全文获取类型
收费全文 | 401篇 |
免费 | 17篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 6篇 |
大气科学 | 47篇 |
地球物理 | 75篇 |
地质学 | 153篇 |
海洋学 | 56篇 |
天文学 | 64篇 |
自然地理 | 21篇 |
出版年
2023年 | 4篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 5篇 |
2014年 | 10篇 |
2013年 | 16篇 |
2012年 | 11篇 |
2011年 | 22篇 |
2010年 | 28篇 |
2009年 | 24篇 |
2008年 | 13篇 |
2007年 | 16篇 |
2006年 | 15篇 |
2005年 | 13篇 |
2004年 | 16篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 9篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1996年 | 13篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 11篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 10篇 |
1974年 | 6篇 |
1973年 | 12篇 |
1972年 | 3篇 |
1967年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有422条查询结果,搜索用时 15 毫秒
371.
Petr Dobrovolný Anders Moberg Rudolf Brázdil Christian Pfister Rüdiger Glaser Rob Wilson Aryan van Engelen Danuta Limanówka Andrea Kiss Monika Halíčková Jarmila Macková Dirk Riemann Jürg Luterbacher Reinhard Böhm 《Climatic change》2010,101(1-2):69-107
Monthly temperature series for Central Europe back to AD 1500 are developed from documentary index series from Germany, Switzerland and the Czech Republic (1500–1854) and 11 instrumental temperature records (1760–2007). Documentary evidence from the Low Countries, the Carpathian Basin and Poland are used for cross-checking for earlier centuries. The instrumental station records are corrected for inhomogeneities, including insufficient radiation protection of early thermometers and the urban heat island effect. For overlapping period (1760–1854), the documentary data series correlate with instrumental temperatures, most strongly in winter (86% explained variance in January) and least in autumn (56% in September). For annual average temperatures, 81% of the variance is explained. Verification statistics indicate high reconstruction skill for most months and seasons. The last 20 years (since 1988) stand out as very likely the warmest 20-year period, accounting for the calibration uncertainty and decreases in proxy data quality before the calibration period. The new reconstruction displays a previously unobserved long-term decrease in DJF, MAM and JJA temperature variability over last five centuries. Compiled monthly, seasonal and annual series can be used to improve the robustness of gridded large-scale European temperature reconstructions and possible impact studies. Further improvement of the reconstruction would be achieved if documentary data from other European countries are further developed. 相似文献
372.
Bjørn Jamtveit Christine V. Putnis Anders Malthe-Sørenssen 《Contributions to Mineralogy and Petrology》2009,157(1):127-133
Replacement processes are common transformation mechanisms in minerals and rocks at a variety of conditions and scales. The
underlying mechanisms are, in general, poorly understood, but both mechanical and chemical processes are thought to be important.
Replacement of leucite (KAlSi2O6) by analcime (NaAlSi2O6
.H2O) is common in silica-poor igneous rocks. A 10% increase in volume is associated with the replacement process, and this generates
stresses that eventually cause fracturing of the reacting leucite. Experimentally reacted leucite samples display characteristic
fracturing patterns that include both spalling of concentric ‘onion-skin’-like layers near the reacting interface and the
formation of cross-cutting, often hierarchically arranged, sets of fractures that divide the remaining leucite into progressively
smaller domains. These structures may explain the ‘patchy’ alteration patterns observed in natural leucite samples and similar,
so-called, mesh-textures associated with the serpentinization of olivine grains during hydration of mafic or ultramafic rocks.
They are also strikingly similar to larger scale patterns formed during spheroidal weathering processes. A simple discrete
element model illustrates the mechanics that control the formation of such systems, and shows how these replacement processes
may be accelerated due to the generation of new reactive surface area by hierarchical fracturing processes. 相似文献
373.
374.
Tommy Gärling Anders Böök Erik Lindberg Constantino Arce 《The Professional geographer》1991,43(2):143-149
Two groups of subjects with varying amounts of experience with the city in which they lived judged from memory distances between familiar locations. The distance judgments were processed by a multidimensional scaling algorithm (MULTISCALE) that estimates the parameters of a power function transformation of the response scale and the coordinates of the locations in k-dimensional euclidean space. The results for both subject groups suggested that inaccuracies of distance cognition do not reflect the noneuclidean nature of urban cognitive maps but are caused by response bias. 相似文献
375.
North Atlantic Water (NAW) is an important source of heat and salt to the Nordic seas and the Arctic Ocean. To measure the transport and variability of one branch of NAW entering the Arctic, a transect across the entrance to the Barents Sea was occupied 13 times between July 1997 and November 1999, and hydrography and currents were measured. There is large variability between the cruises, but the mean currents and the hydrography show that the main inflow takes place in Bjørnøyrenna, with a transport of 1.6 Sv of NAW into the Barents Sea. Combining the flow field with measurements of temperature and salinity, this results in mean heat and salt transports by NAW into the Barents Sea of 3.9×1013 W and 5.7×107 kg s−1 , respectively. The NAW core increased in temperature and salinity by 0.7 °C yr−1 and 0.04 yr−1 , respectively, over the observation period. Variations in the transports of heat and salt are, however, dominated by the flow field, which did not exhibit a significant change. 相似文献
376.
The metabolism of some xenobiotics can lead to the formation of reactive intermediates with mutagenic/carcinogenic properties. With the carcinogenic PAH these have been identified as bay-region diol-epoxides.1 Phenanthrene, a non-carcinogenic, bay-region containing model PAH, is metabolised in vivo by bony fish at the proximate bay-region position, whereas mammals and other marine organisms mainly form the K-region metabolite 9,10-dihydro-9,10-dihydroxy-phenanthrene.2 We wanted to investigate this difference more closely by studying the regiospecificity of phenanthrene metabolism in vitro both with microsomes from differently pretreated cod and with isolated cytochrome P-450 isozymes from BNF-induced cod.3 Secondly, by preparing antibodies to the major isozyme isolated (called cod P-450c), we investigated the immunochemical properties of the variously treated cod liver microsomes. 相似文献
377.
In this paper a statistical forecasting model designed for bounded areas of near-surface ocean wind speeds is implemented.Dimension reduction is achieved by decomposing the covariance structure into one large-scale and one small-scale component using empirical orthogonal functions. The large-scale component is modelled with an AR process and forecasts are calculated by applying a Kalman filter.The model is suited for stable weather situations as for unsteady situations it requires more frequent wind information. From the prediction variance fields it is possible to identify where unexpected weather usually enters the area. 相似文献
378.
Simulating search behaviour of fish towards bait 总被引:2,自引:0,他引:2
Vabo Rune; Huse Geir; Ferno Anders; Jorgensen Terje; Lokkeborg Svein; Skaret Georg 《ICES Journal of Marine Science》2004,61(7):1224-1232
379.
380.
Henrik Lundstedt Anders Johannesson Göran Scharmer Jan Olof Stenflo Ulf Kusoffsky Birgitta Larsson 《Solar physics》1991,132(2):233-245
A high-resolution videomagnetograph that records the images of opposite circular polarization simultaneously has been constructed for the Swedish vacuum solar telescope at La Palma. Magnetograms are obtained by off-line integration of bursts consisting of typically 50 frames of 20 ms exposures, with bad frames rejected, and the frame-to-frame image motion of the remaining frames compensated for by cross-correlation techniques. The short exposures combined with frame selection and elimination of image motion optimizes the resolution and thereby also the S/N, allowing good magnetograms to be obtained with an effective exposure time of less than 1 s at an image scale of 0.1 pixel–1. The advantages and limitations of the system are discussed and compared with other techniques of making filter magnetograms are discussed. 相似文献