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931.
932.
Blooms of drifting green algae often develop in shallow coastal zones that receive significant nutrient inputs. Each spring and summer, some fifty bays and coves in Brittany (France) are affected in this way. Until now, in this region, only the algae present in the surf zone or stranded ashore, constituting an intertidal stock, have been taken into account. Another stock of algae, which was subtidal and of the same species (Ulva spp.), was found in the Bay of Douarnenez, one of the ten areas most affected by these algal blooms. This subtidal Ulva stock was located beyond the surf zone, at depths reaching 15 m. It was about the same size as the intertidal stock, viz., a few thousand tons on average. Subtidal Ulva stocks were generally found lying on the sandy bottom in a distribution showing no particular pattern. Biomass ranged from almost zero to 1.547 kg m−2 of fresh and spun-dried algae. However, at depths from 3 to 7 m they were often arranged in strips a few dm wide, due to the swell's effect. The bottom conditions of temperature, salinity, irradiance and dissolved inorganic nitrogen measured during spring and summer are suitable for the growth of Ulva in the subtidal zone. Both intertidal and subtidal drifting Ulva stocks are mobile and capable of exchanging material. In spring, the intertidal stock's inoculum is likely to come from the subtidal. Later in the season, the subtidal stock could be supplied, at least partially, by the intertidal.  相似文献   
933.
SATELLITEPROGRAMSFORCOASTALWATERDETECTIONSincethe 1 980s,greatattentionhasbeenpaidtotheadvancedremotesensingtechniqueinChina ,especiallytothedevelopmentofsatelliteprogramsforcoastalwaterenvironment.Twooceancolorchannelsaddedtothefirstremotesensingsatellit…  相似文献   
934.
地理信息系统是一种应用范围很广,地理信息管理功能十分强大的计算机应用软件。这种软件的应用与发展目前也得到海岸带科技、管理人员的重视.我们尝试用MAPINFO建立了江苏海岛资源环境信息系统,实践证明了这一系统的实用性和先进水平。本文介绍了该系统的主要功能,并打算以此为基础建立海岸带资源环境信息系统,为江苏的“海上苏东”建设服务。  相似文献   
935.
The process of upwelling/sinking and associated sea level variations are seen as a response of coastal ocean to pure wind stress forcing. Further,precipitation and monsoonal floods, apart from the marine meteorological parameters, are expected to influence the sea level fluctuations along the coast. This study comprises determining the sea level from the various parameters together with the pure wind stress forcing, which is compared with the observed cycle. However, it is found that there is considerable difference between the computations and observations. This suggests that the sea level is dependent not just on the local forcing alone, but also on the induced background circulation as well. For example, the sea level changes along the east coast of India, particularly the northern region, are more sensitive to freshwater discharge from various rivers joining the Bay of Bengal. This is due to more frequently occurring pre- and postmonsoon cyclonic storms and the associated surges in the Bay of Bengal as compared to the Arabian Sea. Hence the salinity effects are particularly important in the coastal waters off the east coast of India during monsoon months (June-September). For the west coast of India, however, it is expected that the large-scale coastal circulation may play a role in determining sea level changes in addition to other forcings. The salinity effects are negligible along the west coast in the absence of any major river systems that join the Arabian Sea. The local advection currents caused by the offshore directed freshwater discharge from various estuaries joining the coastal bay also seemed to influence the sea level. In order to elucidate the essential dynamics involved and to study the effect of the remote forcing, a three-dimensional baroclinic, nonlinear numerical model is used with appropriate open boundary conditions. The local effect of the current has been incorporated in the west coast model by means of opening a channel at Cochin through which the rainwater is carried away to the model ocean. The low saline plume, cascading from north along the east cost of India, has been incorporated in the east coast model through a proper forcing applied at the northern boundary of the model. With the inclusion of these remote forcings in the models, the disagreement between the simulations and the observations is minimized.  相似文献   
936.
Abstract. This paper briefly summarises research carried out in 1982–1990 in the coastal area off Monte Conero, SW northern Adriatic Sea. Oceanographic data on temperature, salinity, oxygen saturation, nutrients (nitrates, silicates and orthophosphates), and chlorophylls were collected to characterise this coastal ecosystem in view of the setting up of the "Costa del Monte Conero" protected marine area.
Towards the coast the physical and chemical parameters exhibited a seasonal periodicity.
Temperature showed a clear annual periodicity with a certain interannual variability; this also holds true for oxygen saturation, with peaks in March and minima in September, though without hypoxic events.
Nutrient concentrations peaked at the surface layer at the coastal station from December to March (nitrates: 35–50 μmol 1−1; silicates: 22–70 μmol 1−1; orthophosphates: 0.37–0.54 μmol 1−1) and minima in summer (Jul-Aug) on surface and bottom (0–12μmol 1−1, 0–18.5 μmol 1−1, and 0–0.15 μmol 1−1, respectively). From 1988 to 1990 nutrient peaks were lower and coastal salinity exceed 33, with nitrates below 16 μmol 1−1, silicates below 8 μmol 1−1, and orthophosphates less than 0.2 μmol 1−1.
In the coastal area of Senigallia, 40 km to the north, where the influence of the coastal current that carries the river inflows to the south is stronger, the seasonal cycle was similar, albeit with higher values for nutrients and chlorophylls.  相似文献   
937.
The timing and intensity of the effects of the 1997–98 El Niño on sea-surface temperature (SST) and coastal sea level along the US west coast are examined using in situ time-series measurements, and the effects on upper ocean currents on the continental shelf and slope off Oregon and northern California are examined using repeated shipborne ADCP transects, a mid-shelf mooring off Newport Oregon and an HF surface current radar. An initial transient positive anomaly was observed in both adjusted sea level and SST during May–June 1997, followed by anomalously high coastal sea levels, generally strongest during September 1997 through February 1998 and abruptly returned to normal in late February 1998, and by positive temperatures anomalies over the mid-shelf that persisted longer, into April 1998. Low-frequency coastal sea-level anomalies propagated poleward at 2.1 m/s. Poleward flow over the shelf and slope was enhanced at most depths during the El Niño, compared with following years. Northward currents in the upper 12 m over the continental shelf off Newport, Oregon averaged 13.7 cm/s stronger during August 1997 through February 1998 than during the same period the following year. Enhanced poleward flow was present at all latitudes sampled during November 1997 and February 1998, particularly over the continental slope. These transects also provided clear views of a fall/winter equatorward undercurrent, which was both strongest and had the most alongshore similarity of form, during the ENSO. Finally, subsurface-intensified anticyclonic eddies originating in the poleward undercurrent appear to be a recurrent feature of the circulation off Newport late in the upwelling season.  相似文献   
938.
周鲁闽  卢昌义 《台湾海峡》2006,25(2):302-308
海岸带综合管理被广泛认为是实现海岸带社会经济与生态环境可持续发展的重要途径之一.本文运用海岸带综合管理(ICM)的相关理论,结合厦门海岸带管理面临的实际问题, 在对厦门第一轮ICM执行情况进行充分回顾、评估的基础上,对厦门第二轮ICM面临的主要问题、涉及的优先领域及主要目标进行了分析研究;并在此基础上形成了厦门第二轮海岸带综合管理的战略行动计划.  相似文献   
939.
We present here the first high-resolution pollen record of vegetation response to interactions of hurricane and fire disturbances over the past 1200 yr from a small lake in Alabama on the Gulf of Mexico coast. The paleotempestological record inferred from the overwash sand layers suggests that the Alabama coast was directly struck by Saffir-Simpson category 4 or 5 hurricanes twice during the last 1200 yr, around 1170 and 860 cal yr BP, suggesting an annual landfall probability of 0.17% for these intense hurricanes. The charcoal data suggest that intense fires occurred after each of these hurricanes. The pollen data suggest that populations of halophytic plants (Chenopodiaceae) and heliophytic shrubs (Myrica) expanded after the hurricane strikes, probably due to saltwater intrusion into the marshes and soil salinization caused by overwash processes. Populations of pines (Pinus sp.) decreased significantly after each intense hurricane and the ensuing intense fire, suggesting that repeated hurricane-fire interactions resulted in high tree mortality and probably impeded recruitment and recovery. Our data support the hypothesis that the likelihood and intensity of fire increased significantly after a major hurricane, producing responses by vegetation that are more complex and unpredictable than if the disturbance agents were acting singly and independently.  相似文献   
940.
Luminescence ages from a variety of coastal features on the North Carolina Coastal Plain provide age control for shoreline formation and relative sea-level position during the late Pleistocene. A series of paleoshoreline ridges, dating to Marine Isotope Stage (MIS) 5a and MIS 3 have been defined. The Kitty Hawk beach ridges, on the modern Outer Banks, yield ages of 3 to 2 ka. Oxygen-isotope data are used to place these deposits in the context of global climate and sea-level change. The occurrence of MIS 5a and MIS 3 shorelines suggests that glacio-isostatic adjustment (GIA) of the study area is large (ca. 22 to 26 m), as suggested and modeled by other workers, and/or MIS 3 sea level was briefly higher than suggested by some coral reef studies. Correcting the shoreline elevations for GIA brings their elevation in line with other sea-level indicators. The age of the Kitty Hawk beach ridges places the Holocene shoreline well west of its present location at ca. 3 to 2 ka. The age of shoreline progradation is consistent with the ages of other beach ridge complexes in the southeast USA, suggesting some regionally contemporaneous forcing mechanism.  相似文献   
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