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   6345篇
  免费   258篇
  国内免费   10篇
林业   528篇
农学   263篇
基础科学   51篇
  1530篇
综合类   773篇
农作物   347篇
水产渔业   382篇
畜牧兽医   2089篇
园艺   180篇
植物保护   470篇
  2023年   31篇
  2022年   59篇
  2021年   111篇
  2020年   124篇
  2019年   154篇
  2018年   125篇
  2017年   140篇
  2016年   144篇
  2015年   114篇
  2014年   174篇
  2013年   298篇
  2012年   373篇
  2011年   440篇
  2010年   272篇
  2009年   229篇
  2008年   394篇
  2007年   389篇
  2006年   397篇
  2005年   388篇
  2004年   341篇
  2003年   319篇
  2002年   338篇
  2001年   102篇
  2000年   87篇
  1999年   103篇
  1998年   72篇
  1997年   62篇
  1996年   55篇
  1995年   45篇
  1994年   28篇
  1993年   47篇
  1992年   42篇
  1991年   43篇
  1990年   45篇
  1989年   49篇
  1988年   39篇
  1987年   31篇
  1986年   23篇
  1985年   36篇
  1984年   23篇
  1983年   36篇
  1982年   22篇
  1981年   19篇
  1980年   21篇
  1978年   19篇
  1977年   18篇
  1974年   18篇
  1973年   19篇
  1972年   15篇
  1970年   14篇
排序方式: 共有6613条查询结果,搜索用时 15 毫秒
71.
Infections of dogs with Toxocara canis and Echinococcus multilocularis pose an infection-risk particularly for contact persons. We examined specimens of hair coat and faeces of 124 farm dogs, 118 household dogs, 49 kennel dogs, 15 puppies from two litters, and 46 red foxes. Microscopically identified eggs of Toxocara or taeniids were further investigated by species-specific PCRs. In farm dogs, eggs of E. multilocularis or T. canis were identified in each 2.4% of faecal samples, eggs of T. cati (gastrointestinal passage) in 7.3%, respectively. Household dogs excreted eggs of T. canis (0.8%) and of T. cati (2.5%). In kennel dogs, eggs of T. canis (4.1%), but not of T. cati were detectable. Coat samples contaminated with eggs of Toxocara spp. were found from farm dogs (5.6%), household dogs (1.7%) and kennel dogs (2.0%). Taeniid eggs were isolated from the coat samples from only two farm dogs (1.6%); a molecular species determination was not achieved. In six intrauterinely infected puppies, Toxocara-eggs were found in 17/38 samples taken within six weeks. No intact Toxocara eggs could be isolated from the coat of nine puppies from a second litter 13 days after deworming. Of the 46 red foxes investigated (dissection and faecal samples) 13 (28.3%) were infected with E. multilocularis and 20 (43.5%) with Toxocara. Eggs of taeniids and Toxocara were found in 13% (in three cases confirmed as E. multilocularis) and 21.7%, respectively, of the coat samples. None of the retrieved Toxocara eggs in the coat samples were embryonated. Thus, an infection of humans through the transmission of E. multilocularis eggs after direct contact with dogs or foxes is conceivable, whereas a corresponding infection risk by Toxocara eggs must be critically challenged.  相似文献   
72.
A 10-year-old Maltese dog was presented with a firm mass on the left side of his neck. Physical examination confirmed a firm mass in the left and a submandibular swelling in the right cervical region. Sialolithiasis and associated sialocele in both mandibular salivary glands were suspected and bilateral sialoadenectomy was performed. The stones were identified as non-mineral sialoliths.  相似文献   
73.
74.
75.
76.
77.
A 10-year-old neutered female cat had chylothorax, precaval syndrome, and a mediastinal granuloma resulting from infection with Cryptococcus neoformans. Diagnosis of a chylous effusion was made by cytologic examination of pleural fluid and by finding higher triglyceride levels in the effusion than in serum (825 vs. 64 mg/dl, respectively). Postmortem examination revealed cryptococcal organisms in the mediastinal granuloma, lungs, cerebral meninges, and connective tissues adjacent to the thyroid gland. Chylous effusion in a cat associated with cryptococcosis has not been reported previously. Cryptococcosis should be included in the differential diagnosis in chylous effusions in cats.  相似文献   
78.
A randomized, placebo-controlled, four-period cross-over laboratory study involving eight dogs was conducted to confirm the effective analgesic dose of firocoxib, a selective COX-2 inhibitor, in a synovitis model of arthritis. Firocoxib was compared to vedaprofen and carprofen, and the effect, defined as a change in weight bearing measured via peak ground reaction, was evaluated at treatment dose levels. A lameness score on a five point scale was also assigned to the affected limb. Peak vertical ground reaction force was considered to be the most relevant measurement in this study. The firocoxib treatment group performed significantly better than placebo at the 3 h post-treatment time point and significantly better than placebo and carprofen at the 7 h post-treatment time point. Improvement in lameness score was also significantly better in the dogs treated with firocoxib than placebo and carprofen at both the 3 and 7 h post-treatment time points.  相似文献   
79.
Objective: To determine the antinociceptive effects of epidural administration of morphine or buprenorphine in cats by use of a thermal threshold model. ANIMALS: 6 healthy adult cats. PROCEDURES: Baseline thermal threshold was determined in duplicate. Cats were anesthetized with isoflurane in oxygen. Morphine (100 microg/kg diluted with saline [0.9% NaCl] solution to a total volume of 0.3 mL/kg), buprenorphine (12.5 microg/kg diluted with saline solution to a total volume of 0.3 mL/kg), or saline solution (0.3 mL/kg) was administered into the epidural space according to a Latin square design. Thermal threshold was determined at various times up to 24 hours after epidural injection. RESULTS: Epidural administration of saline solution did not affect thermal threshold. Thermal threshold was significantly higher after epidural administration of morphine and buprenorphine, compared with the effect of saline solution, from 1 to 16 hours and 1 to 10 hours, respectively. Maximum (cutout) temperature was reached without the cat reacting in 0, 74, and 11 occasions in the saline solution, morphine, and buprenorphine groups, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Epidural administration of morphine and buprenorphine induced thermal antinociception in cats. At the doses used in this study, the effect of morphine lasted longer and was more intense than that of buprenorphine.  相似文献   
80.
Colibacillosis results from infection with avian pathogenic Escherichia coli bacteria. Healthy broilers are resistant to inhaled E. coli, but previous infection with vaccine or virulent strains of Infectious Bronchitis Virus (IBV) predisposes birds for severe colibacillosis. We investigated whether IBV affects recruitment and function of phagocytic cells and examined NO production, phagocytic and bactericidal activity, and kinetics of peripheral blood mononuclear cells (PBMC) and splenocytes. Moreover, we measured cytokine mRNA expression in lung and spleen samples. Broilers were inoculated with IBV H120 vaccine or virulent M41 and challenged 5 days later with E. coli 506. A PBS control and E. coli group without previous virus inoculation were also included. Birds were sacrificed at various time points after inoculation (h/dpi). Inoculation with IBV induced extended and more severe colibacillosis than with E. coli alone. At 4dpi, the number of KUL-01(+) PBMC in all E. coli-inoculated groups was significantly higher than in PBS-inoculated birds, which correlated with lesion scores. From 1 to 4dpi, NO production by PBMC from all E. coli-inoculated animals was elevated compared to PBS birds. Bactericidal activity of PBMC in IBV-inoculated animals at 7dpi was lower than in PBS- and E. coli-inoculated birds, but phagocytic capacity and recruitment were not severely impaired. In spleen samples of IBV-infected animals reduced expression of IL-1beta, IL-6, IL-8, IL-10, IL-18 and IFN-gamma mRNA was found 1dpi. Our results suggest that enhanced colibacillosis after IBV infection or vaccination is caused at least by altered innate immunity and less by impairment of phagocytic cell function.  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