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本文根据一种气团客观分类方案,在对研究区域气团类型进行分类的基础上,研究了局地SO_2浓度随气团类型的变化。结果表明,SO_2浓度值作为气团类型的函数变化是显著的;较高的SO_2浓度值出现在那些变胜深、移动慢、持续时间长的反气旋中;个例分析揭示了一次持续时间较长的高SO_2浓度事件的出现与对流层中层的一次中期天气过程的发生、发展、崩溃过程间的良好对应关系。 相似文献
94.
Julio Gil 《Estuarine, Coastal and Shelf Science》2003,57(5-6):1139-1149
From September to December 1995, three hydrographic surveys were carried out in the eastern Cantabrian Sea (Bay of Biscay). Changes in the water masses pattern were examined to study the variability and main energetic features in the area. At the beginning of December, an intense Poleward Current (PC), which had come from Portuguese slopes, entered the eastern Cantabrian Sea. This current was the most energetic event in this area in winter. The PC waters increased temperature by about 2 °C (subsurface layers) and salinity by 0.2 (surface layers) in the pattern of water masses in the eastern Cantabrian Sea in winter. The core current was approximately 10 km width and 120 m depth and the water transport, estimated from geostrophic current profiles, was of about 1.3 Sv.A well-defined wavelike front with two significant ridges in the western and eastern sampling area, was observed. The variability and meandering flow of the PC were driven by dominantly baroclinic instabilities, which are due to strong vertical velocity shear. In this synoptic-scale system, the potential vorticity advection, the differential vorticity advection, and the geopotential tendency have shown to be the cause of the ageostrophic motion and the main baroclinic disturbances.One important consequence of the entrance of the PC in the eastern Cantabrian Sea was the profound effect on the pattern of nutrients. The current-induced stratification pattern drives the distribution of nutrients in the different layers and the instabilities and meandering pattern of the PC was an important mechanism of fertilisation offshore. 相似文献
95.
Ann E. Jochens Steven F. DiMarco 《Deep Sea Research Part II: Topical Studies in Oceanography》2008,55(24-26):2541
The circulation and distribution of water properties in the water column of the Gulf of Mexico influence the flux of carbon to the benthic environment. The eddy field of the upper 1000 m creates environmental conditions that are favorable for biological productivity in an otherwise oligotrophic subtropical ocean. This eddy field results in the transport of nutrients and organic matter into the photic zone through cross-margin flow of shelf waters, upwelling in cyclones, and uplift from the interaction of anticyclones with bathymetry. These conditions then allow the productivity that becomes a possible source of carbon to the benthos.Data from four cruises during summers of 2000–2002 are used to describe the currents and water property distributions in the deepwater Gulf of Mexico, which consists of water depths greater than 400 m. Comparisons are made to historical data sets to provide an understanding of the persistence of the characteristics of the Gulf and the processes that occur there.The currents in the Gulf are surface intensified, have minimum in 800–1000 m depths, and also exhibit bottom intensification, especially near sloping topography. Historical time series records show current speeds near-bottom reach 50–100 cm s−1. At basin scales, these currents tend to flow cyclonically (counter-clockwise) along the bathymetry. These near-bottom, episodic, high-speed currents provide a mechanism for the transport of organic material, in both large and small particle sizes, from one benthic area to another.The distributions of temperature, salinity, nutrients, and dissolved oxygen during the study appear to be unchanged from historical findings. The source waters for the deep Gulf are the water masses brought into the Gulf by the Loop Current system. The properties in the upper 100–200 m are the most variable of the water column, consistent with their proximity to wind mixing, river discharge mixing, and atmospheric influences. Below 1500 m, there are no major horizontal variations in these water properties. 相似文献
96.
Several sediment samples collected from the crest and slope of the Chatham Rise, and from the Chatham Islands, to the east of New Zealand, contain Globigerina linaperta‐Globorotalia increbescens foraminiferal faunas of upper Middle and middle Upper Eocene age. The foraminiferal faunas from the Chatham Islands, which include Rectuvigerina, Latibolivina, Dyocibicides, Discorbinella, Patellina, and Wadella, indicate shallow‐water palaeodepths, probably equivalent to the outer shelf (50–150 m). A faunal assemblage from near the crest of the rise is likewise indicative of shallow water, although distinct differences in the benthonic foraminiferal ifauna suggest slightly deeper‐water biofacies than the Eocene of the Chatham Islands. In contrast, a fauna of similar age from 1,100 m on the southern slope of the Chatham Rise contains a much deeper‐water benthonic foraminiferal assemblage including Osangularia, Vulvulina, Stilostomella, hispidocostate Uvigerina, and smooth‐shelled Bulimina, indicative of lower middle bathyal depths (1,500–2,500 m). The nature and distribution of the assemblages, together with previous work by Norris (1964) and Cullen (1965), indicates that the Chatham Rise has been a significant structure since at least the Middle Eocene, with some uplift occurring since then. 相似文献
97.
《African Journal of Marine Science》2013,35(2):239-246
In 2005, 2006, 2007 and 2011, distinct Oegopsida squid egg masses were observed by scuba divers on the narrow southern KwaZulu-Natal (KZN) shelf in depths of 35–50 m off the coastal resorts of Park Rynie, Pumula and Port Edward, South Africa. In 2006, larvae in the egg balloons were sampled. DNA barcoding (i.e. cytochrome c oxidase subunit 1 sequencing) linked the larvae to the genus Lycoteuthis, a group commonly found on the continental slope of the Agulhas Bank and the west coast of South Africa. In all cases, the sightings were concomitant with low water temperatures of 14–18 °C, indicative of shelf edge upwelling. Historical ship-collected CTD data show these cooler waters to originate from a depth of 100–180 m on the KZN continental slope. Complementary satellite imagery revealed the cooler water and discoveries of the egg balloons to be coincident with cold core cyclonic eddies embedded in the shoreward boundary of the Agulhas Current. The temperature data suggest that these egg balloons, in the absence of cyclonic eddy activity, would normally be found in the current on a density surface at a depth of ~130 m where velocities are typically around 100 cm s–1. 相似文献
98.
99.
基于WOD13(World Ocean Database 2013)的温盐观测资料,分析了对马海峡断面和日本海内一断面上温盐分布的季节变化特征,并利用水团组成混合比的方法探讨了对马海峡断面处的水团组成对日本海内断面上温盐分布的影响的季节和年际变化。研究表明:对马海峡断面上水团组成呈现显著的季节变化。冬季,整个水层被高盐水占据;夏季,对马海峡表层出现高温低盐水,底层为高盐水,次表层为表层低盐水和底层高盐水的混合水体;春秋为过渡季节。日本海断面上,秋季温盐分布最为复杂,表层为高温低盐水,次表层为高盐水,其下为低温高密水。两个断面季节变化对比可以看出,夏季对马海峡断面处的水团组成会影响秋季日本海断面上的温盐分布。夏季对马海峡表层和次表层水是秋季日本海断面表层50m以浅出现低盐水的主要原因;对马海峡深层高盐水主要影响秋季日本海断面50~150m水层,混合比可达0.82;其下为日本海固有水。夏季对马海峡处水团组成的年际变化也会影响秋季日本海断面上温盐分布的年际变化。长江流量较大的年份,夏季对马海峡表层和次表层低盐水的核心盐度值偏低,秋季其在日本海断面上的混合比就高于其他年份;对马海峡底层高盐水在日本海断面上混合比的年际变化则决定于其影响水层上的流场结构和温盐分布。 相似文献
100.
Characteristics of the pCO2 distribution in surface water of the Bering Abyssal Plain and their relationships with the ambient hydrological conditions
were discussed using variations of the partial pressure of CO2 in surface water of the Bering Abyssal Plain and the Chukchi Sea. Data in this study are from a field investigation during
the First Chinese National Arctic Research Expedition in 1999. Compared to the high productivity in the Bering Continental
Shelf, much lower levels of chlorophyll a were observed in the Bering Abyssal Plain. The effect of hydrological factors on
the pCO2 distribution in surface seawater of the Plain in summer has become a major driving force and dominated over biological factors.
The Plain also presents a High Nutrient Low Chlorophyll (HNLC). In addition, the pCO2 distribution in the Bering Abyssal Plain has also been found to be influenced from the Bering Slope Current which would transform
to the Anadyr Current when it inflows northwestward over the Plain. The Anadyr Current would bring a high nutrient water to
the western Arctic Ocean where local nutrients are almost depleted in the surface water during the summer time. Resupplying
nutrients would stimulate the growth of phytoplankton and enhance capacity of absorbing atmospheric CO2 in the surface water. Otherwise, in the Bering Sea the dissolved inorganic carbon brought from freshwater are not deposited
down to the deep sea water but most of them would be transported into the western Arctic Ocean by the Alaska Coastal Current
to form a carbon sink there. Therefore, the two carbon sinks in the western Arctic Ocean, one carried by the Anadyr Current
and another by the Alaska Costal Current, will implicate the western Arctic Ocean in global change. 相似文献