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31.
348-YEAR PRECIPITATION RECONSTRUCTION FROM TREE-RINGS FOR THE NORTH SLOPE OF THE MIDDLE TIANSHAN MOUNTAINS*
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Correlation census shows that the correlation between the tree-ring chronologies in the Urumqi River Basin and precipitation during July in the last year to February in the concurrent year is significant,and the best single correlation coefficient is 0.74,with significance level of 0.0001.Using two residual chronologies collected from west Baiyanggou and Boerqingou,precipitation for 348 years can be reconstructed in the North Slope of middle Tianshan Mountains,its explained variance is 62%.According to much verification from independent precipitation data,historical climate records,glacier and other data.it shows that the reconstructed precipitation series of 348 years is reliable.Analysis of precipitation features indicates that there were three wet periods occurring during 1671-1692,1716-1794 and 1825-1866 and three dry periods during 1693-1715,1795-1824 and 1867-1969.Two wet periods,during 1716-1794 and 1825-1866,correspond to the times of the second and the third glacial terminal moraine formation,which is infront of No.1 glacier in Urumqi River source.According to computation,corresponding annual precipitation amounts are 59mm and 30mm more than now.The reconstructed precipitation series has a significant drying trend from 1716 to 1969.and has better representativeness to the precipitation of Urumqi and Changji Prefecture on the North Slope of Tianshan Mountains. 相似文献
32.
JIN Xiaochi WANG Yizhao XIE GuanglianInstitute of Geology Chinese Academy of Geological Sciences Baiwanzhuang Ro Beijing Geological Survey of Yunnan Yujiang Ro Yuxi Yunnan 《《地质学报》英文版》2003,77(4):440-456
Phanerozoic strata are distributed in several north-south trending zones in the central part of the Changning-Menglian Belt. Four types of Devonian to Triassic stratigraphic successions can be identified: (1) elastics with limestone lenses in the mid-section, changing up-section into alternations of fine elastics and cherts; (2) elastics with chert intercalations and limestone lenses, and topped by Permian basic volcanics; (3) elastics-basic volcanics-carbonates-clastics; and (4) limestones, dolomitic limestones-dark gray thin-bedded limestones, argillaceous limestones, mudstones and siliceous mudstones. Devonian to Triassic cherts occur in different horizons and different zones from east to west. These cherts are usually transitional to their neighboring elastics. There is no continuous Devonian to Middle Triassic chert sequence in the central zone of the Changning-Menglian Belt as Liu et al. (1991,1993) reported. Volcanics and the overlying carbonates described by some workers as "seamount" sequences 相似文献
33.
The 1920S Drought Recorded by Tree Rings and Historical Documents in the Semi-Arid and Arid Areas of Northern China 总被引:7,自引:0,他引:7
Eryuan Liang Xiaohong Liu Yujiang Yuan Ningsheng Qin Xiuqi Fang Lei Huang Haifeng Zhu Lily Wang Xuemei Shao 《Climatic change》2006,79(3-4):403-432
Using a network of tree-ring data, we show that there had been significant growth decline in the 1920s and early 1930s throughout
a wide area of northern China. This growth depression is indicative of a severe and sustained drought in the 1920s and early
1930s, which was then confirmed with a variety of historical and instrumental records including hydrological, meteorological,
and documentary evidence. The 1920s drought had a devastating effect not only on agricultural productivity, hydrological resources
and society in the affected areas, but also on natural vegetation, as inferred from the tree-ring network and historical records.
This research offers a picture of the drought calamity during the 1920s and early 1930s in northern China, and demonstrates
the potential to identify spatial anomalies of large-scale drought using tree-ring networks in the semi-arid and arid areas
of northern China. 相似文献
34.
塔克拉玛干沙漠辐射平衡研究 总被引:3,自引:0,他引:3
本文对塔里拉玛干沙漠辐射平衡实测值与计算值进行了对比,分析了辐射平衡不同季节的日变化及年变化特征,并分析了影响辐射平衡的各主要因子,得到了沙漠辐射平衡研究的一些新认识。 相似文献
35.
??????????????????????????????????????????????????????????????????????????????????????????????????仯???????????????1)???????????????????б????????????????Χ?????????????????????????????2)???????????????????????????????????????????????仯???????????????????SEE???????SE??,???????SE-NS-SW??仯??3)????????????????????????????????????10 -8?????????????????????????????????????С????????Σ?4)??????????????????????????佻??????????????????????£???????????н??????????????????????????????????????????????? 相似文献
36.
Sequence variation of partial cytochrome b genes between two Coilia species, C. ectenes and C. mystus, was investigated. Of the 402 nucleotides, twenty-seven (6.72%) are polymorphic and all are synonymous substitutions. At
the third positions of genetic condon of cytochrome b gene, the two species show an extreme anti-G bias (<4%) and a pronounced bias towards A and C (>68%). There is no amino acid
sequence divergence between the partial cytochrome b genes of the two species, indicating a close genetic relationship between them. The k-2p genetic distance of partial cytochrome
b segment of the two species is 0.072, suggesting that the species were separated 3.6 Ma ago, in the middle Pliocene. Our result
reveals that the cytochrome b gene is an appropriate marker for studies of population genetic structures and phylogeographic patterns of the two species. 相似文献
37.
Darije Maričić Bojan Vršnak Andrew L. Stanger Astrid M. Veronig Manuela Temmer Dragan Roša 《Solar physics》2007,241(1):99-112
We analyze the relationship between the acceleration of coronal mass ejections (CMEs) and the energy release in associated
flares, employing a sample of 22 events in which the CME kinematics were measured from the pre-eruption stage up to the post-acceleration
phase. The data show a distinct correlation between the duration of the acceleration phase and the duration of the associated
soft X-ray (SXR) burst rise, whereas the CME peak acceleration and velocity are related to the SXR peak flux. In the majority
of events the acceleration started earlier than the SXR burst, and it is usually prolonged after the SXR burst maximum. In
about one half of the events the acceleration phase is very closely synchronized with the fastest growth of the SXR burst.
An additional one quarter of the events may be still considered as relatively well-synchronized, whereas in the remaining
quarter of the events there is a considerable mismatch. The results are interpreted in terms of the feedback relationship
between the CME dynamics and the reconnection process in the wake of the CME. 相似文献
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