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991.
We present the results of biological and oceanographic investigations performed in the Weddell and Scotia Seas within the framework of the first (January–June, 1997) and second (January–June, 1998) Ukrainian Antarctic marine expeditions. We reveal some regularities in the space distribution of the aggregations of krill and salpae depending on the abiotic (hydrophysical) environmental factors and discuss possible mechanisms promoting the formation of aggregations of krill and salpae in the Antarctic waters. 相似文献
992.
Within the framework of the reduced-gravity model of the ocean taking into account the effect of friction in the Rayleigh form, we study the two-dimensional problem of nonlinear motions of a subsurface front of finite width. We consider the conservation laws and the character of motion of the center-of-mass of the cross section of the front and their variations caused by the losses of energy. For fields with special structure, the problem is reduced to the solution of a system of nonlinear ordinary differential equations. It is shown that the initially geostrophic frontal current decays with time according to a power law. The deviations of the initial state of the front from the state of geostrophic balance result in the generation of superinertial oscillations of the hydrodynamic fields. 相似文献
993.
Gubanova D. P. Chkhetiani O. G. Kuderina T. M. Iordanskii M. A. Obvintsev Y. I. Artamonova M. S. 《Izvestiya Atmospheric and Oceanic Physics》2018,54(8):777-793
Izvestiya, Atmospheric and Oceanic Physics - This paper summarizes the results of long-term (2004–2016) comprehensive experimental studies of microphysical parameters and the mass... 相似文献
994.
This paper studies the causes and mechanisms of the formation of extreme anomalies in the tropospheric temperature associated
with the North Atlantic Oscillation (NAO). Our approach is based on understanding that, in the annual cycle, continental-scale
tropospheric temperature anomalies (planetary waves with longitudinal wave numbers of 1–3) can both intensify under the direct
action of heat inflow as an energy source for these anomalies (radiation cooling/heating) and weaken as a result of the destructive
action of heat inflow under temperature advections with the opposite (to the heat inflow) sign [4, 5]. According to the monthly
mean data of the NCEP/NCAR reanalysis over the 40-year period, seasonal air temperature anomalies have been studied at the
level 850 hPa (T
850) in different regions of Eurasia. It has been confirmed that the negative NAO phase in winter is favorable for preserving
negative T
850 anomalies in the east of the continent at this time of year, whereas the positive NAO phase is favorable for negative T
850 anomalies in the west. However, it has been revealed that this dependence was critically violated during the winter seasons
approximately two years before an extreme event. This was explained by the fact that, in those years, the NAO influence on
winter T
850 anomalies was limited. This paper formally considers a certain mechanism of anomalous heat inflow as an energy source for
these anomalies with functions of the formation (intensification) of negative T
850 anomalies in winter and positive T
850 anomalies in summer, as well as with a function of the limitation of the influence of the predominant dynamic mode on some
regions of the continent. It is shown that, in the 1960s, T
850 anomalies with negative NAO indices in the east of the continent were governed by a hypothetic mechanism of heat inflow as
an energy source for anomalies; in 1980s, at prolonged positive NAO indices, T
850 anomalies in the west of the continent could also be governed by this mechanism. This paper, within the accepted degree of
detail, demonstrates the process of limitation of the NAO influence in some years (1966, 1967, 1987, and 1988), which leads
to an unbalance of the anomalies and a possible extreme phenomenon. It is demonstrated that, in some seasons, the anomalies
were not governed by the hypothetic mechanism of the heat inflow under the action of large NAO changes and a complete upset
of the annual cycle of anomalies. Determining the first indicators of the unbalance, which can lead to extreme anomalies,
is shown to be difficult if it is based only on an analysis of winter seasons (as is the case with most of the works) without
invoking the annual trends of the tropospheric temperature and the NAO index. 相似文献
995.
S. N. Kulichkov I. P. Chunchuzov O. I. Popov 《Izvestiya Atmospheric and Oceanic Physics》2010,46(1):60-68
The results of simulating the influence of an atmospheric fine structure on the characteristics of acoustic signals propagating
throughout the atmosphere for long distances from their sources are presented. A numerical model of an atmospheric fine inhomogeneous
structure within the height range z = 20…120 km is proposed to perform calculations. This model and its numerical parameters are based on the current notions
of the formation of an atmospheric fine structure due to internal gravity waves. The numerical calculations were performed
using the parabolic-equation method. A spatial structure of the acoustic field and the structure of an acoustic signal at
long distances from a pulsed source were calculated. It is shown that the presence of an atmospheric fine structure results
in a scattering of acoustic signals and their recording in the geometric shadow region. The results of calculations of signal
forms are in a satisfactory agreement with data on signals recorded in the geometric shadow region which is formed at a distance
of about 300 km from an experimental explosion. 相似文献
996.
With the UK Marine Bill promoting the creation of a network of marine protected areas and similar commitments in other countries there is a need for tools to assist in their design and management. Although physical science often drives designation, the implementation of marine protected areas also encompasses political and socio-economic issues. This paper focuses on one tool in the armoury of decision-makers: choice experiments. It illustrates its application to the quantification of aspects of socio-economic value not readily incorporated into the evaluation of the costs and benefits of marine protected areas utilising cold-water deep coral reefs off the Republic of Ireland. 相似文献
997.
This paper focuses on changing trust relationships among fishermen following new governance arrangements. The previous ‘thick’ trust relationships that characterized the Dutch fisheries industry under a neo-corporatist arrangement had resulted in an isolation of local fishermen groups vis-à-vis outsiders. However, under new governance arrangements, in particular the so-called Study Groups, these trust relationships are changing. The establishment of Study Groups, where fishermen from different localities have to cooperate on sustainability innovations in order to receive subsidies, lead to more diversity within the industry, more collaborations across localities and new forms of ‘thin’ trust. As such, these Study Groups can be understood as successful experiments in further opening up of the fisheries community. 相似文献
998.
Brian N. Tissot Barbara A. Best Eric H. Borneman Andrew W. Bruckner Cara H. Cooper Heather D’Agnes Timothy P. Fitzgerald Amanda Leland Susan Lieberman Amy Mathews Amos Rashid Sumaila Teresa M. Telecky Frazer McGilvray Brian J. Plankis Andrew L. Rhyne Glynnis G. Roberts Benjamin Starkhouse Todd C. Stevenson 《Marine Policy》2010
As the world’s largest importer of marine ornamental species for the aquaria, curio, home décor, and jewelry industries, the United States has an opportunity to leverage its considerable market power to promote more sustainable trade and reduce the effects of ornamental trade stress on coral reefs worldwide. Evidence indicates that collection of some coral reef animals for these trades has caused virtual elimination of local populations, major changes in age structure, and promotion of collection practices that destroy reef habitats. Management and enforcement of collection activities in major source countries such as Indonesia and the Philippines remain weak. Strengthening US trade laws and enforcement capabilities combined with increasing consumer and industry demand for responsible conservation can create strong incentives for improving management in source countries. This is particularly important in light of the March 2010 failure of the parties to the Convention on International Trade in Endangered Species (CITES) to take action on key groups of corals. 相似文献
999.
A. Goineau C. Fontanier F.J. Jorissen B. Lansard R. Buscail A. Mouret P. Kerhervé S. Zaragosi E. Ernoult C. Artéro P. Anschutz E. Metzger C. Rabouille 《Journal of Sea Research》2011,65(1):58-75
In this paper, we investigate the ecology of live (rose Bengal stained) benthic foraminifera collected at 20 stations ranging from 15 to 100 m depth in the Rhône prodelta (Gulf of Lions, NW Mediterranean). These sites were sampled in September 2006, five months after the Rhône River annual flood. Statistical analyses based on foraminiferal communities (> 150 μm) divide our study area into six main biofacies directly related to environmental conditions. Miliolid species are abundant in the relict prodeltaic lobe which is characterised by sand with low organic matter content. Close to the river mouth, the limited oxygen penetration in the sediment combined with important hydro-sedimentary processes constitute stressful conditions for foraminiferal faunas dominated by opportunistic species (e.g. Leptohalysis scottii). With increasing distance from the river mouth, foraminiferal faunas (e.g. Nonionella turgida, Eggerella scabra) adapted to thrive in sediments enriched in Rhône-derived organic matter under more stable hydro-sedimentary conditions appear. In the distal part of the Rhône River influence, benthic species (e.g. Valvulineria bradyana, Textularia agglutinans) living in fine sediment enriched in both continental and marine organic compounds emerge. At the deepest stations located in the south-eastern part of our study area, benthic foraminiferal faunas (e.g. Bulimina aculeata, Melonis barleeanus, Bigenerina nodosaria) are highly diverse, underlining stable environmental conditions characterised by marine-derived organic matter supplies and relatively deep oxygen penetration depth in the sediment. We also compare foraminiferal faunas sampled in September 2006 with communities sampled in June 2005, one month after the Rhône River annual flood (Mojtahid et al., 2009). This comparison suggests that opportunistic species (e.g. B. aculeata, Cassidulina carinata, V. bradyana) have responded to organic matter inputs related to marine primary production in June 2005. 相似文献
1000.
Vertical distribution and seasonality of peracarid crustaceans associated with intertidal macroalgae
J.M. Guerra-García E. Baeza-Rojano M.P. Cabezas J.C. García-Gómez 《Journal of Sea Research》2011,65(2):256-264
Spatial patterns and seasonal fluctuations of intertidal peracarids from Tarifa Island, Strait of Gibraltar, were studied over a two-year period (December 2005–December 2007). A total of 25,749 individuals were collected, comprising 46 species. Amphipods were best represented in the total number of species (32) and individuals (89% of numerical abundance) followed by isopods (12 species and 11% abundance) and tanaids (2 species and 1%). The highest number of species was registered in intermediate levels (1–1.5 m) dominated by Corallina elongata, although the highest abundances of peracarids were associated to seaweeds of lower levels (0–1 m) such as Gelidium corneum, Osmundea pinnatifida, Valonia utricularis and a turf of Caulacanthus ustulatus. The most abundant peracarids, Hyale stebbingi, H. schmidti, H. perieri, Stenothoe monoculoides, Caprella penantis, C. grandimana, Dynamene edwardsii and Ischyromene lacazei, were present throughout the whole year during 2006 and 2007. The highest peracarid densities were measured in April–August coinciding with the highest development of seaweeds, just before the maximum values of water temperature measured at the end of summer. Multivariate analyses confirmed a clear zonation of algae and associated peracarids in a vertical gradient, which was maintained stable during the two-year study. Several physical and biological factors may regulate such patterns of peracarid abundance and future experimental studies are necessary to explore the importance of factors such as competition, predation or weather conditions. 相似文献