全文获取类型
收费全文 | 59篇 |
免费 | 5篇 |
专业分类
大气科学 | 12篇 |
地球物理 | 18篇 |
地质学 | 21篇 |
海洋学 | 5篇 |
天文学 | 6篇 |
自然地理 | 2篇 |
出版年
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 5篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 8篇 |
2012年 | 3篇 |
2011年 | 3篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 2篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1991年 | 1篇 |
1987年 | 2篇 |
1982年 | 1篇 |
排序方式: 共有64条查询结果,搜索用时 515 毫秒
61.
Knut METZLER Addi BISCHOFF Richard C. GREENWOOD Herbert PALME Marko GELLISSEN Jens HOPP Ian A. FRANCHI Mario TRIELOFF 《Meteoritics & planetary science》2011,46(5):652-680
Abstract– Northwest Africa (NWA) 869 consists of thousands of individual stones with an estimated total weight of about 7 metric tons. It is an L3–6 chondrite and probably represents the largest sample of the rare regolith breccias from the L–chondrite asteroid. It contains unequilibrated and equilibrated chondrite clasts, some of which display shock‐darkening. Impact melt rocks (IMRs), both clast‐free and clast‐poor, are strongly depleted in Fe,Ni metal, and sulfides. An unequilibrated microbreccia, two different light inclusions and two different SiO2‐bearing objects were found. Although the matrix of this breccia appears partly clastic, it is not a simple mixture of fine‐grained debris formed from the above lithologies, but mainly represents an additional specific lithology of low petrologic type. We speculate that this material stems from a region of the parent body that was only weakly consolidated. One IMR clast and one SiO2‐bearing object show Δ17O values similar to bulk NWA 869, suggesting that both are related to the host rock. In contrast, one light inclusion and one IMR clast appear to be unrelated to NWA 869, suggesting that the IMR clast is contaminated with impactor material. 40Ar‐39Ar analyses of a type 4 chondrite clast yield a plateau age of 4402 ± 7 Ma, which is interpreted to be the result of impact heating. Other impact events are recorded by an IMR clast at 1790 ± 36 Ma and a shock‐darkened clast at 2216 ± 40 Ma, demonstrating that NWA 869 escaped major reset in the course of the event at approximately 470 Ma that affected many L–chondrites. 相似文献
62.
The release of new data constituting the Coupled Model Intercomparison Project—Phase 5 (CMIP5) database is an important event in both climate science and climate services issues. Although users’ eagerness for a fast transition from CMIP3 to CMIP5 is expected, this change implies some challenges for climate information providers. The main reason is that the two sets of experiments were performed in different ways regarding radiative forcing and hence continuity between both datasets is partially lost. The objective of this research is to evaluate a metric that is independent of the amount and the evolution of radiative forcing, hence facilitating comparison between the two sets for surface temperature over eastern North America. The link between CMIP3 and CMIP5 data sets is explored spatially and locally (using the ratio of local to global temperatures) through the use of regional warming patterns, a relationship between the grid-box and the global mean temperature change for a certain time frame. Here, we show that local to global ratios are effective tools in making climate change information between the two sets comparable. As a response to the global mean temperature change, both CMIP experiments show very similar warming patterns, trends, and climate change uncertainty for both winter and summer. Sensitivity of the models to radiative forcing is not assessed. Real inter-model differences remain the largest source of uncertainty when calculating warming patterns as well as spatially-based patterns for the pattern scaling approach. This relationship between the datasets, which may escape users when they are provided with a single radiative forcing pathway, needs to be stressed by climate information providers. 相似文献
63.
Field and laboratory studies have been conducted to investigate the effect of surrounding buildings on the plume rise from low-level buoyant sources, such as distributed power generators. The field experiments were conducted in Palm Springs, California, USA in November 2010 and plume rise from a 9.3 m stack was measured. In addition to the field study, a laboratory study was conducted in a water channel to investigate the effects of surrounding buildings on plume rise under relatively high wind-speed conditions. Different building geometries and source conditions were tested. The experiments revealed that plume rise from low-level buoyant sources is highly affected by the complex flows induced by buildings stationed upstream and downstream of the source. The laboratory results were compared with predictions from a newly developed numerical plume-rise model. Using the flow measurements associated with each building configuration, the numerical model accurately predicted plume rise from low-level buoyant sources that are influenced by buildings. This numerical plume rise model can be used as a part of a computational fluid dynamics model. 相似文献
64.
Marko Vana Mikael Ehn Tuukka Petj Henri Vuollekoski Pasi Aalto Gerrit de Leeuw Darius Ceburnis Colin D. O'Dowd Markku Kulmala 《Atmospheric Research》2008,90(2-4):278-ICNAA07
Coastal nucleation events and behavior of cluster ions were characterized through the measurements of air ion mobility distributions at the Mace Head research station on the west coast of Ireland in 2006. We measured concentrations of cluster ions and charged aerosol particles in the size range of 0.34–40 nm. These measurements allow us to characterize freshly nucleated charged particles with diameters smaller than 3 nm. The analysis shows that bursts of intermediate ions (1.6–7 nm) are a frequent phenomenon in the marine coastal environment. Intermediate ion concentrations were generally close to zero, but during some nucleation episodes the concentrations increased to several hundreds per cm3. Nucleation events occurred during most of the measurement days. We classified all days into one of seven classes according to the occurrence and type of new particle formation. Nucleation events were observed during 207 days in 2006, most prominently in the spring and summer months. Rain-induced events, in turn, were observed during 132 days. Particle formation and growth events mostly coincided with the presence of low tide. Also small cluster ions (0.34–1.6 nm) were characterized. Average concentrations of small ions were 440 cm− 3 for the negative ions and 423 cm− 3 for the positive ions. Average mean mobilities of small ions were 1.86 cm2V− 1s− 1 and 1.49 cm2V− 1s− 1 for the negative and positive polarities, respectively. Concentrations of small ions were observed to be strongly dependent on the variations of meteorological parameters including wind speed and direction. 相似文献