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181.
Mónica M.E. Fiore Enrique E. D’Onofrio Jorge L. Pousa Enrique J. Schnack Germán R. Bértola 《Continental Shelf Research》2009
Positive storm surges (PSS) lasting for several days can raise the water level producing significant differences between the observed level and the astronomical tide. These storm events can be more severe if they coincide with a high tide or if they bracket several tidal cycles, particularly in the case of the highest astronomical tide. Besides, the abnormal sea-level elevation near the coast can cause the highest waves generated to attack the upper beach. This combination of factors can produce severe erosion, threatening sectors located along the coastline. These effects would be more serious if the storm surge height and duration increase as a result of a climatic change. The Mar del Plata (Argentina) coastline and adjacent areas are exposed to such effects. A statistical characterization of PSS based on their intensity, duration and frequency, including a surge event classification, was performed utilizing tide-gauge records over the period 1956–2005. A storm erosion potential index (SEPI) was calculated from observed levels based on hourly water level measurements. The index was related to beach profile responses to storm events. Also, a return period for extreme SEPI values was calculated. Results show an increase in the average number of positive storm surge events per decade. Considering all the events, the last decade (1996–2005) exhibits an average 7% increase compared to each one of the previous decades. A similar behavior was found for the decadal average of the heights of maximum annual positive storm surges. In this case the average height of the last two decades exceeds that of the previous decades by approximately 8 cm. The decadal average of maximum annual duration of these meteorological events shows an increase of 2 h in the last three decades. A possible explanation of the changes in frequency, height and duration of positive storm surges at Mar del Plata would seem to lie in the relative mean sea-level rise. 相似文献
182.
Montri Choowong Sumet Phantuwongraj Thasinee Charoentitirat Vichai Chutakositkanon Sombat Yumuang Punya Charusiri 《Geomorphology》2009,104(3-4):134-142
The 2004 Indian Ocean tsunami devastated the coastal areas along the Andaman western coast of Thailand and left unique physical evidence of its impact, including the erosional landforms of the pre-tsunami topography. Here we show the results from monitoring the natural recovery of beach areas at Khuk Khak and Bang Niang tidal channels of Khao Lak area, Phang-nga, Thailand. A series of satellite images before and after the tsunami event was employed for calculating the beach area and locating the position of the changed shoreline. Field surveys to follow-up the development of the post-tsunami beach area were conducted from 2005 to 2007 and the yearly beach profile was measured in 2006. As a result, the scoured beach areas where the tidal channel inlets were located underwent continuous recovery. The return of post-tsunami sediments within the beach zone was either achieved by normal wind and wave processes or during the storm surges in the rainy season. Post-2004 beach sediments were derived mainly from near offshore sources. The present situation of the beach zone has almost completed reversion back to the equilibrium stage and this has occurred within 2 years after the tsunami event. We suggest these results provide a better understanding of the geomorphological process involved in beach recovery after severe erosion such as by tsunami events. 相似文献
183.
亚极光区极化流(Subauroral Polarization Streams, SAPS)为快速流动的西向等离子体流,位于昏侧-子夜前亚极光区,是磁层-电离层-热层耦合的重要过程之一.本文利用密西根大学的RAM (Ring current-Atmosphere Interaction Model)模型对一次典型磁暴期间发生的SAPS事件进行了模拟,并与DMSP卫星观测值进行了比较.结果表明:模拟结果能大致反映观测现象;模拟得到的SAPS峰值速度所在纬度随磁暴时间的变化与观测值有较大差别;SAPS速度观测值在约18∶00 UT和约20∶00 UT左右出现两个峰值,而模拟值只有一个峰值,出现在约18∶00 UT,主要原因是模型对亚暴过程的模拟存在不足. 相似文献
184.
In the karst geologic setting of Greenbrier County, West Virginia, USA, the drainage network in the watersheds do not support surface streams, but depend entirely on sinkholes, solution cavities, or injection wells as discharge points for accumulated storm water. By providing a systematic framework for designing and routing storms in this geologic setting, functioning retention and attenuation structures have been developed which are protective of water quality while still safely discharging storm water in a controlled manner to the subsurface. This article provides a rationale for the design methodology and then examines the successful implementation of an attenuation and storm water retention design to manage the surface discharges for an entire watershed. By examining the pre-development flows and evaluating future land use patterns (i.e., installation of impermeable surfaces over large areas), as well as sinkhole conveyance capabilities, it was necessary to examine alternative disposal options for collected storm water as well as devise a basin-wide management strategy to coordinate future development of the watershed. Additionally, innovative water quality measures were implemented to help prevent contamination from preferentially infiltrating into the subsurface as a result of these land development activities. 相似文献
185.
Influence of enso event on the maintenance of pacific storm track in the northern winter 总被引:1,自引:0,他引:1
l.Intr0ductionItiswellkn0wnthatthereisanobviousinteractionbetweencirculationsin-andextra-tropics,whichusuallyexhibitsauniquefeatureduringENSOPeriod(Bjerknes,l969;Huang,l99l;H0skinsandKaroly,l98l;HorelandWallace,l981famongothers).There-searchrevealsthataneddyfluxcausedbyatransientdisturbanceinthemiddlelatitudedur-ingthePeriodofENSOeventplaysanimPOrtantroleinthemaintenanceofanomalousat-mosphericcirculationpattern,triggeredbyseasurfacetemPeratureanomalyatequator,inthePacificOceanandtheNor… 相似文献
186.
187.
厄尼诺对人类社会的影响 总被引:3,自引:3,他引:0
厄尼诺事件可引起全球气候异常及各种海洋-气象灾害。九十年代以来,前期连续发生三次厄尼诺事件,1997~1998年更发生了一百多年来最强的一次厄尼诺事件。这种异常的厄尼诺形势必将影响到九十年代更为频繁而严重的自然灾害。据1949-1991年历史资料统计,厄尼诺年的当年或次年夏季,西北太平洋的年台风发生总数为低值谷年,江淮流域则是洪涝年。九十年代前期,台风发生总数连续出现三个低值谷年,1998年只有极 相似文献
188.
沙尘暴天气的成因及其天气形势分析 总被引:2,自引:0,他引:2
对我国北方及我省沙尘暴天气发生的机制及其相应的天气形势进行了分析,揭示了沙尘暴天气发生、发展的规律以及在具体预报中的着眼点。 相似文献
189.
Todd L. Walton Jr 《Ocean Engineering》2000,27(1):1811
Investigation of shoreline change signals in the presence of possible non-stationarity is attempted via Karhunen–Loeve filtering to separate the actual shoreline signal change from that of random noise. Interpretation is made of the signal and noise normalized covariance and spectra to help in delineating natural change versus man-made change patterns for a section of shoreline where a navigation channel existed over a portion of the shoreline history. 相似文献
190.
风暴潮漫滩的半隐半显数值模式及其在珠江口的应用 总被引:2,自引:0,他引:2
研究给出了风暴潮漫滩预报的一种半隐半显数值模式,并将其用于珠江口风暴潮漫滩的后报。该模式将风暴潮漫滩的控制方程进行半隐半显离散,使计算稳定性不受时间步长的限制;分别用共轭斜量加速Jacobi法和文中提出的简化算法求解差分方程以提高计算效率。数值模拟试验表明:该模式计算的沿岸风暴潮与天文耦合水位与实测水位值吻合较好,因而对漫滩位置,范围和持续时间的计算应是合理,准确的;因模式允许使用的时间步长比AD 相似文献