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   14篇
林业   2篇
农学   1篇
  3篇
综合类   12篇
水产渔业   2篇
畜牧兽医   133篇
植物保护   3篇
  2019年   1篇
  2018年   5篇
  2017年   1篇
  2016年   1篇
  2014年   1篇
  2013年   6篇
  2012年   2篇
  2011年   4篇
  2010年   7篇
  2009年   3篇
  2008年   6篇
  2007年   6篇
  2006年   9篇
  2005年   1篇
  2004年   7篇
  2003年   6篇
  2002年   8篇
  2001年   9篇
  2000年   6篇
  1999年   2篇
  1998年   1篇
  1997年   2篇
  1996年   4篇
  1995年   2篇
  1994年   3篇
  1993年   4篇
  1992年   3篇
  1991年   5篇
  1990年   1篇
  1989年   4篇
  1988年   4篇
  1987年   2篇
  1986年   4篇
  1985年   4篇
  1984年   3篇
  1983年   2篇
  1981年   1篇
  1980年   1篇
  1979年   5篇
  1978年   1篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1972年   2篇
  1970年   1篇
  1949年   1篇
  1942年   1篇
  1941年   1篇
排序方式: 共有156条查询结果,搜索用时 31 毫秒
1.
To determine the effect of swine hepatitis E virus (HEV) infection on pregnant gilts, their fetuses, and offspring, 12 gilts were intravenously inoculated with swine HEV. Six gilts, who were not inoculated, served as controls. All inoculated gilts became actively infected and shed HEV in feces, but vertical transmission was not detected in the fetuses. There was no evidence of clinical disease in the gilts or their offspring. Mild multifocal lymphohistiocytic hepatitis was observed in 4 of 12 inoculated gilts. There was no significant effect of swine HEV on fetal size, fetal viability, or offspring birth weight or weight gain. The offspring acquired anti-HEV colostral antibodies but remained seronegative after the antibodies waned by 71 days of age. Swine HEV infection induced subclinical hepatitis in pregnant gilts, but had no effect on the gilts' reproductive performance, or the fetuses or offspring. Fulminant hepatitis associated with HEV infection was not reproduced in gilts.  相似文献   
2.
3.
4.
Effects of adding different concentrations of melatonin (10?7, 10?9 and 10?11 M) to maturation (Experiment 1; Control, IVM  + 10?7, IVM  + 10?9, IVM  + 10?11) and culture media (Experiment 2; Control, IVC  + 10?7, IVC  + 10?9, IVC  + 10?11) were evaluated on in vitro bovine embryonic development. The optimal concentration of melatonin (10?9 M) from Experiments 1–2 was tested in both maturation and/or culture media of Experiment 3 (Control, IVM  + 10?9, IVC  + 10?9, IVM /IVC  + 10?9). In Experiment 1, maturated oocytes from Control and IVM  + 10?9 treatments showed increased glutathione content, mitochondrial membrane potential and percentage of Grade I blastocysts (40.6% and 43%, respectively). In Experiment 2, an increase in the percentage of Grade I blastocysts was detected in IVC  + 10?7 (43.5%; 56.7%) and IVC  + 10?9 (47.4%; 57.4%). Moreover, a lower number and percentage of apoptotic cells in blastocysts were observed in the IVC  + 10?9 group compared to Control (3.8 ± 0.6; 3.6% versus 6.1 ± 0.6; 5.3%). In Experiment 3, the IVC  + 10?9 treatment increased percentage of Grade I blastocysts with a lower number of apoptotic cells compared to IVM /IVC  + 10?9 group (52.6%; 3.0 ± 0.5 versus 46.0%; 5.4 ± 1.0). The IVC  + 10?9 treatment also had a higher mRNA expression of antioxidant gene (SOD 2) compared to the Control, as well as the heat shock protein (HSPB 1) compared to the IVM  + 10?9. Reactive oxygen species production was greater in the IVM /IVC  + 10?9 treatment group. In conclusion, the 10?9 M concentration of melatonin and the in vitro production phase in which it is used directly affected embryonic development and quality.  相似文献   
5.
The objective of this research was to evaluate the efficacy of two antimicrobials (ampicillin and ceftiofur), a modified-live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine, and low dose exposure to Streptococcus suis on disease associated with PRRSV/S. suis coinfection. Fifty-six, crossbred, PRRSV-free pigs were weaned at 10-12 days of age and randomly assigned to five treatment groups. All pigs were inoculated with 2ml of 10(6.4) TCID50/ml of high virulence PRRSV isolate VR-2385 intranasally at 29-31 days of age (day 0 of the study) followed 7 days later by intranasal inoculation with 2ml of 10(8.9)colony forming units(CFU)/ml S. suis type 2 isolate ISU VDL #40634/94. Pigs in group 1 (n=10) served as untreated infected positive controls. Pigs in group 2 (n=12) were treated with 5.0 mg/kg ceftiofur hydrochloride intramuscularly (IM) on days 8, 11, and 14. Pigs in group 3 (n=11) were treated with 11 mg/kg ampicillin IM on days 8-10. Pigs in group 4 (n=12) were vaccinated 14 days prior to PRRSV challenge with a commercial modified-live PRRSV vaccine. Pigs in group 5 (n=11) were exposed to a 1:100 dilution of the S. suis challenge inoculum 19 days prior to S. suis challenge. Mortality was 80, 25, 82, 83, and 36% in groups 1-5, respectively. The reduced dose S. suis exposure had some residual virulence, evidenced by S. suis induced meningitis in two pigs after exposure. Treatment with ceftiofur hydrochloride and reduced dose exposure to S. suis were the only treatments which significantly (P<0.05) reduced mortality associated with PRRSV/S. suis coinfection, significantly (P<0.05) reduced recovery of S. suis from tissues at necropsy, and significantly (P<0.05) reduced the severity of gross lung lesions.  相似文献   
6.
Ten swine from each of five herds believed to be affected with mycoplasmal pneumonia of swine and ten swine from each of five herds believed to be mycoplasmal pneumonia-free were selected for postmortem study. Lungs from the 100 swine were examined; grossly and microscopically for lesions typical of mycoplasmal pneumonia of swine and culturally and by an indirect immunofluorescent procedure for the presence of Mycoplasma hyopneumoniae. Nineteen of the lungs had both gross and microscopic lesions typical of mycoplasmal pneumonia of swine and 13 (68%) of these were infected, i.e. were culturally and/or indirect immunofluorescent positive. Absence of gross lesions did not prove freedom from mycoplasmal pneumonia, 14 of 73 (19%) grossly normal lungs were found to be infected with M. hyopneumoniae. Comparison of the indirect immunofluorescent and cultural examination, as methods of diagnosing mycoplasma pneumonia, revealed that neither procedure alone was reliable in the case of negative results. Ten lungs were indirect immunofluorescent negative and culturally positive and seven were culturally negative and indirect immunofluorescent positive (11 lungs were positive by both procedures). It was concluded that a definitive diagnosis of mycoplasmal pneumonia of swine requires that M. hyopneumoniae be visualized in indirect immunofluorescent stained lung sections or that it be recovered culturally.  相似文献   
7.
Smout  TC 《Forestry》2006,79(3):341-349
Human use of the pinewoods in 1600–1900 is briefly reviewed,and related to evidence for differing woodland structure inthese centuries. A certain number of pinewoods were lost between1600 and 1800 and it is suggested that this may be related toclimate change.  相似文献   
8.
The relationship between the serological classification system for serogroup B and for serogroup H of Bacteroides nodosus and cross-protection between subgroups within these serogroups was examined. Protection against ovine footrot following vaccination was achieved against other subgroup strains provided sufficient cross-reactive antibody was induced by shared pilus antigens. Within serogroup B, better cross-protection against one subgroup was obtained with a pili vaccine than a whole cell vaccine which correlated with higher pilus antibody titres induced by the former. For serogroup H, a lack of cross-protection and serological reactivity between subgroups was demonstrated, which indicates that the prototype strain of subgroup H2 should be designated a new serogroup.  相似文献   
9.
The occurrence of fertile oestrus early in the breeding season is of paramount importance to the Thoroughbred industry to facilitate early conception. This paper compares 2 techniques for inducing fertile oestrus in anoestrous mares using either an extended photoperiod alone or together with gonadotrophin-releasing hormone (GnRH) infusions. Eleven mares were placed under conditions of 16 h light and 8 h darkness and 5 of these were implanted with osmotic minipumps delivering approximately 100 ng GnRH/kg/h for 28 days (treated mares). The treated mares ovulated 27.7 days earlier than and conceived 32 days earlier than the 6 mares not given GnRH. GnRH-induced ovulations were followed by a competent luteal phase. The combination of GnRH pumps implanted 2 weeks before commencement of service together with extended photoperiod from July 1 has promise in assisting the stud breeder to improve reproductive efficiency on commercial stud farms.  相似文献   
10.
The myeloid panel of monoclonal antibodies (mAbs) submitted to the Third Swine CD Workshop were analysed for reactivity with bone marrow haematopoietic cells (BMHC). Using single and triple immunofluorescence labelling by flow cytometry (FCM), the mAbs were grouped according to their capacity to recognise myeloid cell populations and/or maturation stages. Group 1 consisted of mAbs labelling the majority of myeloid BMHC, including neutrophilic, eosinophilic and monocytic cells. The ligands for SWC3 and CD11b-like mAbs of group 1 showed a maturation-dependent intensity of expression. The other antibodies of group 1 reacted with BMHC to give a sharp, single peak. Group 2 mAbs reacted only with monocytic cells. The anti-human CD49e mAb Sam-1 was the only mAb detecting the majority of monocytic cells, but not other BMHC. The mAbs in group 3 recognised antigens expressed on granulocytes, but not monocytes. The previously identified SWC8 in this group proved to be useful in differentiating major population of BMHC when cells were double labelled with the pan-myeloid SWC3. Other mAbs within group 3, such as MIL4 and TMG6-5 (an anti-human CD11b), only recognised subsets of neutrophils and eosinophils. Group 4 mAbs reacted with the more mature subpopulations of neutrophils and monocytes. Some of these antibodies might prove useful for assessment of cell maturity, such as anti-CD14 and the anti-human CD50 mAb HP2/19.  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