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   228篇
  免费   20篇
  国内免费   1篇
林业   1篇
综合类   10篇
畜牧兽医   235篇
植物保护   3篇
  2020年   3篇
  2019年   3篇
  2018年   5篇
  2017年   3篇
  2016年   8篇
  2015年   6篇
  2014年   7篇
  2013年   18篇
  2012年   1篇
  2011年   1篇
  2010年   8篇
  2009年   6篇
  2008年   3篇
  2006年   3篇
  2005年   3篇
  2004年   3篇
  2003年   4篇
  2002年   5篇
  2001年   9篇
  2000年   6篇
  1999年   3篇
  1998年   13篇
  1997年   18篇
  1996年   9篇
  1995年   11篇
  1994年   7篇
  1993年   12篇
  1992年   12篇
  1991年   19篇
  1990年   14篇
  1989年   15篇
  1988年   11篇
排序方式: 共有249条查询结果,搜索用时 515 毫秒
131.
132.
Extract

Madam:- I appreciate the opportunity to comment on Mr Wallace's letter concerning the possible risks of disastrous results consequent upon too early withdrawal of vaccination with Brucella abortus Strain 19. He is certainly not alone in expressing this concern.  相似文献   
133.
The cat flea, Ctenocephalides felis, is the recognised vector of Bartonella henselae, B. clarridgeiae and Rickettsia felis. Although these Gram-negative bacteria were only described in the last decade, they are already known to cause a variety of diseases in people, particularly children and the immunosuppressed. Such diseases include cat-scratch disease, bacillary angiomato- sis, endocarditis, bacteraemia, encephalopathy, neuroretinitis, osteomyelitis and peliosis hepatis. Although most infections in cats and dogs appear to be subclinical, recent studies have provided growing evidence that the bartonellas can also cause serious problems in pets, including hepatitis, endocarditis, central nervous system (CNS) signs, lymphadenopathy, uveitis, cataracts and reproductive failure. In 2004, DNA of B. henselae, B. clarridgeiae and R. felis was demonstrated in cat fleas from New Zealand and pets and their owners in the country are thus at risk of infection. While flea control programmes have traditionally been advocated by veterinarians to prevent pruritis and tapeworms in pets, they should now also be recommended to prevent infections with the new flea-borne bacterial pathogens. To raise awareness of the organisms amongst veterinarians and animal health workers, this review describes: the biology of the organisms; clinical and laboratory features of infections in cats, dogs and people; diagnosis; and possible treatments and control of infections with these organisms.  相似文献   
134.
ABSTRACT

Aims: To examine the relationship between liveweight (LWT) at 12 months as a proportion of LWT at 21 months of age (LWT(12/21)%) and first lactation and cumulative 3-year milk production in dairy heifers in New Zealand.

Methods: Liveweight and milk production records were obtained for dairy heifers born from June to December (spring-calving season) between 2006–2007 and 2013–2014 dairy seasons; production records included first lactation (n?=?140,113) and cumulative 3-year (n?=?67,833) milksolids and energy-corrected milk (ECM) yields. Heifers were classified into five breed groups; Holstein-Friesian, Holstein-Friesian crossbred, Jersey, Jersey crossbred and Holstein-Friesian-Jersey crossbred. Within each breed group heifers were categorised into quintiles based on 21-month LWT. The LWT(12/21)% was calculated for each animal. Relationships between LWT(12/21)% and milk production within each breed group and LWT category were estimated using linear mixed effects models including the linear and quadratic effects of LWT(12/21)%.

Results: The relationship between LWT(12/21)% and milk production was predominantly curvilinear, with lower milk production at lesser LWT(12/21)% compared with greater LWT(12/21)%. For all breed groups and most LWT categories, heifers that were 55 or 65% LWT(12/21)% produced greater ECM and milksolids yields compared with heifers that were 45% LWT(12/21)%. Holstein-Friesian, Holstein-Friesian crossbred and Holstein-Friesian-Jersey crossbred heifers that were 65% LWT(12/21)% produced greater cumulative 3-year ECM and milksolids yields compared with heifers of the same breed group that were 45% LWT(12/21)%

Conclusions and clinical relevance: Heifers that were a greater proportion of their 21-month LWT at 12 months of age produced more first lactation and cumulative 3-year milk yields than heifers that were a lesser proportion of their 21-month LWT at 12 months of age. These results indicate that increased growth in early life of New Zealand dairy heifers is beneficial to future milk production.  相似文献   
135.
136.
Long-term survival and infectivity of Salmonella choleraesuis   总被引:1,自引:0,他引:1  
It is believed that Salmonella Choleraesuis, the host-adapted serotype of swine, does not survive well outside the host. We examined the survival capability as well as the presence of latent DNA of S. Choleraesuis in swine feces. Pigs were infected with S. Choleraesuis and feces was collected and pooled on days 2, 4, 7, and 10 post inoculation (PI). Feces was stored in a wet and a dry form and survival was measured over 13 months. Salmonella Choleraesuis was recovered from wet feces through 3 months of storage. In a desiccated (dry) form, S. Choleraesuis was recovered from at least 13 months. Direct PCR analysis did not detect S. Choleraesuis subsequent to the final culture recovery for any stored sample. We also examined the infectivity of S. Choleraesuis resident in dry feces. Six or 13 week old pigs were inoculated with dry feces that had been stored either 2 months or 4 months, respectively. Pigs were inoculated either intranasally or by mixing dry feces with the swine ration. Although clinical signs were mild, S. Choleraesuis was widely disseminated among the tissues of all the pigs inoculated. This study demonstrates that S. Choleraesuis remains viable and infective in the environment. Therefore, contaminated fecal matter can serve as a reservoir for S. Choleraesuis as well as other Salmonella spp. Control measures must consider this environmental reservoir as a source of new infections.  相似文献   
137.
138.
Oxyglobin (OXY) is a hemoglobin‐based oxygen carrier (HBOC) made of glutaraldehyde‐polymerized bovine hemoglobin (bHb). Products similar to OXY are under development for use as temporary blood substitutes in trauma, shock and anemia. Since they all may increase blood O2‐carrying capacity and thus, possibly tissue oxygenation, they may also be used to enhance performance of both equine and human athletes. That is why HBOCs are banned from use in athletic competition. Our goal was to determine the pharmacokinetics of OXY after intravenous (IV) infusion to horses. Blood and urine samples were collected from adult horses that received an IV dose of 32.5 g of OXY. Concentrations of OXY in plasma and urine were quantified using a newly developed LC/Q‐TOF‐MS/MS detection technique. Level of quantification (LOQ) was 50 μg mL–1. The decline of the plasma concentration‐time curve of the HBOC was described by a 2‐compartment model (C1 and C2). The median distribution alpha (t1/2k1,0) and elimination beta (t1/2k2,0) half‐lives were 1.3 and 12.0 hours, respectively. The bHb molecules in OXY are not of uniform size and vary substantially in molecular weight (MW). Of the OXY molecules 53% were eliminated in C1, which represented the smaller MW molecules and 47% in C2, which represented the larger MW bHb. The maximal 0‐time plasma concentration was 662.0 μg/mL and declined to 97.1 μg mL–1 at 24 h. The area below the plasma concentration‐time curve was 5143 μg h–1 mL–1. The volumes of C1 and C2 were 86.9 and 63.9 mL kg–1, respectively. Oxyglobin was not detected in urine. This study shows the detection and quantification in equine plasma of a HBOC following IV infusion and demonstrates the short half‐life of about 50% of infused bHb molecules.  相似文献   
139.
In 1996, data on management practices used on US dairy operations were collected and analyzed for association with fecal shedding of Salmonella by dairy cows. A total of 4299 fecal samples from 91 herds was cultured for Salmonella isolation. Herd-size (adjusted odds ratios (OR) = 5.8, 95% CI 1.1, 31.3), region (OR = 5.7, CI 1.4, 23.5), use of flush water systems (OR = 3.5, CI 0.9, 14.7), and feeding brewers' products to lactating cows (OR = 3.4, CI 0.9, 12.9) were identified as the most important predictive risk factors. The population attributable risks (PARs) for herd-size, region, flush water system, and feeding brewers' products to lactating cows were 0.76, 0.46, 0.37, and 0.42, respectively. The estimated PAR for all four risk factors combined was 0.95. The effects of these factors need to be more-closely evaluated in more-controlled studies, in order to develop intervention programs that reduce Salmonella shedding.  相似文献   
140.
Porcine reproductive and respiratory syndrome virus (PRRSV) and Salmonella choleraesuis are two leading causes of economic loss in the swine industry. While respiratory disease is common in both S. choleraesuis and PRRSV infections, the factors that contribute to its development remain largely undefined. We investigated the interaction of PRRSV, S. choleraesuis, and stress in 5-week-old swine. All combinations of three factors (inoculation with S. choleraesuis on Day 0, PRRSV on Day 3, and treatment with dexamethasone on Days 3-7) were used to produce eight treatment groups in two independent trials. Fecal samples, tonsil and nasal swabs, serum samples and postmortem tissues were collected for bacteriologic and virologic examinations. No clinical signs were observed in pigs inoculated with only PRRSV or only S. choleraesuis. In contrast, pigs which were dually infected with S. choleraesuis and PRRSV exhibited unthriftiness, rough hair coats, dyspnea, and diarrhea. The pigs which received all three treatment factors were the most severely affected and 43% (three of seven) of the animals in this group died. Individuals in this group shed significantly higher quantities of S. choleraesuis in feces and had significantly higher serum PRRSV titers compared to other treatments (p < or = 0.05). In addition, S. choleraesuis and PRRSV were shed longer and by more pigs in this group than other groups and S. choleraesuis was recovered from more tissues in this group on Day 21 post inoculation. These results suggested that PRRSV, S. choleraesuis, and dexamethasone acted synergistically to produce a syndrome similar to that observed in the field.  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