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31.
We report a new and nearly completely articulated rhamphorhynchoid pterosaur, Jeholopterus ningchengensis gen. et sp. nov., with excellently preserved fibres in the wing membrane and "hairs" in the neck, body and tail regions. Many of its characteristics such as a short neck, short metacarpals and distinctively long fifth pedal digit are characteristic of rhamphorhynchoids. The new species can be further referred to the 'strange' short-tailed rhamphorhynchoid family Anurognathidae. It is much more complete than the other known members of the family, namely, Anurognathus from Solnhofen, Germany, Batrachognathus from Karatau, Kazakhstan, and Dendrorhynchoides from Beipiao, Liaoning Province, China. The new pterosaur also shows that the wing membrane is attached to the ankle of the hind limb. The pedal digits are webbed. Furthermore, the "hair" of Jeholopterus bears some resemblance to the hair-like integumental structures of the feathered dinosaur Sinosauropteryx although there is yet no direct evidence to argue for or against their homology.  相似文献   
32.
酸压中活酸作用距离是评价酸压效果的重要因素。活酸作用距离取决于酸岩反应速度,酸岩反应动力学参数是酸压优化设计基础,这些参数的准确性决定优化设计的可靠性。设计了一种测试动态条件下裂缝中酸液有效传质系数和有效消耗时间的新方法,该方法通过酸蚀裂缝导流驱替实验,测试酸化前后岩板质量变化;基于岩板质量变化计算酸液消耗速度、酸液有效传质系数,再基于裂缝中的酸液量和酸液消耗速度计算酸液有效消耗时间。采用延长马家沟组岩板测试了稠化酸和交联酸的反应动力学参数,交联酸比稠化酸黏度高,有效传质系数比稠化酸低,在使用的实验条件下,稠化酸和交联酸在裂缝中的有效消耗时间分别为20 min和28 min左右。研究为酸压优化设计和酸液体系评价提供了依据。  相似文献   
33.
研究了化学镀Ni-Cu-P工艺及镀层性能。当温度控制在70~75℃、pH值控制在7.0~8.0、添加剂B的含量为2.0g/1、CuSO4含量1~2g/1时,所得镀层性能最好。镀层经热处理后,组织和性能将发生变化。发现Ni-Cu-P镀层出现最高硬度的热处理温度为500℃,超过Ni-P化学镀层出现最高硬度的热处理温度。经过正确的热处理后,镀层硬度和耐磨性优于Ni-P化学镀层,且应用温度范围较宽。  相似文献   
34.
利用耦合振动理论研究功率超声技术中大尺寸矩形截面振动系统的多维耦合振动,推出了振动系统的频率方程,分析了振动系统中横向与纵向振动之间的相互关系以及横向振动模式的分布情况,计算并测量了考虑横向振动后系统的纵向谐振频率。  相似文献   
35.
合成了α-乙酰吡啶缩氨基硫脲(HL)与镍(Ⅱ)形成的5个配合物,并通过元素分析;摩尔电导、磁矩的测定和紫外光谱、红外光谱的研究,对其进行了表征。抑菌活性实验表明:[NiL(NCS)]对枯草杆菌、金黄色葡萄球菌和大肠杆菌具有较强的抑制作用。  相似文献   
36.
A Miocene ostrich fossil from Gansu Province,northwest China   总被引:5,自引:0,他引:5  
A pelvic skeleton, recognized as a large terrestrial bird in the field, was recently collected by our paleomammalo-gist colleagues from the Institute of Vertebrate Paleontol-ogy and Paleoanthropology from the late Miocene sandy mudstones in the Linxia Basin in Gansu Province, north-west China. We have further referred this bird to as an early representative of ostrich. Ostrich fossils usually co-existed with the famous Hipparion Fauna from the Mio-cene to Pliocene. The Linxia Basin is we…  相似文献   
37.
提出了用微机演示李萨如图形的简单方法.  相似文献   
38.
We describe two new ornithurine birds from the Early Cretaceous Jiufotang Formation of western Liaoning, northeast China: Yanornis martini gen. et sp. nov. and Yixianornis grabaui gen. et sp. nov. They represent the best fossil record of ornithurine birds known from the Early Cretaceous. They are more advanced than the most primitive ornithurine Liaoningornis, and are more similar to the other two Chinese Early Cretaceous ornithurines Chaoyangia and Songlingornis. Compared with Confuciusornis, Liaoxiornis and Eoenantiornis from the same age, the two new birds show remarkable advanced characteristics and suggest the presence of powerful flight capability like modern birds. Compared with Yixianornis and Chaoyangia, Yanornis is larger, with a more elongated skull and relatively long wings. The new discoveries indicate that by the Early Cretaceous both enantiornithine and ornithurine birds had already radiated significantly. The flight structures of Yanornis and Yixianornis are hardly distinguishable from those of modern birds; however, both retain a few primitive traits such as teeth on the jaws, wing claws and pubic symphysis, which exclude them from being the most recent ancestor of all extant birds.  相似文献   
39.
稀土研究了渗剂在份,共渗温度和时间对欠氮经渗层厚度,表面硬度及其分布的影响。结果表明,稀土的加入能明显加快共渗速度,缩短共渗时间;能提高渗层,特别是扩散层的硬度,使硬度梯度下降;渗层组织致密,过渡层中的碳化物和氮经物细小,弥散。  相似文献   
40.
We report new 40Ar÷39Ar dating results obtained from total fusion and incremental-heating analyses of sanidine and biotite from three tuffs found interbedded within the fossil-bearing deposits of Liaoning, northeast China. The first is a new sample of the Bed 6 Sihetun tuff from the Yixian Formation, previously dated by our team as middle Early Cretaceous, and recently considered by Lo et al., partially reset due to metamorphism from a nearby basaltic sill. The second is the Yixian Bed 9 tuff from Hengdaozi considered by Lo et al. to be unaffected by metamorphism and whose age, based on total fusion 40Ar÷39Ar dating of biotite, argues for a Jurassic age for the Yixian Formation. The third tuff is a previously undated tuff from the upper part of the underlying Tuchengzi Formation. Single crystal total fusion 40Ar÷39Ar analyses of the Sihetun sanidine showed homogeneous radiogenic Ar, Ca÷K ratios, excellent reproducibility and gave a mean age of 125.0±0.18 (1SD)±0.04 (SE) Ma. Single sanidine crystal total fusion 40Ar÷39Ar analyses of the Hengdaozi tuff gave a mean age of 125.0±0.19 (1SD)±0.04 (SE) Ma, which is indistinguishable from the Sihetun tuff. The Tuchengzi Formation tuff gave a mean age of 139.4±0.19 (1SD)±0.05 (SE) Ma. Detailed laser incremental-heating analyses of biotite from Sihetun, Hengdaozi, and Tuchengzi tuffs show disturbed Ar release patterns and evidence of trapped argon components. We conclude from these analyses that the total fusion dates on biotite by Lo et al. are erroneously old and isotopic dating of both biotite and sanidine from tuffs of the Yixian Formation point to a middle Early Cretaceous age. The upper part of the Tuchengzi Formation can be referred to the Early Cretaceous.  相似文献   
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