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   52篇
  免费   6篇
  1篇
综合类   8篇
农作物   1篇
畜牧兽医   48篇
  2020年   1篇
  2018年   1篇
  2017年   2篇
  2016年   2篇
  2015年   2篇
  2014年   1篇
  2013年   5篇
  2012年   2篇
  2011年   1篇
  2009年   5篇
  2008年   3篇
  2007年   2篇
  2006年   1篇
  2005年   5篇
  2004年   1篇
  2003年   2篇
  2001年   3篇
  2000年   4篇
  1999年   3篇
  1998年   3篇
  1997年   2篇
  1996年   3篇
  1995年   1篇
  1991年   2篇
  1990年   1篇
排序方式: 共有58条查询结果,搜索用时 156 毫秒
1.
2.
Medical records from 111 threatened bald eagles (86%, Haliaeetus leucocephalus) and peregrine falcons (14%, Falco peregrinus) admitted to the Wildlife Center of Virginia from 1993 to 2003 were reviewed to identify submitters, causes of morbidity and mortality, and final disposition. Half of all patients admitted were submitted by the Virginia Department of Game and Inland Fisheries personnel. Trauma was the most common reason for presentation in bald eagles (70%) and peregrine falcons (81%). Additional causes of morbidity and mortality in bald eagles included toxicoses (10%), infectious diseases (8%), and orphaned young (1%). Neoplasia was confirmed in two trauma cases, suggesting underlying disease might have increased susceptibility to acute traumatic injuries. Peregrine falcons were also admitted for infectious disease (19%). The most frequent infectious disease for both species was West Nile virus. Thirty-nine percent of patients were released back into the wild, 28% were euthanized, 20% died, and 13% were placed in captivity. Postrelease monitoring that would determine whether rehabilitated animals survived to contribute to threatened populations was not performed in this study.  相似文献   
3.
An absorbed enzyme immunoassay (EIA) test for Johne's disease in cattle was developed in which absorption of cross-reacting antibodies occurred as a rapid reaction in solution rather than overnight with whole organisms and a subsequent centrifugation step. Total test time was reduced to less than 2 h with a minimum of manipulations. The test was evaluated in cattle herds from Johne's disease-endemic and Johne's disease-free regions of Australia. Specificity was 99.8%. Calculations of sensitivity were affected by the history of the herd under test. However, the EIA detected in excess of 80% of animals before onset of clinical disease and 65% of faecal shedders were EIA positive on, or before, first detection of Mycobacterium paratuberculosis in their faeces. The test should aid epidemiological studies and be a useful tool in the management and control of Johne's disease.  相似文献   
4.
Measurements of electrical conductivity at high pressure and temperature were taken on the lower mantle phase magnesiowustite with varying Fe3+ content. Although previous measurements at atmospheric pressure suggest Fe2+-Fe3+ hopping (small polaron) as the dominant conductivity mechanism, the present experiments show a change in charge transport mechanism with temperature. The lower temperature measurements are consistent with small polaron conduction, but at higher temperatures, which are more applicable to the lower mantle, a large polaron mechanism is suggested. Because these mechanisms have different temperature and compositional dependencies, this transition has important implications for extrapolation to mantle conditions.  相似文献   
5.
Pulsed laser deposition (PLD) is a conceptually and experimentally simple yet highly versatile tool for thin-film and multilayer research. Its advantages for the film growth of oxides and other chemically complex materials include stoichiometric transfer, growth from an energetic beam, reactive deposition, and inherent simplicity for the growth of multilayered structures. With the use of PLD, artificially layered materials and metastable phases have been created and their properties varied by control of the layer thicknesses. In situ monitoring techniques have provided information about the role of energetic species in the formation of ultrahard phases and in the doping of semiconductors. Cluster-assembled nanocrystalline and composite films offer opportunities to control and produce new combinations of properties with PLD.  相似文献   
6.
With the use of a crossover study design, we investigated the respiratory and cardiovascular effects of naloxone administration in eight healthy Rocky Mountain wapiti (Cervus elaphus nelsoni) anesthetized with carfentanil (10 microg/kg i.m.) and xylazine (0.1 mg/kg). Anesthetized animals showed profound hypoxemia with mild hypercapnia, tachycardia, hypertension, and acidosis prior to naloxone administration. After monitoring equipment was placed, animals were administered either naloxone (2 microg/microg carfentanil i.v.) or an equivalent volume of normal saline. Mean values for PaO2, PaCO2, heart rate, and respiratory rate were significantly different between naloxone- and saline-treated groups, but mean blood pressure, hematocrit, and serum electrolyte concentrations were not. Mean PaO2 was 23.0 +/- 4.1 mm Hg prior to administration of naloxone or saline and increased to 50.2 +/- 7.3 mm Hg after naloxone administration. Mean PaO2 of saline-treated animals did not change significantly. Electrocardiograms of three saline-treated animals suggested myocardial hypoxia. Hypoxemia appeared to be caused by respiratory depression, hemodynamic alterations, and lateral recumbency. All but one animal remained anesthetized after naloxone administration. Anesthesia in all animals was reversed in < or = 4 min with naltrexone (100 mg/mg carfentanil i.v. s.c.) and yohimbine (0.1 mg/kg i.v.). One bolus of naloxone improved oxygenation in carfentanil-xylazine-anesthetized wapiti.  相似文献   
7.
8.
AIMS: To assess the sensitivity and specificity of a bulk tank milk (BTM) antibody enzyme-linked immunosorbent assay (ELISA) to detect likely infection of a dairy herd with bovine vi- ral diarrhoea virus (BVDV). The ELISA was subsequently used to estimate the prevalence of likely infected herds in parts of the North Island of New Zealand.

METHODS: BTM samples from 724 randomly selected dairy herds in the Waikato, Bay of Plenty and Northland regions of New Zealand were tested for BVDV antibodies. From this group, 20 herds were again randomly selected from each of the quartiles of the ELISA percentage inhibition (%INH) result. From each participant herd, serum from 15 randomly selected calves aged 6–18 months and 15 cows was collected and tested using an indirect blocking ELISA for BVDV antibodies.

RESULTS: Among serum results from calves from 50 herds available for analysis, 34 (68%) herds were classified as likely non-infected (0-3 seropositive among 15 calves) and 16 (32%) as likely infected (5–15 seropositive among 15 calves). Receiver- operator characteristic (ROC) analysis identified an optimal cut-off for BTM of 80%INH associated with 81% sensitivity and 91% specificity for likely herd infection. The prevalence of BVDV antibodies in cows within herds and %INH for BVDV in bulk milk were positively correlated (p<0.01). The association between bulk milk %INH and the prevalence of BVDV antibodies in calves was stronger than the same association in cows. Based on the threshold of 80%INH, the 95% confidence interval (CI) for prevalence of likely infection in the 724 herds in the Waikato, Bay of Plenty and Northland regions of New Zealand was 12–17%. Vaccination against BVDV was not significantly associated with the likely infection status of the herd based on prevalence of BVDV antibodies among calves.

CONCLUSION: An ELISA test result for BVDV antibodies in BTM ≥80%INH can be used as a threshold to indicate the presence of likely infection with BVDV in dairy herds in New Zealand, with 81% sensitivity and 91% specificity.  相似文献   
9.
Because of the importance of reproduction in stock breeding systems, it is necessary to find selection criteria that increase reproductive efficiency. The aim of this study was to estimate genetic parameters for the probability of conception on first service (PROB) in Murrah heifers, and its association with other traits of economic interest [age at first calving (AFC), service period, calving interval and milk yield at 270 days], with the purpose of evaluating their use as selection criteria. Reproductive information and first lactation records of 1200 Murrah heifers were used to perform two‐trait analyses between PROB and the other characteristics. Bayesian inference was used to estimate the variance components, considering PROB as threshold and the other as linear factors. The results demonstrate that this trait has heritability of 0.15, indicating the possibility of a genetic gain by using it for selection. With respect to the genetic correlation estimates, the only high‐magnitude association was with AFC (?0.899), which is the current criterion indicating sexual precocity of females. In the light of the parameters estimated, the first‐service pregnancy rate is an alternative for indication of sexual precocity, although presenting a smaller genetic gain than the current standard AFC. Nevertheless, additional research should be conducted regarding this trait to assess the economic importance of its use in dairy buffalo production systems.  相似文献   
10.
The Eurasian badger (Meles meles) is a wildlife reservoir for Mycobacterium bovis infection in Ireland and Great Britain and has been implicated in the transmission of tuberculosis to cattle. Vaccination of badgers is an option that could be used as part of a strategy to control the disease. In this study we used an endobronchial infection procedure to inoculate groups of badgers with three different doses (3x10(3), 2x10(2) and <10 Colony Forming Units (CFUs)) of M. bovis. After 17 weeks the disease status of each animal was determined by post-mortem pathology and culture for M. bovis. Each of the inoculum doses resulted in establishment of infection in the badgers. The cell-mediated immune (CMI) responses were measured by lymphocyte transformation assay (LTA) of peripheral blood mononuclear cells (PBMCs) cultured with bovine tuberculin (PPD-B). In each infected group the CMI responses increased with a kinetic profile corresponding to the delivered dose and the post-mortem pathology. The serological responses were measured by ELISA and a multi-antigen print immunoassay (MAPIA) in order to investigate any changes in the antigenic repertoire associated with different infective doses. In contrast to the CMI responses, the ELISA and MAPIA showed that the recognition of antigens by the badgers was intermittent and not strongly influenced by the dose of M. bovis.  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