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331.
Current status of multimodel superensemble and operational NWP forecast of the Indian summer monsoon 总被引:1,自引:0,他引:1
In the last thirty years great strides have been made by large-scale operational numerical weather prediction models towards
improving skills for the medium range time-scale of 7 days. This paper illustrates the use of these current forecasts towards
the construction of a consensus multimodel forecast product called the superensemble. This procedure utilizes 120 of the recent-past
forecasts from these models to arrive at the training phase statistics. These statistics are described by roughly 107 weights. Use of these weights provides the possibility for real-time medium range forecasts with the superensemble. We show
the recent status of this procedure towards real-time forecasts for the Asian summer monsoon. The member models of our suite
include ECMWF, NCEP/EMC, JMA, NOGAPS (US Navy), BMRC, RPN (Canada) and an FSU global spectral forecast model. We show in this
paper the skill scores for day 1 through day 6 of forecasts from standard variables such as winds, temperature, 500 hPa geopotential
height, sea level pressure and precipitation. In all cases we noted that the superensemble carries a higher skill compared
to each of the member models and their ensemble mean. The skill matrices we use include the RMS errors, the anomaly correlations
and equitable threat scores. For many of these forecasts the improvements of skill for the superensemble over the best model
was found to be quite substantial. This real-time product is being provided to many interested research groups. The FSU multimodel
superensemble, in real-time, stands out for providing the least errors among all of the operational large scale models. 相似文献
332.
A theoretical analysis based on the equations of magnetofluid-dynamics is undertaken, in order to completely classify the geometry of the motion admitted by this pattern. 相似文献
333.
Presenting a critical review of daily flow simulation models based on the Soil Conservation Service curve number (SCS‐CN), this paper introduces a more versatile model based on the modified SCS‐CN method, which specializes into seven cases. The proposed model was applied to the Hemavati watershed (area = 600 km2) in India and was found to yield satisfactory results in both calibration and validation. The model conserved monthly and annual runoff volumes satisfactorily. A sensitivity analysis of the model parameters was performed, including the effect of variation in storm duration. Finally, to investigate the model components, all seven variants of the modified version were tested for their suitability. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
334.
To form the Hubble diagram for quasi-stellar objects (QSOs),we have made use of the recently published data on X-ray fluxes
of 159 QSOs observed from the Einstein Observatory. The scatter in the Hubble diagram and the lack of an obvious redshift-flux
density correlation for these QSOs have been attributed to the observational selection effect that the intrinsically less
luminous QSOs can be detected only in the nearby region of space. When the optical, radio and X-ray selection effects are
removed, keeping only the intrinsically brighter sources, we obtain a sample of 16 QSOs having a small dispersion in X-ray
luminosities (〈 logL
x〉) = 46.12 ± 0.28), a statistically significant linear correlation between (logf
x, logcz) pairs and a slopeA =-1.906 ± 0.061 of the linear regression oflog f
x on logcz. This slope is consistent, at a confidence level of 95 per cent or greater, with the slope of-2.0 expected theoretically
based on the assumption that the redshifts of QSOs are cosmological in nature. 相似文献
335.
336.
Wolfgang Lutz Mahendra Shah Richard E. Bilsborrow John Bon-gaarts Partha DasGupta Barbara Entwisle Günther Fischer Brigida Garcia Daniel J. Hogan Arne Jernelöv Zhenghua Jiang Robert W. Kates Sanjaya Lall F. Landis MacKellar P.K. Makinwa-Adebusoye Anthony J. McMichael Vinod Mishra Norman Myers Nebojsa Nakicenovic Sten Nilsson Brian C. O'Neill Xizhe Peng Harriet B. Presser Nafis Sadik Warren C. Sanderson Gita Sen Barbara Torrey Dirk van de Kaa Hans J.A. van Ginkel Brenda Yeoh Huda Zurayk 《Global Change & Human Health》2002,3(1):33-35
The forthcoming World Summit on Sustainable Development (WSSD) in Johannesburg (August 26-September 4, 2002) has been set
by the United Nations to consider strategies toward sustainable development in all its dimensions. Hence, its mandate is broader
than that of the Rio 1992 United Nations Conference on Environment and Development (UNCED). Population issues have so far
been discussed in a separate series of World Population Conferences (Bucharest 1974, Mexico City 1984, Cairo 1994). With no
new World Population Conference scheduled for 2004 and Johannesburg having a mandate that is stated to explicitly include
social and economic aspects, population as a key component of sustainable development should figure prominently on the Johannesburg
agenda. Yet, after the third of four preparatory meetings for Johannesburg (which ended in New York on April 5th), consideration
of population is completely absent. The reasons for this are not entirely clear. We assume that they have to do with the fear
of entering into political controversies over abortion. We are concerned that, despite its broader mandate, in most countries
inputs to Johannesburg are being prepared mainly by environment ministries who have little experience in dealing with population
questions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
337.
Summary Lower tropospheric (1000–500) hPa kinetic energy (KE), temporal variations of KE and nonlinear KE transfer of rotational and divergent flows and energy conversion between them, partitioning further into stationary and transient components in the Fourier spectral domain and the mechanism for the evolution of significant transient waves for the month July 1979 in the latitudinal belt 10° S–30° N are studied.Divergent zonal and eddy KE show their maxima at the lowest level 1000 hPa. Lower tropospheric monsoon motion provides a non-divergent level close to 850 hPa. The daily flow patterns bear little resemblence to the climatology over tropics at 500 hPa. Although the transient mode of synoptic scale waves is stronger than that of planetary scale waves they are comparable. Analysis of energetics over global tropics can get signature of transient activities embedded in the large scale system. Summer momentum flux in the lower troposphere is essentially associated with stationary planetary and transient synoptic scale waves. Waves 1, 3 and 6 are the most preferred transient waves. Divergent to rotational KE conversion is the most dominating mechanism for the maintenance of planetary and synoptic scale waves. All categories of waves contribute towards the maintenance of zonal flows. The primary source of energy for transient synoptic scale waves is the transient divergent rotational KE transfer whereas the interaction between zonal stationary and transient wave is likely to be secondary source. Transient KE and all transient interactions, stationary KE and all stationary interactions are found to be strongest at 500 hPa and 850 hPa respectively. Growth and decay of transient waves 1 and 3 are mainly controlled by divergent-rotational KE conversions whereas those of transient wave 6 are controlled by KE transfer due to zonal-wave interaction.With 13 Figures 相似文献
338.
Zooplanktonic fauna of waste water from the industrial complex at Birla Nagar, Gwalior alongwith its seasonal abundance have been studied. In all, 16 species have been identified, viz. Arcella discoides, Lesquereusia modesta, Difflugia corona, D. muriformes and Acanthocystis spinibera under protozoa, Brachionus calyciflorus, Br. caudatus, Br. falcatus and Keratella tropica under rotifera, Daphnia (Daphnia) carinata and Daphnia (Daphnia) lumholtzi under cladocera, Cypris sp. and Cyprinotus qunninqi under ostracoda and Spicodiaptomus chelospinus and Mesocyclops leuckarti under copepoda. In their seasonal abundance members of protozoa showed the maxima in the month of April while the minima were observed in the month of July with an irregular trend of fluctuation. Rotifers, however, exhibited two maxima, one each during winter and early summer. Cladocera were maximum in February, while minimum in October. Ostracodes were maximum during May and June. Copepods were highest in the months of August and lowest in February. The total zooplankton population presented a clear-cut bimodal pattern of their seasonal fluctuation with the first peak appearing in the month of April and the other one in November. Lowest counts were obtained in the month of February. The zooplanktonic organisms belonging to rotifera were relatively abundant, followed by protozoa, copepoda, ostracoda and cladocera in a sequence. 相似文献
339.
Abstract. A simple closed-form expression relating saturated hydraulic conductivity to the van Genuchten capillary retention model parameters is derived. Application of this equation to an experimental data set shows reasonable agreement between measured and predicted saturated conductivity values. The proposed equation provides a consistent theoretical basis for estimating both saturated and unsaturated hydraulic conductivity from statistical pore structure models. 相似文献
340.
Geothermometry based on the fractionation of Mn and Cd between coexisting sphalerite and galena from concordantly banded, strata-bound ores and younger vein ores of Rajpura-Dariba, Zawar, and Bandalamottu has been attempted. Different fractionation trends for the banded and vein ores in the same deposit at Rajpura-Dariba indicate different thermal regimes of final equilibration for the two varieties of ores. In contrast, a single trend incorporating both types of ores is suggestive of isothermal conditions of final equilibration for the banded and vein ores at Zawar. Unrealistically high temperatures obtained for the vein ores of Bandalamottu suggest equilibrium in the sphalerite-galena aggregates of this deposit was not attained. Thermometric data from Mn and Cd fractionation are compared with other independent geothermometric determinations obtained from fluid inclusion homogenization studies and based on phase equilibria. It has been found that, in general, the Cd-fractionation temperature (TCd) is a more reliable geothermometer than the Mn-fractionation temperature (TMn). This presumably may be due to the susceptibility of aqueous Mn species to subtle changes in
in the ore fluid and consequent heterogeneity in Mn concentration in sphalerite, thus affecting the distribution coefficient. The investigation also suggests that TCd becomes increasingly more dependable when the ores are metamorphosed and reequilibrated at higher grades of metamorphism. 相似文献