全文获取类型
收费全文 | 257篇 |
免费 | 6篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 10篇 |
地球物理 | 22篇 |
地质学 | 69篇 |
海洋学 | 21篇 |
天文学 | 100篇 |
综合类 | 2篇 |
自然地理 | 38篇 |
出版年
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 5篇 |
2013年 | 7篇 |
2012年 | 9篇 |
2011年 | 17篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 15篇 |
2007年 | 9篇 |
2006年 | 10篇 |
2005年 | 18篇 |
2004年 | 25篇 |
2003年 | 17篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 9篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1980年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1970年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有263条查询结果,搜索用时 265 毫秒
71.
Gavin Bridge 《Geoforum》2003,34(2):165-174
72.
Z. J. Kabala H. K. El-Sayegh H. P. Gavin 《Stochastic Environmental Research and Risk Assessment (SERRA)》2002,16(6):399-424
Logarithmic sensitivities and plausible relative errors are studied in a simple no-crossflow model of a transient flowmeter
test (TFMT). This model is identical to the model of a constant-rate pumping test conducted on a fully penetrating well with
wellbore storage, surrounded by a thick skin zone, and situated in a homogeneous confined aquifer. The sensitivities of wellbore
drawdown and wellface flowrate to aquifer and skin parameters are independent of the pumping rate. However, the plausible
relative errors in the aquifer and skin parameters estimated from drawdown and wellface flowrate data can be proportionally
decreased by increasing the pumping rate. The plausible relative errors vary by many orders of magnitude from the beginning
of the TFMT. The practically important flowrate and drawdown measurements in this test, for which the plausible relative errors
vary by less than one order of magnitude from the minimum plausible relative errors, can begin approximately when the dimensionless
wellface flowrate exceeds q
D
=q/Q≈0.4. During most of this stage of the test, the plausible relative errors in aquifer hydraulic conductivity (K
a
) are generally an order of magnitude smaller than those in aquifer specific storativity. The plausible relative errors in
the skin hydraulic conductivity (K
s
) are generally larger than the plausible relative errors in the aquifer specific storativity when the thick skin is normal
(K
s
>K
a
) and smaller when the thick skin is damaged (K
s
<K
a
). The specific storativity of the skin zone would be so biased that one should not even attempt to estimate it from the TFMT.
We acknowledge Wiebe H. van der Molen for recommending the De Hoog algorithm and sharing his code. This research was partially
supported by the US Geological Survey, USGS Agreement #1434-HQ-96-GR-02689 and North Carolina Water Resources Research Institute,
WRRI Project #70165. 相似文献
73.
This paper examines the fieldwork undertaken by the distinguished French geographer Pierre Gourou (1900–99) in the Tonkin Delta (Red River Delta) of northern Vietnam in the 1920s and 1930s, and his wider configuration of “the tropical world” as a distinct space of knowledge and radical otherness. Gourou's fieldwork endeavours in French Indochina are interpreted in the light of recent work on “tropicality”: the idea that “the tropics” need to be understood as a western cultural construction and colonising discourse that essentialised the hot, wet regions of the world, and exalted the temperate world over its tropical counterpart. The paper focuses on Gourou's monumental 1936 study Les paysans du delta tonkinois, étude de géographie humaine. It is argued that in this study, and his later comparative work on the tropics, Gourou elaborated a distinct geographical variant of tropicality, but one that, ultimately, reinforced the essentialist logic and momentum of this discourse. Particular attention is paid to the geographical ideas, fieldwork techniques and discursive strategies that Gourou used in his 1936 study, and the French colonial context in which he worked. The article shows how Gourou appealed to western reason and science as tools of study, identified overpopulation as the key problem facing the Tonkin Delta, and suggested that colonial practices of modernisation had a limited place and ineffectual role in the rice plains of the region. 相似文献
74.
75.
The northwest Hatton Bank margin is an ideal locality to demonstrate the interaction between bottom currents and slope configuration in controlling the distribution and morphology of bottom current deposits. The slope area investigated is isolated from any major terrigenous sediment supply and at present is influenced by the Deep Northern Boundary Current (DNBC). Swath bathymetry and high resolution acoustic data allow us to evaluate both local and regional controls on slope sedimentation and the possible mechanisms for bottom-current velocity variability across a slope setting within the NW European continental margin. The slope exhibits sculpting by bottom currents that flow in a predominantly southwest to northeast direction, and is only locally modified by slope failures. Positive relief features such as the Endymion Spur play an important role in constraining and accelerating bottom-current flow and, consequently, in redistributing sediment along the margin. We demonstrate that the size, morphology and distribution of bottom-current deposits along the slope vary as a function of the interaction between bottom currents, regional slope orientation and local seafloor topography. 相似文献
76.
77.
Roberto De Propris Matthew Colless Simon P. Driver Warrick Couch John A. Peacock Ivan K. Baldry Carlton M. Baugh Joss Bland-Hawthorn Terry Bridges Russell Cannon Shaun Cole Chris Collins Nicholas Cross Gavin B. Dalton George Efstathiou Richard S. Ellis Carlos S. Frenk Karl Glazebrook Edward Hawkins Carole Jackson Ofer Lahav Ian Lewis Stuart Lumsden Steve Maddox Darren S. Madgwick Peder Norberg Will Percival Bruce Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2003,342(3):725-737
78.
79.
80.