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   142篇
  免费   5篇
林业   6篇
  8篇
综合类   16篇
农作物   10篇
水产渔业   3篇
畜牧兽医   95篇
植物保护   9篇
  2022年   1篇
  2021年   5篇
  2020年   1篇
  2019年   4篇
  2018年   2篇
  2017年   3篇
  2015年   2篇
  2013年   2篇
  2012年   5篇
  2011年   6篇
  2010年   2篇
  2009年   1篇
  2008年   1篇
  2007年   2篇
  2006年   6篇
  2005年   3篇
  2004年   1篇
  2003年   1篇
  2002年   2篇
  2001年   2篇
  2000年   4篇
  1999年   7篇
  1995年   1篇
  1992年   3篇
  1991年   4篇
  1990年   1篇
  1989年   5篇
  1988年   4篇
  1987年   10篇
  1986年   9篇
  1985年   1篇
  1984年   5篇
  1983年   5篇
  1982年   2篇
  1979年   2篇
  1978年   4篇
  1977年   2篇
  1976年   2篇
  1975年   2篇
  1974年   4篇
  1973年   2篇
  1972年   1篇
  1971年   5篇
  1970年   4篇
  1968年   1篇
  1967年   1篇
  1964年   1篇
  1962年   1篇
  1950年   1篇
  1919年   1篇
排序方式: 共有147条查询结果,搜索用时 31 毫秒
1.
1. Brown egg layers were fed diets differing in oil content, oil source and linoleic acid concentration and the effect on performance from 22 to 69 weeks of age was studied.

2. The birds responded with an increasing mean egg weight up to a linoleic acid intake of 2.75 g/bird d.

3. Increasing the intake of readily absorbable oil without increasing linoleic acid concentration did not increase mean egg weight.  相似文献   

2.
3.
Eggs are important to the diet of Canadians. This product is one of the supply-managed commodities in Canada, but unlike other commodities, where food safety risks are extensively explored and reported, information on the prevalence of enteric organisms (e.g., Salmonella, Campylobacter) and antimicrobial resistance (AMR) in layers in Canada are limited. This study was conducted to determine the prevalence of select bacteria and the associated AMR patterns in layer flocks using 2 sample matrices. Farms were located within FoodNet Canada and the Canadian Integrated Program for Antimicrobial Resistance Surveillance sentinel sites (SS). Fecal samples (Ontario: ONSS1a, ONSS1b) and environmental sponge swabs (British Columbia: BCSS2a) were collected. Salmonella prevalence was 29% and 8% in ONSS1a and ONSS1b, respectively, and 7% in BCSS2a. S. Kentucky and S. Livingstone were the most frequently isolated serovars and no S. Enteritidis was detected. Campylobacter was not detected in the BC sponge swabs but was isolated from 89% and 53% of Ontario fecal samples (ONSS1a and ONSS1b, respectively). Seven C. jejuni from Ontario were ciprofloxacin-resistant. Escherichia coli prevalence was high in both sample types (98%). Overall, tetracycline resistance among E. coli ranged from 26% to 69%. Resistance to ceftiofur (n = 2 isolates) and gentamicin (n = 2) was relatively low. There were diverse resistance patterns (excludes susceptible isolates) observed among E. coli in Ontario (10 patterns) and British Columbia (14 patterns). This study revealed that fecal samples are more informative for farm-level monitoring of pathogen and AMR prevalence. Without further validation, sponge swabs are limited in their utility for Campylobacter detection and thus, for public health surveillance.  相似文献   
4.
Cattle ticks pose a significant threat to the health and profitability of cattle herds globally. The investigation of factors leading to natural tick resistance in cattle is directed toward targeted breeding strategies that may combat cattle tick infestation on the genetic level. Exosomes (EXs), small extracellular vesicles (EVs) of 50 to 150 nm diameter, are released from all cell types into biofluids such as blood plasma and milk, have been successfully used in diagnostic and prognostic studies in humans, and can provide essential information regarding the overall health state of animals. Mass spectrometry (MS) is a highly sensitive proteomics application that can be used to identify proteins in a complex mixture and is particularly useful for biomarker development. In this proof of principle study, EXs were isolated from the blood plasma of cattle (Bos taurus) with high (HTR) and low tick resistance (LTR) (n = 3/group). Cattle were classified as HTR or LTR using a tick scoring system, and EXs isolated from the cattle blood plasma using an established protocol. EXs were subjected to MS analysis in data-dependent acquisition mode and protein search performed using Protein Pilot against the B. taurus proteome. A total of 490 unique proteins were identified across all samples. Of these, proteins present in all replicates from each group were selected for further analysis (HTR = 121; LTR = 130). Gene ontology analysis was performed using PANTHER GO online software tool. Proteins unique to HTR and LTR cattle were divided by protein class, of which 50% were associated with immunity/defense in the HTR group, whereas this protein class was not detected in EXs from LTR cattle. Similarly, unique proteins in HTR cattle were associated with B-cell activation, immunoglobins, immune response, and cellular iron ion homeostasis. In LTR cattle, unique exosomal proteins were associated with actin filament binding, purine nucleotide binding, plasma membrane protein complex, and carbohydrate derivative binding. This is the first study to demonstrate that MS analysis of EXs derived from the blood plasma of HTR and LTR cattle can be successfully applied to profile the systemic effects of tick burden.  相似文献   
5.
6.
7.
Colostral immunity to colibacillosis in the neonatal calf   总被引:2,自引:0,他引:2  
  相似文献   
8.
AIM: To determine whether the generic composition of nematode parasites in lactating ewes varies between geographic regions in New Zealand and whether age and fecundity of ewes affect nematode egg output. METHODS: Four ram breeding properties in each of the northern (NNI) and southern (SNI) North Island and the northern South Island (NSI) regions, together with six properties in the southern South Island (SSI) were investigated. Faecal samples were obtained on one occasion, 2-6 weeks after lambing, from at least 60 ewes on each property, stratified according to age and reproductive status. Nematode eggs were counted and coprocultures prepared to identify genera present. Information on the history of anthelmintic use on each property was also collected. RESULTS: Highest faecal egg counts (FEC) were observed from ewes in the NNI and SSI regions. Lambed hoggets and twin-rearing two-tooth ewes had higher FEC than their unlambed or single-lamb-rearing contemporaries, respectively. However, no significant effect of reproductive effort on FEC was demonstrated in mixed-aged ewes. Significant regional differences in generic composition of nematode parasites were observed: Teladorsagia spp (also referred to as Ostertagia spp) eggs made up 56% of total eggs shed from sheep in the SSI compared with14% in the NNI, and values for Haemonchus spp were 1%and 24% for these same regions, respectively. Trichostrongylus colubriformis and T. vitrinus together made up 7, 15, 13 and15% of eggs counted from sheep in the SSI, NSI, SNI and NNI, respectively. CONCLUSIONS: More comprehensive epidemiological information may suggest regional-specific approaches to the management of nematode parasites in ewes should be devised in the future.  相似文献   
9.
10.
A pet cannot be healthy without oral health. Periodontal is a significant disease that has local and systemic ramifications. It has been stated earlier that effective plaque control prevents gingivitis. In human beings, 90% of periodontitis occurs as the result of progression gingivitis, and this type of periodontitis can be completely prevented by plaque control. It is reasonable that dogs and cats react similarly and that effective plaque control could prevent a large percentage of periodontitis cases. Proper nutrition and effective oral hygiene are necessary components of oral health and should be jointly promoted in the management of oral disease in dogs and cats.  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