全文获取类型
收费全文 | 118篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 9篇 |
大气科学 | 9篇 |
地球物理 | 27篇 |
地质学 | 37篇 |
海洋学 | 7篇 |
天文学 | 26篇 |
综合类 | 1篇 |
自然地理 | 14篇 |
出版年
2023年 | 1篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 7篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 8篇 |
2009年 | 5篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1907年 | 1篇 |
1905年 | 3篇 |
1900年 | 1篇 |
1899年 | 4篇 |
1898年 | 4篇 |
排序方式: 共有130条查询结果,搜索用时 15 毫秒
101.
LaForce Tara Ebeida Mohamed Jordan Spencer Miller Terry A. Stauffer Philip H. Park Heeho Leone Rosie Hammond Glenn 《Mathematical Geosciences》2023,55(2):129-161
Mathematical Geosciences - Mesh generation lies at the interface of geological modeling and reservoir simulation. Highly skewed or very small grid cells may be necessary to accurately capture the... 相似文献
102.
Rates of in situ microbial sulfate reduction in response to geochemical perturbations were determined using Native Organism Geochemical Experimentation Enclosures (NOGEEs), a new in situ technique developed to facilitate evaluation of controls on microbial reaction rates. NOGEEs function by first trapping a native microbial community in situ and then subjecting it to geochemical perturbations through the introduction of various test solutions. On three occasions, NOGEEs were used at the Norman Landfill research site in Norman, Oklahoma, to evaluate sulfate-reduction rates in wetland sediments impacted by landfill leachate. The initial experiment, in May 2007, consisted of five introductions of a sulfate test solution over 11 d. Each test stimulated sulfate reduction with rates increasing until an apparent maximum was achieved. Two subsequent experiments, conducted in October 2007 and February 2008, evaluated the effects of concentration on sulfate-reduction rates. Results from these experiments showed that faster sulfate-reduction rates were associated with increased sulfate concentrations. Understanding variability in sulfate-reduction rates in response to perturbations may be an important factor in predicting rates of natural attenuation and bioremediation of contaminants in systems not at biogeochemical equilibrium. 相似文献
103.
Tara Catherine LaForce 《Computational Geosciences》2012,16(4):1007-1020
In this work, the analytical and numerical solutions for modeling miscible gas and water injection into an oil reservoir are presented. Conservation laws with three levels of complexity are considered. Only the most complex model has the correct phase behavior for the example system, which is a multicontact miscible condensing gas drive with simultaneous water and gas injection. Example displacements in which one or both of the simpler models result in accurate simulations in a fraction of the computation time are presented, along with an example in which neither simplified thermodynamic model achieves a truly satisfactory result. A methodology is presented that can be used to establish the accuracy of simplified models in 1-D simulation based on convergence to analytical solutions for the full three-phase system. 相似文献
104.
Optimization of groundwater and other subsurface resources requires analysis of multiple‐well systems. The usual modeling approach is to apply a linear flow equation (e.g., Darcy's law in confined aquifers). In such conditions, the composite response of a system of wells can be determined by summating responses of the individual wells (the principle of superposition). However, if the flow velocity increases, the nonlinear losses become important in the near‐well region and the principle of superposition is no longer valid. This article presents an alternative method for applying analytical solutions of non‐Darcy flow for a single‐ to multiple‐well systems. The method focuses on the response of the central injection well located in an array of equally spaced wells, as it is the well that exhibits the highest pressure change within the system. This critical well can be represented as a single well situated in the center of a closed square domain, the width of which is equal to the well spacing. It is hypothesized that a single well situated in a circular region of the equivalent plan area adequately represents such a system. A test case is presented and compared with a finite‐difference solution for the original problem, assuming that the flow is governed by the nonlinear Forchheimer equation. 相似文献
105.
Erin Lee Hestir David H. Schoellhamer Jonathan Greenberg Tara Morgan-King Susan L. Ustin 《Estuaries and Coasts》2016,39(4):1100-1112
Submerged aquatic vegetation (SAV) has well-documented effects on water clarity. SAV beds can slow water movement and reduce bed shear stress, promoting sedimentation and reducing suspension. However, estuaries have multiple controls on turbidity that make it difficult to determine the effect of SAV on water clarity. In this study, we investigated the effect of primarily invasive SAV expansion on a concomitant decline in turbidity in the Sacramento-San Joaquin River Delta. The objective of this study was to separate the effects of decreasing sediment supply from the watershed from increasing SAV cover to determine the effect of SAV on the declining turbidity trend. SAV cover was determined by airborne hyperspectral remote sensing and turbidity data from long-term monitoring records. The turbidity trends were corrected for the declining sediment supply using suspended-sediment concentration data from a station immediately upstream of the Delta. We found a significant negative trend in turbidity from 1975 to 2008, and when we removed the sediment supply signal from the trend it was still significant and negative, indicating that a factor other than sediment supply was responsible for part of the turbidity decline. Turbidity monitoring stations with high rates of SAV expansion had steeper and more significant turbidity trends than those with low SAV cover. Our findings suggest that SAV is an important (but not sole) factor in the turbidity decline, and we estimate that 21–70 % of the total declining turbidity trend is due to SAV expansion. 相似文献
106.
Paul Jacob Hancock Paul Roberts Michael J. Kesteven Ronald D. Ekers Elaine M. Sadler Tara Murphy Marcella Massardi Roberto Ricci Mark Calabretta Gianfranco de Zotti Philip G. Edwards Jennifer A. Ekers Carole A. Jackson Mark Leach Chris Phillips Robert J. Sault Lister Staveley-Smith Ravi Subrahmanyan Mark A. Walker Warwick E. Wilson 《Experimental Astronomy》2011,32(2):147-177
The Australia Telescope 20 GHz (AT20G) survey is a large area (2?? sr), sensitive (40 mJy), high frequency (20 GHz) survey of the southern sky. The survey was conducted in two parts: an initial fast scanning survey, and a series of more accurate follow-up observations. The follow-up survey catalog has been presented by Murphy et al. (MNRAS 402:2403, 2010). In this paper we discuss the hardware setup and scanning survey strategy as well as the production of the scanning survey catalog. 相似文献
107.
Takuro Kobashi Jeffrey P. Severinghaus Jean-Marc Barnola Kenji Kawamura Tara Carter Tosiyuki Nakaegawa 《Climatic change》2010,100(3-4):733-756
Future Greenland temperature evolution will affect melting of the ice sheet and associated global sea-level change. Therefore, understanding Greenland temperature variability and its relation to global trends is critical. Here, we reconstruct the last 1,000 years of central Greenland surface temperature from isotopes of N2 and Ar in air bubbles in an ice core. This technique provides constraints on decadal to centennial temperature fluctuations. We found that northern hemisphere temperature and Greenland temperature changed synchronously at periods of ~20 years and 40–100 years. This quasi-periodic multi-decadal temperature fluctuation persisted throughout the last millennium, and is likely to continue into the future. 相似文献
108.
Elizabeth G. Malcolm Amanda C. Ford Tara A. Redding Matthew C. Richardson Brianna M. Strain Scott W. Tetzner 《Journal of Atmospheric Chemistry》2009,63(3):221-234
Sea salt aerosol may be an important sink for reactive gaseous mercury (RGM) in the marine boundary layer, reducing ambient
RGM concentrations and transferring the mercury (Hg) to the oceans and coastal ecosystems. The goal of this study was to determine
the affinity of gaseous mercury for sea salt aerosol (SSA) by conducting adsorption experiments with sea salt-coated sampling
denuders. In the first set of experiments, ambient outdoor air was passed through denuders coated with either KCl, as in the
widely accepted method to sample RGM, or with NaCl, a primary component of sea salt aerosols. On the one sampling day in which
RGM was above the MDL, the NaCl coated denuders removed Hg from the ambient air, equivalent to 87% of the RGM in the air (as
determined by KCl denuders). For the second set of experiments HgCl2 generated in the laboratory was passed through denuders coated with KCl and either NaCl or sea salt. The NaCl denuders collected
an average of 99 ± 16% of the mercury that the KCl denuders collected. Newly coated sea salt denuders collected 88 ± 17% of
the amount of mercury that the KCl denuders collected, but interestingly the sea salt denuders capacity decreased with repeated
use. These experiments demonstrate that HgCl2, a major component of RGM has a strong affinity for NaCl and sea salt and is therefore likely to be scavenged by SSA. This
study adds to the growing evidence that RGM is scavenged by sea salt aerosols and therefore more quickly deposited to the
ocean and coastal environment. 相似文献
109.
110.
Recent observations of the rotation curves of large disk galaxies of all Hubble-types have shown that they possess flat or slowly rising rotation curves up to large distances from the centre. It has been suggested here that such rotation curves are understood under normal fluid dynamical considerations provided that viscous (and/or magnetic) transfer of mass and angular momentum from inner to outer regions of these galaxies is efficient. Flow of gas from halo to the disk in regions close to the axis of rotation is also suggested. The existence of rising rotation curves in some galaxies with varying gradients and flat rotation curves in others suggest that probably these galaxies are not coeval. The formers are probably of more recent origin. 相似文献