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排序方式: 共有385条查询结果,搜索用时 31 毫秒
251.
Joanna Dukes-McEwan BVMS MVM PhD DVC MRCVS Anne T. French MVB DVC MRCVS Brendan M. Corcoran MVB DipPharm PhD MRCVS 《Veterinary radiology & ultrasound》2002,43(2):144-152
Serial Doppler echocardiographic examinations were carried out in random order on six boxer dogs, on 3 separate days, by two experienced Doppler echocardiographers, to assess measurement variability and reproducibility of 65 parameters. Large numbers of parameters exhibited significant differences for each of the categories of intraobserver, interobserver, interday and interoperator. The coefficients of variation for all parameters measured ranged from 5.03 to 46.43%, but most were less than 20%. In general, least variation was found for the intraobserver category, and the best reproducibility for M-mode and left ventricular volumetric data. The worst reproducibility was found for tricuspid inflow and pulmonary venous flow measurements. The results of this study suggest differences greater than 20% for serial scans must be achieved to document genuine change, although the specific data should be consulted. Furthermore, variability and reproducibility are improved if a single experienced operator/observer acquires and measures serial scans. 相似文献
252.
IntroductionIn1980,ThomasLovejoyoftheWorldWildlifeFundStatedthatreduCtioninthebiologicaldiversityoftheplanetisthemoStbasicissueofourtimeandthatslowingthisprocessof"bioticimpoverishment"isagreatchallengetotheingenuityofbiologiSts.Extinctionofaspeciesrepresentsthelossofaresourcethathasevolvedthroughthousands,perhapsmillions,ofyearsofmutationandnaturalseleCtion(Durrant,1990).Asthenumberofbieds'speciesthreatenedwitheXtinCtionincrease,agriculturistsandconservationistshavejoinedforceinaneffortt… 相似文献
253.
A continuous supply of sucrose together with 8-hydroxyquinoline citrate to cut Lilium Asiatic hybrid ‘Prima’ inflorescences resulted in buds opening satisfactorily and increased their longevity. The best results were obtained using 30 g l?1 sucrose. Cut Lilium inflorescences could be stored at 1°C for 4 weeks without a great loss in potential vase-life and decorative value when the inflorescences were pre-treated with silver thiosulphate + 100 g l?1 sucrose for 24 h before cold storage, kept in a cold room in a solution containing 50 mg l?1 silver nitrate, and after cold storage kept in a solution containing 30 g l?1 sucrose and 200 mg l?1 8-hydroxyquinoline citrate. Such treatment greatly improved bud opening, increased the diameters of individual flowers and prolonged their life. 相似文献
254.
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256.
Grint NJ Lorena SE Johnson CB Luna SP Whay HR Murrell JC 《Veterinary anaesthesia and analgesia》2011,38(5):484-489
ObjectiveTo report the severe metabolic acidosis identified in a group of 11 healthy mules anaesthetized with halothane for castration.Study designData generated from a prospective study.AnimalsEleven mules aged 2.5–8 years, weighing 230–315 kg and 11 horses aged 1.5–3.5 years, weighing 315–480 kg.MethodsAnimals were anaesthetized for castration as part of an electroencephalographic study. Preanaesthetic medication was acepromazine (0.03 mg kg?1) administered through a preplaced jugular venous catheter. Anaesthesia was induced 30–90 minutes later with intravenous thiopental (10 mg kg?1). After orotracheal intubation, anaesthesia was maintained with halothane vaporised in oxygen. The animals’ lungs were ventilated to maintain the end-tidal CO2 concentration between 3.9 and 4.5 kPa (29–34 mmHg). Anaesthetic monitoring included invasive blood pressure measurement via the auricular artery (mules) and submandibular branch of the facial artery (horses). Arterial blood gas samples were drawn from these catheters at three time points during surgery and pH, PaCO2, base excess (ecf) and HCO3? were measured. Values were compared between groups using a Mann–Whitney test. p was taken as <0.05. Results are reported as median (range).ResultsPaCO2 did not differ between groups but pH was significantly lower in mules [7.178 (7.00–7.29)] compared to horses [7.367 (7.24–7.43)] (p = 0.0002). HCO3? values were significantly lower in the mules [16.6 (13.0–22.3) mM] compared to horses [23.7 (20.9–23.7) mM] (p = 0.0001), whilst base excess (ecf) was significantly more negative in the mules [?11.4 (?1.27 to ?16) mM] compared to horses [?1.3 (?5.8 to +2.4) mM] (p = 0.0004).Conclusion and clinical relevanceThis study demonstrated severe metabolic acidosis in healthy mules, which may have prompted intervention with drug therapies in a clinical arena. It is probable that the acidosis existed prior to anaesthesia and caused by diet, but other possible causes are considered. 相似文献
257.
Pollen beetle (Meligethes aeneus F.) (PB) causes very serious problems in oilseed rape (Brassica napus var. oleifera L.) cultivations in Poland and other European countries. Pyrethroid insecticides are the most frequently used type for controlling
PB in Poland. This chemical group has been used in Poland since the beginning of the 1980’s and its strong selection pressure
on PB resulted in some level of resistance of this pest to many active substances. The aim of this investigation was to analyze,
with the use of synergists, the main mechanisms responsible for resistance of PB to pyrethroids. The results indicate the
main resistance factor in Polish PB populations to be monooxygenase enzymes. 相似文献
258.
This paper discusses strategic decision making in firms pursuing biotechnology innovation and the influence of risk regulation on firm strategy. Data from three research projects, involving interviews with over 60 managers from agricultural and food related biotechnology companies and also over 60 key participants in the regulatory process in the UK and EC, shows a diversity of strategy and opinion. While some industry representatives identified new risk regulations governing the release of genetically manipulated organisms (GMOs) as the primary constraint on biotechnology innovation, the findings of the study painted a more complex picture. The controversies surrounding the issue of risk regulation and its impact on innovation are best understood if viewed in the context of other political and economic factors. We conclude that the actual impact of risk regulation on industry strategies is probably less than the rhetoric of industry lobbyists would suggest. At the same time, the very act of lobbying so forcefully could lead to a public backlash against industry that would be much more damaging than the regulation itself. 相似文献
259.
Hernandez RD Kelley JL Elyashiv E Melton SC Auton A McVean G; Genomes Project Sella G Przeworski M 《Science (New York, N.Y.)》2011,331(6019):920-924
Efforts to identify the genetic basis of human adaptations from polymorphism data have sought footprints of "classic selective sweeps" (in which a beneficial mutation arises and rapidly fixes in the population).Yet it remains unknown whether this form of natural selection was common in our evolution. We examined the evidence for classic sweeps in resequencing data from 179 human genomes. As expected under a recurrent-sweep model, we found that diversity levels decrease near exons and conserved noncoding regions. In contrast to expectation, however, the trough in diversity around human-specific amino acid substitutions is no more pronounced than around synonymous substitutions. Moreover, relative to the genome background, amino acid and putative regulatory sites are not significantly enriched in alleles that are highly differentiated between populations. These findings indicate that classic sweeps were not a dominant mode of human adaptation over the past ~250,000 years. 相似文献