A long-snouted predatory dinosaur from africa and the evolution of spinosaurids     

PC Sereno  AL Beck  DB Dutheil  B Gado  HCE Larsson  GH Lyon  JD Marcot  OWM Rauhut  RW Sadleir  CA Sidor  DD Varricchio  GP Wilson  JA Wilson 《Science (New York, N.Y.)》1998,282(5392):1298-1302

Fossils discovered in Lower Cretaceous (Aptian) rocks in the Tenere Desert of central Niger provide new information about spinosaurids, a peculiar group of piscivorous theropod dinosaurs. The remains, which represent a new genus and species, reveal the extreme elongation and transverse compression of the spinosaurid snout. The postcranial bones include blade-shaped vertebral spines that form a low sail over the hips. Phylogenetic analysis suggests that the enlarged thumb claw and robust forelimb evolved during the Jurassic, before the elongated snout and other fish-eating adaptations in the skull. The close phylogenetic relationship between the new African spinosaurid and Baryonyx from Europe provides evidence of dispersal across the Tethys seaway during the Early Cretaceous.  相似文献   

Unconditional quantum teleportation   总被引：5，自引：0，他引：5  

A Furusawa  JL Sorensen  SL Braunstein  CA Fuchs  HJ Kimble  ES Polzik 《Science (New York, N.Y.)》1998,282(5389):706-709

Quantum teleportation of optical coherent states was demonstrated experimentally using squeezed-state entanglement. The quantum nature of the achieved teleportation was verified by the experimentally determined fidelity Fexp = 0.58 +/- 0.02, which describes the match between input and output states. A fidelity greater than 0.5 is not possible for coherent states without the use of entanglement. This is the first realization of unconditional quantum teleportation where every state entering the device is actually teleported.  相似文献   

Thermodynamics of calcite growth: baseline for understanding biomineral formation     

HH Teng  PM Dove  CA Orme  De Yoreo JJ 《Science (New York, N.Y.)》1998,282(5389):724-727

The complexity of biomineralized structures suggests the potential of organic constituents for controlling energetic factors during crystal synthesis. Atomic force microscopy was used to investigate the thermodynamic controls on carbonate growth and to measure the dependence of step speed on step length and the dependence of critical step length on supersaturation in precisely controlled solutions. These data were used to test the classic Gibbs-Thomson relationship and provided the step edge free energies and free energy barriers to one-dimension nucleation for calcite. Addition of aspartic acid, a common component in biomineralizing systems, dramatically affected growth morphology and altered the magnitude of the surface energy.  相似文献   

Tetraoxanes as a new class of efficient herbicides comparable with commercial products          下载免费PDF全文

Raphael C Cusati  Luiz CA Barbosa  Célia RA Maltha  Antônio J Demuner  Alberto Oliveros‐Bastidas  Antônio A Silva 《Pest management science》2015,71(7):1037-1048

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Impact of 24-h Cooling Prior to Freezing on the Survival of Domestic Cat (Felis catus) Epididymal Sperm     

JLA Martins  AISB Villaverde  AFM Lima  PVM Steagall  JCP Ferreira  CA Taconeli  MD Lopes 《Reproduction in domestic animals》2009,44(S2):366-368

The aim of this study was to investigate the impact of a 24-h cooling period prior to freezing on domestic cat epididymal sperm viability. Fifteen tomcats were submitted to routine orchiectomy and sperm samples were retrieved from both epididymides in a Tris–glucose–20% egg yolk extender. For each tomcat, the diluted sperm was split into two equal volumes and cooled to 5°C at a rate of 0.5°C/min; one sample for 60 min (control) and the other for 24 h (cooled). After the cooling period, samples from both groups were frozen using an identical freezing protocol. Sperm samples were evaluated in three different periods: immediately after harvesting, after cooling at 5°C for 24 h (cooled group) and after freezing–thawing of control and cooled groups. Evaluations consisted of sperm motility and progressive status, sperm morphology and plasma membrane integrity (PMI) using two fluorescent probes. After cooling for 24 h, a decrease (p < 0.05) in sperm motility, progressive status and PMI was observed when compared to sperm samples immediately after collection. Comparing the results obtained after thawing, no difference (p < 0.05) was found regarding sperm motility, progressive status, PMI and sperm morphology between control and cooled groups. The results from the present study show that cooling cat epididymal spermatozoa at 5°C for 24 h prior to freezing does not lead to major damage of spermatozoa impairing the freeze–thaw process.  相似文献   

Are ovine fenugreek (Trigonella foenum‐graecum) staggers and kangaroo gait of lactating ewes two clinically and pathologically similar nervous disorders?   总被引：1，自引：1，他引：0  

CA Bourke 《Australian veterinary journal》2009,87(3):99-101

Fenugreek staggers has occurred in sheep in Victoria, as both an acute and a chronic syndrome. Signs included quadraparesis, a high stepping fore limb gait and a 'bunny-hopping' hind limb gait. Changes consistent with acute oedema were found in the brain and spinal cord of acute cases, and Wallerian degeneration in the peripheral nerves of chronic cases. Kangaroo gait occurred in ewes in New South Wales, and the clinical signs and microscopic changes were remarkably similar to those of fenugreek staggers. Although the diet associated with each is different the causal agent may be the same.  相似文献   

Letter to the Editor          下载免费PDF全文

A. Willems DVM  DECVIM‐CA  D. Paepe DVM  DECVIM‐CA  S. Daminet DVM  DECVIM‐CA  DACVIM 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2017,31(5):1370-1370

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Laparoscopic evaluation of the small intestine in the standing horse: Technique and effects*          下载免费PDF全文

Andrew R. E. Jones BVetMed MRCVS  Claude A. Ragle DVM  DACVS  DABVP  Dusty Anderson BS  Coryelle Scott BS 《Veterinary surgery : VS》2017,46(6):812-820

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Identification and characterization of a serine protease from wheat leaves     

Tao?Fan  Natalia?V.?Bykova  Christof?RampitschEmail author  Tim?XingEmail author 《European journal of plant pathology / European Foundation for Plant Pathology》2016,146(2):293-304

A putative serine protease with a potential role in the plant biotic and abiotic stress response was purified from wheat leaf apoplastic fluid and partially characterized. Following two-dimensional electrophoresis a protein of M_r = 75 k and a pI of 4.2 to 4.5 was observed. This protein displayed in-gel protease activity and was specifically inhibited by phenylmethanesulfonyl fluoride and partially inhibited by Ca²⁺ and Zn²⁺, but not by E-64 or leupeptin. An internal tryptic fragment of 13 amino acids was identified by MALDI QqTOF MS/MS, and this peptide showed a high level of homology (85–100 % identity) to a highly conserved region of known plant subtilisin-like proteases. We demonstrated that the protease activity increased until a late stage of wheat leaf development and increased in response to heat shock. In both cases Rubisco large subunit was degraded with time. Protease activity was also increased during biotic stress. Leaves challenged with leaf rust (Puccinia triticina), showed an approximately three fold increase in protease activity during an incompatible interaction, compared to activity in mock-inoculated leaves and to leaves in a compatible leaf rust interaction. These results suggest that the expression of this serine protease could be involved in the defense response against both abiotic and biotic stresses.  相似文献   

Larvicidal activities and chemical composition of essential oils from Piper klotzschianum (Kunth) C. DC. (Piperaceae)     

Jeferson C do Nascimento  Jorge M David  Luiz CA Barbosa  Vanderlucia F de Paula  Antonio J Demuner  Juceni P David  Lucia M Conserva  Jésu C Ferreira Jr  Elsie F Guimarães 《Pest management science》2013,69(11):1267-1271

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