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61.
62.
球孢白僵菌生长及毒力影响因子的研究进展 总被引:1,自引:0,他引:1
随着害虫综合治理的提出,昆虫病原真菌在防治农林害虫上的应用日趋广泛,白僵菌是世界各国研究应用最多的真菌杀虫剂。从白僵菌生长所需的营养、温湿度条件等方面的研究进展进行阐述,总结了提高菌株生长水平和杀虫效果的主要措施,以期对今后白僵菌的培养及应用提供参考。 相似文献
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64.
Potential impact of climate warming on recreational fishing opportunities for Atlantic salmon, Salmo salar L., in Newfoundland, Canada 总被引:1,自引:1,他引:1
Potential impacts of climate warming on recreational fishing opportunities were addressed by assessing the frequency and extent that Atlantic salmon, Salmo salar L., rivers in Newfoundland have been closed over a 25-year period (1975 to 1999) because of warm water temperatures and low water levels. On average, approximately 28% of all salmon rivers were temporarily closed annually, with over 70% affected in some years. This has resulted in a loss of 35–65% of the potential fishing days available in some salmon fishing areas with the collective 1995 to 1999 period being impacted the most over the past two decades. Geographically, west and south-west coastal rivers were affected less from environmental closures than east and some south coast fishing areas. A trend for increased closures of rivers related to environmental reasons could reduce the economic importance of the recreational salmon fishery and also make it more difficult to assess the status of Atlantic salmon stocks, which is a requirement for conservation of the resource. 相似文献
65.
Conor P. McGowan Mark R. Ryan Michael C. Runge Joshua J. Millspaugh Jean Fitts Cochrane 《Biological conservation》2011,(2):730-737
Many endangered species laws provide exceptions to legislated prohibitions through incidental take provisions as long as take is the result of unintended consequences of an otherwise legal activity. These allowances presumably invoke the theory of demographic compensation, commonly applied to harvested species, by allowing limited harm as long as the probability of the species’ survival or recovery is not reduced appreciably. Demographic compensation requires some density-dependent limits on survival or reproduction in a species’ annual cycle that can be alleviated through incidental take. Using a population model for piping plovers in the Great Plains, we found that when the population is in rapid decline or when there is no density dependence, the probability of quasi-extinction increased linearly with increasing take. However, when the population is near stability and subject to density-dependent survival, there was no relationship between quasi-extinction probability and take rates. We note however, that a brief examination of piping plover demography and annual cycles suggests little room for compensatory capacity. We argue that a population’s capacity for demographic compensation of incidental take should be evaluated when considering incidental allowances because compensation is the only mechanism whereby a population can absorb the negative effects of take without incurring a reduction in the probability of survival in the wild. With many endangered species there is probably little known about density dependence and compensatory capacity. Under these circumstances, using multiple system models (with and without compensation) to predict the population’s response to incidental take and implementing follow-up monitoring to assess species response may be valuable in increasing knowledge and improving future decision making. 相似文献
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Fresh, mature, ungrazed Tribulus terrestris plant material was subjected to a standard alkaloid extraction procedure. The extract was fractionated by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Two major alkaloid fractions were demonstrated. These fractions were identified by means of TLC, ultraviolet spectrofluorimetry (UVS) and HPLC, as the beta-carboline indoleamines harmane and norharmane. The extractable alkaloid content was determined to be 44 mg/kg dry matter. Synthetic harmane and norharmane were administered subcutaneously to sheep at a dose rate of 54 mg/kg. Both compounds caused similar nervous effects. The main effect observed was limb paresis, which in some sheep was body side blased. The clinical signs observed in the experimental sheep were consistent with those described for naturally occurring cases of Tribulus terrestris staggers. It was proposed that harmane and norharmane accumulate in tryptamine-associated neurones of the central nervous system, during months of tribulus ingestion, and gradually interact irreversibly with a specific neuronal gene DNA sequence. 相似文献
68.
Pharmacokinetics of phenobarbital in the cat following intravenous and oral administration. 总被引:1,自引:1,他引:0
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S M Cochrane W D Black J M Parent D G Allen J H Lumsden 《Canadian journal of veterinary research》1990,54(1):132-138
Phenobarbital was administered to eight healthy cats as a single intravenous dose of 10 mg/kg. Serum phenobarbital concentrations were determined using an immunoassay technique. The intravenous data were fitted to one-, two- and three-compartment models. After statistical comparison of the three models, a two-compartment model was selected. Following intravenous administration, the drug was rapidly distributed (distribution half-life = 0.046 +/- 0.007 h) with a large apparent volume of distribution (931 +/- 44.8 mL/kg). Subsequent elimination of phenobarbital from the body was slow (elimination half-life = 58.8 +/- 4.21 h). Three weeks later, a single oral dose of phenobarbital (10 mg/kg) was administered to the same group of cats. A one-compartment model with an input component was used to describe the results. After oral administration, the initial rapid absorption phase (absorption half-life = 0.382 +/- 0.099 h) was followed by a plateau in the serum concentration (13.5 +/- 0.148 micrograms/mL) for approximately 10 h. The half-life of the terminal elimination phase (76.1 +/- 6.96 h) was not significantly different from the half-life determined for the intravenous route. Bioavailability of the oral drug was high (F = 1.20 +/- 0.120). Based on the pharmacokinetic parameters determined in this study, phenobarbital appears to be a suitable drug for use as an anticonvulsant in the cat. 相似文献
69.
70.
Ultracentrifugal Studies of Sera from Cattle Vaccinated or Naturally Infected with Brucella Abortus
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Christine E. Rice Joan Tailyour Delma Cochrane 《Canadian journal of veterinary research》1966,30(10):270-278
In conformity with the findings of previous investigators, it was shown by density gradient ultracentrifugation that the antibodies in sera collected from calves shortly after vaccination with Brucella abortus, strain 19, were entirely or mainly rapidly-sedimenting. These macroglobulin (19S or IgM) antibodies showed complement-fixing as well as agglutinative activity with Br. abortus antigen. In later bleedings from the same vaccinated calves, antibodies with an intermediate sedimentation rate, (IgG), were present, as well as IgM. Sera from 15 of 22 non-vaccinated, relatively recent field cases of brucellosis appeared to contain only the IgG class of antibodies. In one herd, however, two cows with IgM only and five with both IgM and IgA were found; all seven of these cattle had been serologically negative before their introduction into this known infected herd a few months earlier. The agglutinative activity of sera from four cases of brucellosis of long standing and from eight cows, 4 to 13 years of age, that had been vaccinated as calves, was confined to the IgG fraction. 相似文献