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41.
As is widely recognised, fossil florules are difficult to correlate because they appear to have been more controlled by environmental and ecological factors than uniform changes which reflect the passage of geological time. Here I present a worked example of a generally applicable approach to this problem in dating and mapping fossil plant associations.

Floral associations are best described and named by the classical methods of phytosociology. The three dimensional shape of an association in rocks and its palaeoecology can then be critically assessed. For example, during Middle Triassic time the following plant associations would have been encountered on a traverse from the coast to several hundred kilometres inland from the Pacific margin of Gondwanaland: Pachydermophylletum (mangrove scrub), Linguifolietum (coastal swamp woodland), Dicroidietum odontopteroidium (floodplain forest), Phoenicopsetum (levee bank scrub), Dicroidietum odontopteroidium xylopterosum (xerophytic woodland) and Johnstonietum (mallee-like woodland).

The fourth dimension of fossil plant associations (time) is best assessed from the evolution of a prominent group of plants. In conjunction with the ranges of other plant megafossils, evolutionary changes can be used to define Oppel-zones. For the Late Permian to Early Jurassic of eastern Australasia, I have used the evolution of Dicroidium and leaves of related pteridosperm plants together with other species of restricted stratigraphic range or prominent in the definition of the fossil plant associations. From this evidence four Oppel-zones can be recognised. ‘Thinnfeldia’ callipteroides Oppel-zone (Chhidruan to Smithian, 250–230 × 106 years), Dicroidium zuberi Oppel-zone (Smithian to Middle Anisian, 230–220 × 106 years), D. odontopteroides Oppel-zone (Late Anisian to Ladinian, 220–210 × 106 years) and Yabeiella Oppel-zone (Carnian to Rhaetian, 210–200 × 106 years.

In a complete revision of the pteridosperm form-genera Dicroidium, Johnstonia and Xylopteris, a large number of new combinations and the following new taxa are proposed; Dicroidium gouldii sp. nov., D. odontopteroides var. argenteum var. nov., D. odontopteroides var. moltenense var. nov., D. radiatum sp. nov., D. townrovii sp. nov. and Johnstonia coriacea var. obesa var. nov.  相似文献   
42.
The US–Republic of Korea (ROK) alliance had significantly developed asset specificities and common social identities attached to it during the cold war period. If institutional features and ideational factors originating from the cold war threat can account for alliance resilience in the post-cold war period, the US–ROK alliance should be a ‘most likely case’ to support those causal links. This article shows that such is not the case. This article, instead, argues that the US–ROK alliance went beyond being an instrument of threat response to becoming a more complicated mechanism for serving ‘general interests’ in relation to North-East Asian regional order maintenance and order-building, which drove the US–ROK alliance between 1998 and 2008.  相似文献   
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Re‐melting experiments were conducted with specimens made of high‐arsenic copper alloys containing lead, iron and sulphur. The melting treatment at 1000°C in ambient conditions for 5 min was found to cause an almost complete removal of iron and sulphur along with a notable reduction of arsenic levels. Evidence was found that the preferential oxidation of iron and arsenic was responsible for this change in composition. The treatment also brought about perfect dissolution of speiss particles scattered throughout the original specimen, suggesting the possibility of the addition of speiss to molten copper for the production of arsenical copper.  相似文献   
45.
Binder (1996) and Schickler (2000) define the current debate as to why the U.S. House has changed its standing rules regarding the majority rule and the minority rights. I revisit their empirical models—binary logit and ordered logit—and theoretically and statistically test the appropriateness of these models. I find that both of them are actually choosing inappropriate models. Their theoretical claims cannot be properly examined by utilizing their choices of models. In addition, the data do not satisfy the “parallel regression” assumption but do satisfy the “independence of irrelevant alternatives” assumption, which supports using an alternative multinomial logit model. I further extend the model, and find the dynamic nature of rules changes in the U.S. House. It appears there is no symmetry between the rules changes that promote the majority rule and the rules changes that enhance the minority rights.  相似文献   
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In this study we analyse the spatial distribution patterns of professionals and related workers in high-skilled occupations and elementary workers in low-skilled occupations in the Seoul metropolitan area and explore their geographical factors. Spatial autocorrelation relates to the formation and clustering of hot spots according to each occupational characteristic. Geographic factors affecting the distribution of workplaces and residences in professionals-related occupations and elementary-related occupations act differently for each middle occupational classification. However, some occupations show similar spatial distribution patterns. In particular, we found that industrial economic drivers have influence more significant than other regional factors in determining the distribution of workplace and residence by occupation. The spatial coefficient of geographical adjacency varies with the attributes of each occupation and tends to be larger in professional jobs. Findings from the study will help prepare policies related to local talents for specialisation and advancement of the occupational structure and will be of wider interest.  相似文献   
48.
This paper reports student perceptions of the benefits and challenges of Bring Your Own Device (BYOD) in a fieldwork context. Student perceptions from six field courses across two institutions have been gathered using questionnaires and focus groups. Whilst a number of studies have focused on BYOD in a classroom context, little research has been undertaken about BYOD in a fieldwork context. The key findings suggest that around one fifth of students were not willing to use their own device during fieldwork citing loss or damage as the main reason. This key challenge is different to that which are found in a classroom which generally focus on network security, connectivity etc. The findings also suggest that some students believe that BYOD can have a negative impact on group work. There is a misalignment here between student and practitioner thinking with previous literature which suggests that practitioners believe BYOD and smart devices can enhance group work. The one key challenge which is found regardless of learning environment is inequality between those who have a device and those who do not.  相似文献   
49.
Lavishly decorated wagons excavated from royal Xiongnu burials are generally regarded as tribute items from China offered to Xiongnu elites, symbolizing important political and economic interactions between the Xiongnu state (209 BC–155 AD) and the Han dynasty (206 BC–220 AD). This theory views such vehicles as having no relation to indigenous Xiongnu craftsmanship. Furthermore, specialized products delivered to the northern nomadic peoples from the Han state are often cited in support of the notion of Xiongnu dependency on foreign states for technological and political development. Expecting to find evidence of China’s traditional iron and bronze technology, we examined a number of key metallic components of these wagons excavated from the royal Xiongnu burial at Golmod 2 in central Mongolia, radiocarbon dated to 109 BC–AD 75. Surprisingly, the iron metallurgy in question was based primarily on the bloomery process while low tin bronze and arsenical copper alloys dominated the pertinent bronze production. These respective technological traditions are typical of Xiongnu manufacture but significantly different from traditional Han metallurgy. We interpret this evidence as suggesting the need for a more balanced evaluation of foreign influence on the rise and development of the Xiongnu state.  相似文献   
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