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551.
552.
This article aims at providing a simple way for water quality monitoring in a set of reservoirs using an earth observation‐based approach and the assessment of the use of this technique for a monitoring network in order to meet the requirements and objectives of the Water Framework Directive (WFD) by the Member States of the European Union. The study carried out was preformed in 42 reservoirs of the Ebro River Basin, in the northeast of Spain. The proposed methodology is based on the development of an algorithm for the estimation of water quality by means of LANDSAT TM band reflectance. Some band ratios were used in the model as well. Trophic State Index (TSI), calculated by means of Secchi Disc Transparency data, was estimated using a forward stepwise multiple regression analysis and the TM2 band and TM1/TM2 ratio. The final results showed a large variability in water quality across reservoirs. Moreover, substantial spatial heterogeneity was also observed in the water bodies. These results demonstrate the likelihood of developing a monitoring network based on remote sensing techniques for the implementation of the WFD.  相似文献   
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554.
Baurusuchus salgadoensis is a new baurusuchid crocodylomorph from Bauru Basin (Cretaceous), Brazil, partially preserved through a complete skull. The fossil comes from a fine sandstone sequence of Adamantina Formation, General Salgado County, São Paulo State. The sedimentary sequence where it was found, located in Fazenda Buriti, is considered Turonian-Santonian in age. The described species _Baurusuchus salgadoensis sp. nov. _ is a baurusuchid with an antorbital fenestra, double external nares with a bony septum, two well-fused supraorbitals, the supratemporal fenestrae larger than the orbits and a quadrangular-shaped laterotemporal fenestra. The position of the external nares, located on anterior and terminal portion of the rostrum together with the theropod-like lateral compression of the snout and teeth are indicators that Baurusuchus salgadoensis was a terrestrial crocodyliform. This was a carnivorous species and the lateral compression of the rostrum could be interpreted as a mechanism to increase the skull resistance forces during biting. The pointed, conical teeth, some with crenulated borders, could be used to perforate and to carve the prey. The geological context of Baurusuchus salgadoensis indicates that it probably lived in a hot and arid climate.  相似文献   
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556.
The temporal variability in abundance and population structure of the gastropodChilina ovalis Sowerby was studied in the upper intertidal zone of Queule River estuary, south-central Chile (c. 40°S). Snails were collected monthly (September 1995–December 1997) from haphazardly-located quadrats (50×50 cm, n=5 each time), and counted and measured (shell height) in the laboratory. Water and sediment samples were collected at the same time to study the snail's habitat characteristics. Overall mean abundance was 115 individuals m?2 (SD=55). Monthly abundance estimates indicated a clear decrease during 1997. This decrease appeared to be related to the annual recruitment success of the species and at least partially to water temperature and sedimentological variability. Overall size range ofC. ovalis was 1.5–27.5 mm shell height. Growth varied seasonally with highest growth rates observed after recruitment (November–February). Slower growth continued throughout the austral winter months. Despite changes in abundance between 1996 and 1997, no differences were detected when population growth estimates were compared between years. A maximum longevity of approximately 4 yr was estimated from the growth curves of the cohorts, and a life cycle with more than one reproductive period is suggested.  相似文献   
557.
Abstract Carbonate platform growth in active tectonic settings may be strongly influenced by the structural evolution of the basin, including volcanic activity. In this paper, the sedimentary–tectonic evolution of the Duranguesado carbonate platform (Larrano) in northern Spain is described, and an evolutionary depositional model is presented. The Albian Duranguesado carbonate platform deposits are dominated by rudist and coral limestones with small intervening argillaceous limestone-filled troughs (10–30 m deep). The platform succession is divided into two parts. The lower platform deposits were intruded by volcanics and tilted before the deposition of the upper platform succession. A volcanic vent plug filling an upward-flaring pipe occurs in the lower carbonate platform succession. The timing of intrusion is well constrained to the early Albian. Tectonic extension and active deep-seated strike-slip faults induced magma ascent at a fault intersection. Sedimentological analysis of these areas indicates that, before volcanic intrusion, they acted as weakened zones of extension, and were slightly more subsident basinal areas. These sites contain anomalous accumulations of siliceous sponge spicule deposits, linked to the release of hydrothermal fluids on the sea floor. After the phase of intrusion, tilting and erosion of the platform and its associated volcanic products occurred. As the intrusion cooled, the platform downwarped, leading to the formation of an overlying perched capping basin bordered by carbonate platforms. Over the volcanic plug, carbonate mounds grew on local palaeohighs. The presence of strike-slip and magma emplacement in the Duranguesado platform is related to movements between the Iberian and European lithospheric plates, which were accommodated by rotation and lateral movement of the crust along wrench faults.  相似文献   
558.
New UPb zircon crystallization ages and 40Ar/39Ar cooling ages from the Colombian Andes confirm the existence of rocks metamorphosed during the Orinoquian Orogenic Event (ca. 1.0 Ga) of northern South America. εNd (t = 1.1 Ga) for these rocks range from −3.9 to +0.91, which is interpreted as a mixture of Late Archean-Early Proterozoic crust with juvenile material produced during the 1.1 Ga orogenic event. The Colombian Grenville age rocks are part of a much longer metamorphic pericratonal belt, sporadically exposed along the Andes, in western-central Peru, southern Bolivia and northern Argentina. In addition, Nd model (TDM) ages for the Colombian rocks range from 1.9 to 1.45 Ga, similar to those obtained in the Grenville Province of the eastern U.S. and in the Mexican basement, placing constraints on Late Proterozoic-Early Paleozoic paleocontinental reconstructions.  相似文献   
559.
Paleoparasitology has contributed to resolving the debate about the peopling of the Americas and determining the antiquity of human parasite infection. Hookworm (Ancylostomidae) and whipworm (Trichuris trichiura) and other exclusive human intestinal parasites have been recorded in pre-Columbian America. These parasite species originated in pre-hominids and have accompanied humans across continents when people went out of Africa. However, for those human populations that crossed the Bering Land Bridge from Siberia to Alaska, cold climate conditions hampered parasite transmission. Alternative migration routes have been proposed to explain the presence of these parasites in pre-Columbian populations in the Americas. Other parasites were established in the New World long before humans entered the American continents.One such malady is Chagas disease. Chagas disease, caused by Trypanosoma cruzi, offers an example of how animals and humans have interacted in the past. Classical theory points to the origin and dispersion of human T. cruzi infection among Andean populations, starting with sedentary habits and animal domestication 6000 years ago. However, recent PCR results in mummified bodies outside the Andean region have challenged this theory. Pre-Columbian Brazilian mummies were found positive for T. cruzi infection, raising an alternative hypothesis on the antiquity of Chagas disease in the Americas. Paleoparasitology is a new tool to study past events, shedding light on human and other animal behavior, migration routes, diet, and other aspects of host–parasite environment evolution.  相似文献   
560.
In Brazil, zooarchaeology is not well known, although imposing shell mounds dot the coast. Dating from 5020–2670 BP, the populations that deposited these shell mounds subsisted on hunting and gathering of several marine resources. Cetaceans were not the main source of food for the shell mound populations. Nevertheless, at least ten species were consumed. Individuals were equally divided between physically mature and immature, and marks left on the bones indicate anatomical knowledge. Further analysis of other shell mounds is necessary.  相似文献   
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