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   539篇
  免费   28篇
林业   15篇
农学   19篇
基础科学   3篇
  101篇
综合类   67篇
农作物   59篇
水产渔业   52篇
畜牧兽医   204篇
园艺   12篇
植物保护   35篇
  2023年   8篇
  2022年   9篇
  2021年   17篇
  2020年   19篇
  2019年   15篇
  2018年   15篇
  2017年   10篇
  2016年   10篇
  2015年   14篇
  2014年   14篇
  2013年   31篇
  2012年   32篇
  2011年   45篇
  2010年   23篇
  2009年   20篇
  2008年   23篇
  2007年   32篇
  2006年   34篇
  2005年   22篇
  2004年   35篇
  2003年   22篇
  2002年   21篇
  2001年   10篇
  2000年   3篇
  1998年   4篇
  1996年   5篇
  1994年   3篇
  1993年   4篇
  1992年   4篇
  1989年   5篇
  1988年   5篇
  1987年   2篇
  1984年   2篇
  1983年   6篇
  1980年   2篇
  1979年   2篇
  1978年   4篇
  1977年   3篇
  1976年   2篇
  1975年   2篇
  1973年   2篇
  1972年   2篇
  1971年   2篇
  1966年   3篇
  1959年   1篇
  1956年   1篇
  1954年   1篇
  1938年   1篇
  1937年   1篇
  1936年   1篇
排序方式: 共有567条查询结果,搜索用时 31 毫秒
41.
This retrospective study of 51 dogs with atopic dermatitis (AD) treated with cyclosporine (CsA) for a minimum of 6 months assessed the frequency of dosing and the need for continual treatment to control clinical signs. The study evaluated both medical records and information supplied by the owners in the form of written questionnaires and telephone follow-up. Laboratory parameters, possible adverse effects and owner satisfaction were assessed. The dose of CsA was 5 mg/kg orally per day and dogs received CsA for 6-30 months. At the conclusion of the study period, 28 dogs (55%) needed ongoing CsA to control clinical signs of AD: 8 (15%) received CsA 2-3 days per week, 10 (20%) 4-5 days per week, and 10 (20%) daily. CsA was discontinued in 23 dogs (45%) after 6-24 months due to either a limited response (22%) or after achieving a clinical response (24%). The results suggest that some dogs with AD treated with CsA may not require daily or even ongoing treatment to control clinical signs. Laboratory abnormalities were detected in 13 dogs (25%) during their CsA treatment. Two dogs developed oral growths and three developed hirsuitism. Forty owners (78%) reported no adverse events in their dogs during the treatment period. Thirty-six owners (71%) were satisfied with CsA as treatment for their atopic dog.  相似文献   
42.
43.
OBJECTIVE: To determine whether specific treadmill exercise regimens would accelerate age-related changes in collagen fibril diameter distributions in the common digital extensor tendon (CDET) of the forelimbs of young Thoroughbreds. ANIMALS: 24 female Thoroughbreds. PROCEDURE: Horses were trained for 18 weeks (6 horses; short term) or 18 months (5 horses; long term) on a high-speed treadmill; 2 age-matched control groups (6 horses/group) performed walking exercise only. Horses were (mean +/- SD) 24 +/- 1 months and 39 +/- 1 months old at termination of the short-term and long-term regimens, respectively. Midmetacarpal CDET specimens were obtained and processed for transmission electron microscopy. Diameter and area of at least 1,000 collagen fibrils/specimen were measured by use of computerized image analysis. Mass-average diameter (MAD) of collagen fibrils and collagen fibril index were calculated for each horse. RESULTS: Collagen fibril MAD for the older horses was significantly less than that for the younger horses. Exercise did not significantly affect fibril diameter or distributions in either age group, and collagen fibril index did not differ significantly between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Age-related reduction in collagen fibril MAD agreed with findings for other tendons and species. Training did not accelerate age-related change in the CDET in contrast to a reported decrease in collagen fibril MAD in the superficial digital flexor tendon of horses trained long term. Our results support the concept that the functionally distinct nature of the CDET and superficial digital flexor tendon in horses results in fundamentally different responses to high-speed exercise regimens.  相似文献   
44.
This paper provides a working framework for enhancing the well-being of senior pet dogs and cats. Approaches to screening the medical status of senior pets are described in detail, with particular emphasis on establishing baseline data in healthy animals, the testing of clinically ill animals, and assessing senior pets prior to anesthesia and surgery. The management of pain and distress and the application of hospice and palliative care are addressed. Advice on ways to approach euthanasia and dealing with end-of-life issues is also provided.  相似文献   
45.
46.
47.
The isotype-specific antibody responses of sheep immunised with keyhole limpet hemocyanin by a peripheral route (intramuscular (i.m.) injection) were compared to those induced by immunisation via different mucosal routes: (1) intra-nasal spray; (2) rectal deposition with cholera toxin; (3) injection into the mucosa of the small intestine or rectum. Antigen-specific IgG1 antibodies were induced in the i.m., intra-intestinal and intra-rectal injection groups and in a proportion of the cholera toxin immunised sheep, but not in the intra-nasal immunisation group. IgA was the only antibody isotype detected in serum collected from the intra-nasal immunisation group. No significant differences in serum IgA levels were detected in any of the mucosal immunisation groups as compared to the i.m. injection group. In contrast, analysis of the in vitro antibody profiles secreted by circulating antibody-secreting cells (ASC) revealed significantly higher IgA responses in the supernatants from all mucosal immunisation groups. This suggests that the measurement of antibodies secreted by circulating ASCs may be a better correlate of local mucosal responses in ruminants, as has been previously demonstrated in human studies. In addition to IgG1 and IgA responses, immunisation by direct injection of antigen formulations into the intestinal and rectal mucosa were the only groups to induce consistently high IgG2 antibodies in serum and ASC cultures.  相似文献   
48.
49.
Clostridium perfringens is a cause of economically significant enteritis in livestock. Beta2 toxin, encoded by one of two cpb2 alleles, is implicated as a virulence factor in this disease. Previous studies determined that the consensus cpb2 allele is preferentially associated with C. perfringens isolated from pigs. In C. perfringens strain 13, the consensus cpb2 allele is found on the plasmid pCP13, which also carries cna, encoding a putative collagen binding protein, CpCna. This protein was shown to be a bona fide collagen adhesin, as recombinant, HIS-tagged CpCna bound collagen type I as determined by Far Western blotting. Genomic DNA from C. perfringens isolated from a variety of host species were subjected to PCR to determine the prevalence of cna in these strains and correlate its carriage with the presence and type of cpb2 allele. The cna gene was found in 55.8% of isolates from all host species (n=208) and 68.1% of porcine isolates (n=119). In cpb2+ isolates, cna was present in 69.9% of isolates from all hosts (n=153), but was found in 98.7% of porcine isolates (n=75). Furthermore in porcine isolates, the consensus cpb2 allele and cna were absolutely correlated with the presence of pcp12, a pCP13-encoded gene, and pcp12 was never found in any isolate that lacks either cpb2 allele. The finding that CpCna binds collagen and that the cna gene is associated with the consensus cpb2 allele implicates CpCna as a potential virulence factor in porcine enteritis caused by C. perfringens.  相似文献   
50.
A retrospective study of 91 dogs with pemphigus foliaceus was performed. Clinical signs of the disease included crusts (n=79), pustules (n=36), and alopecia (n=33). Lesions were most common on the trunk (n=53), inner pinnae (n=46), face (n=37), and foot pads (n=32). Cytological evaluation revealed acantholytic keratinocytes in 37 of 48 dogs. Results of combination treatment with prednisolone and azathioprine were comparable to results with prednisolone therapy alone. More than half of the dogs achieved remission with appropriate therapy, and another 25% significantly improved.  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