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   468篇
  免费   40篇
林业   31篇
农学   6篇
基础科学   2篇
  68篇
综合类   26篇
农作物   8篇
水产渔业   36篇
畜牧兽医   260篇
园艺   4篇
植物保护   67篇
  2023年   6篇
  2022年   4篇
  2021年   16篇
  2020年   20篇
  2019年   8篇
  2018年   9篇
  2017年   16篇
  2016年   18篇
  2015年   20篇
  2014年   24篇
  2013年   24篇
  2012年   24篇
  2011年   20篇
  2010年   15篇
  2009年   22篇
  2008年   42篇
  2007年   26篇
  2006年   13篇
  2005年   11篇
  2004年   20篇
  2003年   26篇
  2002年   12篇
  2001年   17篇
  2000年   18篇
  1999年   2篇
  1997年   4篇
  1993年   2篇
  1992年   5篇
  1991年   4篇
  1990年   2篇
  1989年   3篇
  1987年   6篇
  1986年   5篇
  1985年   9篇
  1984年   3篇
  1982年   2篇
  1980年   3篇
  1979年   1篇
  1978年   3篇
  1977年   3篇
  1976年   1篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
  1972年   4篇
  1971年   1篇
  1970年   1篇
  1969年   3篇
  1968年   1篇
  1949年   1篇
排序方式: 共有508条查询结果,搜索用时 15 毫秒
151.
The authors report the efficacy of an injectable, moxidectin sustained release (SR) formulation for the prevention of canine heartworm infection in endemic areas in northern and central Italy. Three field trials were carried out on a total of 324 dogs. Two hundred forty-three dogs were treated with moxidectin SR 6 months apart and 81 dogs (positive controls) with moxidectin tablets given monthly for 5 consecutive months during the risk season each year throughout the study. Results of testing for microfilariae and circulating adult female antigens were negative for all the experimentally treated dogs at the 6, 7, 11 and 19 months after the last injection. No adverse reactions to moxidectin SR were observed but a moderate pain at palpation and swelling (5-6 cm) at the injection site after the first treatment. In the study areas, prevalence of Dirofilaria immitis infection calculated by testing dogs which had no preventive treatment in the previous transmission season ranged from 33 to 63%. This study confirms the efficacy and safety of injectable, moxidectin SR formulation in the prevention of heartworm infection in dogs and demonstrates that the prophylactic efficacy lasts for the full season and strongly suggests that the product gives 1-year protection.  相似文献   
152.
To compare cultured bone marrow mesenchymal cells (cBMSC), bone marrow mononucleated cells (BMMNCs), and placebo to repair collagenase-induced tissue damage in an equine model of experimental tendonitis, 6 Standardbred horses with no signs of previous SDF tendon injury have been recruited. Three weeks after collagenase treatment an average of either 5.5 x 10(6) cBMSCs or 122.3 x 10(6) BMMNCs, saline solution (placebo) or fibrin glue were injected intralesionally in random order. Horses were stall rested for 21 weeks, and tendon ultrasound scans performed before and during this period. Horses were euthanized and tendons harvested for histology and immunohistochemistry. Data observed in this study showed effectiveness of cBMSC and BMMNC in regenerating tendon tissue after collagenase -induced tendonitis. Both cBMSC and BMMNC transplantation resulted in qualitatively similar regeneration of tendon extracellular matrix in terms of type I/III collagen ratio, fiber orientation, and COMP expression. After this favourable results, 20 horses were recruited referred for spontaneous lesions of the flexor tendons or the suspensory ligament. Horses were treated with autologous graft of BMMNCs.After treatment the. the exercise program allowed was 8 weeks stall rest, 4 weeks hand walking, 4 weeks trotting, 4 weeks of gradually raising of exercise level then horses were gone back to race. US characteristics of lesions started to improve at T3. CSA-l, FPS and TLS were better in all patients, with an appreciable filling of lesions indicated by a decreasing of CSA-l and increasing of TLS. When horses started the exercise program T8 tendon architecture improved, demonstrated by their longitudinal alignment and length. At T6, and persistently in later follow-up, no lameness was evident by clinical examination. At time of writing 12 patients (60%) were go back to races, while other 8 (40%) are under controlled exercise program. Re-injury rate was assessed at 25%. All the owners judged good to excellent the outcome in term of athletic success.  相似文献   
153.
154.
A 7-year-old neutered female domestic short hair cat was presented with hind limb ataxia. A subarachnoid cyst in the T10-T11 spinal cord region was identified by myelography as a collection of contrast medium in the subarachnoid space.  相似文献   
155.
F. Rossi  DVM    G. Seiler  DVM    A. Busato  DVM habil.  MSc.    C. Wacker  DVM    J. Lang  DVM habil. 《Veterinary radiology & ultrasound》2004,45(5):381-387
The geometry of the lumbosacral region has been suspected to play a role in the development of degenerative lumbosacral stenosis in the dog. In this study, 50 dogs (21 German Shepherd dogs and 29 dogs of other breeds) with clinical signs of cauda equina compression were studied by magnetic resonance (MR) imaging. The orientation of the articular process joints in the L5-S1 region and the angle difference between two adjacent motion segments were calculated. Intervertebral disc degeneration of the same region was identified and classified in four stages. A positive association between MR-imaging stage and articular process joint angle difference in the transverse plane was found in the two groups of animals. German Shepherd dogs and dogs of other breeds had different geometry of the lumbosacral region with different articular process joint angles in the transverse plane and statistically different stages of disc degeneration.  相似文献   
156.
157.
This retrospective study describes testing patterns and the incidence of Streptococcus equi subsp. equi in Ontario to assess the utility of laboratory data for surveillance purposes. Laboratory records for equine infectious disease test submissions were extracted from the Animal Health Laboratory (AHL) at the University of Guelph for the years 2008 to 2018. Yearly and seasonal trends in S. equi testing and the proportion of tests that returned positive results were assessed. The number of samples submitted for S. equi testing decreased over the 11-year period (odds ratio = 0.96, 95% confidence interval: 0.92 to 0.999; P = 0.04). A generalized linear model identified a significant seasonal effect for animals recognized as clinically ill, with the highest test positivity noted in the winter. Although this study identified important trends in the incidence of S. equi in Ontario, the variability in information accompanying test submissions made the data challenging to interpret, highlighting the need for more complete diagnostic submission data for S. equi.  相似文献   
158.
In 2002 and 2003, two successive outbreaks of classical swine fever were declared in wild boar in northern France. The first was in Moselle, near the town of Thionville and the border with Luxembourg, and the second was in the northern Vosges area, near the German border. The outbreaks were investigated by serological and virological diagnosis of dead or shot animals. Hunting restrictions were applied to limit the spread of the outbreaks. The virus was detected eight times between April and July 2002 in the Thionville area, an area well delimited by natural or artificial barriers such as rivers or highways. Cooperation between the authorities concerned was good, and hunting restrictions were applied for one year. No virus was detected after July 2002 and the Thionville outbreak was officially considered over in March 2005. In the northern Vosges the situation was different, with no barriers to animal movements, continuous forest, difficulties in establishing hunting restrictions in this huge area, and the circulation of the virus in Germany close to the frontier. Virus of a different strain from that isolated in the Thionville outbreak was still being isolated in the northern Vosges in 2004, and owing to the failure of the hunting restrictions, the French health authorities decided to vaccinate wild boar.  相似文献   
159.
Two experiments were conducted to investigate a feeding regimen in which a programmed amount of feed was offered daily to control growth rate of steers. In Exp. 1, steers (n = 107, 309 +/- 3 kg) were used to determine effects of offering ad libitum access to feed (AL) vs a programmed intake feeding regimen (PI) and the number of days steers were fed (168 vs 203) on performance and carcass characteristics. Steers in the programmed intake feeding regimen were fed to achieve a predicted gain of 1.13 kg/d for the first 78 kg of gain, 1.36 kg/d for the next 124 kg of gain, and were given ad libitum access to feed for the final 54 or 103 kg of gain before slaughter (for steers fed for 168 d or 203 d, respectively). Feed efficiency was greater (P < 0.02) for steers in the PI than for those in the AL feeding regimen (0.193 vs 0.183 kg gain/kg feed, respectively). From d 169 to 203, steers in the PI feeding regimen had greater (P < 0.06) ADG (1.60 vs 1.38 kg/d) and similar (P = 0.38) feed efficiency than steers in the AL regimen. In Exp. 2, steers (n = 96; 308 +/- 3 kg BW) were offered feed ad libitum throughout the experiment (AL) or were programmed to gain at a high (PI-H) or low (PI-L) growth rate. For the first 78 kg of gain, intake was restricted to achieve predicted gains of 1.13 kg/d (PI-L) or 1.25 kg/d (PI-H). For the next 124 kg of gain, intake was restricted to achieve predicted gains of 1.36 kg/d (PI-L) or 1.47 kg/d (PI-H). Feed was offered ad libitum for the final 58 kg of gain. Overall ADG was similar (P > 0.37) among feeding regimens despite lower DMI for the steers in the PI-L and PI-H feeding regimens than for those in the AL regimen. Feeding regimen did not affect (P < 0.22) carcass characteristics. Programmed intake feeding regimens sustained growth rate and feed efficiency for an extended period of time without detrimental effects on carcass characteristics.  相似文献   
160.
The polypeptide profiles of the type strains of Mycoplasma gallisepticum (PG 31) and M. synoviae (WVU 1853) resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis were compared. Except for a few discrete peptides that were similar, the species varied considerably in peptide profiles. Congruence was observed between the type strains of each species and homologous cloned serotypes. Protein blots of each species were probed with 2 mouse monoclonal antibodies. Monoclonal antibody G 46 was specific for the antigen p 110 (G) in M. gallisepticum, and S 221 was specific for an antigen complex p 45-50 (S) in M. synoviae. The 2 monoclonal antibodies clearly distinguished between all serotypes of M. gallisepticum and M. synoviae that were examined by Western blot transfer. Autoradiographs of 125I-labeled M. gallisepticum and M. synoviae indicated that p 110 (G) and p 45-50 (S) were surface membrane peptides. Indirect immunofluorescence of M. gallisepticum and M. synoviae in Vero cell cultures supported the autoradiographic findings. The p 110 (G) antigen of M. gallisepticum was heat-stable, pronase-sensitive, and resistant to periodate oxidation, suggesting that its chemical composition is protein. In contrast, the p 45-50 antigen complex of M. synoviae appeared as a broad band in protein blots treated with monoclonal antibody S 221, was sensitive to pronase, and responded to Schiff's reagent but was not completely inhibited by periodate oxidation, suggesting that it is a complex of repeating sequences probably composed of glycosylated peptides.  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