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   550篇
  免费   61篇
林业   18篇
农学   15篇
基础科学   3篇
  81篇
综合类   77篇
农作物   15篇
水产渔业   30篇
畜牧兽医   327篇
园艺   18篇
植物保护   27篇
  2023年   7篇
  2022年   5篇
  2021年   14篇
  2020年   11篇
  2019年   8篇
  2018年   13篇
  2017年   5篇
  2016年   9篇
  2015年   12篇
  2014年   22篇
  2013年   29篇
  2012年   36篇
  2011年   32篇
  2010年   21篇
  2009年   21篇
  2008年   20篇
  2007年   29篇
  2006年   37篇
  2005年   27篇
  2004年   17篇
  2003年   22篇
  2002年   26篇
  2001年   10篇
  2000年   8篇
  1999年   6篇
  1998年   5篇
  1997年   7篇
  1995年   9篇
  1994年   4篇
  1993年   5篇
  1992年   4篇
  1989年   9篇
  1988年   4篇
  1987年   5篇
  1986年   5篇
  1985年   6篇
  1984年   4篇
  1983年   6篇
  1980年   6篇
  1979年   8篇
  1978年   7篇
  1977年   3篇
  1975年   3篇
  1974年   6篇
  1973年   8篇
  1972年   3篇
  1970年   3篇
  1969年   5篇
  1965年   3篇
  1960年   3篇
排序方式: 共有611条查询结果,搜索用时 303 毫秒
71.
72.
73.
Feline herpesvirus 1 (FHV-1) is one of the most common viral infections of domestic cats worldwide, estimated to cause 50% of all respiratory infections in this species. Feline herpesvirus 1 is also an important ocular pathogen of cats, causing conjunctivitis, epithelial and stromal keratitis, symblepharon formation, keratocon-junctivitis sicca, and corneal sequestration. Despite the importance of this viral disease, major questions remain unanswered concerning the pathogenesis of its most important manifestation, the recrudescent infection. Although the taxonomic classification of FHV-1 as an alpha herpesvirus implies the ability of FHV-1 to establish neural latency, attempts at recovering the virus from the trigeminal ganglia of latently infected cats have typically yielded negative results. This failure has stimulated speculation that neural tissue is not an important site for latent FHV-1. However, in the most successful of such studies, FHV-1 was isolated from the trigeminal ganglia of 3 of 17 cats using an explant technique. In the present study, we describe the successful isolation of FHV-1 from the trigeminal ganglia of cats using a similar tissue culture method.  相似文献   
74.
Possible relationship of proliferative enteritis in pigs and hamsters   总被引:4,自引:0,他引:4  
Three- to six-week-old hamsters were orally inoculated with broths containing one of the following cultures: Campylobacter mucosalis; C. hyointestinalis; C. coli; C. jejuni, all of porcine proliferative enteritis origin, or else C. jejuni of hamster origin. Hamsters given the last of those organisms were shown to have colonisation of their intestines by C. jejuni and 36 of 40 developed an acute enteritis. Mild hyperplasia of enterocytes in ileal crypts was evident in one hamster 2 days after it was given C. coli. No other lesions were detected. Further 3-week-old hamsters were orally inoculated with homogenised intestinal mucosa collected from 4 pigs (A-D) affected by proliferative enteritis. Lesions of proliferative enteritis were detected in 7 of 41 hamsters necropsied 10-21 days after being dosed with mucosas B or D. Marked hyperplasia of ileal enterocytes, associated with numerous intracellular Campylobacter-like organisms, were invariably detected in experimentally affected hamsters. No particular Campylobacter sp. was consistently isolated. None of the controls had demonstrable lesions. The results suggested that cross-species transmission of proliferative enteritis was possible from pigs to hamsters. Therefore a common initiating or aetiological agent may be present. No specific organism was identified as filling this role by inoculation of hamsters with pure cultures.  相似文献   
75.
Mitral stenosis was diagnosed in 15 young to middle-aged dogs. There were 5 Newfoundlands and 4 bull terriers affected, suggesting a breed predisposition for this disorder. Clinical signs included cough, dyspnea, exercise intolerance, and syncope. Soft left apical diastolic murmurs were heard only in 4 dogs, whereas 8 dogs had systolic murmurs characteristic of mitral regurgitation. Left atrial enlargement was the most prominent radiographic feature. Left-sided congestive heart failure was detected by radiographs in 11 dogs within 1 year of diagnosis. Electrocardiographic abnormalities varied among dogs and included atrial and ventricular enlargement, as well as atrial and ventricular arrhythmias. Abnormalities on M-mode and two-dimensional echocardiograms included abnormal diastolic motion of the mitral valve characterized by decreased leaflet separation, valve doming, concordant motion of the parietal mitral valve leaflet, and a decreased E-to-F slope. Increased mitral valve inflow velocities and prolonged pressure half-times were detected by Doppler echocardiography. Cardiac catheterization, performed in 8 dogs, documented a diastolic pressure gradient between the left atrial, pulmonary capillary wedge, or pulmonary artery diastolic pressures and the left ventricular diastolic pressure. Necropsy showed mitral stenosis caused by thickened, fused mitral valve leaflets in 5 dogs and a supramitral ring in another dog. The outcome in affected dogs was poor; 9 of 15 dogs were euthanatized or died by 2 1/2 years of age.  相似文献   
76.
77.
Pseudomonas aeruginosa has been associated with conjunctivitis, enteritis, pneumonia, septicemia, sudden death, and abortion in chinchillas. This case report describes an unusual clinical presentation and diagnosis of P. aeruginosa otitis media and interna with neurologic manifestations. To our knowledge, this clinical presentation has not been reported previously in chinchillas.  相似文献   
78.
79.
OBJECTIVE: To determine whether the literature filtering process, a vital initial component of a systematic literature review, could be successfully completed by nutrition professionals or non-professionals. DESIGN: Using a diet-disease relationship as the guideline topic, inter-rater agreement for the title and abstract filtering processes between and among professionals and non-professionals was assessed and compared with an expert reference standard. Predetermined eligibility criteria were applied by all raters to 185 titles and 90 abstracts. Filtering decisions were initially made independently and then revised after a within-pair consensus meeting. SUBJECTS: The raters were six dietitians (RD) and six nutrition graduate students (Grad). To assess inter-rater agreement (reliability), each group was divided into three pairs. RESULTS: Weighted and unweighted kappa statistics and percentage agreement were calculated to determine the inter-rater agreement within pairs. Sensitivity and specificity estimates were determined by comparing responses with those of an expert reference standard. Overall, Grad pairs demonstrated greater inter-rater agreement than RD pairs for title filtering (P<0.05); no differences were observed for abstract filtering. Compared with the expert reference standard, every rater and pair had false-negative responses for both title and abstract filtering. CONCLUSIONS: After consensus meetings, both RDs and Grads were comparable in their agreement on title and abstract filtering, although important differences remained compared with the expert reference standard. This study provides preliminary findings on the value of utilising a non-expert pair in developing guidelines, and suggests that the literature filtering process is complex and quite subjective.  相似文献   
80.
CASE DESCRIPTION: A 4-year-old English Pointer was examined because of chronic, progressive signs of pulmonary disease and failure to respond to medical treatment. CLINICAL FINDINGS: At examination, radiography of the thorax revealed increased pulmonary opacity and air bronchograms in the right caudal lung lobe, and radiography of the forelimbs revealed periosteal bone production typical of hypertrophic osteopathy. Attempts to isolate a causative organism included bacterial culture of bronchoalveolar lavage fluid and a lung tissue specimen obtained via fine-needle aspiration. Despite a cytologic diagnosis of septic suppurative inflammation in the lavage fluid, those specimens did not yield bacterial growth. However, a biopsy specimen obtained during a lung lobectomy procedure yielded growth of Eikenella corrodens. TREATMENT AND OUTCOME: Despite successful surgical removal of the consolidated lung lobe and initiation of antimicrobial treatment, the dog died 6 days after surgery. CLINICAL RELEVANCE: The authors are not aware of reports of pulmonary infection with E. corrodens in animals. Infection with the organism is rare, but it is possible that infections are underreported given that the organism is difficult to culture and biopsy may be necessary to obtain enough tissue to yield a diagnosis.  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