全文获取类型
收费全文 | 89675篇 |
免费 | 5584篇 |
国内免费 | 46篇 |
专业分类
林业 | 3735篇 |
农学 | 3466篇 |
基础科学 | 632篇 |
11245篇 | |
综合类 | 13526篇 |
农作物 | 3359篇 |
水产渔业 | 4936篇 |
畜牧兽医 | 47626篇 |
园艺 | 1165篇 |
植物保护 | 5615篇 |
出版年
2020年 | 732篇 |
2019年 | 953篇 |
2018年 | 1582篇 |
2017年 | 1845篇 |
2016年 | 1660篇 |
2015年 | 1404篇 |
2014年 | 1718篇 |
2013年 | 3716篇 |
2012年 | 2929篇 |
2011年 | 3587篇 |
2010年 | 2339篇 |
2009年 | 2329篇 |
2008年 | 3470篇 |
2007年 | 3208篇 |
2006年 | 3135篇 |
2005年 | 2668篇 |
2004年 | 2575篇 |
2003年 | 2591篇 |
2002年 | 2372篇 |
2001年 | 3389篇 |
2000年 | 3304篇 |
1999年 | 2553篇 |
1998年 | 983篇 |
1997年 | 1051篇 |
1996年 | 883篇 |
1995年 | 1022篇 |
1994年 | 895篇 |
1993年 | 896篇 |
1992年 | 1845篇 |
1991年 | 1919篇 |
1990年 | 1856篇 |
1989年 | 1859篇 |
1988年 | 1607篇 |
1987年 | 1594篇 |
1986年 | 1627篇 |
1985年 | 1526篇 |
1984年 | 1225篇 |
1983年 | 1032篇 |
1982年 | 713篇 |
1979年 | 1060篇 |
1978年 | 816篇 |
1975年 | 815篇 |
1974年 | 897篇 |
1973年 | 864篇 |
1972年 | 805篇 |
1971年 | 795篇 |
1970年 | 800篇 |
1969年 | 780篇 |
1968年 | 708篇 |
1967年 | 734篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study—A Randomized Clinical Trial 下载免费PDF全文
A. Boswood J. Häggström S.G. Gordon G. Wess R.L. Stepien M.A. Oyama B.W. Keene J. Bonagura K.A. MacDonald M. Patteson S. Smith P.R. Fox K. Sanderson R. Woolley V. Szatmári P. Menaut W.M. Church M. L. O'Sullivan J.‐P. Jaudon J.‐G. Kresken J. Rush K.A. Barrett S.L. Rosenthal A.B. Saunders I. Ljungvall M. Deinert E. Bomassi A.H. Estrada M.J. Fernandez Del Palacio N.S. Moise J.A. Abbott Y. Fujii A. Spier M.W. Luethy R.A. Santilli M. Uechi A. Tidholm P. Watson 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2016,30(6):1765-1779
992.
Influence of Breed Size,Age, Fecal Quality,and Enteropathogen Shedding on Fecal Calprotectin and Immunoglobulin A Concentrations in Puppies During the Weaning Period 下载免费PDF全文
993.
994.
The Influence of Pituitary Size on Outcome After Transsphenoidal Hypophysectomy in a Large Cohort of Dogs with Pituitary‐Dependent Hypercortisolism 下载免费PDF全文
995.
Australian Cattle Dogs with Neuronal Ceroid Lipofuscinosis are Homozygous for a CLN5 Nonsense Mutation Previously Identified in Border Collies 下载免费PDF全文
A. Kolicheski G.S. Johnson D.P. O'Brien T. Mhlanga‐Mutangadura D. Gilliam J. Guo T.D. Anderson‐Sieg R.D. Schnabel J.F. Taylor A. Lebowitz B. Swanson D. Hicks Z.E. Niman F.A. Wininger M.C. Carpentier M.L. Katz 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2016,30(4):1149-1158
996.
Kinematic Magnetic Resonance Imaging for Evaluation of Disc‐Associated Cervical Spondylomyelopathy in Doberman Pinschers 下载免费PDF全文
997.
998.
S. Li M. Johansson J. K. Vidanarachchi J. Pickova G. Zamaratskaia 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2016,66(4):199-205
The aim of this study was to develop a high-performance thin-layer chromatography densitometry method to simultaneously evaluate levels of different biogenic amines (BAs) in beef stored aerobically at 4°C. Steaks from M. longissimus thoracis et lumborum muscles were overwrapped with polyvinyl chloride film and stored for 0, 4, 7, and 10 days. For this purpose, the solvent system and pH for the derivatization of BAs with dansyl chloride were optimized. Moreover, this method was also validated for linearity, limits of detection and quantification, precision, and recovery. As found using this method in beef samples, spermine content decreased significantly after 7 days of storage, and tyramine and cadaverine were not detected until day 10. 相似文献
999.
M. Pettersson S. Eriksson 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2016,66(4):183-189
There is substantial international influence on the Swedish Warmblood (SWB) sport horse population. The SWB Association suspects that imported horses are pre-selected based on their anticipated performance level, which could lead to biased estimated breeding values (EBVs) for stallions. This study examined different strategies to handle records for imported horses in the genetic evaluation. The stallions were evaluated for 10 traits using 3 different EBV estimation methods that were compared based on ranking comparisons of stallions, accuracy, correlations and absolute differences between EBVs. The results showed that the stallions’ EBVs were affected by imported offspring which, as a group, had higher average scores than horses born in Sweden. Sire EBVs differed by up to 0.6 genetic standard deviation of the trait between methods for stallions with >50% imported offspring. Excluding imported offspring lowered the accuracies and caused larger re-ranking compared with including a fixed effect of origin in the model. 相似文献
1000.
M. Slagboom M. Kargo D. Edwards A. C. Sørensen J. R. Thomasen L. Hjortø 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2016,66(3):177-182
The aim of this study was to characterize preferences of farmers for breeding goal traits with Danish Red (DR) or Danish Jersey (DJ) cows. A breed-specific survey was established to characterize farmers’ preferences for improvements in 10 traits, by means of pairwise rankings using the online software 1000Minds. These pairwise rankings were based on equal economic worth of trait improvements. The DR survey was filled in by 87 farmers and the DJ survey by 76 farmers. Both DR and DJ farmers gave the highest preference to improvements in mastitis, and the lowest to calving difficulty. By means of a cluster analysis, three distinct clusters of farmers were identified per breed. Comparisons of herd characteristics between clusters suggest that farmers choose to improve traits that are problematic in their herds. This study shows that heterogeneity exists in farmers’ preferences for trait improvements and that herd characteristics influence these preferences in DR and DJ. 相似文献