首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   65篇
  免费   4篇
测绘学   6篇
地球物理   9篇
地质学   18篇
天文学   34篇
自然地理   2篇
  2021年   1篇
  2020年   1篇
  2018年   7篇
  2017年   2篇
  2015年   1篇
  2014年   3篇
  2013年   9篇
  2012年   5篇
  2011年   2篇
  2010年   2篇
  2009年   1篇
  2008年   2篇
  2007年   2篇
  2006年   1篇
  2005年   2篇
  2003年   1篇
  2001年   1篇
  1999年   1篇
  1997年   3篇
  1993年   2篇
  1989年   1篇
  1988年   2篇
  1987年   4篇
  1986年   1篇
  1985年   4篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1981年   1篇
  1980年   1篇
  1972年   1篇
排序方式: 共有69条查询结果,搜索用时 15 毫秒
41.
Zusammenfassung Die Serpentine von Bernstein und Steinbach (mittleres Burgenland) werden als Intrusionen im festen Zustand gedeutet.Während man für Bernstein und seine Umgebung auf Grund fehlender Reliktminerale lediglich eine Einstufung des Serpentinisierungsvorganges in die Grünschieferfazies vornehmen kann, lassen zahlreiche Relikte und das Auftreten verschiedener Pyroxeniteinschlüsse im Serpentin von Steinbach Aussagen über die vormetamorphe Genese dieses Gesteinskörpers zu, dessen Herkunft aus dem oberen Erdmantel abgeleitet wird. Die Serpentinisierung fand unter Bedingungen der Albit-Epidot-Amphibolit-Fazies statt. Daraus und aus allgemeinen Überlegungen ist eine Zuordnung des Serpentinkörpers von Steinbach zur Sieggraben-Schäffern-Serie gegeben, während das Vorkommen von Bernstein der Rechnitzer Serie angehört.
The serpentinites of Bernstein and Steinbach (Burgenland, Austria)
Summary The serpentinites of Bernstein and Steinbach (Burgenland, Austria) are interpreted to be intrusions at solid state.Numerous relics and the occurrence of various inclusions of pyroxenites in the Steinbach serpentinite indicate its origin from the Upper Mantle. The serpentinization took place under the conditions of the albite-epidote-amphibolite facies.The absence of relics in the Bernstein rocks only permits a classification of the serpentinization itself which corresponds to the greenschist facies. Transfered to the local geological and tectonical situation a coordination of the Steinbach serpentinite body to the Sieggraben-Schäffern series and the Bernstein serpentinites to the Rechnitzer Serie can be accepted.


Mit 4 Abbilungen  相似文献   
42.
Two-colour light curves of Z Her were obtained observing the system from 1978 to 1981. The wave-like distortion at outside eclipses were derived. The amplitudes of the wave increase and its minimum migrates towards the decreasing orbital phase with a period of about 1.4 yr. An attempt was made to represent the wave-like distortions with a truncated Fourier series. The representation was found to be unsatisfactory since the distribution of the present observations is not regular but forms separate groups along the time axis. Therefore, further observations to cover the phases evenly in between the minima are needed.  相似文献   
43.
Evren  S.  Ibanoğlu  C.  Tunca  Z.  Tümer  O. 《Astrophysics and Space Science》1986,120(1):97-106
The light curves of V471 Tau obtained in four successive years from 1981 to 1984 are presented. The light variations due to the tidally distorted red dwarf have been computed and subtracted out from the light curves obtained so far. A pure shape of the wave-like distortion has therefore been derived. The period of the retrograde migration has been found to be 182.17 days. On the other hand, the mean brightness of the system seems to vary with a period of about 18 years. The amplitude of the variation is greater at longer wavelength. The periodic variation of the mean brightness resembles the solar cycle of about 11.2 years, which depends upon the number of spots or spot groups.  相似文献   
44.
The eclipsing variable RT Lac, which is classified as an RS CVn-type binary by Hall, was observed in two colours,B andV, during the summer seasons of 1978 and 1979. The observations made during two successive seasons indicate that, outside eclipses, the system has brightened by about 0.12 and 0.15 magnitudes on average inB andV, respectively. Moreover, RT Lac was even fainter when observed by Milone in 1965. While the total brightness of the system remained unchanged at mid-secondary, it increased at mid-primary and outside eclipses. This may be interpreted as indicating that the cooler component is responsible for the peculiar light variations.  相似文献   
45.
Obtaining information about tree species distribution in agricultural lands is a topic of interest for various applications, such as tree inventory, forest management, agricultural land management, crop estimation, etc. This information can be derived from images obtained from modern remote sensing technology, which is the most economical way as compare to field surveys covering large geographic areas. Therefore, in this study, a new method is proposed for extraction and counting of sparse and regular distributed individual pistachio trees from agricultural areas on large scale from high-resolution digital ortho-photo maps, which were obtained using an airborne sensor (Ultracam-X). The input images were first smoothed by applying Gaussian filter to reduce the impact of noise. Normalized difference vegetation indices (NDVI) were then derived to obtain vegetation areas followed by Otsu’s global thresholding algorithm to obtain candidate tree areas. Further, connected component (CC) analysis was applied to segregate each object. Morphological processing was performed to fill holes within tree objects and get smooth contours, which were obtained by using the Moore-neighbor tracing method (MNTM) for each CC, while geometrical constraints were applied to undermine possible non-tree elements from output image. To further improve the segmentation results for sparse trees, a new method was applied, called quadratic local analysis (QLA). QLA helped to segment the trees, which were missed by the Otsu method due to low contrast and resulted in improved accuracy (3–6%). The obtained results were compared with well-known support vector machine (SVM) classifier. Proposed method produced slightly better results (1–5%) than SVM for extraction of pistachio trees and obtained accuracy for QLA and SVM were 96 and 91% for region 1, while 91 and 90% for region 2 respectively.  相似文献   
46.
The present study investigates the dynamic impact of biomass energy consumption on economic growth across nine (9) ASEAN economic union member countries for the period of 1980–2011. We applied heterogeneous panel cointegration techniques. The result based on Pedroni panel cointegration test shows that, variables have long-run relationship as the null hypothesis of no cointegration was rejected at 1% and 5% respectively. Kao residual cointegration test also shows the same result as null hypothesis of no cointegration is rejected at 1% level of significance. The main empirical finding based on dynamic OLS, fully modified OLS and panel OLS reveals that; there is a positive and significant relationship between biomass energy consumptions and economic growth in the region. Moreover, the result based on dynamic ordinary least square (DOLS) also shows that; capital stock and human capital have a positive and significant impact on economic growth. Same result is also obtained from fully modified OLS (FMOLS) with the exception of human capital which is insignificant on economic growth. Panel ordinary least square also reconfirmed the finding of DOLS as all the three variables significantly influences economic growth. The policy suggestion remains that, authorities in ASEAN economic union should focus more on encouraging the use of renewable sources of energy, particularly biomass source of energy considering its positive impact on enhancing economic growth with little or no environmental degradation.  相似文献   
47.
Ilgin Seker 《Solar physics》2013,286(2):303-314
We study whether the birthplaces of sunspots (defined as the location of first appearance in the photosphere) are related to the planetary tides on the Sun. The heliocentric longitudes of newly emerging sunspots are statistically compared to the longitudes of tidal peaks caused by the tidal planets Mercury, Venus, Earth, and Jupiter. The longitude differences between new sunspots and tidal planets (and their conjugate locations) as well as the magnitudes of the vertical and horizontal tidal forces at the birthplace of new sunspots are calculated. The statistical distributions are compared with simulation results calculated using a random sunspot distribution. The results suggest that the birthplaces of sunspots (in the photosphere) are independent of the positions of tidal planets and the strength of tidal forces caused by them. However, since the sunspots actually originate near the tachocline (well below the photosphere) and it takes considerable time for the disturbances to reach photosphere, we hesitate to conclude that the formation of sunspots are not related to planetary positions.  相似文献   
48.
The most significant morphological property of a river is the meandering process, which is dominated and governed by hydraulic, hydrologic and topographic characteristics of the river and its drainage area. It is possible to obtain reliable data on river morphology in the long term by using remotely sensed data. In this study the Filyos River, located at the Western Black Sea region of Turkey, has been selected as the study area to show the capabilities of remote sensing technology and to define the appropriate techniques for achieving the most reliable information on the river morphology by monitoring the meandering processes. The findings of the study indicate that remotely sensed data can be used successfully in defining some basic characteristics of the meandering process on rivers. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
49.
50.
The observations of the peculiar eclipsing binary RT Lac were continued during the observing seasons of 1982 and 1983. The salient properties of the light curves were presented. The shallowest primary eclipse was observed in 1983. When the light curves, obtained in six years sucessively, are interpreted together it is seen that the variations of the brightness at mid-primary and second maximum are too similar to each other. The colour variations at mid-primary also follow those variations in the brightness. These circumstances indicate that the starspot hypothesis is insufficient alone to explain all the phenomena observed. The earlier spectral type G9 companion may be intrinsically variable and the unusual distortion on the light curves following the secondary eclipse may arise from the gas-stream from larger K star to the G9 star.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号