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501.
502.
Kathi Wilson 《The Professional geographer》2013,65(1):133-134
This paper expands the human capital model to compare the migration propensities of Cubans, Mexicans, and Puerto Ricans within the U.S. between 1985 and 1990. Using the 5% PUMS from the 1990 U.S. Census, both aggregate migration streams and micro-level migration propensities are estimated for Cubans, Mexicans, and Puerto Ricans. The effects of personal factors, the economic environment, and the presence of fellow nationals are examined in the context of larger geographic patterns, and discussed in terms of each nationality's immigration history and cultural context. While many factors effect migration behavior similarly, there are notable differences in the way education, English fluency, and unemployment rate affect migration propensity of the native-born and foreign-born of each nationality. Differences are also apparent at the macro-level. Puerto Ricans show signs of dispersing out of New York; Mexicans are redistributing within the Southwest; and Cubans are re-concentrating in Florida. Both levels of analysis point to how immigration history, settlement patterns, and cultural context influence migration behavior. The results demonstrate the benefits of using an expanded human capital approach to explain migration differences, and highlight the diversity of population redistribution occurring within Hispanic nationalities. 相似文献
503.
James L. Wilson 《The Professional geographer》2013,65(4):624-626
In this article, we examine graffiti abatement policies and programs in three West Coast U.S. cities: Portland, San Francisco, and Seattle. Through this analysis, several similarities in the graffiti abatement efforts of each city emerged. Since the 1990s, graffiti abatement efforts in these cities have become increasingly formalized and coordinated. By the early 2000s, the cities of Portland, San Francisco, and Seattle adopted zero-tolerance approaches toward handling graffiti and those caught making graffiti. City governments have placed increasing responsibility for cleaning up graffiti on private property onto property owners. Despite the increased coordination and effort, annual abatement estimates are hard to obtain because tracking spending on graffiti abatement across agencies and bureaus is difficult and often the cities do not comprehensively compile these data. 相似文献
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Matthew W. Wilson 《Geoforum》2012,43(6):1266-1275
The production and consumption of geographic information is becoming a more mobile practice, with more corporate actors challenging the traditional stronghold of Esri- and government-based geospatial developments. What can be considered a geographic information system has expanded to include web-based technologies like Google Earth/Maps, as well as more recent developments of Microsoft’s Bing Maps and the mobile version of ArcGIS available for the iPhone. In addition to these developments, a discursive shift toward ‘location’ is occurring across the Internet industry. Location has become the new buzzword for social-spatial strategies to target consumers. As reported in 2010, venture capitalists have, since 2009, invested $115 million into ‘location start-ups’ – software companies that provide location-based services to mobile computing consumers (Miller and Wortham, 2010). Applications like Foursquare, Loopt, Gowalla, and most recently, Facebook Places allow users to ‘check-in’ at restaurants, bars, gyms, retail outlets, and offices, thereby sharing their location within their social network. These developments enable consumers to (re)discover their proximities to products, while feeding a desire for making known one’s everyday movements. Here, I discuss the development of location-based services as the proliferation of a peculiar form of geographic information: conspicuous mobility. Through discussion of a recent gathering of location-aware software professionals and through analysis of discourses that emerge over a battle between ‘check in’ companies, I sketch an area of study that explores the implications of these emerging geographic information ‘systems’, and new everyday cartographers. 相似文献
506.
Climate Change Impact on Hydrological Extremes: Preliminary Results from the Polish-Norwegian Project 总被引:2,自引:1,他引:1
Renata J. Romanowicz Ewa Bogdanowicz Sisay E. Debele Joanna Doroszkiewicz Hege Hisdal Deborah Lawrence Hadush K. Meresa Jaroslaw J. Napiórkowski Marzena Osuch Witold G. Strupczewski Donna Wilson Wai Kwok Wong 《Acta Geophysica》2016,64(2):477-509
This paper presents the background, objectives, and preliminary outcomes from the first year of activities of the Polish–Norwegian project CHIHE (Climate Change Impact on Hydrological Extremes). The project aims to estimate the influence of climate changes on extreme river flows (low and high) and to evaluate the impact on the frequency of occurrence of hydrological extremes. Eight “twinned” catchments in Poland and Norway serve as case studies. We present the procedures of the catchment selection applied in Norway and Poland and a database consisting of near-natural ten Polish and eight Norwegian catchments constructed for the purpose of climate impact assessment. Climate projections for selected catchments are described and compared with observations of temperature and precipitation available for the reference period. Future changes based on those projections are analysed and assessed for two periods, the near future (2021–2050) and the far-future (2071–2100). The results indicate increases in precipitation and temperature in the periods and regions studied both in Poland and Norway. 相似文献
507.
Inversion of gravity and/or magnetic data attempts to recover the density and/or magnetic susceptibility distribution in a 3D earth model for subsequent geological interpretation. This is a challenging problem for a number of reasons. First, airborne gravity and magnetic surveys are characterized by very large data volumes. Second, the 3D modelling of data from large‐scale surveys is a computationally challenging problem. Third, gravity and magnetic data are finite and noisy and their inversion is ill posed so regularization must be introduced for the recovery of the most geologically plausible solutions from an infinite number of mathematically equivalent solutions. These difficulties and how they can be addressed in terms of large‐scale 3D potential field inversion are discussed in this paper. Since potential fields are linear, they lend themselves to full parallelization with near‐linear scaling on modern parallel computers. Moreover, we exploit the fact that an instrument’s sensitivity (or footprint) is considerably smaller than the survey area. As multiple footprints superimpose themselves over the same 3D earth model, the sensitivity matrix for the entire earth model is constructed. We use the re‐weighted regularized conjugate gradient method for minimizing the objective functional and incorporate a wide variety of regularization options. We demonstrate our approach with the 3D inversion of 1743 line km of FALCON gravity gradiometry and magnetic data acquired over the Timmins district in Ontario, Canada. Our results are shown to be in good agreement with independent interpretations of the same data. 相似文献
508.
GRACE's spatial aliasing error 总被引:2,自引:0,他引:2
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510.
G. W. Wilson J. E. Austermann T. A. Perera K. S. Scott P. A. R. Ade J. J. Bock J. Glenn S. R. Golwala S. Kim Y. Kang D. Lydon P. D. Mauskopf C. R. Predmore C. M. Roberts K. Souccar M. S. Yun 《Monthly notices of the Royal Astronomical Society》2008,386(2):807-818
AzTEC is a mm-wavelength bolometric camera utilizing 144 silicon nitride micromesh detectors. Here, we describe the AzTEC instrument architecture and its use as an astronomical instrument. We report on several performance metrics measured during a three-month observing campaign at the James Clerk Maxwell Telescope and conclude with our plans for AzTEC as a facility instrument on the Large Millimetre Telescope. 相似文献