全文获取类型
收费全文 | 134篇 |
免费 | 7篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 27篇 |
地球物理 | 34篇 |
地质学 | 35篇 |
海洋学 | 10篇 |
天文学 | 23篇 |
自然地理 | 8篇 |
出版年
2021年 | 2篇 |
2020年 | 6篇 |
2019年 | 1篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 5篇 |
2012年 | 4篇 |
2011年 | 8篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 7篇 |
2007年 | 13篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有141条查询结果,搜索用时 15 毫秒
91.
Alistair McIlgorm Susan Hanna Gunnar Knapp Pascal Le Floc’H Frank Millerd Minling Pan 《Marine Policy》2010
We examine the implications of climate change for fishery governance using seven international fishery case studies in low, mid and high latitudes, including eastern Australia, the western Pacific Ocean, Alaska, west coast United States, Hawaii, west coast Canada and France. Climate change adds uncertainty about fish stock productivity, migratory patterns, trophic interactions and vulnerability of fish populations to fishing pressure. 相似文献
92.
93.
美国地质调查局(USGS)5月18日宣布开放一个可显示加州地区未来24小时内发生地震概率的公共网站。在余震或可能的前震序列期间,它以地图的形式向人们展示地震发生概率的变化。 相似文献
94.
Zakaria M. Sawan Louis I. Hanna Willis L. McCuistion Richard J. Foote 《Theoretical and Applied Climatology》2010,99(1-2):217-227
The information on impact of climatic factors on cotton production is not generally available, or at least not available in the required form. Understanding this impact may help physiologists determine a possible control of the flowering mechanism in the cotton plant. Two field trials were conducted to investigate the relationships between climatic factors, soil moisture status, and flower and boll production of Gossypium barbadense. The climatic factors considered were daily maximum air temperature (°C), minimum air temperature (°C), maximum–minimum temperature (diurnal temperature range) (°C), sunshine duration (h day?1), maximum relative humidity (%), minimum relative humidity (%), and wind speed (m s?1). Minimum relative humidity and sunshine duration were the most significant climatic factors affecting flower and boll retention and production. Temperature appeared to be less important in the reproduction growth stage of cotton in Egypt than minimum relative humidity and sunshine duration. The soil moisture status showed low and insignificant correlation to flower and boll production. High minimum relative humidity, short period of sunshine duration, and low temperatures enhanced flower and boll formation. 相似文献
95.
Francis M. McCubbin Nicholas J. Tosca Hanna Nekvasil Marc Fries Donald H. Lindsley 《Geochimica et cosmochimica acta》2009,73(16):4907-318
Low-temperature aqueous processes have been implicated in the generation of jarosite and hematite on the martian surface, but little is known regarding the role that high-temperature magmatic fluids may have played in producing similar assemblages on Mars. We have identified jarosite and hematite in a clinopyroxene-hosted melt inclusion in martian meteorite MIL 03346 that shows evidence of having been hydrothermally precipitated. In addition to jarosite and hematite, the melt inclusion contains titanomagnetite, pyrrhotite, potassic-chlorohastingsite, an iron-rich silicate glass and possibly goethite. These phases were identified and characterized using scanning electron microscopy (SEM), con-focal Raman-spectroscopy and electron probe microanalysis (EPMA).Based on observed textural relationships and the compositions of the hosted phases, we report that the jarosite-bearing melt inclusion in MIL 03346 has recorded a fluid-rich history that began in the magmatic stage and continued to low-temperatures. This history begins at entrapment of a volatile-rich silicate melt that likely reached fluid-saturation after only minor crystallization within the melt inclusion. This fluid, rich in chlorine, reacted with surrounding silicate material to produce the potassic-chlorohastingsite. As cooling proceeded, the liquid phase eventually became more oxidized and reacted with the pyrrhotite. Sulfide oxidation resulted in SO42− formation and concomitant acid production, setting the stage for jarosite formation once the fluid cooled beyond the upper thermal stability of jarosite (∼200 °C). As the fluid cooled below 200 °C, jarosite continued to precipitate with hematite and/or goethite until equilibrium was established or reactions became kinetically unfavorable.This work suggests an additional jarosite-hematite formation pathway on Mars; one that may be important wherever magmatic-hydrothermal fluids come into contact with primary sulfide grains at the martian surface or subsurface. Moreover, hydrothermal fluids rich in chlorine, sulfur, and iron are important for ore-forming processes on Earth, and their indirect identification on Mars may have important implications for ore-formation on Mars. 相似文献
96.
Sawomir Breiter Hanna Michalska 《Monthly notices of the Royal Astronomical Society》2008,388(2):927-944
The second-order analytical approximation of the mean Yarkovsky–O'Keefe–Radzievskii–Paddack (YORP) torque components is given as an explicit function of the shape spherical harmonics coefficients for a sufficiently regular minor body. The results are based upon a new expression for the insolation function, significantly simpler than in previous works. Linearized plane-parallel model of the temperature distribution derived from the insolation function allows us to take into account a non-zero conductivity. Final expressions for the three average components of the YORP torque related with rotation period, obliquity and precession are given in a form of the Legendre series of the cosine of obliquity. The series have good numerical properties and can be easily truncated according to the degree of the Legendre polynomials or associated functions, with first two terms playing the principal role. 相似文献
97.
Water balance estimation under the challenge of data scarcity in a hyperarid to Mediterranean region
下载免费PDF全文
![点击此处可从《水文研究》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Agnes Sachse Christian Fischer Jonathan B. Laronne Hanna Hennig Amer Marei Olaf Kolditz Tino Rödiger 《水文研究》2017,31(13):2395-2411
Water budget analyses are important for the evaluation of the water resources in semiarid and arid regions. The lack of observed data is the major obstacle for hydrological modelling in arid regions. The aim of this study is the analysis and calculation of the natural water resources of the Western Dead Sea subsurface catchment, one which is highly sensitive to rainfall resulting in highly variable temporal and spatial groundwater recharge. We focus on the subsurface catchment and subsequently apply the findings to a large‐scale groundwater flow model to estimate the groundwater discharge to the Dead Sea. We apply a semidistributed hydrological model (J2000g), originally developed for the Mediterranean, to the hyperarid region of the Western Dead Sea catchment, where runoff data and meteorological records are sparsely available. The challenge is to simulate the water budget, where the localized nature of extreme rainstorms together with sparse runoff data results in few observed runoff and recharge events. To overcome the scarcity of climate input data, we enhance the database with mean monthly rainfall data. The rainfall data of 2 satellites are shown to be unsuitable to fill the missing rainfall data due to underrepresentation of the steep hydrological gradient and temporal resolution. Hydrological models need to be calibrated against measured values; hence, the absence of adequate data can be problematic. Therefore, our calibration approach is based on a nested strategy of diverse observations. We calculate a direct surface runoff of the Western Dead Sea surface area (1,801 km2) of 3.4 mm/a and an average recharge (36.7 mm/a) for the 3,816 km2 subsurface drainage basin of the Cretaceous aquifer system. 相似文献
98.
Hanna Kim 《Ocean Engineering》2011,38(1):148-158
In the present paper, analytic solutions are derived for scattering of water waves obliquely incident to a partially reflecting semi-infinite breakwater or breakwater gap. In order to examine the correctness of the derived solutions, they are compared with the solutions derived by McIver (1999) and Bowen and McIver (2002) for a semi-infinite breakwater and a breakwater gap, respectively, in the case of perfect reflection. The derived analytic solutions are used to investigate the effect of reflection coefficient of the breakwater and wave incident angle upon the tranquility at harbor entrance. The tranquility is deteriorated by the reflected waves as the reflection coefficient increases and as waves are incident more obliquely. 相似文献
99.
Martin Finné Miryam Bar-Matthews Karin Holmgren Hanna S. Sundqvist Ilias Liakopoulos Qiong Zhang 《Quaternary Research》2014
We present stable isotope data (δ18O, δ13C) from a detrital rich stalagmite from Kapsia Cave, the Peloponnese, Greece. The cave is rich in archeological remains and there are reasons to believe that flooding of the cave has directly affected humans using the cave. Using a combination of U–Th and 14C dating to constrain a site-specific correction factor for (232Th/238U) detrital molar ratio, a linear age model was constructed. The age model shows that the stalagmite grew during the period from ca. 950 BC to ca. AD 830. The stable oxygen record from Kapsia indicates cyclical changes of close to 500 yr in precipitation amount, with rapid shifts towards wetter conditions followed by slowly developing aridity. Superimposed on this signal, wetter conditions are inferred around 850, 700, 500 and 400–100 BC, and around AD 160–300 and AD 770; and driest conditions are inferred to have occurred around 450 BC, AD 100–150 and AD 650. Detrital horizons in the stalagmite indicate that three major floods took place in the cave at 500 BC, 70 BC and AD 450. The stable carbon isotope record reflects changes in biological activity being a result of both climate and human activities. 相似文献
100.
Summary ?A new occurrence of carbonatites associated with intrusive ijolite and syenite has been discovered within the Hawasina Complex
underlying the Semail Ophiolite Complex at the southern part of the Rawda-Masfut ridge, Northern Oman Mountains. The carbonatites
occur as dikes and sills with lengths of several hundreds of meters and range in composition from calciocarbonatites to ferruginous
calciocarbonatites. The carbonatites intruded the ijolite and the associated radiolarian cherts of the Early Cretaceous Sid’r
Formation. The close spatial association of carbonatite, ijolite, syenite and radiolarian cherts along with geological, petrographical
and geochemical data indicates that these rocks are of intra-oceanic origin. Petrological and field relationships between
the carbonatite and associated alkaline silicate intrusives from the Masfut area are consistent with the carbonatites being
generated as derivative magmas through liquid immiscibility. They appear to represent magmas related to the volcanism associated
with regional crustal extension that preceded the genesis of the Semail Ophiolite.
Received April 19, 2001; revised version accepted February 18, 2002 相似文献