全文获取类型
收费全文 | 335篇 |
免费 | 21篇 |
国内免费 | 1篇 |
专业分类
林业 | 21篇 |
农学 | 18篇 |
基础科学 | 6篇 |
47篇 | |
综合类 | 49篇 |
农作物 | 12篇 |
水产渔业 | 10篇 |
畜牧兽医 | 184篇 |
园艺 | 3篇 |
植物保护 | 7篇 |
出版年
2022年 | 3篇 |
2021年 | 8篇 |
2020年 | 7篇 |
2018年 | 8篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 13篇 |
2012年 | 13篇 |
2011年 | 17篇 |
2010年 | 14篇 |
2009年 | 7篇 |
2008年 | 11篇 |
2007年 | 20篇 |
2006年 | 18篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 10篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 11篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 9篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1970年 | 3篇 |
1968年 | 2篇 |
1961年 | 3篇 |
1929年 | 3篇 |
排序方式: 共有357条查询结果,搜索用时 15 毫秒
121.
Cows and heifers from 22 herds were used in a trial to determine the effect on milk yield of anthelmintic treatment given at calving. Alternate animals were treated with either fenbendazole suspension or a placebo. Cows given fenbendazole showed a mean reduction in milk yield of 221 kg in the subsequent lactation compared with the placebo-treated cows, a difference which was statistically significant. In heifers no significant effect of the treatment was found on milk yield. When looking at the pooled data from both cows and heifers, the reduction in milk yield of the fenbendazole-treated animals was 151 kg, which also was statistically significant. The results indicate that anthelmintic treatment of dairy cows cannot be generally recommended in Norway. 相似文献
122.
M J Coyne J H Burr T D Yule M J Harding D B Tresnan D McGavin 《The Veterinary record》2001,149(18):545-548
The necessity for cats to be vaccinated annually against common pathogens has been questioned because sarcomas have infrequently been reported at the injection site. However, with few exceptions, the duration of immunity induced by vaccination or infection is uncertain, and there may therefore be a risk associated with a decision not to revaccinate. This article reviews the information available about the duration of immunity induced by vaccination or infection in cats, and reveals many shortcomings that make blanket recommendations impossible. Each vaccine must be considered individually. 相似文献
123.
Two-dimensional ultrasound was used in combination with colour-coded and pulsed Doppler sonography to study the blood flow of the testes and prostate gland in a total of 30 male dogs. After detection of the vessels by colour-coded Doppler sonography, the blood flow patterns were determined by pulsed Doppler sonography measuring and describing the systolic and diastolic peak velocity (SPV, DPV), the end-diastolic velocity, the time-averaged maximum velocity (TAMAX), the pulsatility and resistance index, as well as the ratios of the systolic peak velocity and end-diastolic velocity and of the systolic and diastolic peak velocities. The blood flow of the testicular artery was measured within the pampiniform plexus and the marginal location. The prostatic blood supply was measured in the artery of the deferential duct (cranial), the prostatic artery outside (lateral) and within the gland (subcapsular). The physiological testicular flow pattern was monophasic with a high diastolic flow. Testes with neoplastic alterations showed a significant increase of SPV and TAMAX. The epididymal vessels could not be detected. Under physiological conditions the prostatic blood flow pattern was biphasic in the cranial and lateral location and monophasic in the subcapsular location. Benign prostatic hyperplasia was characterized by a significant increase of SPV, DPV and TAMAX. The results of the present investigation demonstrate that the colour-coded and pulsed Doppler sonography give additional valuable information which improves the andrological diagnostics in the dog. 相似文献
124.
125.
Mette Fertner Anette Boklund Nana Dupont Claes En?e Helle Stege Nils Toft 《Acta veterinaria Scandinavica》2015,57(1)
Background
Health, productivity and antimicrobial use in the production of pigs are expected to be interrelated to some extent. Previous studies on register-based data have investigated these correlations with a subsequent large variation residing at the farm level. In order to study such farm factors in more detail we designed an elaborate interview-guide. By in-depth interviews of farmers with well-managed 7–30 kg (weaner) productions we sought to describe a set of common key-factors characterizing their management practices. Identification of such common practices could be used in follow-up projects, investigating whether identified factors really are characteristic for good-practicing famers.Results
Eleven farms were selected for a farm visit and in-depth interview. Participating farms used less antimicrobials than the national median (8.2 animal daily doses/100 weaners/day), had a mortality below the national average (2.9%) and an average daily weight gain above the national average (443 g/day). Similarities were observed among participating farms, including the sectioning of farms, use of all-in-all-out procedures with subsequent cleaning, purchasing 7 kg weaners from only one source, as well as active participation in management by a committed farm owner. Most farmers had a specific point of focus in their management, and were convinced that this was the reason for their success. This included; feeding, treatment strategy, refurbishment of facilities and presence in the shed.Conclusion
According to register data, participating farms were alike; in the good league regarding use of antimicrobials, mortality and daily growth. However, on-farm interviews elucidated more heterogeneity among farmers than expected. Most of the farmers had a specific point of focus, which they considered to be crucial for their good results. These results indicate the importance of non-registerable factors, highlighting the value of qualitative study techniques in the understanding of human actions. Further studies on the effect of various farmer types are recommended. 相似文献126.
127.
128.
Hestbjerg H Nielsen KF Thrane U Elmholt S 《Journal of agricultural and food chemistry》2002,50(26):7593-7599
Fusarium culmorum and F. equiseti were characterized with regard to production of trichothecenes and other secondary metabolites. Results following growth on laboratory media are interpreted with the aim of increasing the understanding of fungal metabolism in the field environment. While trichothecene production was detected for 94 of 102 F. culmorum isolates, only 8 of 57 F. equiseti isolates were positive. Profiles of secondary metabolites were compared by following growth on yeast extract sucrose agar (YES), potato sucrose agar (PSA), and an agar medium, prepared from soil organic matter (SOM), which was included to simulate growth conditions in soil. SOM supported the production of chrysogine by F. culmorum. The two species utilized the media differently. F. culmorumproduced zearalenone (ZEA) on YES, whereas some F. equiseti isolates produced ZEA on PSA. Other F. equiseti isolates produced equisetin. These differences may reflect that F. culmorum depends on a pathogenic life style while F. equiseti has a more saprotrophic mode of existence. 相似文献
129.
C. E. Logsdon H. W. Poulsen John J. Adams J. W. Scannell C. W. Frutchey Robert Hickman T. C. Blackburn J L. Robinson E. L. Newdick Paul J. Eastman L. O. Weaver H. C. Moore A. G. Tolaas L. A. Yager P. J. Hoff C. A. Lyon W. M. Cranstoun J. T. Stovall K. H. Fernow F. W. McLaughlin R. C. Hastings C. F. Campbell John Noonan H. L. Bruer J. W. Scott S. F. Grubbs L. W. King H. M. Darling C. M. Rincker 《American Journal of Potato Research》1957,34(5):142-148
130.
Liselotte Rothmann Norup Tina S. Dalgaard Janne Pleidrup Anders Permin Torben W. Schou Gregers Jungersen Dorte R. Fink Helle R. Juul-Madsen 《Veterinary parasitology》2013,191(1-2):187-190
Increasingly large numbers of poultry are held in production systems with access to outdoor areas. In these systems intestinal helminths are found with flock prevalences of up to 100%. Helminth infections influence chicken health negatively, which is why the following investigation has been performed.In the present experiment, 20 chickens of two inbred chicken lines containing the major histocompatibility complex (MHC) haplotypes, B14 and R5, were inoculated with 500 embryonated Ascaridia galli eggs. The A. galli-specific IgG titres of serum samples and the excretion of A. galli eggs in chicken faeces were measured for a period of 81 weeks.The level of excreted A. galli eggs measured as eggs per gram chicken faeces (EPG) varied greatly between chickens in each line. Significant differences were found between the two lines and with the R5 chickens reaching the highest levels. Likewise, the A. galli-specific IgG titres in serum differed significantly between the two lines, and an inverse relationship between infection level (EPG) and antibody titres was found. Although this inverse relationship suggests that humoral immunity may be involved in protection against A. galli infection, the high antibody titres did not prevent continued infection. 相似文献