全文获取类型
收费全文 | 604篇 |
免费 | 58篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 18篇 |
大气科学 | 57篇 |
地球物理 | 228篇 |
地质学 | 221篇 |
海洋学 | 7篇 |
天文学 | 85篇 |
综合类 | 9篇 |
自然地理 | 40篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 11篇 |
2019年 | 11篇 |
2018年 | 49篇 |
2017年 | 43篇 |
2016年 | 60篇 |
2015年 | 45篇 |
2014年 | 52篇 |
2013年 | 54篇 |
2012年 | 31篇 |
2011年 | 25篇 |
2010年 | 30篇 |
2009年 | 24篇 |
2008年 | 24篇 |
2007年 | 25篇 |
2006年 | 21篇 |
2005年 | 13篇 |
2004年 | 7篇 |
2003年 | 10篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 5篇 |
1998年 | 9篇 |
1997年 | 3篇 |
1996年 | 9篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有665条查询结果,搜索用时 62 毫秒
661.
Changes of snow cover in Poland 总被引:2,自引:2,他引:0
Małgorzata Szwed Iwona Pińskwar Zbigniew W. Kundzewicz Dariusz Graczyk Abdelkader Mezghani 《Acta Geophysica》2017,65(1):65-76
The present paper examines variability of characteristics of snow cover (snow cover depth, number of days with snow cover and dates of beginning and end of snow cover) in Poland. The study makes use of a set of 43 long time series of observation records from the stations in Poland, from 1952 to 2013. To describe temporal changes in snow cover characteristics, the intervals of 1952–1990 and of 1991–2013 are compared and trends in analysed data are sought (e.g., using the Mann–Kendall test). Observed behaviour of time series of snow-related variables is complex and not easy to interpret, for instance because of the location of the research area in the zone of transitional moderate climate, where strong variability of climate events is one of the main attributes. A statistical link between the North Atlantic Oscillation (NAO) index and the snow cover depth, as well as the number of snow cover days is found. 相似文献
662.
What can we learn from the projections of changes of flow patterns? Results from Polish case studies 总被引:1,自引:1,他引:0
Mikołaj Piniewski Hadush Kidane Meresa Renata Romanowicz Marzena Osuch Mateusz Szcześniak Ignacy Kardel Tomasz Okruszko Abdelkader Mezghani Zbigniew W. Kundzewicz 《Acta Geophysica》2017,65(4):809-827
River flow projections for two future time horizons and RCP 8.5 scenario, generated by two projects (CHASE-PL and CHIHE) in the Polish-Norwegian Research Programme, were compared. The projects employed different hydrological models over different spatial domains. The semi-distributed, process-based, SWAT model was used in the CHASE-PL project for the entire Vistula and Odra basins area, whilst the lumped, conceptual, HBV model was used in the CHIHE project for eight Polish catchments, for which the comparison study was made. Climate projections in both studies originated from the common EURO-CORDEX dataset, but they were different, e.g. due to different bias correction approaches. Increases in mean annual and seasonal flows were projected in both studies, yet the magnitudes of changes were largely different, in particular for the lowland catchments in the far future. The HBV-based increases were significantly higher in the latter case than the SWAT-based increases in all seasons except winter. Uncertainty in projections is high and creates a problem for practitioners. 相似文献
663.
Katarzyna Kowalczewska-Madura Ryszard Gołdyn Julia Bogucka Katarzyna Strzelczyk 《国际泥沙研究》2019,34(1):14-26
Strzeszynskie Lake was formerly a slightly eutrophic (meso-eutrophic) water body. The aim of the current research was to define variables on both spatial and seasonal internal phosphorus loading from bottom sediments at five stations located in zones varying in depth, oxygenation, macrophyte presence, and uses of the neighboring catchment area. Ex situ experiments done with the use of intact bottom sediment cores have shown that the highest phosphorus release occurred in the deepest part of the lake and reached 3.6?mg?P/m2d under anoxic conditions during summer thermal stratification. In turn, the internal loading from littoral sediments, which were well aerated all year round, was clearly lower. Furthermore, phosphorus accumulation in the bottom sediment was observed to reach a maximum of 1.45?mg?P/m2 d in autumn. A comparison of the internal loading intensity in lake zones with different land uses of the neighboring catchment area has shown slightly higher values at stations adjacent to the forest catchment area than those used for recreation. Changes in the land use of the catchment area of Strzeszynskie Lake, especially the increase in impermeable surfaces, have led to an increased inflow of external loads after heavy rains, resulting in deterioration in water quality and a delayed increase in internal loading. 相似文献
664.
A simple algorithm for generating streamflow networks for macroscale hydrological models (MHMs) from digital elevation models (DEMs) is presented. Typically these hydrological models are grid based, with the simulated runoff produced within each cell routed through a stream network which connects the centers of cells in the direction of the major streams. Construction of such stream networks is a time consuming task, which has generally been done by hand with the aid of maps. Results indicate that the algorithm works satisfactorily in areas of both high and low relief, and for a wide range of model cell resolutions, although some manual adjustments may be necessary. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
665.
The goal of the research was to demonstrate the impact of thin porous interfacial transition zones (ITZs) between aggregates and cement matrix on fluid flow in unsaturated concrete caused by hydraulic/capillary pressure. To demonstrate this impact, a novel coupled approach to simulate the two-phase (water and moist air) flow of hydraulically and capillary-driven fluid in unsaturated concrete was developed. By merging the discrete element method (DEM) with computational fluid dynamics (CFD) under isothermal settings, the process was numerically studied at the meso-scale in two-dimensional conditions. A flow network was used to describe fluid behaviour in a continuous domain between particles. Small concrete specimens of a simplified particle mesostructure were subjected to fully coupled hydro-mechanical simulation tests. A simple uniaxial compression test was used to calibrate the pure DEM represented by bonded spheres, while a permeability and sorptivity test for an assembly of spheres was used to calibrate the pure CFD. For simplified specimens of the pure cement matrix, cement matrix with aggregate, and cement matrix with aggregate and ITZ of a given thickness, DEM/CFD simulations were performed sequentially. The numerical results of permeability and sorptivity were directly compared to the data found in the literature. A satisfactory agreement was achieved. Porous ITZs in concrete were found to reduce sorption by slowing the capillary-driven fluid flow, and to speed the full saturation of pores when sufficiently high hydraulic water pressures were dominant. 相似文献