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Sperm cryopreservation is a useful tool in captive fish reproduction management, that is to synchronize gamete production, especially in the case of species as the European eel, where the time of female spawning readiness is unpredictable. Several protocols to cryopreserve sperm of this species have been described, but until recently fertilization trials were not feasible. This study evaluated the effect of cold storage of diluted sperm prior to fertilizations and tested whether a previously defined protocol for European eel sperm cryopreservation can be successfully applied in fertilization trials to produce viable offspring. In our experiment, the sperm motility was evaluated after the extraction and the best samples were selected and pooled. Until stripping of eggs and fertilization, diluted sperm samples were maintained at either 4 or 20°C, or cryopreserved, following existing protocols. Fertilization of two egg batches was attempted. Diluted sperm caused a similar percentage of fertilized eggs and a similar number of embryos and larvae, independently of storage temperature (4 or 20°C). The cryopreserved sperm resulted in a lower percentage of fertilized eggs, but embryos developed and a few larvae (‘cryolarvae’) were obtained 55 h after fertilization in one of the two egg batches. This result evidences that the tested cryopreservation protocol is applicable for eel reproduction management, although improvements will be required to enhance fertilization success.  相似文献   
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Objective To estimate the prevalence of infection with Trichomonas gallinae and other parasites of the alimentary tract in psittacine and columbid birds in Perth and to determine in vitro the effectiveness of drugs commonly recommended for treating trichomoniasis.
Design and procedures Samples of crop contents were collected from aviary flocks of budgerigars (Melopsittacus undulatus) and other psittacine and columbid birds in both private and commercial collections in Perth. Similar samples from wild Senegal doves (Streptopelia senegalensis) also were collected. Crop contents were examined and cultured for Trichomonas gallinae and in vitro studies were conducted on the susceptibility of isolates to several drugs used commonly. Other parasites also were detected by faecal examination and/or necropsy.
Results T gallinae was recovered from birds in 1 of 13 private collections of budgerigars (2/289 birds in total). Direct wetmount examination of crop fluid identified 36.4% of samples at four commercial bird dealers which were later determined by culture to contain T gallinae . The prevalence of T gallinae infection ranged from 0 to 11.4% in budgerigars. The prevalence of T gallinae infection in wild Senegal doves was 46% and from one flock of racing pigeons was 59%. The in vitro minimum lethal concentrations of metronidazole, dimetridazole and ronidazole ranged from 40 to 96, 30 to 80 and 40 to 92 μg/mL respectively for six isolates of T gallinae . Other alimentary parasites detected during the survey included Spironucleus sp (syn Hexamita sp), coccidia, Ascaridia platycerci and Raillietina sp.
Conclusions Thirteen budgerigar flocks belonging to members of avicultural societies in Perth had a low prevalence of trichomoniasis and other parasitic infections. The dose rate currently recommended for ronidazole may not result in complete protozoacidal activity against T gallinae infection.  相似文献   
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Summary Phytophthora root rot of alfalfa (Medicago sativa L.) is a serious problem in wet soils. This disease is caused by Phytophthora megasperma f. sp. medicaginis. The influence of soil-water interactions with P. megasperma f. sp. medicaginis and other factors on the severity of phytophthora root rot of mature alfalfa plants (10–12 weeks) was studied in greenhouse experiments. Severe and reproducible root rot was produced by subsurface (3–4 cm) placement of mycelial suspension. Soil saturation 3 days prior to inoculation followed by alternating 3-day wet (soil saturation) and 4-day dry (surface watering once a day) moisture regimes (for 30–40 days following inoculation) resulted in severe root damage.The severity of root rot was greater when the inoculation was done at an ambient temperature of 20°C than at 15°C. Water quality (tap water or deionized distilled water) had no effect on severity of infection. The isolates PT 78-3 (Minnesota) and TN-2 (Maryland) were equally effective in terms of severity of damage.The impact of excess soil water stress (described above) alone on the shoot and root dry weight as well as on shoot symptoms was similar to that of root rot stress. However, root symptoms showed a marked difference. A close examination of root symptoms is highly recommended to differentiate clearly the plant injury due to root rot from that due to excess soil water stress.  相似文献   
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Measurements of bone strain in the walking animal   总被引:1,自引:0,他引:1  
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