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101.
秤锤树属(Sinojackia)是中国特有属,包括7个物种,各物种的种群及个体数量均较少,预测其潜在适宜分布区及其主要影响因素对制定保护措施至关重要。该研究在全面收集秤锤树属植物分布位点数据的基础上,结合气候、土壤和植被数据,运用物种分布模型(MaxEnt)和ArcGIS,预测该属植物当前的分布范围以及未来(2050s和2070s)潜在分布区的变化,分析影响该属植物分布的主要环境变量。预测结果显示:(1)当前秤锤树属高适宜地区主要在我国的亚热带地区,分布在长江中下游平原,包括湖南、浙江的大部分地区,河南、安徽和江苏南部地区以及湖北和江西两省交界处,四川、贵州零星分布着高适宜度位点;纬度范围为25.42°~31.84°N。(2)当前秤锤树属的高适宜性(0.665)生境面积仅为4.07×104 km2,占国土面积的4.23%,分布区极为狭窄。未来(2050s和2070s)的高适宜分布地区将大幅度缩减,其中在2070s的RCP8.5排放情景下减少最多。(3)随着温度的上升,秤锤树属植物有向高纬度迁移的趋势。研究结果可为濒危植物的就地保护提供科学依据,同时也可为其迁地保护位点的选择提供参考。 相似文献
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An enigmatic,diminutive theropod footprint in the shallow marine Pliensbachian Hasle Formation,Bornholm, Denmark 下载免费PDF全文
Jesper Milàn Finn Surlyk 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2015,48(4):429-435
A well‐preserved three‐toed footprint, measuring 34 mm in length from a very small predatory dinosaur with an estimated hip height of 153 mm and a total body length around 50 cm including tail, is reported from the type section of the marine Lower Jurassic (Pliensbachian), Hasle Formation on the Danish island of Bornholm in the Baltic Sea. The morphology of the footprint is similar to the ichnogenus Stenonyx Lull 1904 from the contemporaneous Pliensbachian Szydlowek site in Poland. Apart from the Polish material, footprints from diminutive dinosaurs are rare and reported from few other localities around the world. The occurrence of a diminutive dinosaur footprint in a shallow marine sandstone is enigmatic. The well‐defined morphology of the footprint, together with the very small size of the trackmaker, excludes the possibility that the track was emplaced by a swimming or wading animal. At the type locality where the footprint was found the formation consists of ferruginous coarse siltstone and very fine‐grained sandstone, showing hummocky and swaley cross‐stratification and rare large‐scale trough cross‐bedding and planar lamination. Deposition took place mainly in the upper shoreface in a storm‐dominated environment 1 km west of the N?S‐oriented faulted coastline. The formation becomes thinner and finer grained with heterolithic intercalations towards the south, indicating coast‐parallel transport in this direction. The extreme uniformity in sedimentary facies as seen in two nearby fully cored boreholes shows that the accommodation space created by rapid subsidence along the fault was continuously filled in to upper shoreface level by rapid longshore sediment influx from the north. In quiet periods with easterly winds and extreme low‐water low tide, the small dinosaur creating the newly found footprint is interpreted to have walked in shallow beach pools, thus explaining the strange occurrence of the footprint in a marine deposit. 相似文献
104.
M Mooses B Tippi K Mooses J Durussel J M?estu 《Biology of sport / Institute of Sport》2015,32(2):155-159
Given the ongoing interest in ways to improve the specificity of testing elite athletes in their natural environment, portable metabolic systems provide an opportunity to assess metabolic demand of exercise in sport-specific settings. Running economy (RE) and maximal oxygen uptake (O2max) were compared between track and treadmill (1% inclination) conditions in competitive level European distance runners who were fully habituated to treadmill running (n = 13). All runners performed an exercise test on running track and on treadmill. While O2max was similar on the track and on the treadmill (68.5 ± 5.3 vs. 71.4 ± 6.4 ml·kg−1·min−1, p = 0.105, respectively), superior RE was found on the track compared to the treadmill (215.4 ± 12.4 vs. 236.8 ± 18.0 O2 ml·kg−1·km−1, p < 0.001). RE on the track was strongly correlated with RE on the treadmill (r = 0.719, p = 0.006). The present findings indicate that high-level distance runners have significantly better RE but not O2max on the track compared to treadmill. This difference may be due to biomechanical adjustments. As RE is strongly correlated between the two conditions, it would be reasonable to assume that interventions affecting RE on the treadmill will also affect RE on the track. 相似文献
105.
Potential geographical distribution of Rhagoletis pomonella (Diptera: Tephritidae) in China 总被引:1,自引:0,他引:1
Jian Geng Zhi‐Hong Li Edwin G. Rajotte Fang‐Hao Wan Xiao‐Yu Lu Zhi‐Ling Wang 《Insect Science》2011,18(5):575-582
Abstract Apple maggot fly, Rhagoletis pomonella (Walsh) is a major pest causing considerable economic losses of fruits in North America. During the development of international trade, apple maggot fly has become a threat to Chinese agriculture. In this study, CLIMEX and ArcGIS were used to predict the potential geographical distribution of apple maggot fly in China. The parameters used in CLIMEX for apple maggot fly were derived from ecological data and the present geographical distribution of apple maggot fly in North America. Then the potential distribution map in China was presented based on the adjusted values of these parameters. The results showed that apple maggot fly has a wide potential distribution area in China; 47.5% of 748 meteorological stations presented high or medium suitability of pest establishment. These high suitable stations are mainly located in northeast, southwest and northwest of China, such as Liaoning, Shandong, Gansu and Shaanxi Provinces. These areas are also the central regions of apple, pear and peach production in China. Two hundred and twenty‐five stations (30.1%) in western and southern China, such as Tibet, Qinghai, Guangdong, Guangxi, Hainan and Taiwan, were unsuitable for establishment of apple maggot fly populations. In order to prevent the introduction of apple maggot fly in China, the present plant quarantine measures should be enhanced, especially in the areas with high suitability for the presence of apple maggot fly. 相似文献
106.
The occurrence of sauropod manus-only trackways in the fossil record is poorly understood, limiting their potential for understanding locomotor mechanics and behaviour. To elucidate possible causative mechanisms for these traces, finite-element analyses were conducted to model the indentation of substrate by the feet of Diplodocus and Brachiosaurus. Loading was accomplished by applying mass, centre of mass and foot surface area predictions to a range of substrates to model track formation. Experimental results show that when pressure differs between manus and pes, as determined by the distribution of weight and size of respective autopodia, there is a range of substrate shear strengths for which only the manus (or pes) produce enough pressure to deform the substrate, generating a track. If existing reconstructions of sauropod feet and mass distributions are correct, then different taxa will produce either manus- or pes-only trackways in specific substrates. As a result of this work, it is predicted that the occurrence of manus- or pes-only trackways may show geo-temporal correlation with the occurrence of body fossils of specific taxa. 相似文献
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快速康复外科(fast track surgery,FTS)是胃肠道肿瘤围手术期护理发展的新趋势,它全面改变了胃肠外科的面貌,并且对传统护理学形成强烈冲击,传统的护理模式已无法适应现代FTS的发展。本文对近年来FTS在胃肠道肿瘤围手术期的护理进行综述,并结合临床工作实践,探讨目前护理理念的转变,并对未来的胃肠道肿瘤围手术期的护理模式进行展望。 相似文献
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ABSTRACT Numerous techniques have been proposed to estimate carnivore abundance and density, but few have been validated against populations of known size. We used a density estimate established by intensive monitoring of a population of radiotagged leopards (Panthera pardus) with a detection probability of 1.0 to evaluate efficacy of track counts and camera-trap surveys as population estimators. We calculated densities from track counts using 2 methods and compared performance of 10 methods for calculating the effectively sampled area for camera-trapping data. Compared to our reference density (7.33 ± 0.44 leopards/100 km2), camera-trapping generally produced more accurate but less precise estimates than did track counts. The most accurate result (6.97 ± 1.88 leopards/100 km2) came from camera-trap data with a sampled area buffered by a boundary strip representing the mean maximum distance moved by leopards outside the survey area (MMDMOSA) established by telemetry. However, contrary to recent suggestions, the traditional method of using half the mean maximum distance moved from photographic recaptures did not result in gross overestimates of population density (6.56 ± 1.92 leopards/100 km2) but rather displayed the next best performance after MMDMOSA. The only track-count method comparable to reference density employed a capture-recapture framework applied to data when individuals were identified from their tracks (6.45 ± 1.43 leopards/100 km2) but the underlying assumptions of this technique limit more widespread application. Our results demonstrate that if applied correctly, camera-trap surveys represent the best balance of rigor and cost-effectiveness for estimating abundance and density of cryptic carnivore species that can be identified individually. 相似文献