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   115篇
  免费   33篇
林业   2篇
  14篇
综合类   10篇
水产渔业   5篇
畜牧兽医   109篇
植物保护   8篇
  2021年   2篇
  2020年   4篇
  2019年   1篇
  2018年   4篇
  2017年   5篇
  2016年   15篇
  2015年   11篇
  2014年   6篇
  2013年   9篇
  2012年   2篇
  2011年   4篇
  2010年   4篇
  2009年   4篇
  2008年   3篇
  2007年   1篇
  2006年   4篇
  2005年   1篇
  2003年   3篇
  2002年   1篇
  2000年   3篇
  1999年   3篇
  1998年   3篇
  1997年   1篇
  1993年   2篇
  1992年   5篇
  1991年   3篇
  1990年   3篇
  1989年   3篇
  1988年   2篇
  1987年   2篇
  1986年   3篇
  1985年   7篇
  1983年   2篇
  1982年   2篇
  1980年   2篇
  1977年   2篇
  1976年   4篇
  1974年   2篇
  1973年   1篇
  1972年   2篇
  1970年   3篇
  1967年   1篇
  1963年   1篇
  1903年   1篇
  1900年   1篇
排序方式: 共有148条查询结果,搜索用时 15 毫秒
1.

Objectives

To describe colostrum management practices carried out in northern Victorian dairy herds and to identify weaknesses in these areas that may affect calf health and welfare by comparing the results with the current industry recommendations

Methods

A questionnaire to obtain information about colostrum management and calf‐rearing practices was sent to commercial dairy farming clients of Rochester Veterinary Practice between June and September 2013. The questionnaire consisted of a general herd overview and colostrum harvesting practices.

Results

The response rate was 39% (58/150). Many dairy producers were not meeting the current industry recommendations in the following areas: (1) time of removal calf from the dam, (2) relying on calf suckling colostrum from the dam to achieve adequate passive transfer, (3) failing to supplement calves with colostrum, (4) feeding inadequate volumes of colostrum, (5) delayed colostrum harvesting, (6) pooling of colostrum, (7) failing to objectively assess colostrum quality or relying on visual assessment and (8) storing colostrum for a prolonged periods of time at ambient temperatures.

Conclusion

The results from this survey highlight the need for greater awareness of industry standards for colostrum management and feeding hygiene.
  相似文献   
2.
3.
DNA barcoding has been proposed as a method for species identification. However, this method has been criticised for its over-reliance on a single mitochondrial gene. In this study, four mitochondrial gene regions and one nuclear gene region were used to investigate their different abilities to identify tissue associated with museum specimens of Aethomys chrysophilus, Aethomys ineptus and Micaelamys namaquensis. Aethomys chrysophilus and the more recently elevated A. ineptus are indistinguishable on morphological grounds; however, their ranges are largely parapatric with only one syntopic locality currently known. All of the mitochondrial gene regions were able to separate M. namaquensis from A. chrysophilus and A. ineptus, but they varied in their abilities to resolve differences between A. chrysophilus and A. ineptus. The sequence results identified a specimen from KwaZulu-Natal that was misclassified and should have been identified as A. ineptus. Seven specimens that had not been reclassified following the elevation of A. ineptus to species level were identified as A. ineptus. Individuals of A. chrysophilus from Malawi could not be classified as either A. chrysophilus or A. ineptus, and may be a hybrid or a new, distinct species. This study indicates that DNA barcoding may be used to separate M. namaquensis from A. chrysophilus and A. ineptus, and although it was not able to separate A. chrysophilus and A. ineptus, it did indicate specimens from Malawi may be a new cryptic species.  相似文献   
4.
5.
The sedative and analgesic effects of medetomidine were evaluated in heartworm-infected (HW+) and uninfected (HW–) beagle dogs by intravenous (IV) and intramuscular (IM) administration of 30 µg/kg and 40 µg/kg doses, respectively. Posture, response to noise and the pedal reflex were monitored. A procedure for mock radiographic positioning was performed to evaluate its overall clinical use. Observation times were 0, 15, 30, 60, 90, 120 and 180 min. In addition, the times from injection until the dog could not stand on its feet (down time), from lateral to sternal recumbency (sternal recumbency time), and from sternal recumbency to rising again (rising time) were also noted.Medetomidine produced rapid sedation and analgesia by both routes. Down times for the IM and IV routes were similar, which verified the manufacturer's recommended doses. The HW+ dogs had shorter down times, probably owing to increased blood flow to the brain caused by adrenergic alpha-2 activity. Sternal recumbency and rising times did not differ between the groups, suggesting a similar metabolism. Sedation and analgesia were adequate for performing the procedure in all dogs. HW– dogs showed less resistance to handling during the procedure than HW+ dogs. Overall, medetomidine seems to be a suitable agent for short-term chemical restraint in dogs, even with subclinical heartworm infestation.  相似文献   
6.
Persistence of avian influenza viruses in water   总被引:9,自引:0,他引:9  
Persistence of five avian influenza viruses (AIVs) derived from four waterfowl species in Louisiana and representing five hemagglutinin and neuraminidase subtypes was determined in distilled water at 17 C and 28 C. Infectivity was determined over 60 days by microtiter endpoint titration. One AIV was tested over 91 days at 4 C. Linear regression models for these viruses predicted that an initial concentration of 1 x 10(6) TCID50/ml water could remain infective for up to 207 days at 17 C and up to 102 days at 28 C. Significant differences in slopes for AIV persistence models were detected between treatment temperatures and among viruses. Results suggest that these viruses are adapted to transmission on waterfowl wintering habitats. Results also suggest a potential risk associated with waterfowl and domestic poultry sharing a common water source.  相似文献   
7.
A commercial broth microdilution system for testing the antimicrobial susceptibility of gram-positive cocci was compared with the standardized disk agar-diffusion method by testing 254 clinical strains of staphylococci and streptococci using both methods. A total of 2,794 parallel determinations were made with 92.3% complete agreement between the 2 methods; of the discrepancies encountered, 3.0% were minor, 2.5% were major, and 2.1% were very major. The results indicate that the commercial microdilution system may provide a reliable quantitative method for antimicrobial susceptibility testing of clinical isolates from animals.  相似文献   
8.
The ring‐tailed coati (Nasua nasua) is a procyonid whose population is in sharp decline. Therefore, studies are needed to better understand the reproduction of this animal. For this reason, this study aimed to evaluate the morphology, morphometry and sperm ultrastructure of ring‐tailed coati sperm. Four captive adult males were used for this study. Slides stained with Bengal Rose were used for the morphometric and morphologic analyses. The length and width of the head were measured, as well as the length of the midpiece and tail and the total length of the sperm. Scanning electron microscopy and transmission electron microscopy were used for the ultrastructural analyses. The most obvious morphological abnormalities observed were coiled tails (6.1 ± 8.7%) and the lack of acrosomes (5.4 ± 4.4%). Regarding the morphometry, the measurements of the head (length × width), midpiece (length) and tail (length) were (mean ± SD) 6.2 ± 0.4 × 8.1 ± 0.6 μm, 14.1 ± 0.5 and 63.9 ± 4.1 μm, respectively, and the total length of the sperm was 86.1 ± 4.3 μm. Through electron microscopy, the presence of electron‐lucent points in the nucleus and the presence of approximately 55 mitochondrial spirals in the midpiece were identified. The data obtained in this study provide detailed information on the sperm characteristics of coatis and may inform future research on germplasm conservation, both for this species and other threatened procyonids.  相似文献   
9.
Pulmonary edema is the most common complication of left‐sided heart failure in dogs and early detection is important for effective clinical management. In people, pulmonary edema is commonly diagnosed based on transthoracic ultrasonography and detection of B line artifacts (vertical, narrow‐based, well‐defined hyperechoic rays arising from the pleural surface). The purpose of this study was to determine whether B line artifacts could also be useful diagnostic predictors for cardiogenic pulmonary edema in dogs. Thirty‐one normal dogs and nine dogs with cardiogenic pulmonary edema were prospectively recruited. For each dog, presence or absence of cardiogenic pulmonary edema was based on physical examination, heartworm testing, thoracic radiographs, and echocardiography. A single observer performed transthoracic ultrasonography in all dogs and recorded video clips and still images for each of four quadrants in each hemithorax. Distribution, sonographic characteristics, and number of B lines per thoracic quadrant were determined and compared between groups. B lines were detected in 31% of normal dogs (mean 0.9 ± 0.3 SD per dog) and 100% of dogs with cardiogenic pulmonary edema (mean 6.2 ± 3.8 SD per dog). Artifacts were more numerous and widely distributed in dogs with congestive heart failure (P < 0.0001). In severe cases, B lines increased in number and became confluent. The locations of B line artifacts appeared consistent with locations of edema on radiographs. Findings from the current study supported the use of thoracic ultrasonography and detection of B lines as techniques for diagnosing cardiogenic pulmonary edema in dogs.  相似文献   
10.
The effect of footrot on body weight and wool growth of sheep   总被引:1,自引:0,他引:1  
Body weight and traits associated with production of wool were measured over a 2-year period between 1985 and 1987 in south-western New South Wales in a flock of Merino wethers experimentally infected with footrot. The disease was allowed to spread freely amongst 150 of the flock but kept at very low prevalence in the remaining 50 by preventive footbathing during transmission periods. Severe, underrunning footrot had a significant adverse effect on body weight, for each year of the trial. Body weight was most severely reduced at times of the year when footrot was spreading among animals and lesions were severe. The mean body weight of the infected group at the end of the 2 years of observation was 7.3 kg (11.6%) below that of the control group. Footrot also depressed wool growth, with the mean clean fleece weight of the infected group being 0.4 kg (8%) lighter than that of the controls at each of the 2 annual shearings. There were no consistent differences between the groups for the other wool characteristics measured.  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