithm to update the positions of all the particles.The improved particle swarm optimization is used in the location of the critical slip surface of soil slope,and it is found that the improved particle swarm optimization algorithm is insensitive to the two parameters while the original particle swarm optimization algorithm can be sensitive to its three parameters. 相似文献
996.
Using widespread conductivity–temperature–depth (CTD) data in the Philippine Sea and northern South China Sea near the Luzon
Strait together with altimeter data, we identified an intrusion of water from the Kuroshio into the South China Sea (SCS)
through the Luzon Strait in September 2008. The Kuroshio water obviously intruded into the SCS from 20 to 21°N, and existed
mainly in the upper 300 m. The intrusion water extended as far west as 117°E, then looped around in an anticyclonic eddy and
returned to the Philippine Sea further north. The dynamics of the Kuroshio intrusion are discussed using a 1.5-layer nonlinear
shallow-water reduced-gravity model. The analysis suggests that the strong cyclonic eddy to the east of the Kuroshio in September
2008 was of benefit to the intrusion event. 相似文献
997.
998.
999.
The Optimal Cross-section Design of the “Trapezoid-V” Shaped Drainage Canal of Viscous Debris Flow 总被引:1,自引:0,他引:1
Debris flow drainage canal is one of the most widely used engineering measures to prevent and manage debris flow hazards.The shape and the sizes of the cross-section are important parameters when design debris flow drainage canal.Therefore,how to design the appropriate shape and sizes of the cross-section so that the drainage canal can have the optimal drainage capacity is very important and few researched at home and abroad.This study was conducted to analyze the hydraulic condition of a Trapezoid-V shaped drainage canal and optimize its cross-section.By assuming characteristic sizes of the cross-section,the paper deduced the configuration parameter of the cross-section of a Trapezoid-V shaped debris flow drainage canal.By theory analysis,it indicates that the optimal configuration parameter is only related to the side slope coefficient and the bottom transverse slope coefficient.For this study,the Heishui Gully,a first-order tributary of the lower Jinsha River,was used as an example to design the optimal cross-section of the drainage canal of debris flow. 相似文献
1000.
台风“莫拉克”影响期间浙江大风成因分析 总被引:1,自引:0,他引:1
利用常规资料、浙江省自动站加密资料、NCEP/NCAR1°×1°每日4次再分析资料和多普勒天气雷达资料对2009年第8号台风“莫拉克”影响期间浙江大风的成因进行了分析。此次台风大风影响具有影响时间早、持续时间长、影响范围大和大风强度强的特点。副热带高压快速加强西进是造成台风大风提早出现的主要原因之一。鞍型场、3个台风相互影响使得“莫拉克”台风移速减慢,导致台风大风对浙江沿海的影响时间增长。“莫拉克”登陆福建后其西北侧华北高压以及东南侧海上高压的存在使得地面气压梯度维持,导致大风影响时间增长和影响范围增大。垂直方向环流将高层动量下传导致低层风速猛增。多普勒天气雷达径向速度产品VCP21进行速度退模糊后可以作为台风大风分布范围和极大风速预测的一个参考依据,预测时其在沿海海面效果要较内陆好。 相似文献