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Apesteguía S 《Die Naturwissenschaften》2004,91(10):493-497
Ornithischian and theropod dinosaurs were morphologically diverse during the Cretaceous. In contrast, sauropods were relatively more conservative. The anatomy of Bonitasaura salgadoi, a new 9-m titanosaurian sauropod from Upper Cretaceous beds of Patagonia, suggests that sauropod anatomical diversity would have included unexpected items. Its unusual, rectangular lower jaw possesses narrow, anteriorly restricted teeth and shows evidence of a sharp keratinous sheath over the non-dentigerous region that probably worked to guillotine plant material. This discovery definitely demonstrates that titanosaurs acquired a mandibular configuration similar to that of some basal diplodocoids, as had already been suggested by the lower jaw of the controversial genus Antarctosaurus. This oral configuration, plus the beak-like structure and the skull shape, resemble some traits more commonly seen in Laurasian ornithischians, mostly unexpressed in southern continents. A high sauropod morphological diversity seems to be in agreement with the poorly represented ornithischian clades of the southern hemisphere.Communicated by G. Mayr 相似文献
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《环境科学学报(英文版)》2017,29(5):363
正Dr.Susan D.Richardson,a member of the Editorial Advisory Board of the Journal of Environmental Sciences,is recently appointed an Associate Editor of Environmental ScienceTechnology.She also serves as an Associate Editor of Water 相似文献
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Anopheles gambiae s.l. is the main vector of malaria in Sub-Saharan Africa. Here, an estimated 1 million people die every year from this disease.
Despite considerable research on An. gambiae that increasingly explores sub-organismal phenomena, important facets of the field biology of this deadly insect are yet
being discovered. In the current study, we used simple observational tools to reveal that the habitat of larval An. gambiae is not limited within the boundaries of temporary mud puddles, as has been the accepted generalization. Thus, control tactics
aimed at immatures must consider zones larger than puddles per se. In fact, eggs are more likely to be found outside than
inside puddles. Eggs can develop and larvae can emerge on mud. Larvae are then capable of three distinct modes of terrestrial
displacement (two active and one passive), whereby, they can reach standing water. On mud bearing a film of water, larvae
actively displace backwards by sinusoidal undulations shown to be only a slight variation of the swimming motor program. On
drying mud, larvae switch to a slower and forward form of active locomotion resembling that of a crawling caterpillar. During
rains, small larvae may be passively displaced by flowing rainwater so as to be deposited into puddles. These capabilities
for being amphibious, along with very rapid growth and development, help explain how An. gambiae thrives in a highly uncertain and often hostile larval environment.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
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Caesalpinia echinata (brazilwood or Pernambuco wood) comprises a complex of three morphological leaf variants, characterized by differences in
the number and size of the pinnae and leaflets, and occurring in allopatric and sympatric populations. The present study evaluates
the utility of the chloroplast DNA trnL intron in a phylogenetic analysis of the three leaf variants along with other species of Caesalpinia and generic relatives. Our study supports the hypothesis that the name C. echinata designates a species complex and provides evidence that one of the forms, the highly divergent C. echinata large-leafleted variant, represents a distinct taxon. 相似文献
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Cytogenetic analysis in three pregnancies revealed chromosomal mosaicism confined to chorionic villi. They were ascertained in the third trimester by intrauterine growth retardation (IUGR) in otherwise normal fetuses. In case of triple trisomy 6,21,22 and trisomy 16, it was obvious that these findings were most likely restricted to the placenta. These trisomies act as early lethal factors when they occur in the embryo itself. With trisomy 18, however, the interpretation of the cytogenetic finding remains ambiguous. The question arises as to whether an abnormal karyotype may be the cause of placenta insufficiency or is just coincidentally associated. 相似文献
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We compared the quantity and quality of the epicuticular wax of diapause and non-diapause pupae in two closely related Pieris species, P. brassicae and P. rapae crucivora. Main components of their epicuticular wax were identified as hydrocarbons. In P. brassicae, more than 95% of hydrocarbons were saturated regardless of whether the pupae were in diapause or not. In P. rapae crucivora, 93% of hydrocarbons were saturated in non-diapause pupae whereas in diapause pupae 41% were saturated and 59% unsaturated. From measurements of body surface area by nuclear magnetic resonance microimaging, we calculated the average thickness of the wax layer. The thickness in diapause and non-diapause pupae of P. brassicae was 800 and 160 nm, respectively. In P. rapae crucivora, the thickness was 195 nm in diapause and 11 nm in non-diapause. This is the first report to clarify the compositional difference in epicuticular wax between diapause and non-diapause pupae. 相似文献
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美国对邻避冲突现象的关注和研究较早,2015年刚被时任总统奥巴马否决的加拿大横加公司(Trans Canada Corp)"拱心石XL管道"(Keystone XL Pipeline)项目,是一起引发大规模邻避冲突的典型案例。本文介绍了"拱心石XL管道"项目的概况,分析了项目激起邻避冲突的原因,以及俄克拉荷马州政府和联邦政府在对待"拱心石XL管道"项目上的迥异态度。据此得出对我国应对环境邻避冲突的法律启示:跨区域公共项目在央地层面应保持一致、从项目选址的地方立法寻求突破、加大环境影响评价报告等信息公开力度、强化示范项目建设及规范企业行为。 相似文献
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Huang V Sakata JT Rhen T Coomber P Simmonds S Crews D 《Die Naturwissenschaften》2008,95(12):1137-1142
Kratochvil et al. (Naturwissenschaften 95:209–215, 2008) reported recently that in the leopard gecko (Eublepharis macularius) of the family Eublepharidae with temperature-dependent sex determination (TSD), clutches in which eggs were incubated at
the same temperature produce only same-sex siblings. Interpreting this result in light of studies of sex steroid hormone involvement
in sex determination, they suggested that maternally derived yolk steroid hormones could constrain sex-determining mechanisms
in TSD reptiles. We have worked extensively with this species and have routinely incubated clutches at constant temperatures.
To test the consistency of high frequency same-sex clutches across different incubation temperatures, we examined our records
of clutches at the University of Texas at Austin from 1992 to 2001. We observed that clutches in which eggs were incubated
at the same incubation temperature produced mixed-sex clutches as well as same-sex clutches. Furthermore, cases in which eggs
within a clutch were separated and incubated at different temperatures produced the expected number of mixed-sex clutches.
These results suggest that maternal influences on sex determination are secondary relative to incubation temperature effects. 相似文献
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S. Rouifed M. Cottet M. de Battista Y-F Le Lay F. Piola P. Rateau A. Rivière-Honegger 《Die Naturwissenschaften》2018,105(11-12):67
Choices have to be made to manage invasive species because eradication often is not possible. Both ecological and social factors have to be considered to improve the efficiency of management plans. We conducted a social study on Fallopia spp., a major invasive plant taxon in Europe, including (1) a survey on the perception of a landscape containing Fallopia spp. using a photoquestionnaire and (2) an analysis of the social representations of Fallopia spp. of managers and users in one highly invaded area and one less invaded area. The respondents to the photoquestionnaire survey appreciated the esthetics of the landscapes less when tall Fallopia spp. were present. Few people were able to identify and name the plant, and this knowledge negatively affected the appreciation of the photos containing Fallopia spp. The central core of the social representation of Fallopia spp. was composed of the invasive status of the plant, its density, and its ecological impacts. The peripheral elements of the representation depended on the people surveyed. The users highlighted the natural aspect whereas the managers identified the need for control. In the invaded area, the managers qualified the species as “unmanageable,” whereas the species was qualified as “foreign” in the less invaded area. Those results provide insights that have to be included when objectives of management plans of these species are selected. 相似文献