全文获取类型
收费全文 | 687篇 |
免费 | 31篇 |
国内免费 | 1篇 |
专业分类
林业 | 28篇 |
农学 | 10篇 |
基础科学 | 4篇 |
68篇 | |
综合类 | 71篇 |
农作物 | 24篇 |
水产渔业 | 65篇 |
畜牧兽医 | 365篇 |
园艺 | 15篇 |
植物保护 | 69篇 |
出版年
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 18篇 |
2018年 | 9篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 3篇 |
2014年 | 13篇 |
2013年 | 33篇 |
2012年 | 21篇 |
2011年 | 26篇 |
2010年 | 22篇 |
2009年 | 19篇 |
2008年 | 36篇 |
2007年 | 40篇 |
2006年 | 21篇 |
2005年 | 25篇 |
2004年 | 33篇 |
2003年 | 35篇 |
2002年 | 25篇 |
2001年 | 18篇 |
2000年 | 22篇 |
1999年 | 22篇 |
1998年 | 8篇 |
1997年 | 9篇 |
1996年 | 14篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 12篇 |
1992年 | 16篇 |
1991年 | 5篇 |
1990年 | 12篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1975年 | 9篇 |
1974年 | 14篇 |
1973年 | 7篇 |
1972年 | 3篇 |
1950年 | 2篇 |
1947年 | 3篇 |
排序方式: 共有719条查询结果,搜索用时 15 毫秒
31.
A novel pox virus, condorpox virus (CPV) isolated from the spleen of an Andean condor (Vultur gryphus) by inoculation of chorioallantoic membranes (CAM) of specific pathogen free (SPF) chicken embryos was compared biologically, antigenically and genetically with fowlpox virus (FPV), the type species of the genus Avipoxvirus. Susceptible chickens inoculated with CPV developed only mild localized lesions but were not protected against subsequent challenge with FPV. Based on Western blotting, in addition to the presence of cross-reacting antigens, distinct differences in antigenic profiles of CPV and FPV were observed. Sequence analysis of a 4.5 kb HindIII fragment of CPV genomic DNA revealed the presence of eight co-linear genes corresponding to FPV open reading frame (ORF)193-198, 201 and 203. Interestingly, reticuloendotheliosis virus (REV) sequences present in the genome of all FPV were absent in CPV. Although, the results of a phylogenic analysis suggested that CPV is a member of the genus Avipoxvirus, its unique antigenic, biologic and genetic characteristics distinguish it from FPV to be considered as a new member of this genus. 相似文献
32.
33.
34.
Jolly RD Allan FJ Collett MG Rozaklis T Muller VJ Hopwood JJ 《New Zealand veterinary journal》2000,48(5):144-148
AIM: To investigate the nature of a progressive ataxia in a New Zealand Huntaway dog. METHODS: The affected dog was examined clinically before being humanely killed and necropsied. Selected tissues were submitted to light and electron microscopy and to biochemical analyses. RESULTS: The histological lesions were interpreted as indicative of one of the forms of mucopolysaccharidosis type-III (MPS-III), a lysosomal storage disease. Biochemically there was a deficiency of heparan sulphamidase. All the heparan sulphate chains had non-reducing-end glucosamine-N-sulphate residues. CONCLUSION: The disease is MPS-IIIA (Sanfilippo syndrome). An autosomal recessive mode of inheritance can be provisionally assumed from the nature of this disease in other species. 相似文献
35.
CASE: An 11-year-old female domestic shorthaired cat presenting with clinical signs of depression, anorexia, weight loss, fever, anaemia and a mid-abdominal mass was referred for abdominal ultrasound examination. CLINICAL FINDINGS: Ultrasonography of the abdomen identified a markedly enlarged spleen. Ultrasound-guided fine-needle aspiration biopsy of the spleen revealed a uniform population of mast cells, 11% of which were observed to have phagocytosed erythrocytes. It is speculated that this may have been a contributing factor in the development of anaemia in this case. Mast cells were detected in a peripheral-blood smear and a diagnosis of systemic mastocytosis (splenic mast cell tumour together with mastocytaemia) was made. This diagnosis was subsequently confirmed by histopathology of the spleen. CONCLUSION: Splenectomy and treatment with corticosteroids appears to have resulted in remission of clinical signs and anaemia. A reduction in the concentration of mast cells in the peripheral blood had not occurred 6 weeks postsplenectomy, but was evident by 10 months post-splenectomy. 相似文献
36.
Allan FJ Pfeiffer DU Jones BR Esslemont DH Wiseman MS 《Preventive veterinary medicine》2000,46(3):183-196
This study was done to identify risk factors for obesity in an urban cat population in New Zealand. A door-to-door survey (conducted within the city limits of Palmerston North) obtained information on the diet, health and behaviour of 202 cats. One hundred and eighty-two of these cats were weighed and their back and leg lengths were measured. The interviewer's assessment of the body condition of each cat was the dependent variable used in this study. Variables that were identified as significant (p< or =0.1) following univariable analysis were grouped into one of the three models for stepwise logistic multiple regression (one each for cat characteristics, environmental and management variables and feeding variables). A combined logistic-regression analysis was performed on the significant variables identified from the three component models. In the combined model, only three variables were significant: the presence of dogs in a household (decreased odds of obesity), longer leg length and owners underestimating cats' body condition (both increased odds). 相似文献
37.
A 12-week-old, clinically normal Chihuahua was referred for investigation for a continuous heart murmur. Cardiac evaluation revealed an anatomically and haemodynamically typical left-to-right shunting patent ductus arteriosus. The continuous wave Doppler measurement of peak ductal jet velocity of 5.6 m/s was suggestive of a normal pulmonary to systemic arterial pressure ratio. The dog returned 16 days later with right heart failure and severe pulmonary hypertension. Marked reduction in left-to-right shunting was demonstrated and the ductal jet velocity had decreased to 2.5 m/s. Immediate ductus ligation, oxygen therapy before and after the operation, and administration of hydralazine failed to reduce pulmonary hypertension, and the dog was euthanased. Histopathological examination of the lung showed pulmonary necrotising arteritis with acute and chronic arterial lesions. Chronic pulmonary vascular changes related to high flow have been associated with altered nitric oxide and endothelin responses. These changes may be responsible for the acute onset of pulmonary hypertension due to relatively minor vascular insults in some human and veterinary patients with left-to-right shunts. The potential for acute progression supports the recommendations for early ductus ligation and the prognostic importance of detecting pulmonary hypertension presurgically in patent ductus arteriosus patients. 相似文献
38.
A strain of Pasteurella haemolytica biotype A serotype 1, which had been isolated from a pathologically-confirmed outbreak of bovine pneumonic pasteurellosis, was used successfully to reproduce the disease in conventional calves. The development of the various pathological features was studied at regular intervals following infection. The acute inflammatory reaction which had developed by day 2 after initial infection was characterised by flooding of the alveoli by oedema and neutrophils together with a mild degree of bronchiolar epithelial necrosis. This progressed to an acute exudative fibrinous pneumonia with extensive involvement of the interlobular septa and often with pleurisy. Subsequently, these pulmonary lesions became walled off by fibrous tissue which became infiltrated by plasma cells and lymphocytes. At this stage organisms could be demonstrated only within these nodules in the lung tissue. 相似文献
39.
Summary The receptivity of graft-polyacrolein on wood to hydroxylamine is discussed in terms of a geometric model for the voids and surfaces formed in wood by the swelling action of water. The receptivity of the carbonyl group of graft-polyacrolein varies inversely with the number of graft sites. This relationship is a consequence of decrease in the spacing between graft chains on the primary surface. The receptivity increases gradually with an increase in the amount of graft polymer, and this is a result of the swelling action of graft-polyacrolein which extends to the microscopically visible macropores of wood. 相似文献
40.