全文获取类型
收费全文 | 3166篇 |
免费 | 251篇 |
国内免费 | 15篇 |
专业分类
林业 | 288篇 |
农学 | 126篇 |
基础科学 | 15篇 |
699篇 | |
综合类 | 181篇 |
农作物 | 140篇 |
水产渔业 | 368篇 |
畜牧兽医 | 1247篇 |
园艺 | 73篇 |
植物保护 | 295篇 |
出版年
2023年 | 35篇 |
2022年 | 52篇 |
2021年 | 90篇 |
2020年 | 100篇 |
2019年 | 87篇 |
2018年 | 171篇 |
2017年 | 158篇 |
2016年 | 165篇 |
2015年 | 104篇 |
2014年 | 160篇 |
2013年 | 217篇 |
2012年 | 266篇 |
2011年 | 241篇 |
2010年 | 135篇 |
2009年 | 123篇 |
2008年 | 160篇 |
2007年 | 172篇 |
2006年 | 162篇 |
2005年 | 134篇 |
2004年 | 112篇 |
2003年 | 101篇 |
2002年 | 100篇 |
2001年 | 60篇 |
2000年 | 35篇 |
1999年 | 43篇 |
1998年 | 16篇 |
1997年 | 17篇 |
1996年 | 8篇 |
1995年 | 21篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 17篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1975年 | 5篇 |
1973年 | 8篇 |
1970年 | 6篇 |
1969年 | 4篇 |
排序方式: 共有3432条查询结果,搜索用时 359 毫秒
61.
62.
There are very few resistance records on cattle nematodes. South American successive records have been increasing rapidly since the year 2000. In Argentina, increasing dissatisfaction based on the exclusive use of macrocyclic lactones has prompted the use of benzimidazoles in the Pampean region. The studied farm is located in the Argentina humid Pampas and had apparently poor results after anthelmintic treatments. Evaluation of resistance was firstly based on faecal egg reduction after treatment in November 2001 and June 2002 and was complemented with worm counts obtained by necropsy in June 2002. The study reports that the reduction of faecal egg excretion after benzimidazole (reduction 31-79%) or ivermectin treatments (76-97%) in November 2001 was insufficient and these poor results were confirmed in June 2002 (benzimidazoles (65-89%) and ivermectin (47-77%)). Several methods for evaluating faecal egg count reduction were performed and yielded different results. A new method based on the estimated faecal egg counts (corrected from the initial faecal egg counts and animal type using a general linear model) was used and gave higher flexibility in the interpretation of putative resistance to anthelmintics. From necropsy results, it could be concluded that Cooperia oncophora was resistant to avermectins and benzimidazoles and that Cooperia punctata, Ostertagia ostertagi and Haemonchus placei were resistant to benzimidazoles. This case of multispecies and multidrug resistance is probably not unique and could reflect the emergence of resistances in Argentina. This emergence is probably due to the intensive use of anthelmintics, the absence of refugia, and the frequent circulation of infected cattle. 相似文献
63.
64.
Núñez A McNeilly F Perea A Sánchez-Cordón PJ Huerta B Allan G Carrasco L 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2003,50(5):255-258
Routine histopathological diagnosis of one representative 3-month-old pig from a group suffering from diarrhoea revealed a massive degree of parasitation by Cryptosporidium parvum, with a concomitant infection by porcine circovirus type 2 (PCV2), that was confirmed by immunohistochemical procedures. The areas of intestine where parasites were more numerous presented abundant PCV2 infected cells in mucosa and submucosa. The concurrence of C. parvum, a rare primary intestinal pathogen in post-weaning and growing pigs, and PCV2 infections suggest an increased susceptibility as a result of an immunosuppression state. 相似文献
65.
This study was designed to investigate the presence of leptospiral antigens in kidney and liver of naturally infected cattle using an immunoperoxidase (IP) staining and Levaditi's staining methods. A total of 39 cattle suspected from leptospirosis were examined histologically and immunohistochemically for the presence of leptospiral antigens. The leptospiral antigens were detected in 16 out of 39 cases (seven kidneys, three livers, and six kidneys and livers) when IP staining method was used, whereas leptospiral antigens were detected in 6 out of 39 cases (four kidneys and two livers) when Levaditi's staining method was used. This study ascertained that IP staining was more sensitive method than Levaditi's staining method for demonstrating the presence of leptospirosis in cattle. 相似文献
66.
Lora-Michiels M Biller DS Olsen D Hoskinson JJ Kraft SL Jones JC 《Journal of the American Animal Hospital Association》2003,39(5):452-458
Diseases of the accessory lung lobe (AccLL) are often overlooked in dogs and cats, perhaps because of its recessed location. Diseases of this lobe also can mimic diseases of the diaphragm or structures comprising the caudal mediastinum. Normal anatomy of the AccLL and the diagnostic tools used today will be reviewed to help differentiate disease of adjacent organs. Four cases will also be described to illustrate disease presentation and radiographic findings affecting this lobe. 相似文献
67.
68.
Van Israël N French AT Dukes-McEwan J Corcoran BM 《The Journal of small animal practice》2002,43(9):395-400
The case records of 98 dogs with a left-to-right shunting patent ductus arteriosus (PDA) were reviewed. There were 35 breeds represented, with a female to male ratio of 3:1. Forty per cent of the dogs were older than one year at initial presentation and 31 per cent had clinical signs attributable to PDA. A left heart base continuous murmur of grade IV/VI or higher was noted in 90 per cent of the dogs. On electrocardiography, the most common abnormalities were tall R waves (63 per cent) and deep QII waves (62 per cent). The radiographic triad of dilation of the descending aorta with enlargement of the main pulmonary artery segment and left atrium, typical of PDA, was noted in only 26 per cent of cases. Two-dimensional (2D) and M-mode echocardiography detected left atrial enlargement (35 per cent) and an increased left ventricular diameter in diastole (82 per cent) and systole (84 per cent) as the most common abnormalities. Doppler echocardiography demonstrated increased aortic outflow velocities in 66 per cent of cases. The overall short-term successful outcome in this study was 95 per cent. There was no significant difference between surgical ductal ligation using a standard technique or the Jackson-Henderson technique in terms of survival, occurrence of haemorrhage or residual shunting. The number of interventional procedures used in this study was too low for statistical comparison, but there appeared to be a trend towards a higher rate of residual shunting and a lower fatality rate using a coil occlusion technique. 相似文献
69.
A two-month-old female Tibetan terrier was re-presented with an incomplete closure of the patent ductus arteriosus. Following a second attempt to close the shunt by coil embolisation, arterial embolisation occurred. The successful removal of the embolised coil is described. 相似文献
70.
Oral administration of yeast, Saccharomyces cerevisiae, enhances the cellular innate immune response of gilthead seabream (Sparus aurata L.) 总被引:3,自引:0,他引:3
Ortuño J Cuesta A Rodríguez A Esteban MA Meseguer J 《Veterinary immunology and immunopathology》2002,85(1-2):41-50
The effects of including lyophilised whole yeast, Saccharomyces cerevisiae, in the diet on the seabream innate immune response were investigated. Gilthead seabream (Sparus aurata L.) specimens were fed four different diets for 4 weeks: a commercial diet as control and the same diet supplemented with 1, 5 or 10 g/kg yeast. After 1, 2 and 4 weeks, serum complement titres, as a humoral parameter, and phagocytic, respiratory burst, myeloperoxidase and natural cytotoxic activities of head-kidney leucocytes, as cellular parameters, were evaluated. The results showed that yeast supplements enhanced all the latter responses, but not the humoral response. This enhancement was dose-dependent except for the cytotoxic activity that was only stimulated by the lower dose of yeast assayed. As yeast cell walls are able to enhance the seabream cellular innate immune response, these results support the possible use of whole yeast as natural inmunostimulants in common fish diets. 相似文献