全文获取类型
收费全文 | 41452篇 |
免费 | 591篇 |
国内免费 | 321篇 |
专业分类
测绘学 | 959篇 |
大气科学 | 2945篇 |
地球物理 | 8003篇 |
地质学 | 14226篇 |
海洋学 | 3848篇 |
天文学 | 9759篇 |
综合类 | 74篇 |
自然地理 | 2550篇 |
出版年
2021年 | 404篇 |
2020年 | 401篇 |
2019年 | 453篇 |
2018年 | 940篇 |
2017年 | 844篇 |
2016年 | 1091篇 |
2015年 | 609篇 |
2014年 | 1003篇 |
2013年 | 2073篇 |
2012年 | 1132篇 |
2011年 | 1621篇 |
2010年 | 1475篇 |
2009年 | 1984篇 |
2008年 | 1648篇 |
2007年 | 1731篇 |
2006年 | 1588篇 |
2005年 | 1317篇 |
2004年 | 1270篇 |
2003年 | 1245篇 |
2002年 | 1194篇 |
2001年 | 1057篇 |
2000年 | 980篇 |
1999年 | 810篇 |
1998年 | 813篇 |
1997年 | 829篇 |
1996年 | 670篇 |
1995年 | 656篇 |
1994年 | 617篇 |
1993年 | 570篇 |
1992年 | 526篇 |
1991年 | 495篇 |
1990年 | 506篇 |
1989年 | 496篇 |
1988年 | 474篇 |
1987年 | 554篇 |
1986年 | 489篇 |
1985年 | 604篇 |
1984年 | 650篇 |
1983年 | 592篇 |
1982年 | 527篇 |
1981年 | 577篇 |
1980年 | 469篇 |
1979年 | 458篇 |
1978年 | 433篇 |
1977年 | 433篇 |
1976年 | 383篇 |
1975年 | 378篇 |
1974年 | 376篇 |
1973年 | 384篇 |
1971年 | 224篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
D. M. Morrison 《Pure and Applied Geophysics》1989,129(3-4):619-645
Microseismic systems at five mines in the Sudbury Basin provide the basic data for Falconbridge Limited's rockburst research. Daily and long-term analysis of this data as well as underground observations have confirmed the fault-slip mechanism at three mines. A detailed analysis of the complete history of Falconbridge Mine is being conducted and Distinct Element numerical models are being used to simulate both the stick-slip behaviour of faults and the dynamic effects of the induced vibrations on rock and backfill. University research includes acoustic tomographic imaging of the rock mass based on seismic wave propagation and collection of full microseismic waveforms to allow application of advanced seismic and statistical analysis techniques.Formerly with Mines Technical Services, Falconbridge Limited, Sudbury Operations, Falconbridge , Ont., P0M 1S0.Presented at the Fred Leighton Memorial Workshop on Mining Induced Seismicity, Montreal, Canada, August 30, 1987. 相似文献
92.
93.
Comprehensive distribution patterns of physical and chemical characteristics have been obtained from a series of cruises in Liverpool Bay. The marked feature of these distributions was their temporal variability, suggesting that the surface residual circulation is also temporally variable. The influence of wind stress upon the circulation pattern and hence water quality of this sea area is illustrated. 相似文献
94.
I. D. Somerville 《Geological Journal》1979,14(2):69-86
For the first time, minor cyclicity is described from some limestones in the lower part of the Brigantian (D2) succession of the Mold district North Wales which can be traced throughout the area enabling a detailed correlation to be established. The minor cyclicity may have been caused by eustatic sea-level fluctuations. Periods of emergence associated with each regressive phase are demonstrated by the presence of subaerial features and terrestrial deposits. The lateral persistence of the cycles is confirmed by comparison with established faunal and lithological horizons. Correlation with other cyclic Brigantian strata in Yorkshire, Derbyshire and Bristol is briefly discussed. The Asbian/Brigantian (D1/D2) boundary in North Wales is described and distinctive faunal and lithological changes similar to those in the area of the stratotype in north England have been recorded. 相似文献
95.
P. J. Michaels P. J. Stenger D. E. Sappington 《Theoretical and Applied Climatology》1986,37(1-2):39-50
Summary This report details as statistical model that relates changes in areal coverage of the Southern Pine Beetle (Dendroctonus frontalis Zimm.) to a multivariate combination of temperature and moisture status indices. It is applicable to larger geographic areas than our previous work (Michaels 1984). Performance in a true test (predictive) mode detected the algebraic sign of major coverage changes in a highly significant fashion. The results are purely correlative, rather than causative.This report describes a test-proven tool that can be used by planners to determine whether coverage will change, based upon easily accessed climatic data. An example of its application is provided.
With 5 Figures 相似文献
Zusammenfassung Diese Untersuchung führt ein statistisches Modell aus, welches das flächenmäßige Auftreten vonDendroctonus frontalis Zimm. mit einer Kombination von Temperaturund Feuchteverhältnisindikatoren in Verbindung bringt. Es kann für größere Gebiete verwendet werden als ein früher vorgestelltes (Michaels 1984). Die Anwendung zur Vorhersage zeigte in einem Test gute Übereinstimmung mit der tatsächlich aufgetretenen Richtung der Veränderung in der Verbreitung des Käfers. Die Ergebnisse zeigen Korrelationen, keine Kausalitäten auf.Es wird also ein Werkzeug für den Planer vorgestellt, mit dem die Verbreitungsänderung mit Hilfe leicht zugänglicher klimatologischer Daten bestimmt werden kann. Ein Anwendungsbeispiel wird näher ausgeführt.
With 5 Figures 相似文献
96.
C. D. Eysberg drs 《GeoJournal》1987,15(4):367-373
This essay focuses on the distinctive geographic setting of viticulture in California. It assesses the significance of the prevailing environmental conditions for wine growing in California and offers an explanation of the spatial pattern of Californian wine climate regions. Wine varieties in California, as almost everywhere in the world, are of European origin (Vitis vinifera). The ultimate result of a bio-geographic diffusion process of Vitis vinifera was the development of superior wine varieties in a climate that is marginal for wine growing in Western Europe (Cf-Köppen). Nestled in a cooler and more precarious macro-climatological environment, the relatively warm micro climates of the slopes (cotes) allow wine growing. The noble varieties peculiar to the slopes have been successfully transplanted in California's coastal valleys, this not-withstanding the California environment, which is diametrically opposed to that in Western Europe. In a hot macro environment (Cs-Köppen), high-quality wine growing is only possible due to the cool airconditioned micro climate in the valleys. 相似文献
97.
98.
The Dynamical Attitude Model (DAM) is a simulation package developed to achieve a detailed understanding of the Gaia spacecraft attitude. It takes into account external physical effects and considers internal hardware components controlling the satellite. The main goal of the Gaia mission is to obtain extremely accurate astrometry, and this necessitates a good knowledge of Gaia’s behaviour as a spinning rigid body under the influence of various perturbations. This paper describes these perturbations and how they are modelled in DAM. 相似文献
99.
100.