首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   44篇
  免费   1篇
基础科学   11篇
综合类   4篇
水产渔业   1篇
畜牧兽医   27篇
植物保护   2篇
  2020年   1篇
  2018年   1篇
  2016年   1篇
  2013年   1篇
  2008年   1篇
  2007年   1篇
  2005年   7篇
  2004年   2篇
  2003年   1篇
  2001年   4篇
  2000年   5篇
  1999年   4篇
  1998年   2篇
  1996年   4篇
  1990年   3篇
  1989年   1篇
  1984年   3篇
  1982年   1篇
  1980年   1篇
  1977年   1篇
排序方式: 共有45条查询结果,搜索用时 31 毫秒
1.
2.
Pneumonia caused by Pasteurella (Mannheimia) haemolytica was induced in weaned beef heifer calves, approximately 6 months of age. Calves were treated at 20 h after challenge with therapeutic doses of danofloxacin or tilmicosin. Peripheral blood neutrophils were collected at 3, 24 and 48 h after treatment. The ex vivo effects on neutrophil function, neutrophil apoptosis, and hematological parameters were examined, as was the effect on percentage lung consolidation. Neutrophil function assays included random migration under agarose, cytochrome C reduction, iodination, Staphylococcus aureus ingestion, chemotaxis, and antibody-dependent and antibody-independent cell-mediated cytotoxicity. Apoptosis was determined using a cell death detection kit. Killing was performed at 72 h after treatment. Statistical comparisons were made among the three groups of challenged-treated animals: saline, danofloxacin, and tilmicosin. Comparisons were also made between nonchallenged nontreated animals (NCH) and challenged saline-treated animals. There were no significant differences for any of the neutrophil function assays or neutrophil apoptosis among the challenged-treated groups. This suggests that danofloxacin and tilmicosin have no clinically significant effects on neutrophil function or apoptosis. There were also no significant differences in percentage lung consolidation among the challenged-treated groups. Significant differences were found between the NCH calves and the challenged saline-treated calves in several neutrophil assays, which were attributed to effects of P. haemolytica infection.  相似文献   
3.
A single dose of 5 x 10(8) bacilli of Pseudomonas pseudomallei by intratracheal injection resulted in acute (21 cases) or chronic (19 cases) melioidosis in 40 of 48 pigs. Fifteen (10 acute and 5 chronic) had been immunosuppressed by cyclophosphamide before inoculation. The major clinical signs were initial fever, marked neutrophilia and, in the acute cases, respiratory distress. There were no signs of the nasal and ocular discharge, paresis or diarrhoea seen in acute cases in south-east Asia. The cyclophosphamide treatment caused a significant decrease in the neutrophil count by 7 d after inoculation in all 15 immunosuppressed pigs, and all were culture positive at necropsy. Eight of the 33 non-treated pigs were culture negative at necropsy. Pigs overcoming the initial phase of infection had more abscess-like nodules that were bacteriologically sterile at necropsy than the pigs with acute cases of melioidosis. P. pseudomallei was isolated predominantly from the spleen, lungs and the injection site. Although only one strain was used in this study, it is likely that Australian strains of P. pseudomallei are not as virulent as the south-east Asian isolates.  相似文献   
4.
The therapeutic efficacy and field safety of tulathromycin were evaluated in stocker calves with undifferentiated bovine respiratory disease (BRD) in three field studies conducted over two consecutive grazing seasons in Nebraska. Eight hundred calves exhibiting clinical signs of BRD and with rectal temperatures of 104 degrees F or higher were treated with tulathromycin (n = 340), florfenicol (n = 240), or tilmicosin (n = 220) and evaluated for approximately 60 days. Florfenicol and tilmicosin were administered as single SC injections according to labeled dosage. Tulathromycin was administered as a single SC injection of 2.5 mg/kg. In all three studies, the cure rate of calves 60 days after treatment with tulathromycin was significantly higher (P < or = .05) than that of calves treated with florfenicol or tilmicosin. Suspected adverse reactions were not reported for any of the study drugs. Tulathromycin proved to be significantly more effective than either florfenicol or tilmicosin in the treatment of BRD in stocker calves.  相似文献   
5.
OBJECTIVE: To compare concentrations of danofloxacin, enrofloxacin, and ciprofloxacin in plasma and respiratory tissues of calves treated after challenge with Mannheimia haemolytica. ANIMALS: 75 calves. PROCEDURE: 24 hours after challenge with M. haemolytica, 72 calves with clinical signs of respiratory tract disease were randomly assigned to 1 of 12 equal treatment groups.Three nonchallenged, nontreated calves formed a control group. Challenged calves were treated with danofloxacin (6 and 8 mg/kg, SC) and enrofloxacin (8 mg/kg, SC) once. At 1, 2, 6, and 12 hours after treatment, 6 calves from each treatment group were euthanatized. Antimicrobial drug concentrations were assayed in various specimens. Peak plasma concentration (Cmax)-to-minimum inhibitory concentration (MIC; Cmax-to-MIC) ratios and the area under the concentration versus time curve over a 12-hour period-to-MIC ratios (AUC(12h)-to-MIC) were calculat-ed. RESULTS: Danofloxacin and enrofloxacin had MICs of 0.03 microg/mL for the M. haemolytica challenge isolate. Danofloxacin administered at doses of 6 and 8 mg/kg resulted in numerically higher geometric mean concentrations of danofloxacin in plasma and all respiratory tissues than geometric mean concentrations of enrofloxacin after treatment with enrofloxacin. Geometric mean concentrations of enrofloxacin were numerically higher than geometric mean concentrations of ciprofloxacin metabolite in plasma and almost all respiratory tissues. Danofloxacin and enrofloxacin achieved Cmax-to-MIC ratios >10 and AUC(12h)-to-MIC ratios >125 hours. CONCLUSIONS AND CLINICAL RELEVANCE: When used to treat pneumonic pasteurellosis in calves, danofloxacin and enrofloxacin can be expected to deliver concentration-dependent bactericidal activity against M. haemolytica, the bacteria most commonly associated with bovine respiratory tract disease.  相似文献   
6.
7.
Effects of small population size and reduced genetic variation on the viability of wild animal populations remain controversial. During a 35-year study of a remnant population of greater prairie chickens, population size decreased from 2000 individuals in 1962 to fewer than 50 by 1994. Concurrently, both fitness, as measured by fertility and hatching rates of eggs, and genetic diversity declined significantly. Conservation measures initiated in 1992 with translocations of birds from large, genetically diverse populations restored egg viability. Thus, sufficient genetic resources appear to be critical for maintaining populations of greater prairie chickens.  相似文献   
8.
Two studies were conducted in North America to evaluate the persistent activity of doramectin injectable formulation against experimental challenge with Haemonchus placei. In both studies, calves were randomly assigned to 1 of 4 treatment groups (n = 10 per group) or a larval viability group (n = 2). Calves were treated subcutaneously in the lateral midline of the neck with saline (1 ml/50 kg) on Day 0, or with doramectin (200 mg/kg = 1 ml/50 kg) on Day 0, 7, or 14. Animals used to assess larval viability did not receive any treatment. Beginning on Day 14 and continuing through Day 28, each of the 40 treated calves were given approximately 300 infective larvae of H. placei per os. The two larval viability animals received approximately 10,000 larvae as a single dose on Day 28. Approximately two weeks later, all animals were slaughtered and the abomasum from each calf processed for nematode recovery. A 2% aliquot of abomasal contents plus wash was examined for enumeration and identification of nematodes. Geometric mean H. placei counts were calculated from the log (H. placei count +1) and used to estimate percentage reduction. Overall, doramectin was > or =96.9% efficacious in reducing infection with H. placei when challenged daily 14-28 days after treatment.  相似文献   
9.
A study of the aquatic fate of the triethylamine salt of triclopyr (3,5,6‐trichloro‐2‐pyridinyloxyacetic acid) was conducted in three bays of Lake Minnetonka, Minnesota. Triclopyr is under review by the US Environmental Protection Agency as a selective aquatic herbicide. The primary purpose of this study was to determine dissipation rates of the parent active ingredient, triclopyr, and its major metabolites, 3,5,6‐trichloropyridinol (TCP) and 3,5,6‐trichloro‐2‐methoxypyridine (TMP) in selected matrices including water, sediment, plants, finfish and shellfish. Two 6.5‐ha plots dominated by the weedy species Eurasian watermilfoil (Myriophyllum spicatum L) were treated with triclopyr‐triethylammonum at a rate of 2.5 mg AE liter−1 (2.5 ppm) on 21–23 June 1994. A third 6.5‐ha plot was established as an untreated reference. Water and sediment samples were collected from within the plots and at selected locations up to 1600 m outside of the plots through six weeks post‐treatment for chemical residue analysis. In addition, residue samples were collected from the target and non‐target plants and other non‐target matrices, including game and rough fish, clams and crayfish. All test animals were sequestered in cages located in the center of each plot and samples were collected through four weeks post‐treatment. Half‐lives for dissipation of triclopyr and TCP in water ranged from 3.7 to 4.7 days and from 4.2 to 7.9 days, respectively, with trace amounts of TMP found. Peak triclopyr sediment values ranged from 257 to 335 ng gram−1, with a mean half‐life of 5.4 days, while peak TCP sediment levels ranged from 27 to 65 ng gram−1 (mean half−life = 11.0 days). Trace levels of TMP were detected at one treatment site at one sampling event. Triclopyr and TCP accumulated and cleared from animal tissues proportionately to concentrations in the water (triclopyr dissipation half‐lives <11 days, TCP < 14 days). TMP levels were two to three times higher than those of the other compounds, particularly in visceral tissue. In all cases, residues of these compounds were higher in the inedible portions of the animals, and were usually higher in bottom‐feeding fish species. © 2000 Society of Chemical Industry  相似文献   
10.
The objectives of this study were to determine effects of cyfluthrin and pyrethrin spray products, used in combination with cyfluthrin topical and ear tag applications, on bull reproductive parameters over 18 weeks. Angus or Angus x Simmental bulls were randomly assigned to one of three treatment groups: (i) no exposure to pyrethrins/cyfluthrin (CONT; n = 10), (ii) cyfluthrin ear tag and topical applications (ET; n = 10), or (iii) cyfluthrin ear tag, topical, premise spray and pyrethrin fog spray applications (ET+S; n = 8). Bull body weight was measured every 3 week, and body condition score and scrotal circumference were recorded on weeks 0, 9 and 18. Semen and serum were collected every 3 weeks for sperm evaluation and testosterone measurement, respectively. There was a treatment × week interaction (p < 0.01) for sperm with primary defects; bulls in CONT group had a greater (p = 0.01) percentage of sperm with primary defects than bulls treated with insecticides at week 18. Overall and progressive sperm motility, normal sperm morphology, secondary sperm defects and serum testosterone concentrations changed (p < 0.01) over time in all bulls; however, treatment did not affect (p ≥ 0.13) any of these parameters. There were also no treatment effects (p ≥ 0.08) on bull body weight, body condition score or scrotal circumference. The use of pyrethrin‐ and cyfluthrin‐based insecticides, regardless of application, did not negatively affect reproductive parameters in beef bulls when administered over 18 weeks.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号