全文获取类型
收费全文 | 746篇 |
免费 | 19篇 |
国内免费 | 17篇 |
专业分类
测绘学 | 7篇 |
大气科学 | 42篇 |
地球物理 | 177篇 |
地质学 | 189篇 |
海洋学 | 218篇 |
天文学 | 106篇 |
综合类 | 4篇 |
自然地理 | 39篇 |
出版年
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2017年 | 12篇 |
2016年 | 20篇 |
2015年 | 11篇 |
2014年 | 19篇 |
2013年 | 27篇 |
2012年 | 23篇 |
2011年 | 33篇 |
2010年 | 32篇 |
2009年 | 38篇 |
2008年 | 35篇 |
2007年 | 40篇 |
2006年 | 48篇 |
2005年 | 37篇 |
2004年 | 55篇 |
2003年 | 27篇 |
2002年 | 22篇 |
2001年 | 24篇 |
2000年 | 16篇 |
1999年 | 8篇 |
1998年 | 21篇 |
1997年 | 10篇 |
1996年 | 17篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 12篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 18篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 7篇 |
1970年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有782条查询结果,搜索用时 62 毫秒
781.
Abstract: A total of 189 runs were completed to determine the rate of dissolved oxygen consumption in water by the reaction humic acid at 25°, 45°, and 65°C. Glass vial bottles were used as reaction vessels, and humic aicd and pure water of different intitial O2 concentration was loaded with humic acid/water weight of 0.008 and 0.009. Vials were opened periodically to measure O2 concentrations. The pH of the solution fluctuated in the early stages of the experiments and gradually decreased to a constant value. Dissolved oxygen concentration decreased, for example, from initial value of 12 mg/l to 9 mg/l at 25°C, to 5 mg/l at 45°C, and to 2 mg/l at 65°C after the reaction of 500 hours. Analyses of rates suggest that the reaction is first order, and rate constants are 8.42 × 10-9 at 25°C, 2.22 × 10-8 at 45°C, and 1.28 × 10-7 moles m-2 s-1 at 65°C. 相似文献
782.
The notion that the Yakuno ophiolite and overlying Maizuru Group represents an accretionary prism formed during the Permian evolution of Japan on the Yakuno eruptive sequence, association of hemipelagic mudstone with silicic tuff, exotic fossiliferous limestones derived from previously accreted sea-mounts, upward coarsening of sequences terrigenous sandstone and conglomerate, and mildly deformed Permian and Triassic forearc basin formations. The most important indicator, however, is the seaward imbrication and repetition observed in both the Maizuru Group and the ophiolite itself. D1 deformation structures include axial–planar foliations (pressure-solution cleavage for the Maizuru Group and granulite–amphibolite metamorphic layering in the ophiolite), flattening type strain, symmetric pressure shadows and fringes, and isoclinal folds showing axial–planar foliations and thrust faulting at their overturned limb. The exceptional asymmetry observed indicates seaward-directed shearing near the thrust, while D1 structures in the Maizuru zone are explained by off-scraping, above the basal decollement. The later Jurassic D2 kink fold structure includes a first-order asymmetric kink with a brittle thrust at its overturned limb, more-or-less coeval with M2 retrograde metamorphism. Medium-pressure M1 prograde metamorphism in the Yakuno ophiolite produced layering of granulite and amphibolite, and in the Maizuru Group, formation of illite along pressure-solution cleavage of mudstones. The metamorphic grade is controlled by the stratigraphic relationships and appears typical of that in ocean floor regions. However, there was only one episode of M1 prograde metamorphism which occurred contemporaneously with D1 off-scraping. Given that subduction zones are normally characterized by high P/T metamorphic regimes, the observed P/T history appears to reflect relatively unusual conditions. Such high thermal gradients may plausibly reflect the approach of a young, hot oceanic plate which continued subducting beneath the Japanese arc. Accordingly, the Yakuno ophiolite was probably formed at the trench–trench–ridge triple junction. 相似文献