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471.
M. B. Beck J. R. Ravetz L. A. Mulkey T. O. Barnwell 《Stochastic Environmental Research and Risk Assessment (SERRA)》1997,11(3):229-254
The development and use of models for predicting exposures are increasingly common and are essential for many risk assessments
of the United States Environmental Protection Agency (EPA). Exposure assessments conducted by the EPA to assist regulatory
or policy decisions are often challenged to demonstrate their “scientific validity”. Model validation has thus inevitably
become a major concern of both EPA officials and the regulated community, sufficiently so that the EPA's Risk Assessment Forum
is considering guidance for model validation. The present paper seeks to codify the issues and extensive foregoing discussion
of validation with special reference to the development and use of models for predicting the impact of novel chemicals on
the environment. Its preparation has been part of the process in formulating a White Paper for the EPA's Risk Assessment Forum.
Its subject matter has been drawn from a variety of fields, including ecosystem analysis, surface water quality management,
the contamination of groundwaters from high-level nuclear waste, and the control of air quality. The philosophical and conceptual
bases of model validation are reviewed, from which it is apparent that validation should be understood as a task of product
(or tool) design, for which some form of protocol for quality assurance will ultimately be needed. The commonly used procedures
and methods of model validation are also reviewed, including the analysis of uncertainty. Following a survey of past attempts
at resolving the issue of model validation, we close by introducing the notion of a model having maximum relevance to the
performance of a specific task, such as, for example, a predictive exposure assessment. 相似文献
472.
Hydrologic regionalization is a useful tool that allows for the transfer of hydrological information from gaged sites to ungaged
sites. This study developed regional regression equations that relate the two parameters in Nash's IUH model to the basin
characteristics for 42 major watersheds in Taiwan. In the process of developing the regional equations, different regression
procedures including the conventional univariate regression, multivariate regression, and seemingly unrelated regression were
used. Multivariate regression and seeming unrelated regression were applied because there exists a rather strong correlation
between the Nash's IUH parameters. Furthermore, a validation study was conducted to examine the predictability of regional
equations derived by different regression procedures. The study indicates that hydrologic regionalization involving several
dependent variables should consider their correlations in the process of establishing the regional equations. The consideration
of such correlation will enhance the predictability of resulting regional equations as compared with the ones from the conventional
univariate regression procedure. 相似文献
473.
Sirsendu Chatterjee Rudradeb Bhattacharyya Laju Michael Kolluru Sree Krishna Tapan Jyoti Majumdar 《Marine Geodesy》2007,30(3):197-216
Geoid and gravity anomalies derived from satellite altimetry are gradually gaining importance in marine geoscientific investigations. Keeping this in mind, we have validated ERS-1 (168 day repeat) altimeter data and very high-resolution free-air gravity data sets generated from Seasat, Geosat GM, ERS-1 and TOPEX/POSEIDON altimeters data with in-situ shipborne gravity data of both the Bay of Bengal and the Arabian Sea regions for the purpose of determining the consistencies and deviations. The RMS errors between high resolution satellite and ship gravity data vary from 2.7 to 6.0 mGal, while with ERS-1 data base the errors are as high as 16.5 mGal. We also have generated high resolution satellite gravity maps of different regions over the Indian offshore, which eventually have become much more accurate in extracting finer geological structures like 85° E Ridge, Swatch of no ground, Bombay High in comparison with ERS-1satellite-derived gravity maps. Results from the signal processing related studies over two specific profiles in the eastern and western offshore also clearly show the advantage of high resolution satellite gravity compared to the ERS-1 derived gravity with reference to ship gravity data. 相似文献
474.
475.
Age validation in horse mackerel (Trachurus trachurus) otoliths 总被引:1,自引:0,他引:1
476.
Validating a Tsunami Vulnerability Assessment Model (the PTVA Model) Using Field Data from the 2004 Indian Ocean Tsunami 总被引:2,自引:1,他引:2
The “PTVAM” tsunami vulnerability assessment model [Papathoma and Dominey-Howes: 2003, Nat. Hazards Earth Syst. Sci. 3, 733–744; Papathoma et al.: 2003, Nat. Hazards Earth Syst. Sci. 3, 377–389], like all models, requires validation. We use the results from post-tsunami surveys in the Maldives following the
December 26, 2004 Indian Ocean tsunami to ‘evaluate’ the appropriateness of the PTVAM attributes to understanding spatial
and temporal vulnerability to tsunami damage and loss. We find that some of the PTVAM attributes are significantly important
and others moderately important to understanding and assessing vulnerability. Some attributes require further investigation.
Based upon the ground-truth data, we make several modifications to the model framework and propose a revised version of the
PTVAM (PTVAM 2). 相似文献
477.
A model for studying the heat and mass exchange between the atmosphere and a water body is developed, in which the phase change process of water freezing in winter and melting in summer and the function of the convective mixing process are taken into consideration. The model uses enthalpy rather than temperature as the predictive variable. It helps to set up governing equations more concisely, to deal with the phase change process more easily, and make the numerical scheme simpler. The model is verified by observed data from Lake Kinneret for a non-frozen lake in summer time, and Lake Lower Two Medicine for a frozen lake in winter time. Reasonably good agreements between the model simulations and observed data indicate that the model can serve as a component for a water body in a land surface model. In order to more efficiently apply the scheme in a climate system model, a sensitivity study of various division schemes with less layers in the vertical direction in the water body is conducted. The results of the study show that the division with around 10 vertical layers could produce a prediction accuracy that is comparable to the fine division with around 40 layers. 相似文献
478.
479.
Operational Implementation of the ATOVS Processing Procedure in KMA and Its Validation 总被引:1,自引:0,他引:1
The Korea Meteorological Administration (KMA) has processed the data from the advanced TOVS(ATOVS) onboard NOAA-16 satellite since May 2001. The operational production utilizes the AAPP(ATOVS and AVHRR Processing Package) of EUMETSAT and IAPP (International ATOVS ProcessingPackage) of the University of Wisconsin. For the initial guess profiles, the predicted fields (usually 6 to 12hour forecasted fields) from the global aviation model of NOAA/NCEP are used. The average number ofprofiles retrieved from the ATOVS data is about 1,300 for each morning and afternoon orbit at about 18 and06 UTC, respectively. The retrieved temperature and dew point temperatures are provided to forecastersin real time and used for initialization of prediction models. With the advanced microwave sensor (AMSU;Advanced Microwave Sounding Unit), accuracy of the ATOVS products is expected to be better than thatof the TOVS products, especially in cloudy conditions. Indeed, the preliminary results from a validationstudy with the collocated radiosonde data during a 8-month period, from May to December 2001, for theEast Asia region show an improved accuracy of the ATOVS products for cloudy skies versus the TOVS,especially for higher altitudes. The RMS (Root Mean Square) difference between the ATOVS productsand radiosonde data is about 1.3℃ for both clear and cloudy conditions, except for near the ground and athigher altitudes, at around 200 hPa. There is no significant temporal variation of the error statistics at allpressure levels. In case of the water vapor mixing ratio, the largest difference is shown at lower altitudes,while the accuracy is much better for the clear sky cases than the cloudy sky cases. The bias and RMSEat lower altitudes is about 0.557 g kg-1 and 2.5 g kg-1 and decrease significantly with increasing altitude. 相似文献
480.