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排序方式： 共有252条查询结果，搜索用时 15 毫秒
141.
Wing-Keong Ng Young-Chul Kim Nicholas Romano Chik-Boon Koh Si-Yong Yang 《Journal Of Applied Aquaculture》2013,25(1):22-31
An eight-week trial was performed to evaluate three commercial/prototype probiotics supplemented in red hybrid tilapia, Oreochromis sp. diets. Triplicate groups of tilapia were measured for growth performance, feeding efficiencies, and whole-body composition. After the feeding trial, duplicate groups of tilapia were assessed for their resistance to Streptococcus agalactiae over 23 days. Six diets were supplemented with 0.1% or 0.3% PB1 consisting of Bacillus subtilis, 0.1% or 0.3% PB2 consisting of B. licheniformis or 0.1% MPB consisting of Bacillus sp. and Pediococcus sp. Probiotics had no effect (p > 0.05) on growth or feeding efficiencies, although whole-body crude protein was significantly higher in the PB1 0.3% treatment. Tilapia in the probiotic treatments had a higher resistance to S. agalactiae and, with the exception of the PB2 0.1% diet, were all significantly higher than the control treatment. Although the tested probiotics were not growth promoters, dietary B. subtilis was the most effective prophylactic against pathogenic bacteria. 相似文献
142.
143.
SR Scofield CM Tobias JP Rathjen JH Chang DT Lavelle RW Michelmore BJ Staskawicz 《Science (New York, N.Y.)》1996,274(5295):2063-2065
Transient expression of the Pseudomonas syringae avirulence gene avrPto in plant cells resulted in a Pto-dependent necrosis. The AvrPto avirulence protein was observed to interact directly with the Pto resistance protein in the yeast two-hybrid system. Mutations in the Pto and avrPto genes which reduce in vivo activity had parallel effects on association in the two-hybrid assay. These data suggest that during infection the pathogen delivers AvrPto into the plant host cell and that resistance is specified by direct interaction of Pto with AvrPto. 相似文献
144.
汽蒸处理对落叶松木材物理性质的影响 总被引：1，自引：0，他引：1
本文取兴安落叶松(Larix gmelinii Rupr)生材加工成规格为20mm×20mm×20mm的试样;于常压下汽蒸1、2、4、8、16、32、48、64、96h。测定了气干和全干状态的干缩率、气干密度、基本密度和平衡含水率(EMC)等物理性质的变化情况。结果表明:①木材全干干缩率除汽蒸初始1h略有下降外,均随汽蒸的延续而逐渐增加,至64 h达最大值,径向、弦向和体积干缩率分别为7.28％、13.40％和21.85％,若继续延长汽蒸时间,干缩率稍有降低。②汽蒸过程中差异干缩值的变化不大,稍有降低。因而,汽蒸不会加剧差异干缩,并能使其有所改善。③气干密度和基本密度均随汽蒸的延续而逐渐降低,至48h降达最低值,分别为0.615g/cm~3和0.487g/cm~3,若继续汽蒸,气干密度和基本密度均稍有回升。④平衡含水率(EMC)随汽蒸的延续而逐渐降低,汽蒸96h降为8.53％。因此,汽蒸处理对落叶松木材物理性质的影响不大,落叶松成材汽蒸处理时间,一般不宜超过16h。 相似文献
145.
Hideyuki Kawai Nobuo Ishiyama Koh Hasegawa Futoshi Nakamura 《Ecology of Freshwater Fish》2013,22(4):645-653
Flow regime is one of the major determinants of establishment success for non‐native aquatic organisms. Here, we examine the influence of flow variability associated with snowmelt flood on the establishment success of non‐native brown trout in 10 streams in northern Japan. We regarded the presence of Age‐0 brown trout as the index of the successful establishment. The emergence of Age‐0 brown trout in our study region begins in May, a time that overlaps with the occurrence of snowmelt flood. The presence of Age‐0 brown trout was negatively associated with flow variability, and it was also negatively associated with summer water temperature. Our results indicate that the non‐native brown trout tends to establish in the streams with smaller snowmelt floods and lower summer water temperatures. Brown trout is an invasive, non‐native species that is problematic all over the world, and effective management strategies for preventing their further expansion are urgently needed. This study suggests that river managers should recognise that stable streams such as spring‐fed streams (i.e., low flow and summer water temperature) and flow‐regulated streams, have a higher potential risk of brown trout invasion. 相似文献
146.
Chik‐Boon Koh Nicholas Romano Abdullah Siti Zahrah Wing‐Keong Ng 《Aquaculture Research》2016,47(2):357-369
A 20‐week feeding trial was conducted to measure growth, nutrient utilization and faecal/gut bacterial counts in triplicate groups of red hybrid tilapia, Oreochromis sp., when fed diets supplemented with 0.5% organic acids blend (OAB), 1.0% OAB, 0.5% oxytetracycline (OTC) or a control diet (no additives). At the end of the feeding trial, tilapia were challenged with Streptococcus agalactiae for 22 days. Fish fed the OTC diet had significantly higher (P < 0.05) growth than the control treatment, while growth between fish fed the OTC or OAB diets was not significantly different (P > 0.05). Phosphorus, dry matter and ash digestibility were significantly higher in the 1.0% OAB diet than the control diet. Fish fed the OAB diets had significantly lower colony‐forming units of adherent gut bacteria compared to the control or OTC treatments while those fed the 1.0% OAB diet had the lowest total faecal bacterial counts. Tilapia fed the 0.5% OTC or OAB diet had significantly higher resistance to S. agalactiae than those fed the control diet. This study indicates that dietary organic acids can potentially replace OTC as a growth promoter and antimicrobial in tilapia feeds. 相似文献
147.
A conditioner containing lugworm autolysate was prepared, and its feasibility as a new conditioner was investigated. The treatment of hair with the conditioner, before and after dyeing showed positive effects on the thickness, weight, and amino acid contents of the hair. These properties were significantly enhanced, and similar results were obtained by hair surface examination by using scanning electron microscopy and tensile strength measurements. The surface of the cuticles in the experimental group was smoother than that of the control group, and the arrangement of the hair scales was maintained even after shampooing for 20 times. The hair tensile strength of the experimental group was significantly higher than that of the control group. The significant treatment effect of the conditioner containing lugworm autolysate could be attributed to the synergistic effect of adhesive strength and effective film formation properties of lugworm autolysate. 相似文献
148.
Influences of dietary uptake and reactive sulfides on metal bioavailability from aquatic sediments 总被引：1，自引：0，他引：1
Lee BG Griscom SB Lee JS Choi HJ Koh CH Luoma SN Fisher NS 《Science (New York, N.Y.)》2000,287(5451):282-284
Understanding how animals are exposed to the large repository of metal pollutants in aquatic sediments is complicated and is important in regulatory decisions. Experiments with four types of invertebrates showed that feeding behavior and dietary uptake control bioaccumulation of cadmium, silver, nickel, and zinc. Metal concentrations in animal tissue correlated with metal concentrations extracted from sediments, but not with metal in porewater, across a range of reactive sulfide concentrations, from 0.5 to 30 micromoles per gram. These results contradict the notion that metal bioavailability in sediments is controlled by geochemical equilibration of metals between porewater and reactive sulfides, a proposed basis for regulatory criteria for metals. 相似文献
149.
150.
Q Fang J Wang YY Hao H Li JX Hu GS Yang JH Hu 《Reproduction in domestic animals》2017,52(6):1061-1066
Microbial environment is one of the important factors that affect the quality of preserved semen. Iodine methionine (IM), participating in the production and activation of metabolic enzymes, is a new type of amino acid chelate. To date, there has been no report to evaluate the effects of IM on boar semen preservation at 17°C. This study was designed to investigate the effects of IM on boar sperm quality and reproductive performance during liquid storage at 17°C and its antibacterial effect. Semen samples collected from six Yorkshire boars were diluted with basic liquid containing different concentrations of IM (0, 20, 40, 80, 160 and 320 μM). Subsequently, sperm motility, plasma membrane integrity and acrosome integrity were determined. After 6 days of preservation, the difference in microbial composition between control group and 80 μM IM group was compared using 16S rDNA sequencing, and the effects of IM on reproductive performance were also compared and analysed between the two groups. The results demonstrated that 20, 40 and 80 μM IM improved boar sperm motility, plasma membrane integrity and acrosome integrity. 80 μM IM was the optimum concentration. Conversely, 160 and 320 μM IM resulted in deleterious consequences to boar sperm quality compared to the control group and other treatment groups (p < .05). After 6 days of preservation, sperm motility, plasma membrane integrity and acrosome integrity were 56.0%, 51.8% and 59.4%, respectively. There was no significant difference in non‐return rate between the two groups (p > .05). But the litter size of 80 μM IM group was significantly higher than that of control group (p < .05). 80 μM IM inhibited proliferation of the phylum Proteobacteria and the genus Staphylococcus as well as Pseudomonas (p < .05). Further studies are required to understand the antibacterial mechanism of IM in liquid‐preserved boar semen. 相似文献