全文获取类型
| 收费全文 | 2306篇 |
| 免费 | 439篇 |
| 国内免费 | 625篇 |
专业分类
| 测绘学 | 200篇 |
| 大气科学 | 179篇 |
| 地球物理 | 509篇 |
| 地质学 | 1609篇 |
| 海洋学 | 219篇 |
| 天文学 | 370篇 |
| 综合类 | 117篇 |
| 自然地理 | 167篇 |
出版年
| 2024年 | 4篇 |
| 2023年 | 17篇 |
| 2022年 | 64篇 |
| 2021年 | 62篇 |
| 2020年 | 72篇 |
| 2019年 | 72篇 |
| 2018年 | 65篇 |
| 2017年 | 80篇 |
| 2016年 | 76篇 |
| 2015年 | 86篇 |
| 2014年 | 111篇 |
| 2013年 | 145篇 |
| 2012年 | 152篇 |
| 2011年 | 124篇 |
| 2010年 | 119篇 |
| 2009年 | 182篇 |
| 2008年 | 167篇 |
| 2007年 | 175篇 |
| 2006年 | 185篇 |
| 2005年 | 151篇 |
| 2004年 | 174篇 |
| 2003年 | 139篇 |
| 2002年 | 131篇 |
| 2001年 | 108篇 |
| 2000年 | 109篇 |
| 1999年 | 108篇 |
| 1998年 | 105篇 |
| 1997年 | 81篇 |
| 1996年 | 58篇 |
| 1995年 | 58篇 |
| 1994年 | 46篇 |
| 1993年 | 32篇 |
| 1992年 | 30篇 |
| 1991年 | 22篇 |
| 1990年 | 16篇 |
| 1989年 | 8篇 |
| 1988年 | 13篇 |
| 1987年 | 8篇 |
| 1986年 | 6篇 |
| 1984年 | 1篇 |
| 1983年 | 2篇 |
| 1982年 | 1篇 |
| 1979年 | 1篇 |
| 1978年 | 3篇 |
| 1977年 | 1篇 |
排序方式： 共有3370条查询结果，搜索用时 15 毫秒
951.
本文以深入学习实践科学发展观活动为切入点,结合甘肃省国土资源工作实际,就如何贯彻落实科学发展观,构建保障和促进科学发展新机制,大力推进国土资源信息化建设,为甘肃经济社会发展提供服务保障,提出了一些看法和建议,与大家共同商榷。 相似文献
952.
We estimate spatiotemporal models of average neighborhood single family home prices to use in predicting individual property prices. Average home-price variations are explained in terms of changes in average neighborhood house attributes, spatial attributes,
and temporal economic variables. Models adopting three different definitions of neighborhoods are estimated with quarterly
cross-sectional data over the period 2000–2004 from four cities in Southern California. Heteroscedasticity and autocorrelation
problems are detected and adjusted for via a sequential routine. Results of these models suggest that forecasts obtained using
city neighborhood average price equations may have advantage over forecasts obtained using city aggregated price equations.
相似文献
953.
954.
带空洞面对象间拓扑关系形式化描述 总被引：1，自引：0，他引：1
利用Egenhofer等提出的含空洞的两面对象间空间拓扑关系描述框架,在四交差模型的基础上,提出了一种能描述带空洞复杂面对象间的空间拓扑关系的扩展模型——4-4ID模型,并用该模型详细推导了简单面对象和仅带一个空洞面对象间以及两个仅带一个空洞面对象间有意义的拓扑关系。 相似文献
955.
Chris Koen 《Monthly notices of the Royal Astronomical Society》2003,346(2):473-482
76 hours of CCD photometry of 11 L dwarfs and one T dwarf is described. Three objects, including the T dwarf ε Indi B, showed convincing evidence for variability. A periodicity of 8 h is clearly visible in the light curve of 2MASS J1155395−372735. 相似文献
956.
J. H. KRUHL 《Journal of Metamorphic Geology》1993,11(1):31-47
Abstract At the basement-cover boundary of the north-eastern Tauern Window (Eastern Alps), the following Alpine P-T-d development has been reconstructed on the basis of macro- and micro-structures as well as preferred crystallographic orientations, mineral parageneses and compositions.
During increasing P-T conditions in the greenschist facies a first period of deformation produced imbrication of the basement gneisses and cover sediments, and then monoclinal folds up to the kilometre scale. Tectonic transport was continuously top-to-the-ENE. A second period of deformation began at about peak P-T conditions of 9 kbar and c. 540–560°C in the south, and about 7–9 kbar and 490–500° C in the north; this continued locally to lower temperature. During the second period, transport was continuously top-to-the-SE. Crystallographic orientations of white mica and plagioclase give particularly useful information on the kinematic framework. In addition, data on the ductile behaviour of dolomite and plagioclase can be inferred. At c. 7–9 kbar, dolomite recrystallization starts at 450–480° C, and the beginning of plagioclase recrystallization coincides with the oligoclase boundary.
In general, the Alpine geodynamic history of the basement-cover boundary may be related to continental collision processes between a northerly plate (European or Briançonnais) and a southerly (Adriatic) one. The first deformation period possibly reflects subduction of the gneiss-sediment boundary toward the WSW, to a depth of 31–32 km. The second period may be a result of obduction toward the NW, followed by late-stage uplift. Most of the basement domes of the eastern Tauern Window appear as a result of the final stage of the first deformation, formed prior to the peak of metamorphism, possibly partly influenced by the final collision between the northern and the southern continents. 相似文献
During increasing P-T conditions in the greenschist facies a first period of deformation produced imbrication of the basement gneisses and cover sediments, and then monoclinal folds up to the kilometre scale. Tectonic transport was continuously top-to-the-ENE. A second period of deformation began at about peak P-T conditions of 9 kbar and c. 540–560°C in the south, and about 7–9 kbar and 490–500° C in the north; this continued locally to lower temperature. During the second period, transport was continuously top-to-the-SE. Crystallographic orientations of white mica and plagioclase give particularly useful information on the kinematic framework. In addition, data on the ductile behaviour of dolomite and plagioclase can be inferred. At c. 7–9 kbar, dolomite recrystallization starts at 450–480° C, and the beginning of plagioclase recrystallization coincides with the oligoclase boundary.
In general, the Alpine geodynamic history of the basement-cover boundary may be related to continental collision processes between a northerly plate (European or Briançonnais) and a southerly (Adriatic) one. The first deformation period possibly reflects subduction of the gneiss-sediment boundary toward the WSW, to a depth of 31–32 km. The second period may be a result of obduction toward the NW, followed by late-stage uplift. Most of the basement domes of the eastern Tauern Window appear as a result of the final stage of the first deformation, formed prior to the peak of metamorphism, possibly partly influenced by the final collision between the northern and the southern continents. 相似文献
957.
韩容畴 《广东海洋大学学报》1993,(2)
湛江某琼胶厂在生产初期出现产品颜色发黄,其原因是由于该厂使用了含铁地下水作为生产用水所致。湛江市区的地下水是属于第二类型含铁地下水,可对该类型的地下水进行深度处理,来达到除铁、提高产品质量的目的。 相似文献
958.
959.
960.