全文获取类型
收费全文 | 300篇 |
免费 | 16篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 6篇 |
大气科学 | 13篇 |
地球物理 | 75篇 |
地质学 | 85篇 |
海洋学 | 64篇 |
天文学 | 54篇 |
综合类 | 7篇 |
自然地理 | 16篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 11篇 |
2016年 | 15篇 |
2015年 | 6篇 |
2014年 | 11篇 |
2013年 | 14篇 |
2012年 | 8篇 |
2011年 | 14篇 |
2010年 | 14篇 |
2009年 | 20篇 |
2008年 | 12篇 |
2007年 | 19篇 |
2006年 | 14篇 |
2005年 | 20篇 |
2004年 | 22篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有320条查询结果,搜索用时 31 毫秒
21.
22.
A 6.2 m thick core of Gucheng Lake sediment provided a 3600 years record of climate change. The contents of the TOC in the
core changed from 2.63% to 8.48%, and the δ13C values of organic matter were from −21.54% to −27.3%. The TOC/TN ratios indicated that the organic materials in sediments
were from lake plankton and land-derived plants.
The 2.9–22 m core interval with high TOC/TN ratios, low δ13C values and low contents of TOC indicated a cold climate stage. The 6.2–5.5 m and 0.4–0.1 m intervals were characterized
by low TOC/TN ratios, high δ13C values and high contents of TOC, and reflected temperate climate stages.
Project 49372129 supported by NSFC. 相似文献
23.
M. Matsumoto S. Wallis M. Aoya M. Enami J. Kawano Y. Seto N. Shimobayashi 《Journal of Metamorphic Geology》2003,21(4):363-376
A largely undocumented region of eclogite associated with a thick blueschist unit occurs in the Kotsu area of the Sanbagawa belt. The composition of coexisting garnet and omphacite suggests that the Kotsu eclogite formed at peak temperatures of around 600 °C synchronous with a penetrative deformation (D1). There are local significant differences in oxygen fugacity of the eclogite reflected in mineral chemistries. The peak pressure is constrained to lie between 14 and 25 kbar by microstructural evidence for the stability of paragonite throughout the history recorded by the eclogite, and the composition of omphacite in associated eclogite facies pelitic schist. Application of garnet‐phengite‐omphacite geobarometry gives metamorphic pressures around 20 kbar. Retrograde metamorphism associated with penetrative deformation (D2) is in the greenschist facies. The composition of syn‐D2 amphibole in hematite‐bearing basic schist and the nature of the calcium carbonate phase suggest that the retrograde P–T path was not associated with a significant increase or decrease in the ratio of P–T conditions following the peak of metamorphism. This P–T path contrasts with the open clockwise path derived from eclogite of the Besshi area. The development of distinct P–T paths in different parts of the Sanbagawa belt shows the shape of the P–T path is not primarily controlled by tectonic setting, but by internal factors such as geometry of metamorphic units and exhumation rates. 相似文献
24.
To assess the post-earthquake seismic safety of buildings, it is crucial to predict seismic response, and it is necessary to set the appropriate physical parameters of the response analysis model. Numerous methods have been proposed to identify physical parameters. However, most of them are limited to linear systems, and previous researches on nonlinear systems have difficulties in practical applications. In this paper, a nonlinear response analysis model is identified for a full-scale ten-story reinforced concrete building with the degrading tri-linear stiffness model by the modal iterative error correction (MIEC) method, and the accuracy of this technique is discussed by comparing with the shaking table test. 相似文献
25.
1 INTRODUCTION δ13C in organic matters from lacustrine sedi- ments varies with several factors including aquatic plants, vegetation type in the catchment, atmos- pheric CO2 concentration, climate (temperature and precipitation), and properties of water, … 相似文献
26.
Jun‐ichi Matsuda Miwa Namba Teruyuki Maruoka Takuya Matsumoto Gero Kurat 《Meteoritics & planetary science》2005,40(3):431-443
Abstract— We have carried out noble gas measurements on graphite from a large graphite‐metal inclusion in Canyon Diablo. The Ne data of the low‐temperature fractions lie on the mixing line between air and the spallogenic component, but those of high temperatures seem to lie on the mixing line between Ne‐HL and the spallogenic component. The Ar isotope data indicate the presence of Q in addition to air, spallogenic component and Ar‐HL. As the elemental concentration of Ne in Q is low, we could not detect the Ne‐Q from the Ne data. On the other hand, we could not observe Xe‐HL in our Xe data. As the Xe concentration and the Xe/Ne ratio in Q is much higher than that in the HL component, it is likely that only the contribution of Q is observed in the Xe data. Xenon isotopic data can be explained as a mixture of Q, air, and “El Taco Xe.” The Canyon Diablo graphite contains both HL and Q, very much like carbonaceous chondrites, retaining the signatures of various primordial noble gas components. This indicates that the graphite was formed in a primitive nebular environment and was not heated to high, igneous temperatures. Furthermore, a large excess of 129Xe was observed, which indicates that the graphite was formed at a very early stage of the solar system when 129I was still present. The HL/Q ratios in the graphite in Canyon Diablo are lower than those in carbonaceous chondrites, indicating that some thermal metamorphism occurred on the former. We estimated the temperature of the thermal metamorphism to about 500–600 °C from the difference of thermal retentivities of HL and Q. It is also noted that “El Taco Xe” is commonly observed in many IAB iron meteorites, but its presence in carbonaceous chondrites has not yet been established. 相似文献
27.
28.
29.
30.
Fa-Wu?WangEmail author Ye-Ming?Zhang Zhi-Tao?Huo Tatsunori?Matsumoto Bo-Lin?Huang 《Landslides》2004,1(2):157-162
The Qianjiangping landslide occurred after the first impoundment of the Three Gorges Reservoir in July 2003. Field investigation revealed that failure occurred when the reservoir reached 135 m, but the stability of the affected slope was already reduced by pre-existing bedding-plane shears, quarrying of mudstone from the landslide toe, and previous heavy rain. A possible explanation of the rapid and long runout mechanism of the landslide is that movement on a bedding-plane shear ruptured the calcite cement and rapidly reduced the sandstone strength to residual shear strength. 相似文献