全文获取类型
收费全文 | 1053篇 |
免费 | 42篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 11篇 |
大气科学 | 94篇 |
地球物理 | 269篇 |
地质学 | 356篇 |
海洋学 | 107篇 |
天文学 | 119篇 |
综合类 | 4篇 |
自然地理 | 140篇 |
出版年
2022年 | 7篇 |
2021年 | 13篇 |
2020年 | 14篇 |
2019年 | 21篇 |
2018年 | 20篇 |
2017年 | 20篇 |
2016年 | 27篇 |
2015年 | 31篇 |
2014年 | 28篇 |
2013年 | 57篇 |
2012年 | 44篇 |
2011年 | 56篇 |
2010年 | 38篇 |
2009年 | 59篇 |
2008年 | 37篇 |
2007年 | 46篇 |
2006年 | 37篇 |
2005年 | 41篇 |
2004年 | 36篇 |
2003年 | 40篇 |
2002年 | 41篇 |
2001年 | 38篇 |
2000年 | 22篇 |
1999年 | 22篇 |
1998年 | 28篇 |
1997年 | 11篇 |
1996年 | 14篇 |
1995年 | 12篇 |
1994年 | 14篇 |
1993年 | 9篇 |
1992年 | 15篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 11篇 |
1986年 | 15篇 |
1985年 | 10篇 |
1984年 | 17篇 |
1983年 | 10篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 5篇 |
1973年 | 15篇 |
1970年 | 3篇 |
排序方式: 共有1100条查询结果,搜索用时 953 毫秒
1.
Edward P. F. Rose 《Geology Today》2019,35(3):107-114
During the Second World War, the Allied invasion of the French coast of Normandy on D‐Day, 6 June 1944, was the greatest amphibious assault in world history. An article in Geology Today (v.11, for 1995, pp.58–63) marked the 50th anniversary of the end of the war in Europe, on 8 May 1945, by describing how British military geologists had participated in planning for D‐Day and in the NW Europe campaign that followed it. The work of these geologists provides a classic case history, revealing that ‘military geology’ has many potential applications. Geological factors influenced site selection for temporary airfields, predictions of trafficability for the Normandy beaches, the development of potable water supplies, and quarrying for road metal—and more besides. This new article helps to mark the 75th anniversary of D‐Day by further details of how geologists and geology contributed to Allied victory. 相似文献
2.
Steven J. Ostro Lance A. M. Benner Christopher Magri Jon D. Giorgini Randy Rose Raymond F. Jurgens Donald K. Yeomans Alice A. Hine Michael C. Nolan Daniel J. Scheeres Stephen B. Broschart Mikko Kaasalainen Jean‐Luc Margot 《Meteoritics & planetary science》2005,40(11):1563-1574
Abstract— We present June 2004 radar images of asteroid 25143 Itokawa (1998 SF36) that improve upon the longitude‐latitude coverage of images obtained in 2001 by Ostro et al. (2004) and use the 2001–2004 data to refine that paper's constraints on Itokawa's shape. The 2004 images, the first of the asteroid's southern side, look distinctly different from the 2001 images, revealing leading edges that are much more curved and rugged than the nearly convex leading edges seen at northern latitudes in 2001. Itokawa is shaped like a slightly asymmetrical, bent, lumpy ellipsoid with dimensions along the principal axes within 10% of 594 times 320 times 288 m. To illustrate the uncertainty space associated with shape reconstruction from images with suboptimal orientational coverage, we present two alternative three‐dimensional models of the object. 相似文献
3.
P. A. M. Van Hoof M. E. Foord R. F. Heeter J. E. Bailey H.-K. Chung M. E. Cuneo W. H. Goldstein V. Jonauskas F. P. Keenan R. Kisielius D. A. Liedahl C. Ramsbottom S. J. Rose P. T. Springer R. S. Thoe 《Astrophysics and Space Science》2005,298(1-2):147-153
In experiments at the high-power Z-facility at Sandia National Laboratory in Albuquerque, New Mexico, we have been able to
produce a low density photoionized laboratory plasma of Fe mixed with NaF. The conditions in the experiment allow a meaningful
comparison with X-ray emission from astrophysical sources. The charge state distributions of Fe, Na and F are determined in
this plasma using high resolution X-ray spectroscopy. Independent measurements of the density and radiation flux indicate
unprecedented values for the ionization parameter ξ = 20–25 erg cm s−1 under nearly steady-state conditions. First comparisons of the measured charge state distributions with X-ray photoionization
models show reasonable agreement, although many questions remain. 相似文献
4.
Marie K. McCabe Zdeněk F. Švestka Russell A. Howard Bernard V. Jackson Neil R. Sheeley Jr. 《Solar physics》1986,103(2):399-408
By using a combination of X-ray (HXIS), H (Haleakala), white-light corona (Solwind), and zodiacal light (Helios) images on 21–22 May, 1980 we demonstrate, and try to explain, the co-existence of a coronal mass ejection with a stationary post-flare coronal arch. The mass ejection was seen, both by Solwind and Helios, in prolongation of the path of a powerful spray, whereas the active region filament did not erupt. A tentative comparison is made with other occurrences of stationary, or quasi-stationary post-flare coronal arches. 相似文献
5.
激光拉曼光谱法分析多种显微组分荧光变化及其应用 总被引:1,自引:1,他引:0
利用激发488 nm激光的氩离子激光器作为RENISHAW inVia型激光拉曼光谱仪的光源,建立了多种显微组分荧光变化(FAMM)分析方法,并对镜质体反射率明显抑制的东营凹陷有效烃源岩进行了测定。结果表明,东营凹陷有效烃源岩的有机质类型越好,镜质体反射率抑制程度越高,有效烃源岩的真实成熟度应主要处于0.64%~1.30%,而不是实测镜质体反射率所反映的0.37%~1.10%。 相似文献
6.
Imad A.M. Ahmed Neil M.J. Crout Scott D. Young 《Geochimica et cosmochimica acta》2008,72(6):1498-1512
Time-dependent sorption and desorption of Cd on calcite was studied over 210 days utilizing 109Cd as a tracer to distinguish between ‘labile’ and ‘non-labile’ forms of sorbed Cd. Stabilizing the calcite suspensions for 12 months under atmospheric PCO2 and controlled temperature was necessary to reliably follow Cd dynamics following initial sorption. Results revealed time-dependant Cd sorption and marked desorption hysteresis by calcite under environmentally relevant conditions. Data obtained were fitted to a first-order kinetic model and a concentric shell diffusion model. Both models described the progressive transfer of Cd2+ to a less reactive form within calcite and subsequent desorption of Cd subject to different initial contact times. The kinetic model provided a better fit to the combined sorption and desorption data (R2 = 0.992). It differentiates between two ‘pools’ of sorbed Cd2+ on calcite, ‘labile’ and ‘non-labile’, in which labile sorbed Cd is in immediate equilibrium with the free Cd2+ ion activity in solution whereas non-labile Cd is kinetically restricted. For the diffusion model (R2 = 0.959), the rate constants describing Cd dynamics in calcite produced a half-life for Cd desorption of ∼175 d, for release to a ‘zero-sink’ solution. Results from this study allow comment on the likely mechanisms occurring at the calcite surface following long-term Cd sorption. 相似文献
7.
8.
9.
The prevalence of dermal neoplasia among neotenic tiger salamanders (Ambystoma tigrinum) collected from the Reese Air Force Base sewage lagoon far exceeded that among salamanders from nearby uncontaminated lagoons. Perylene was the predominant pglycyclic aromatic hydrocarbon contaminant in this lagoon. Perylene was shown to be a substrate for monooxygenases in skin and liver homogenates and formed DNA-binding metabolites. Perylene exposure appeared to augment subsequent perylene metabolism by dermal enzymes but it was not a strong inducer of hepatic monooxygenases. Aroclor 1254 induced benzo(a)pyrene and perylene metabolism by both skin and liver enzymes. However, perylene apparently was not activated by salamander enzymes, as suggested by its lack of in vitro mutagenicity and failure to induce tumors. 相似文献
10.
This paper presents the findings from an in-depth analysis of the (axial) stiffness data recorded during tension–tension fatigue tests on wire ropes, particularly in relation to how changes in stiffness during testing relate to changes in rope strength. A linear relationship between stiffness and strength is shown to exist and a methodology presented for quantifying residual strength with applied cycles. New lower bound fatigue lines for six-strand rope and spiral strand are presented which are based on a 10% loss of strength. These new lines have the advantage of having been established using a common discard criterion for wire ropes. 相似文献